Border Gateway Protocol (BGP)

Border Gateway Protocol (BGP) exchanges routing information among neighboring routers in different Autonomous Systems (AS). Arista switches use BGP version 4+, incorporating the multiprotocol extensions defined by RFC 4760 so that BGP can carry both IPv4 and IPv6 routes simultaneously over a single BGP peering.

This section contains the following topics:

Arista switches support these BGP functions:

  • a single BGP instance.
  • simultaneous internal (iBGP) and external (eBGP) peering.
  • multiprotocol BGP.
  • BGP confederations.
  • BGP Selective Route Download.
  • BGP Route Reflection.

BGP Conceptual overview

BGP is a protocol that exchanges routing information among neighboring routers in different autonomous systems through TCP sessions.

BGP neighbors (peers) communicate through a TCP session on port 179. They are established by manual configuration commands (static peers) or by creating a peer group listen range and accepting incoming peering requests in that range (dynamic peers). Internal BGP (iBGP) peers operate within a single autonomous system (AS). External BGP (eBGP) peers operate between autonomous systems. Border routers are on AS boundaries and exchange information with other autonomous systems; the primary function of border routers is distributing routes. Internal routers do not distribute route updates that they receive.

BGP defines a state machine for establishing connections. BGP routers maintain a state variable for each peer-to-peer session to track connection status. The state machine consists of these states:

  • Idle: the router initializes BGP resources, refuses inbound BGP connection attempts, initiates a TCP connection to the peer, then transitions to the Connect state.
  • Connect: the router waits for the TCP connection to complete, then sends an OPEN message to the peer and transitions to the OpenSent state if successful. If unsuccessful, it sets the ConnectRetry timer and transitions to the Active state upon expiry.
  • Active: the router sets the ConnectRetry timer to zero and returns to the Connect state.
  • OpenSent: the router waits for an OPEN message from the peer. After receiving a valid message, it transitions to the OpenConfirm state.
  • OpenConfirm: the router waits for a keepalive message from its peer. If the message is received prior to a timeout expiry, the router transitions to the Established state. If the timeout expires or an error condition exists, the router transitions to the Idle state.
  • Established: peers exchange UPDATE messages about routes they advertise. If an UPDATE message contains an error, the router sends a NOTIFICATION message and transitions to the Idle state.

During established BGP sessions, routers exchange UPDATE messages about the destinations to which they offer connectivity. The route description includes the destination prefix, prefix length, autonomous systems in the path, the next hop, and information that affects the acceptance policy of the receiving router. UPDATE messages also list destinations to which the router no longer offers connectivity.

BGP detects and eliminates routing loops while making routing policy decisions by using the network topology as defined by AS paths and path attributes.

Configuring BGP

Configuring BGP Instances

Creating an Instance and Entering BGP Configuration Mode

The switch supports one BGP instance, which is associated with a specified autonomous system (AS). To other BGP peers, the AS number uniquely identifies the network to which the switch belongs. Arista switches support four-byte AS numbers as described in RFC 4893. Four-byte AS number capability is communicated to BGP peers in OPEN messages. When communicating with a BGP peer which does not support four-byte AS numbers, the switch will replace AS numbers greater than 65535 with the well-known two-byte AS number 23456 (also called AS_TRANS), and encode the actual four-byte AS numbers using the AS4_PATH attribute.

The switch must be in router-BGP configuration mode to run BGP configuration commands. The router bgp command places the switch in router-BGP configuration mode for creating a BGP instance if one was not previously created. BGP configuration commands apply globally to the BGP instance.

Example
  • This command places the switch in router-BGP configuration mode. It also creates a BGP instance in AS 50 if an instance was not previously created.

    switch(config)#router bgp 50
    switch(config-router-bgp)#

When a BGP instance exists, the router bgp command must include its autonomous system. Any attempt to create a second instance results in an error message.

Example
  • This command attempts to open a BGP instance with a different AS number from that of the existing instance. The switch displays an error and stays in global configuration mode.

    switch(config)#router bgp 100
    % BGP is already running with AS number 50
    switch(config)#

Configuring BGP in a VRF

IPv6 VRF support in eos allows application of a BGP configuration to a single VRF instance, overriding global commands. To apply VRF-specific BGP configuration, use the vrf command within router-BGP configuration mode to enter BGP VRF configuration mode. IPv6 BGP VRF configuration is performed in the VRF submode of the router-BGP configuration mode. This submode is also where a route distinguisher (RD) is configured for a VRF on switches running Ethernet VPN (EVPN): use the rd (Router-BGP VRF and VNI Configuration Modes) command to configure an RD for a VRF.

Examples
  • These commands place the switch in BGP VRF configuration mode for VRF “purple.” Commands issued in this mode will override global BGP configuration for the specified VRF instance.

    switch(config)#router bgp 1
    switch(config-router-bgp)#vrf purple
    switch(config-router-bgp)#
  • These commands activate IPv6 address-family support for the IPv6 neighbor 2001:0DB8:8c01::1 in VRF “purple.”

    switch(config-router-bgp-vrf-purple)#router-id 1.1.1.1
    switch(config-router-bgp-vrf-purple)#neighbor 2001:0DB8:8c01::1 remote-as 16
    switch(config-router-bgp-vrf-purple)#address-family ipv6
    switch(config-router-bgp-vrf-purple-af)#neighbor 2001:0DB8:8c01::1 activate
    switch(config-router-bgp-vrf-purple-af)#
  • This command configures a route distinguisher for VRF “purple.”

    switch(config-router-bgp-vrf-purple)#rd 530:12
    switch(config-router-bgp-vrf-purple)#

Configuring BGP Neighbors

Establishing BGP Neighbors

BGP neighbors, or peers, are established by configuration commands that initiate a TCP connection. BGP supports two types of neighbors:

  • Internal neighbors are in the same autonomous system.
  • External neighbors are in different autonomous systems.

BGP neighbors can be either static or dynamic:

  • Static neighbors are established by manually configuring the connection.
  • Dynamic neighbors are established by creating a listen range and accepting incoming connections from neighbors in that address range.

Static neighbors may belong to a static peer group, allowing them to be configured as a group. Configuration applied to an individual member of a static peer group overrides the group configuration for that peer. Dynamic neighbors must belong to a dynamic peer group, and can only be configured as a group.

Static BGP Neighbors

The neighbor remote-as command connects the switch with a peer, establishing a static neighbor.

Once established, a static neighbor may be added to an existing peer group. Any configuration applied to the peer group then is inherited by the neighbor, unless a conflicting configuration has been entered for that peer. Settings applied to a member of the peer group override group settings.

Note: To establish a BGP session, there must be an IPv4 router ID configured in the same VRF or at least one L3 interface with an IPv4 address in the same VRF. If the VRF contains no L3 interfaces with IPv4 addresses (for example, in an IPv6-only environment), configure an appropriate router ID using the router-id (BGP) command.
Example
  • These commands establish an internal BGP connection with the peer at 10.1.1.14.
    switch(config)#router bgp 50
    switch(config-router-bgp)#neighbor 10.1.1.14 remote-as 50
    switch(config-router-bgp)#
  • These commands establish an external BGP connection with the peer at 192.168.2.5.
    switch(config)#router bgp 50
    switch(config-router-bgp)#neighbor 192.168.2.5 remote-as 100
    switch(config-router-bgp)#
Dynamic BGP Neighbors

The bgp listen range command specifies a range of IPv4 addresses from which the switch will accept incoming dynamic BGP peering requests, and creates the named dynamic peer group to which those peers belong. Dynamic BGP neighbors are peers which have not been manually established, but are accepted into a dynamic peer group when the switch receives a peering request from them.

Dynamic peers cannot be configured individually, but inherit any configuration that is applied to the peer group to which they belong. Peering relationships with dynamic peers are terminated if the peer group is deleted.

Example
  • These commands create a peer group called “brazil” which accepts dynamic peering requests from the 192.168.2.0/24 subnet.
    switch(config)#router bgp 50
    switch(config-router-bgp)#bgp listen range 192.168.2.0/24 peer-group brazil remote-as 50
    switch(config-router-bgp)#
Displaying Neighbor Connections

The show ip bgp summary and show ip bgp neighbors commands display neighbor connection status.

Example
  • This command indicates the connection state with the peer at 192.168.2.5 is Estab (established). The peer is an external neighbor because it is in AS 100 and the local server is in AS 50.e
    switch#show ip bgp summary
    BGP summary information for VRF default
    BGP router identifier 192.168.104.2, local AS number 50
    Neighbor Status Codes: m - Under maintenance
    Neighbor VASMsgRcvdMsgSentInQ OutQUp/Down StatePfxRcd PfxAcc
    192.168.2.54100 19828100 03:11:31 Estab12 12
    switch#
Static BGP Peer Groups

A static BGP peer group is a collection of BGP neighbors which can be configured as a group. Once a static peer group is created, the group name can be used as a parameter in neighbor configuration commands, and the configuration will be applied to all members of the group. Neighbors added to the group will inherit any settings already created for the group. Static peer group members may also be configured individually, and the settings of an individual neighbor in the peer group override group settings for that neighbor.

When the default form of a BGP configuration command is entered for a member of a static peer group, the peer inherits that configuration from the peer group.

A static peer group is created with the neighbor peer group (create) command, or by using the bgp listen range command to accept dynamic peering requests. Once a static peer group has been created, static neighbors can be manually added to the group by using the neighbor peer-group (neighbor assignment) command. The no neighbor peer-group (neighbor assignment) command removes a neighbor from a static peer group.

The no neighbor peer group (create) command will delete a static peer group. When a peer group is deleted, the members of that group revert to their individual configurations, or to the system default for any attributes that have not been specifically configured for that peer.

Examples
  • These commands create a peer group named “akron.”
    switch(config)#router bgp 50
    switch(config-router-bgp)#neighbor akron peer-group
    switch(config-router-bgp)#
  • This command adds the neighbors at 1.1.1.1 and 2.2.2.2 to peer group “akron.”
    switch(config-router-bgp)#neighbor 1.1.1.1 peer-group akron
    switch(config-router-bgp)#neighbor 2.2.2.2 peer-group akron
    switch(config-router-bgp)#
  • These commands configure the members of peer group “akron,” but cause the neighbor at 1.1.1.1 to use the system default value for out-delay.
    switch(config-router-bgp)#neighbor akron remote-as 109
    switch(config-router-bgp)#neighbor akron out-delay 101
    switch(config-router-bgp)#neighbor akron maximum-routes 12000
    switch(config-router-bgp)#no neighbor 1.1.1.1 out-delay
    switch(config-router-bgp)#
Dynamic BGP Peer Groups

A dynamic BGP peer group is a collection of BGP neighbors in a specified address range which makes a peer request to the switch. Members of dynamic peer group are configured in groups and not as individuals. A dynamic peer group name is used as a parameter to apply the configuration across all the members in the group. Neighbors joining the group inherit any settings already created for the group.

The bgp listen range command is used to create a dynamic peer group. This command identifies the BGP peering request from a range of IP address, and names the dynamic peer group to which those peers belong to. The bgp listen range command can be configured to accept a peering request from a single AS number or to accept peer request from the range of AS numbers. To accept the request from the range of AS numbers use the peer filter option in the command as shown. If the peer filter referred by the bgp listen range command does not exist, or if the filter exists but has no match commands, it will accept any AS number.

Note: When a listen range command is modified, any existing dynamic neighbor that is already established will get reset.

To delete a dynamic peer group, use the no or default form of the bgp listen range command. All peering relationships with group members are terminated when the dynamic peer group is deleted.

Example
  • These commands create a dynamic peer group called “brazil” in a single AS, which accepts peering requests from the 192.0.2.0/24 subnet the single AS is 5.
    switch(config)#router bgp 1
    switch(config-router-bgp)#bgp listen range 192.0.2.0/24 peer-group brazil 
    remote-as 5
    switch(config-router-bgp)#
  • These commands create a dynamic peer group called “brazil” in a range of ASNs, which accepts peering requests from the 192.0.2.0/24 subnet. The range of AS numbers is defined by peer filter option.
    switch(config)#router bgp 1
    switch(config-router-bgp)#bgp listen range 192.0.2.0/24 peer-group brazil peer-filter group-1
    switch(config-router-bgp)#

The show ip bgp peer group command displays the source of a listen range’s remote AS number definition as shown.

switch(config-router-bgp)#show ip bgp peer-group
BGP peer-group is brazil
 BGP version 4
 Listen-range subnets:
VRF default:
192.0.2.0/24, remote AS 5
192.0.2.0/24, peer filter group1
switch(config-router-bgp)#

Peer Filter

A peer filter defines a set of rules to decide whether to accept or reject the incoming peer request based on the peer’s attributes. The peer filter is defined using a sequence number and a match statement, and supports one new match statement for matching against a range of BGP AS numbers. A peer filter is defined in peer filter configuration mode as shown. The peer filter command supports only matching AS ranges. Unlike route maps, peer filters do not support sets, continues or subroutines.

To delete a peer filter, use the no peer filter or default peer filter commands.

Example
  • These commands define a peer filter that accepts any AS number.
    switch(config)#peer-filter group1
    switch(config-peer-filter-group1)#10 match as-range 1-4294967295 result accept
    switch(config-peer-filter-group1)#
  • These commands define a peer filter that accepts any AS number between 65000 and 65100 (inclusive) except 65008 and 65009.
    switch(config)#peer-filter group2
    switch(config-peer-filter-group2)#10 match as-range 65008-65009 result reject
    switch(config-peer-filter-group2)#20 match as-range 65000-651000 result accept
    switch(config-peer-filter-group2)#
  • These commands define a peer filter that accepts 3 specific remote AS numbers.
    switch(config)#peer-filter group3
    switch(config-peer-filter-group3)#10 match as-range 65003 result accept
    switch(config-peer-filter-group3)#20 match as-range 65007 result accept
    switch(config-peer-filter-group3)#30 match as-range 65009 result accept
    switch(config-peer-filter-group3)#

The show peer-filter command displays the peer filter definition.

switch(config)#show ip bgp peer-group3
peer-filter group3
 10 match as-range 65003 result accept
 20 match as-range 65007 result accept
30 match as-range 65009 result accept
switch(config)#

Special Considerations for IPv6

BGP predates the use of IPv6, and BGP configuration assumes IPv4 connections by default. The following additional steps are used to configure IPv6 BGP neighbors.

Note: To establish a BGP session, there must be an IPv4 router ID configured in the same VRF or at least one L3 interface with an IPv4 address in the same VRF. If the VRF contains no L3 interfaces with IPv4 addresses (e.g., in an IPv6-only environment), configure an appropriate router ID using the router-id (BGP) command.
Activating IPv6 Neighbors

By default, the switch does not negotiate or advertise IPv6 BGP routes. In order to establish a session with an IPv6 neighbor, it must be made active in the IPv6 address family. The ipv6-unicast option of the bgp default command causes the switch to send IPv6 capability messages and all network advertisements with IPv6 prefixes to all BGP neighbors. The neighbor activate command issued in IPv6 address family configuration mode does the same for a single BGP neighbor.

Examples
  • These commands make all BGP neighbors active in the IPv6 address family.
    switch(config)#router bgp 11
    switch(config)#address-family ipv6
    switch(config-router-bgp-af)#bgp default ipv6-unicast
    switch(config-router-bgp-af)#exit
    switch(config-router-bgp)#
  • These commands make the BGP neighbor at 2001:0DB8:8c01::1 active in the IPv6 address family.
    switch(config)#router bgp 11
    switch(config)#address-family ipv6
    switch(config-router-bgp-af)#neighbor 2001:0DB8:8c01::1 activate
    switch(config-router-bgp-af)#exit
    switch(config-router-bgp)#
Sending IPv4 NLRIs over IPv6 Connections

The switch supports the exchange of IPv4 NLRIs with IPv6 neighbors. To enable this feature for all IPv6 neighbors, use the ipv4-unicast transport ipv6 option of the bgp default command in IPv4 address family configuration mode. To enable it for a single IPv6 neighbor, use the neighbor activate command for that neighbor in IPv4 address family configuration mode.

To send IPv4 NLRIs to IPv6 neighbors, the IPv4 next-hop address must also be communicated. To explicitly configure an IPv4 next hop to send to a specific IPv6 neighbor, use the neighbor local-v4-addr command. In some network configurations, the switch can also be configured to automatically determine the best IPv4 next-hop address for an individual IPv6 neighbor or for all neighbors in the VRF using the neighbor auto-local-addr command.

Examples
  • These commands permit IPv4 NLRI transport over all IPv6 connections by making the IPv4 address family active on IPv6 BGP neighbors, then configure the switch to automatically select a local IPv4 address to be sent in NLRIs to the IPv6 neighbors in a peer group called “indianapolis.”
    switch(config)#router bgp 11
    switch(config-router-bgp)#address-family ipv4
    switch(config-router-bgp-af)#bgp default ipv4-unicast transport ipv6
    switch(config-router-bgp-af)#exit
    switch(config-router-bgp)#neighbor indianapolis auto-local-addr
    switch(config-router-bgp)#
  • These commands permit IPv4 NLRI transport with the IPv6 neighbor at 2001:0DB8:8c01::1 using a local IPv4 address of 10.7.5.11.
    switch(config)#router bgp 11
    switch(config-router-bgp)#address-family ipv4
    switch(config-router-bgp-af)#neighbor 2001:0DB8:8c01::1 activate
    switch(config-router-bgp-af)#exit
    switch(config-router-bgp)#neighbor 2001:0DB8:8c01::1 local-v4-addr 10.7.5.11
    switch(config-router-bgp)#

Maintaining Neighbor Connections

BGP neighbors maintain connections by exchanging KEEPALIVE, UPDATE, and NOTIFICATION messages. Neighbors that do not receive a message from a peer within a specified period (hold time) close the BGP session with that peer. Hold time is typically three times the period between scheduled KEEPALIVE messages. The default keepalive period is 60 seconds; default hold time is 180 seconds.

The timers bgp command configures the hold time and keepalive period. A peer retains its BGP connections indefinitely when its hold time is zero.

Example
  • This command sets the keepalive period to 15 seconds and the hold time to 45 seconds.
    switch(config-router-bgp)#timers bgp 15 45
    switch(config-router-bgp)#

The show ip bgp neighbors command displays the hold time.

Example
  • This command indicates the BGP hold time is 45 seconds.
    switch#show ip bgp neighbors 10.100.100.2
    BGP neighbor is 10.100.100.2, remote AS 100
    BGP version 4, remote router ID 192.168.100.13, VRF default
    Negotiated BGP version 4
    Last read 00:00:05, last write 00:00:05
    Hold time is 45, keepalive interval is 15 seconds <= hold time
    Configured hold time is 45, keepalive interval is 15 seconds
    Connect timer is inactive
    Idle-restart timer is inactive
    BGP state is Established, up for 04:44:05
    Number of transitions to established: 11
    Last state was OpenConfirm
    Last event was RecvKeepAlive
    Last sent notification:Cease/administrative reset, Last time 04:44:09
    Last rcvd notification:Cease/peer de-configured, Last time2d02h, First time 7d08h, Repeats 1
    Neighbor Capabilities:
    Multiprotocol IPv4 Unicast: advertised and received and negotiated
    Four Octet ASN: advertised and received
     <-------OUTPUT OMITTED FROM EXAMPLE------->
    switch#

Neighbor Route Configuration

Maximum Routes

The neighbor maximum-routes command determines the number of BGP routes the switch accepts from a specified neighbor. The switch disables peering with the neighbor when this number is exceeded.

Example
  • This command configures the switch to accept 15,000 routes from the peer at 192.168.18.24.
    switch(config-router-bgp)#neighbor 192.168.18.24 maximum-routes 15000
    switch(config-router-bgp)#
Route Reflection

Participating BGP routers within an AS communicate eBGP-learned routes to all of their peers; they do not re-advertise iBGP-learned routes within the AS to prevent routing loops. Although a fully meshed network topology ensures that all AS members share routing information, this topology can result in high volumes of iBGP messages when scaled. Alternatively, one or more routers are configured as route reflectors in larger networks.

A route reflector re-advertises routes learned through iBGP to a group of BGP neighbors within the AS, replacing the function of a fully meshed topology. The neighbor route-reflector-client command configures the switch to act as a route reflector and configures the specified neighbor as a client. The bgp client-to-client reflection command enables client-to-client reflection.

When using route reflectors, an AS is divided into clusters. A cluster contains at least one route reflector and a group of clients to which they re-advertise route information. A cluster may contain multiple route reflectors to provide redundancy protection. Each reflector has a cluster ID. When the cluster has a single route reflector, the cluster ID is its router ID. When a cluster has multiple route reflectors, a 4-byte cluster ID is assigned to all route reflectors in the cluster, allowing them to recognize updates from other cluster reflectors. The bgp cluster-id command configures the cluster ID in a cluster with multiple route reflectors.

Example
  • These commands configure the switch as a route reflector and the neighbor at 172.72.14.5 as one of its clients, and set the cluster ID to 172.22.30.101.
    switch(config-router-bgp)#neighbor 172.72.14.5 route-reflector-client
    switch(config-router-bgp)#bgp cluster-id 172.22.30.101
    switch(config-router-bgp)#

Usually the clients of a route reflector are not interconnected, and any routes learned by a client are mirrored to other clients and re-advertised within the AS by the route reflector. If the clients of a route reflector are fully meshed, routes received from a client do not need to be mirrored to other clients. In this case, client-to-client reflection should be disabled (no bgp client-to-client reflection).

Route Preference

The primary function of external peers is to distribute routes they learn from their peers. Internal peers receive route updates without distributing them. External peers receive route updates, then distribute them to internal and external peers.

Local preference is a metric that iBGP sessions use to select an external route. Preferred routes have the highest local preference value. UPDATE packets include this metric in the LOCAL_PREF field.

The neighbor export-localpref command specifies the LOCAL_PREF that the switch sends to an internal peer. The command overrides previously assigned preferences and has no effect on external peers.

Example
  • This command configures the switch to enter 200 in the LOCAL_PREF field of UPDATE packets it sends to the peer at 10.1.1.45.
    switch(config-router-bgp)#neighbor 10.1.1.45 export-localpref 200
    switch(config-router-bgp)#

The neighbor import-localpref command assigns a local preference to routes received through UPDATE packets from an external peer. This command has no effect when the neighbor is an internal peer.

Example
  • This command configures the switch to assign the local preference of 50 for routes advertised from the peer at 172.16.5.2.
    switch(config-router-bgp)#neighbor 172.16.5.2 import-localpref 50
    switch(config-router-bgp)#

The show ip bgp command displays the LOCAL_PREF value for all listed routes.

Example
  • This command indicates the route to network 10.10.20.0/24 has a local preference of 400.
    switch#show ip bgp
    BGP routing table information for VRF default
    Router identifier 192.168.100.23, local AS number 64512
    Route status codes: s - suppressed, * - valid, > - active, # - not installed, E - ECMP head, e - ECMP S - Stale, c - Contributing to ECMP, b - backup, L - labeled-unicast
    Origin codes: i - IGP, e - EGP, ? - incomplete
    AS Path Attributes: Or-ID - Originator ID, C-LST - Cluster List, LL Nexthop - Link Local Nexthop
    
    Network Next Hop MetricLocPref WeightPath
     * >Ec 10.10.20.0/24192.168.31.3 0 400 0 64521 i
    switch#
Graceful Restart

Graceful BGP restart allows a BGP speaker with separate control plane and data plane processing to continue forwarding traffic during a BGP restart. Its neighbors (receiving speakers) may retain routing information from the restarting speaker while a BGP session with it is being re-established, reducing route flapping.

Arista switches can act as helpers (receiving speakers) for graceful BGP restart with neighbors that advertise graceful restart capability.

Graceful restart helper mode is enabled by default, but can be turned off globally with the no graceful-restart-helper command. Per-peer configuration takes precedence over the global configuration.

Examples
  • This command disables graceful restart helper mode for all BGP peers.
    switch(config-router-bgp)#no graceful-restart-helper
    switch(config-router-bgp)#
  • This command disables graceful restart helper mode for the neighbor at 192.168.32.5 regardless of global configuration.
    switch(config-router-bgp)#no neighbor 192.168.32.5 graceful-restart-helper
    switch(config-router-bgp)#

Peers with graceful restart capability advertise a restart time value as an estimate of the time it will take them to restart a BGP session. When a BGP session with a restarting speaker goes down, the switch (receiving speaker) marks routes from that peer as stale and starts the restart timer. If the session with the peer is not re-established before the restart time runs out, the switch deletes the stale routes from that peer. If the session is re-established within that time, the stale path timer is started. If the stale paths are not updated by the restarting speaker before the stale path time runs out, they are deleted. The maximum time these stale paths will be retained after the BGP session is re-established is 300 seconds by default, but can be configured using the graceful-restart stalepath-time command.

Example
  • This command configures BGP to discard stale paths from a restarting peer 500 seconds after the BGP session with that peer is re-established.
    switch(config-router-bgp)#graceful-restart stalepath-time 500
    switch(config-router-bgp)#

Filtering Routes

Filtering with Route Maps

Route maps are used in BGP to directly filter IPv4 unicast routes. The neighbor route-map (BGP) command applies a route map to inbound or outbound BGP routes. To display the route maps associated with a specific BGP neighbor, use the show ip bgp neighbors command.

Filtering with BGP Communities

Community values are assigned to a set of subnet prefixes through route map set commands. Route map match commands subsequently use community values to filter routes. The switch uses the following ip community-list commands to filter community routes into a BGP domain:

  • ip community-list creates a community list by explicitly referencing one or more communities by name or number.
  • ip community-list regexp creates a community list by referencing one or more communities by regular expression.
  • ip extcommunity-list creates an extended community list to identify routes for VRFs or for link bandwidth (LBW) by explicitly referencing extended communities by prefix and number.
  • ip extcommunity-list regexp creates an extended community list to identify routes for VRFs or for link bandwidth (LBW) by regular expression.

The BGP community attribute is a 32 bit value formatted as follows:

  • an integer between 0 and 4294967040.
  • AA:NN, where AA is 65535 and NN specifies the community number (0-65535) within the AS.

These four community attribute values, and the associated BGP speaker actions, are predefined:

  • no-export: speaker does not advertise the routes beyond the BGP domain.
  • no-advertise: speaker does not advertise the routes to any BGP peers.
  • local-as: speaker does not advertise route to any external peers.
  • internet: speaker advertises the route to the Internet community. By default, this includes all prefixes.

Example

  • These commands assign two network subnets to a prefix list, assign a community number to the prefix list members, then utilize that community in an ip community-list command to permit the routes into the BGP domain.
  1. Compose the IP prefix list.
    switch(config)#ip prefix-list PL_1 permit 10.1.2.5/24
    switch(config)#ip prefix-list PL_1 permit 10.2.5.1/28
    switch(config)#
  2. Create a route map that matches the IP prefix list and sets the community value.
    switch(config)#route-map MAP_1 permit
    switch(config-route-map-MAP_1)#match ip address prefix-list PL_1
    switch(config-route-map-MAP_1)#set community 500
    switch(config-route-map-MAP_1)#exit
    switch(config)#
  3. Create a community list that references the community.
    switch(config)#ip community-list CL_1 permit 500
    switch(config)#

BGP extended communities identify routes for VRFs or for link bandwidth (LBW). Extended community clauses utilize route target (rt) and site of origin options (soo):

  • route targets identify sites that may receive appropriately tagged routes.
  • site of origin identifies the site where the router learned the route.
Filtering with AS Path Access Lists

An AS path access list is a named list of permit and deny statements which use regular expressions to filter BGP routes based on their AS path attribute. AS path access lists are created using the ip as-path access-list command, and are applied using a route map match clause with the name of the access list as a parameter.

Example

  • These commands create an AS path access list identifying routes which pass through AS 3, create a route map which references the access list, assign the routes it filters to community 300, and apply the route map to the neighbor at 192.68.14.5 to assign a community value of 300 to inbound routes received from that neighbor.
  1. Create the AS path access list.
    switch(config)#ip as-path access-list as_list3 permit _3_
  2. Create a route map that matches the AS path access list and sets the community value.
    switch(config)#route-map MAP_3 permit
    switch(config-route-map-MAP_3)#match as-path as_list3
    switch(config-route-map-MAP_3)#set community 300
    switch(config-route-map-MAP_3)#exit
  3. Apply the route map to the neighbor.
    switch(config)#router bgp 1
    switch(config-router-bgp)#neighbor 192.68.14.5 route-map MAP_3 in
    switch(config-router-bgp)#

Configuring GTSM for BGP

The Generalized TTL Security Mechanism (GTSM) uses a packet's Time to Live (TTL) (IPv4) or Hop Limit (IPv6) to protect BGP peering sessions from denial-of-service (DoS) attacks based on forged protocol packets.

An IP packet received from a BGP peer is discarded when its current TTL value is less than (255-n) where n is the configured maximum number of hops to the peer. Use the neighbor ttl maximum-hops command to configure the maximum hop count.

Note: IP packets to GTSM enabled BGP peers are sent with the configured TTL value of 255.

Configuring Routes

Advertising Routes

A BGP neighbor advertises routes it can reach through UPDATE packets. The network (BGP) command specifies a prefix that the switch advertises as a route originating from its AS.

The configuration clears the host portion of addresses entered in network commands. For example, 192.0.2.4/24 is stored as 192.0.2.0/24.

Example
  • This command configures the switch to advertise the 10.5.8.0/24 network.
    switch(config-router-bgp)#network 10.5.8.0/24
    switch(config-router-bgp)#

By default, BGP will advertise only those routes that are active in the switch’s RIB. This can contribute to dropped traffic. If a preferred route is available through another protocol (like OSPF), the BGP route will become inactive and not be advertised; if the preferred route is lost, there is no available route to the affected peers. Advertising inactive BGP routes minimizes traffic loss by providing alternative routes.

The bgp advertise-inactive command causes BGP to advertise inactive routes to BGP neighbors. Inactive route advertisement is configured globally, but the global setting can be overridden on a per-VRF basis.

Examples
  • This command configures the switch to advertise routes learned through BGP even if they are not active on the switch.
    switch(config-router-bgp)#bgp advertise-inactive
    switch(config-router-bgp)#
  • This command overrides inactive route advertisement for VRF “purple.”
    switch(config-router-bgp)#vrf purple
    switch(config-router-bgp-vrf-purple)#no bgp advertise-inactive
    switch(config-router-bgp-vrf-purple)#

Advertising ISIS Routes into BGP Network

The redistribute isis route-map isis-to-bgp command advertises the routes learned through IS-IS routes into the BGP network. It also allows the user to selectively advertise some routes and modify route attributes before advertising using route maps.

The command is available in both address-family mode and router BGP mode, but the command is rejected if configured in both address-family mode and router mode at the same time.

While redistributing IS-IS routes into BGP, the Level-1 or Level-2 keyword can be used to selectively redistribute Level-1 routes or Level-2 routes into BGP. The keyword is optional, and defaults to level-2 when not configured.

Use the show ipv6 bgp detail command to verify that routes are advertised with correct attributes.

Note: If the command is configured in router-af mode, it only redistributes routes with matching address family. If it is configured in router mode, it applies to all enabled address-families.
Examples
  • These commands redistribute IS-IS routes into BGP in address-family mode.
    switch(config)#router bgp 1
    switch(config-router-bgp)#address-family ipv4
    switch(config-router-bgp-af)#redistribute isis level-1 route-map isis-to-bgp-v4
    switch(config-router-bgp-af)#
  • These commands redistribute IS-IS routes into BGP in router BGP mode.
    switch(config)#router bgp 1
    switch(config-router-bgp)#redistribute isis level-1 route-map isis-to-bgp
    switch(config-router-bgp)#

BGP Route Aggregation

Aggregation combines the characteristics of multiple routes into a single route for advertisement by the BGP speaker. Aggregation can reduce the amount of information that a BGP speaker is required to store and transmit when advertising routes to other BGP speakers. Aggregation options affect the attributes associated with the aggregated route, the advertisement of the contributor routes that comprise the aggregate, and which contributor routes are included.

Aggregate routes are created with the aggregate-address command, which takes an IP subnet as an argument; any routes configured on the switch that lie within that subnet then become contributors to the aggregate. Note that on Arista switches the BGP aggregate route will become active if there are any available contributor routes on the switch, regardless of the originating protocol. This includes routes configured statically.

BGP speakers display aggregate routes that they create as null routes (with one exception: if all the contributors to the aggregate have the same BGP path attributes, then the BGP aggregate copies those attributes and is no longer a null route). Aggregate routes are advertised into the BGP autonomous system and redistributed automatically, and their redistribution cannot be disabled. BGP neighbors display inbound aggregate routes as normal BGP routes. Null routes are displayed with the show ip route command; normal BGP routes (and null aggregate routes) are displayed with the show ip bgp and show ip route commands.

Aggregation Options

The aggregate-address command provides the following aggregate route options:

  • AS_PATH attribute inclusion: the as-set option controls the aggregate route’s AS_PATH and ATOMIC_AGGREGATE attribute contents. AS_PATH identifies the autonomous systems through which UPDATE message routing information passes. ATOMIC_AGGREGATE indicates that the route is an aggregate or summary of more specific routes.

    When the command includes as-set, the aggregate route’s AS_SET attribute contains the AS numbers of contributor routes. This can help BGP neighbors to prevent loops by rejecting aggregate routes that include their AS number in the AS_SET.

    When the command does not include as-set, the aggregate route’s ATOMIC_AGGREGATE attribute is set and the AS_PATH attribute does not include AS numbers of contributing routes.

  • Attribute assignment: the attribute-map option assigns attributes contained in set commands in a specified route map’s lowest sequence with any set command to the aggregated route, overriding the automatic determination of the aggregate route’s attributes by the switch.
  • Route suppression: the summary-only option suppresses the advertisement of the contributor routes that comprise the aggregate.
  • Contributor filtering: the match-map option uses a route map to filter out contributor routes that would otherwise be included in the aggregate.
Example
  • These commands create an aggregate route (10.16.48.0/20) from four contributor routes (10.16.48.0/23, 10.16.50.0/23, 10.16.52.0/23, and 10.16.54.0/23). The aggregate route includes the AS_PATH information from the contributor routes.
    switch(config)#router bgp 1
    switch(config-router-bgp)#aggregate-address 10.16.48.0/20 as-set
    switch(config-router-bgp)#exit
    switch(config)#
  • These commands create an aggregate route and use a route map to add a local-preference attribute to the route.
    switch(config)#route-map map1 permit 10
    switch(config-route-map-map1)#set local-preference 40
    switch(config-route-map-map1)#exit
    switch(config)#router bgp 1
    switch(config-router-bgp)#aggregate-address 10.16.48.0/20 attribute-map map1
    switch(config-router-bgp)#exit
    switch(config)#
  • These commands create an aggregate route and use a route map to allow only those contributors which match a specified prefix list to be included in the aggregate route.
    switch(config)#route-map matchmap permit 10
    switch(config-route-map-matchmap)#match ip address prefix-list agglist
    switch(config-route-map-matchmap)#exit
    switch(config)#router bgp 1
    switch(config-router-bgp)#aggregate-address 1.1.0.0/16 match-map matchmap
    switch(config-router-bgp)#

Customizing the BGP AS-Path Attribute

The BGP Replace AS-Path feature allows the user to customize the AS_PATH attribute for prefixes that are either received from a BGP neighbor or advertised to a BGP neighbor. To configure the BGP Replace AS-Path feature, use the set as-path match and set as-path prepend commands.

To replace the AS_PATH attribute of routes received from a BGP neighbor, configure a route map and attach the policy to the corresponding BGP neighbor statement in the inbound direction.

To replace the AS_PATH attribute of routes that are advertised to a neighbor, configure a route map and attach the policy to the corresponding BGP neighbor statement in the outbound direction.

The Replace AS-Path feature works in conjunction with the AS-Path Prepend feature which is also used to modify the AS_PATH attribute. However, if both features are configured within the same route map, then the replace AS-Path feature takes precedence over the AS-Path Prepend.

Note: The BGP Replace AS-Path feature supports both eBGP and iBGP neighbors. The locally configured AS number is always prefixed to the AS-Path of routes advertised to the eBGP neighbors. This RFC behavior is retained in Arista’s implementation of the Replace AS-Path feature as well.

BGP Replace AS-Path has the following limitations:

  • Replacing the AS-Path should be used cautiously since it may impact BGP loop prevention.
  • A few duplicated routes may be advertised and installed on a router after the original AS-Path of those routes are replaced.To fix this issue, it is always suggested to filter out such routes by prefix with BGP Community.
Example
  • This command replaces the AS-Path with the none option.
    switch#show ip bgp neighbors 80.80.1.2 advertised-routes
    BGP routing table information for VRF default
    Router identifier 202.202.1.1, local AS number 200
    Route status codes: s - suppressed, * - valid, > - active, # - not installed, E 
    - ECMP head, e - ECMP
    S - Stale, c - Contributing to ECMP, b - backup, L - labeled-unicast, q - Queued 
    for advertisement
    Origin codes: i - IGP, e - EGP, ? - incomplete
    AS Path Attributes: Or-ID - Originator ID, C-LST - Cluster List, LL Nexthop - 
    Link Local Nexthop
    
    NetworkNext Hop MetricLocPref Weight Path
    * > 101.101.1.0/24 80.80.1.1- - -200 i
    * > 102.102.1.0/24 80.80.1.1- - -200 i
    * > 103.103.1.0/24 80.80.1.1- - -200 302 i
    * > 202.202.1.0/24 80.80.1.1- - -s200 i
    switch#configuration terminal
    switch(config)#route-map foo permit 10
    switch(config-route-map-foo)#set as-path match all replacement none
    switch(config-route-map-foo)#exit
    switch(config)#router bgp 200
    switch(config-router-bgp)#neighbor 80.80.1.2 route-map foo out
    switch(config-router-bgp)#end
    switch#show ip bgp neighbors 80.80.1.2 advertised-routes
    BGP routing table information for VRF default
    Router identifier 202.202.1.1, local AS number 200
    Route status codes: s - suppressed, * - valid, > - active, # - not installed, E 
    - ECMP head, e - ECMP
    S - Stale, c - Contributing to ECMP, b - backup, L - labeled-unicast, q - Queued 
    for advertisement
    Origin codes: i - IGP, e - EGP, ? - incomplete
    AS Path Attributes: Or-ID - Originator ID, C-LST - Cluster List, LL Nexthop - 
    Link Local Nexthop
    
    NetworkNext Hop MetricLocPref Weight Path
    * > 101.101.1.0/24 80.80.1.1- - -200 i
    * > 102.102.1.0/24 80.80.1.1- - -200 i
    * > 103.103.1.0/24 80.80.1.1- - -200 i
    * > 202.202.1.0/24 80.80.1.1- - -200 i
    switch#

The AS-Path of matching prefixes are replaced with an empty or a null AS-Path. AS 302 is removed from prefix 103.103.1.0/24 as shown in the above output.

  • This command replaces the AS-Path with the auto option.
    switch(config)#route-map foo permit 10
    switch(config-route-map-foo)#set as-path match all replacement auto
    switch(config-route-map-foo)#end
    switch#show ip bgp neighbors 80.80.1.2 advertised-routes
    BGP routing table information for VRF default
    Router identifier 202.202.1.1, local AS number 200
    Route status codes: s - suppressed, * - valid, > - active, # - not installed, E 
    - ECMP head, e - ECMP
    S - Stale, c - Contributing to ECMP, b - backup, L - labeled-unicast, q - Queued 
    for advertisement
    Origin codes: i - IGP, e - EGP, ? - incomplete
    AS Path Attributes: Or-ID - Originator ID, C-LST - Cluster List, LL Nexthop - 
    Link Local Nexthop
    
    NetworkNext Hop MetricLocPref Weight Path
    * > 101.101.1.0/24 80.80.1.1- - -200 200 i
    * > 102.102.1.0/24 80.80.1.1- - -200 200 i
    * > 103.103.1.0/24 80.80.1.1- - -200 200 i
    * > 202.202.1.0/24 80.80.1.1- - -200 200 i
    switch#

The AS-path of matching prefixes are replaced with the locally configured AS 200.

AS-path Modifications for Split ASes

By default, BGP rejects routes that contain the local autonomous system number (ASN). Sometimes a single autonomous system is divided geographically or otherwise with one or more provider ASes in between. In these cases, a valid route can sometimes be dropped by a customer edge router because the local ASN appears in the AS-path of route advertisements that have traveled through one or more provider networks. To ensure that these routes are not dropped, the provider edge router can be configured to replace the customer AS with its own, or the customer edge router can be configured to ignore its local AS number in received routes.

Replacing Remote ASN in Outbound Route Announcements

To replace a remote ASN with the local ASN in BGP route announcements sent to a specified router, use the neighbor as-path remote-as replace out command.

Example
  • These commands configure the switch to substitute its local ASN for the ASN of the BGP neighbor at 192.168.2.15 in BGP routes advertised to that neighbor.
    switch(config)#router bgp 1
    switch(config-router-bgp)#neighbor 192.168.2.15 as-path remote-as replace out
    switch(config-router-bgp)#
Ignoring Local ASN in Incoming Route Announcements

To accept BGP routes that include the local ASN in their AS-path attribute, use the neighbor allowas-in command.

Example
  • These commands configure the switch to accept routes from the BGP neighbor at 192.168.1.30 which contain the switch’s ASN in their AS paths as many as 3 times.
    switch(config)#router bgp 1
    switch(config-router-bgp)#neighbor 192.168.1.30 allowas-in
    switch(config-router-bgp)#

Configuring Address Families

The switch determines the network prefixes that peering sessions advertise and the BGP neighbor addresses that receive advertisements through address family activity configuration.

An address family is a data structure that defines route advertising status to BGP neighbor addresses. Each BGP neighbor address is assigned an activity level for each address family on the switch. The switch sends capability and network prefix advertisements to neighbor addresses that are active within specified address families:

  • IPv4 address family: switch advertises IPv4 capability and network commands with IPv4 prefixes to neighbor addresses configured as IPv4 address family active.
  • IPv6 address family: switch advertises IPv6 capability and network commands with IPv6 prefixes to neighbor addresses configured as IPv6 address family active.

Neighbor Address Family Configuration

Address family activity levels for neighbor addresses are configured through bgp default and neighbor activate commands.

  • The bgp default command specifies the default activity level of BGP neighbor addresses for a specified address family.
  • The neighbor activate command specifies deviations from default address family activity level for a specified BGP neighbor address.
Default Neighbor Activation

The bgp default command configures the default address family activity level of all configured BGP neighbor addresses. The switch advertises the following to address family active addresses:

  • IPv4 address family active: IPv4 capability and all network advertisements with IPv4 prefixes.
  • IPv6 address family active: IPv6 capability and all network advertisements with IPv6 prefixes.

These commands configure default address family activity levels for configured BGP neighbor addresses:

  • bgp default ipv4-unicast: all BGP neighbor addresses are IPv4 address family active (this is the switch default).
  • no bgp default ipv4-unicast: no BGP neighbor addresses are IPv4 address family active.
  • bgp default ipv6-unicast: all BGP neighbor addresses are IPv6 address family active.
  • no bgp default ipv6-unicast: no BGP neighbor addresses are IPv6 address family active (this is the switch default).
  • bgp default ipv4-unicast transport ipv6: all BGP neighbor addresses are IPv4 address family active and IPv6 neighbors can receive IPv4 NLRIs.
    Note: If it is necessary to exchange IPv4 NLRIs over an IPv6 connection, the IPv4 address family must be activated on the IPv6 neighbor. To do this for all IPv6 neighbors, use the command bgp default ipv4-unicast transport ipv6. For an individual neighbor, use the neighbor activate command for the IPv6 neighbor in the IPv4 address-family configuration mode as described below.
Activating Individual Neighbor Addresses

The address-family command places the switch in address family mode to configure the address family activity level of individual BGP neighbor addresses. The switch supports these address families:

  • ipv4-unicast
  • ipv6-unicast

Running-config displays address family commands in sub-blocks of the BGP configuration. The neighbor activate command is available in each address family configuration mode and defines the configuration mode address family activity level of a specified configured BGP neighbor address. Addresses are assigned one of the following states by the activate command:

  • neighbor activate configures the address as active in the configuration mode address family.
  • no neighbor activate configures the address as not active in the configuration mode address family.

The switch sends the following announcements to addresses that are active in an address family:

  • IPv4 address family: IPv4 capability and all network routes with IPv4 prefixes.
  • IPv6 address family: IPv6 capability and all network routes with IPv6 prefixes.

The neighbor route-map (BGP) command applies a route map to inbound or outbound BGP routes. In address-family mode, the route map is applied to routes corresponding to the configuration-mode address family. When a route map is applied to outbound routes, the switch advertises only routes matching at least one section of the route map. One outbound and one inbound route map can be applied to a neighbor for each address family. Applying a route map to a route replaces the previous corresponding route map assignment.

Network Route Advertising in Address Families

The network (BGP) command specifies a network for advertisement through UPDATE packets to BGP peers. The command is available in Router-BGP and Router-BGP-Address-Family configuration modes; the mode in which the command is issued does not affect the command’s execution.

  • Commands with an IPv4 address are advertised to peers that are IPv4 address family-active.
  • Commands with an IPv6 address are advertised to peers that are IPv6 address family-active.
Examples
  • These commands instantiate BGP, configure three neighbors, and configure two network routes.

    The default activity level for IPv4 and IPv6 address families is set to the default; all neighbor addresses are IPv4 address family active and IPv6 address family not active. IPv4 capability and network routes with IPv4 prefixes are advertised to all neighbor IPv4 addresses.

    switch(config)#router bgp 9
    switch(config-router-bgp)#neighbor 172.21.14.8 remote-as 15
    switch(config-router-bgp)#neighbor 172.23.18.6 remote-as 16
    switch(config-router-bgp)#neighbor 2001:0DB8:8c01::1 remote-as 16
    switch(config-router-bgp)#network 172.18.23.9/24
    switch(config-router-bgp)#network 2001:0DB8:de29::/64
    switch(config-router-bgp)#
  • These commands instantiate BGP on the switch, set IPv4 default activity level (not active), set IPv6 default activity level (active), and configure three neighbor addresses and two network route prefixes.

    IPv6 capability and network routes with IPv6 prefixes are advertised to all neighbor addresses.

    switch(config)#router bgp 10
    switch(config-router-bgp)#bgp default ipv6-unicast
    switch(config-router-bgp)#no bgp default ipv4-unicast
    switch(config-router-bgp)#neighbor 172.21.14.8 remote-as 15
    switch(config-router-bgp)#neighbor 172.23.18.6 remote-as 16
    switch(config-router-bgp)#neighbor 2001:0DB8:8c01::1 remote-as 16
    switch(config-router-bgp)#network 172.18.23.9/24
    switch(config-router-bgp)#network 2001:0DB8:de29::/64
    switch(config-router-bgp)#
  • These commands configure three neighbors, two network routes, and the default activity level for each address family (not active), and specify neighbor addresses for each address family that is active.
    switch(config)#router bgp 11
    switch(config-router-bgp)#neighbor 172.21.14.8 remote-as 15
    switch(config-router-bgp)#neighbor 172.23.18.6 remote-as 16
    switch(config-router-bgp)#neighbor 2001:0DB8:8c01::1 remote-as 16
    switch(config-router-bgp)#network 172.18.23.9/24
    switch(config-router-bgp)#network 2001:0DB8:de29::/64
    switch(config-router-bgp)#no bgp default ipv4-unicast
    switch(config-router-bgp)#no bgp default ipv6-unicast
    switch(config-router-bgp)#address-family ipv4
    switch(config-router-bgp-af)#neighbor 172.21.14.8 activate
    switch(config-router-bgp-af)#neighbor 172.23.18.6 activate
    switch(config-router-bgp-af)#exit
    switch(config-router-bgp)#address-family ipv6
    switch(config-router-bgp-af)#neighbor 2001:0DB8:8c01::1 activate
    switch(config-router-bgp-af)#exit
    switch(config-router-bgp)#
  • These commands permit IPv4 NLRI transport over all IPv6 connections by making the IPv4 address family active on IPv6 BGP neighbors.
    switch(config)#router bgp 11
    switch(config)#address-family ipv4
    switch(config-router-bgp-af)#bgp default ipv4-unicast transport ipv6
    switch(config-router-bgp-af)#exit
    switch(config-router-bgp)#

Configuring Best-path Selection

The best-path selection algorithm (described under Best-Path Selection) determines which of multiple paths to the same destination received by BGP will be added to the IP routing table. To shape route preferences and influence best-path selection, use the following commands in router-BGP configuration mode.

  • bgp always-compare-medconfigures the switch to always consider the multi-exit discriminator (MED) value when comparing paths (disabled by default).
  • bgp bestpath as-path ignore configures the switch to ignore the length of the autonomous system (AS) path when comparing routes (disabled by default).
  • bgp bestpath as-path multipath-relaxused in equal-cost multi path (ECMP configuration) and enabled by default; the no form of the command configures the switch to consider paths unequal if their AS paths have different contents.
  • bgp bestpath ecmp-fastthe no form of this command causes the switch to ignore order of arrival in evaluating paths within an ECMP group.
  • bgp bestpath med confedcauses comparison of multi-exit discriminator (MED) values in routes originating within the same confederation as the switch and received from confederation peers (disabled by default).
  • bgp bestpath med missing-as-worstconfigures the switch to treat a missing MED as having the highest (least preferred) value (disabled by default). This command overrides the missing-as-worst setting of the bgp bestpath med confed command.
  • bgp bestpath tie-break cluster-list-length configures the switch to prefer the multipath route with the shortest CLUSTER_LIST length in case of a tie in step 10 of the selection process (disabled by default).
  • bgp bestpath tie-break router-idconfigures the switch to prefer the multipath route with the lowest ROUTER_ID in case of a tie in step 10 (disabled by default).

Displaying Reasons for Best-path Selection

To see the reasons why certain routes were excluded by the best-path selection process, use the detail option of the show ip bgp command. Enter the prefix to which BGP has selected a best path, and the output will display all learned paths. Paths which were not selected as best will display the reason they were not selected after the label not best.

The reason will be listed as one of the following:

  • path weight
  • local preference
  • AS path length
  • origin
  • path MED
  • eBGP path preferred
  • IGP cost
  • AS path details
  • ECMP-Fast configured
  • router ID
  • originator ID
  • router ID tie-break configured
  • cluster list length
  • cluster list length tie-break configured
  • peer IP address
  • path ID
  • redistributed route exists
  • unknown
  • another route from the same AS is a better BGP route
  • peer not ready
  • unusable
Example
  • This command displays the reasons why three routes to 172.16.0.0/24 were rejected by the best-path algorithm. The reason for rejection is preceded by the label Not best:
    switch#show ip bgp 172.16.0.0/24 detail
    BGP routing table information for VRF default
    Router identifier 192.168.100.18, local AS number 64524
    Route status: [a.b.c.d] - Route isqueued for advertisement to peer.
    BGP routing table entry for 204.1.47.220/30
     Paths: 4 available
    64512 64550 65100
    192.168.14.2 from 192.168.14.2 (192.168.100.21)
    Origin IGP, metric 0, localpref 100, weight 0, received 19:15:29 ago, valid, 
    external, ECMP head, ECMP, best, ECMP contributor
    Rx SAFI: Unicast
    64512 64550 65100
    192.168.24.2 from 192.168.24.2 (192.168.100.22)
    Origin IGP, metric 0, localpref 100, weight 0, received 19:15:29 ago, valid, 
    external, ECMP, ECMP contributor
    Rx SAFI: Unicast
    Not best: ECMP-Fast configured
    64512 64550 65100
    192.168.34.2 from 192.168.34.2 (192.168.100.23)
    Origin IGP, metric 0, localpref 100, weight 0, received 19:15:29 ago, valid, 
    external, ECMP, ECMP contributor
    Rx SAFI: Unicast
    Not best: Redistributed route exists
    64512 64550 65100
    192.168.44.2 from 192.168.44.2 (192.168.100.24)
    Origin IGP, metric 0, localpref 100, weight 0, received 19:15:29 ago, valid, 
    external, ECMP, ECMP contributor
    Rx SAFI: Unicast
    Not best: eBGP path preferred
    Not advertised to any peer
    switch#

Configuring BGP Convergence

To avoid hardware updates and route advertisement churn during switch reload or BGP instance start, BGP enters into the convergence state where it waits for all peers to join and receive all routes from all the peers.

BGP Convergence is bound by an upper value of convergence time (default value is 5 minutes) and BGP declares convergence on expiry of convergence timer. At the end of convergence, BGP updates the routes in FIB and advertises to all the peers.

To configure BGP convergence and the different timeout features, use the following commands in router-BGP configuration mode.

Different Cases for Convergence with Default Timeout Configuration

  • Convergence Time < 90 seconds after the first peer has joined: this is the best case when all the configured peers have joined and EORs have been received from all peers in less than 90 seconds after the first peer has joined.
  • Convergence Time = 90 seconds after the first peer has joined: this is the case when one or more BGP peers have joined within 90 seconds and EORs have been received from all peers within 90 seconds, but there are still some configured peers which have not joined yet. In this case, the convergence is declared after slow-peer timeout is reached.
  • Convergence Time > 90 seconds after the first peer has joined: this is the case when one or more BGP peers have joined after 90 seconds, but EORs have not been received from all peers. As soon as EORs are received from all peers which have joined during the first 90 seconds, the convergence is declared.
  • Convergence Time = 300 seconds after the first peer has joined: this is the case when EOR is not received till 300 seconds from some of the peers that have joined during 90 seconds after the first peer has joined.

Displaying BGP Convergence Status

Use the show bgp convergence command to view information about the BGP convergence status, and to know if the convergence timer has started or not. The examples below show the command output at different points in the convergence process.

No Peers Have Joined
  • This is the output when no peers have joined before convergence.
    switch(config-router-bgp)#show bgp convergence
    BGP Convergence information for VRF: default
    Configured convergence timeout: 00:02:30
    Configured convergence slow peer timeout: 00:00:55
    Convergence based update synchronization is enabled
    Last Bgp convergence event : None
    Bgp convergence state : Not Initiated (Waiting for the first peer to join)
     Convergence timer is not running
     Convergence timeout in use: 00:02:30
     Convergence slow peer timeout in use: 00:00:55
     First peer is not up yet
     All the expected peers are up: no
     All IGP protocols have converged: yes
     Outstanding EORs: 0, Outstanding Keepalives: 0
     Pending Peers: 2
     Total Peers: 2
     Established Peers: 0
     Disabled Peers: 0
     Peers that have not converged yet:
     IPv4 peers:
     201.1.1.1 (Session : Connect)
     202.1.1.1 (Session : Connect)
     IPv6 peers:
     None
    switch(config-router-bgp)#
First Peer Has Joined
  • This is the output when the first peer has joined before convergence.
    switch#show bgp convergence
    BGP Convergence information for VRF: default
    Configured convergence timeout: 00:02:30
    Configured convergence slow peer timeout: 00:00:55
    Convergence based update synchronization is enabled
    Last Bgp convergence event 00:00:40 ago
    Bgp convergence state : Pending (Waiting for EORs/Keepalives from peer(s) and IGP 
    convergence)
     Convergence timer running, will expire in 00:01:50
     Convergence timeout in use: 00:02:30
     Convergence slow peer timeout in use: 00:00:55
     First peer came up 00:00:13 ago
     All the expected peers are up: no
     All IGP protocols have converged: yes
     Outstanding EORs: 0, Outstanding Keepalives: 0
     Pending Peers: 1
     Total Peers: 2
     Established Peers: 1
     Disabled Peers: 0
     Peers that have not converged yet:
     IPv4 peers:
     201.1.1.1 (Session : Active)
     IPv6 peers:
     None
    switch#
Convergence Timeout Reached
  • This is the output when the convergence timeout value is reached.
    switch(config-router-bgp)#show bgp convergence
    BGP Convergence information for VRF: default
    Configured convergence timeout: 00:02:30
    Configured convergence slow peer timeout: 00:00:55
    Convergence based update synchronization is enabled
    Last Bgp convergence event 00:02:44 ago
    Bgp convergence state : Timeout reached
     Time taken to converge 00:02:30
     Pending Peers: 1
     Total Peers: 2
     Established Peers: 1
     Disabled Peers: 0
     Peers that did not converge before local bgp convergence:
     IPv4 peers:
     201.1.1.1 (Session : Active)
     202.1.1.1 (Session : Established)
     IPv6 peers:
     None
    switch(config-router-bgp)#
Converged State
  • This is the output during the converged state.
    switch(config-router-bgp)#show bgp convergence
    BGP Convergence information for VRF: default
    Configured convergence timeout: 00:05:00
    Configured convergence slow peer timeout: 00:01:30
    Convergence based update synchronization is enabled
    Last Bgp convergence event 00:00:05 ago
    Bgp convergence state : Converged
     Time taken to converge 00:00:02
     First peer came up 00:00:05 ago
     Pending Peers: 0
     Total Peers: 3
     Established Peers: 3
     Disabled Peers: 0
     Peers that did not converge before local bgp convergence:
     IPv4 peers:
     None
     IPv6 peers:
     None
    switch(config-router-bgp)#

Configuring BGP Graceful Shutdown Community

Creating a Route-Map Entry That Sets the Community for Graceful Shutdown

The set community (route-map) command specifies community attribute modifications to BGP routes.

Example
switch(config)#route-map map1
switch(config-route-map-map1)#set community GSHUT
switch(config)#exit
switch(config)#

Creating a Route-Map Entry with Matching Preferences on Graceful Shutdown Community

The ip community-list command creates and configures a BGP access list that is based on BGP communities.

The match (route-map) command creates a route map clause entry that specifies one route filtering condition.

Example
switch(config)#ip community-list gshut_list permit GSHUT
switch(config)#route-map map1
switch(config-route-map-map1)#match community gshut_list
switch(config-route-map-map1)#exit
switch(config)#

Validating the Route-Map

The show route-map command displays the contents of the specified route maps.

Example
switch#show route-map map1
route-map map1 permit 10
Description:
Match clauses:
Set clauses:
set community GSHUT
switch#

Configuring BGP Selective Route Download

The bgp route install-map command is used in the BGP configuration mode to enable BGP Selective Route Download. BGP Selective Route Download can also be configured in an address family or VRF instance as shown in the following examples.

The following examples show how to configure a prefix list and route map, then apply BGP Selective Route Download to the map.

Examples

  • These commands install BGP routes in the 10.0.0.0/24 and 20.0.0.0/24 ranges in the RIB (and thus in the hardware), but no other BGP routes.
    switch(config)#ip prefix-list PFXL_ALLOW
    switch(config-ip-pfx)#seq 1 permit 10.0.0.0/24 ge 24 le 32
    switch(config-ip-pfx)#seq 2 permit 20.0.0.0/24 ge 24 le 32
    switch(config-ip-pfx)#exit
    switch(config-ip-pfx)#
  • These commands configure the permit and deny rules for BGP routes.
    switch(config)#route-map BGP_INSTALL_MAP permit 10
    switch(config-route-map-BGP_INSTALL_MAP)#match ip address prefix-list PFXL_ALLOW
    switch(config-route-map-BGP_INSTALL_MAP)#exit
    switch(config)#route-map BGP_INSTALL_MAP deny 20
    switch(config)#
  • These commands configure Selective Route Download for the map BGP_INSTALL_MAP.
    switch(config)#router bgp 100 
    switch(config-router-bgp)#bgp route install-map BGP_INSTALL_MAP
    switch(config-router-bgp)#
The following examples show how to configure prefix lists individually for the IPv4 and IPv6 address families, then apply BGP Selective Route Download for these address families.

Examples

  • These commands configure the IPv4 address family prefix list.
    switch(config)#ip prefix-list V4_ALLOW
    switch(config-ip-pfx)#route-map BGP_V4_MAP permit 10
    switch(config-route-map-BGP_V4_MAP)#match ip address prefix-list V4_ALLOW
    switch(config-route-map-BGP_V4_MAP)#route-map BGP_V4_MAP deny 20
    switch(config-route-map-BGP_V4_MAP)#exit
    switch(config-route-map-BGP_V4_MAP)#
  • These commands configure the IPv6 address family prefix list.
    switch(config)#ipv6 prefix-list V6_ALLOW
    switch(config-ipv6-pfx)#route-map BGP_V6_MAP permit 10
    switch(config-route-map-BGP_V6_MAP)#match ipv6 address prefix-list V6_ALLOW
    switch(config-route-map-BGP_V6_MAP)#route-map BGP_V6_MAP deny 20
    switch(config-route-map-BGP_V6_MAP)#exit
    switch(config-route-map-BGP_V6_MAP)#
  • These commands configure Selective Route Download individually for the two address families.
    switch(config)#router bgp 200
    switch(config-router-bgp)#address-family ipv4
    switch(config-router-bgp-af)#bgp route install-map BGP_V4_MAP
    switch(config-router-bgp-af)#exit
    switch(config-router-bgp)#address-family ipv6
    switch(config-router-bgp-af)#bgp route install-map BGP_V6_MAP
    switch(config-router-bgp-af)#

Displaying BGP Selective Route Download Information

The show ip bgp command displays BGP RIB winning paths that are not installed in the RIB.

Example
  • The following command displays BGP routing table information for VRF default, showing winning paths that are not installed in the RIB.
    switch#show ip bgp
    BGP routing table information for VRF default
    Router identifier 1.0.0.2, local AS number 100
    Route status codes: s - suppressed, * - valid, > - active, # - not installed, E 
    - ECMP head, e - ECMP
    S - Stale, c - Contributing to ECMP, b - backup
    Origin codes: i - IGP, e - EGP, ? - incomplete
    AS Path Attributes: Or-ID - Originator ID, C-LST - Cluster List, LL Nexthop - 
    Link Local Nexthop
    
     Network Next Hop MetricLocPref Weight Path
     * > 6.0.0.0/241.0.0.10 100 0 ? 
     * # 7.0.0.0/241.0.0.10 100 0 ? 
    switch#

The show ip bgp command with a specified prefix displays detailed information and the reason for the BGP RIB winning paths to that prefix not being installed in the RIB.

Example
  • The following command displays detailed information for the BGP routing table for VRF default.
    switch#show ip bgp 7.0.0.0/24
    BGP routing table information for VRF default
    Router identifier 1.0.0.2, local AS number 100
    BGP routing table entry for 7.0.0.0/24
     Paths: 1 available
    Local
    1.0.0.1 from 1.0.0.1 (1.0.0.1)
    Origin INCOMPLETE, metric 0, localpref 100, weight 0, valid, internal, not 
    installed (denied by install-map) 
    switch#

The show ip bgp installed command displays the list of installed routes in the BGP RIB.

Example
  • The following command displays the list of installed routes in BGP routing table for VRF defaults.
    switch#show ip bgp installed 
    BGP routing table information for VRF default
    Router identifier 1.0.0.2, local AS number 100
    Route status codes: s - suppressed, * - valid, > - active, # - not installed, E 
    - ECMP head, e - ECMP
    S - Stale, c - Contributing to ECMP, b - backup
    Origin codes: i - IGP, e - EGP, ? - incomplete
    AS Path Attributes: Or-ID - Originator ID, C-LST - Cluster List, LL Nexthop - 
    Link Local Nexthop
    
    Network Next Hop MetricLocPref Weight Path
     * >6.0.0.0/241.0.0.10 100 0?
    switch#

The show ip bgp not-installed displays the list of non-installed routes in the RIB.

Example
  • The following command displays the list of non-installed routes in the BGP routing table for VRF default.
    switch#show ip bgp not-installed 
    BGP routing table information for VRF default
    Router identifier 1.0.0.2, local AS number 100
    Route status codes: s - suppressed, * - valid, > - active, # - not installed, E 
    - ECMP head, e - ECMP
    S - Stale, c - Contributing to ECMP, b - backup
    Origin codes: i - IGP, e - EGP, ? - incomplete
    AS Path Attributes: Or-ID - Originator ID, C-LST - Cluster List, LL Nexthop - 
    Link Local Nexthop
    
    Network Next Hop MetricLocPref Weight Path
     * #7.0.0.0/241.0.0.10 100 0?
    switch#

Configuring BGP Route Reflector

Use the bgp route-reflector preserve-attributes command to configure the switch as a BGP route reflector. The switch then keeps BGP attributes from being changed by outbound policies, except for the policies configured in an outbound route map. BGP route reflection is disabled by default. Use the always option in the bgp route-reflector preserve-attributes command to prevent the BGP attributes from being changed by an outbound route map.

When the bgp route-reflector preserve-attributes command is used with the always option, the following outbound policies cannot change the next-hop, local preference, and metric BGP attributes of reflected routes:

  • neighbor next-hop-self
  • neighbor export-local pref
  • neighbor metric-out

If the always option is not specified, the following route map policies can change the BGP attributes.

  • set ip[v6] next-hop
  • set local-preference
  • set metric

Examples

  • The following commands display the switch configured with a route-reflector client (at 1.0.1.2) and a non-client (at 1.0.0.2). The switch reflects the prefix 1.0.6.0 from the neighbor at 1.0.1.2 to the router at 1.0.0.1. The prefix 1.0.4.0 is not a reflected route. The local preference is 100 by default for all routes.
    switch(config)#router bgp 1
    switch(config-router-bgp)#show active
    router bgp 1
     no bgp default ipv6-unicast
     neighbor 1.0.0.2 remote-as 1
     neighbor 1.0.0.2 maximum-routes 12000
     neighbor 1.0.1.2 remote-as 1
     neighbor 1.0.1.2 route-reflector-client
     neighbor 1.0.1.2 maximum-routes 12000
     network 1.0.4.0/24
    switch(config-router-bgp)#show ip bgp
    BGP routing table information for VRF default
    Router identifier 192.168.201.37, local AS number 1
    Route status codes: s - suppressed, * - valid, > - active, E - ECMP head, e - ECMP
    S - Stale, c - Contributing to ECMP, b - backup
    Origin codes: i - IGP, e - EGP, ? - incomplete
    AS Path Attributes: Or-ID - Originator ID, C-LST - Cluster List, LL Nexthop - Link Local Nexthop
    
     Network Next Hop MetricLocPref Weight Path
     * > 1.0.4.0/24-1 0 - i
     * > 1.0.6.0/241.0.1.20 100 0 i
    switch(config-router-bgp)#show ip bgp neighbors 1.0.0.2 advertised-routes
    BGP routing table information for VRF default
    Router identifier 192.168.201.37, local AS number 1
    Route status codes: s - suppressed, * -valid, > - active, E - ECMP head, e - ECMP, b - backup
    S - Stale, c - Contributing to ECMP,q - Queued for advertisement
    Origin codes: i - IGP, e - EGP, ? - incomplete
    AS Path Attributes: Or-ID - Originator ID, C-LST -Cluster List, LL Nexthop - Link Local Nexthop
    Network Next HopMetricLocPref Weight Path
     * >1.0.4.0/241.0.0.1 - 100 - i
     * >1.0.6.0/241.0.1.2 - 100 - i
    switch(config-router-bgp)#
  • The following command changes the local preference to 201 for all routes advertised to the neighbor at 1.0.0.2.
    switch(config-router-bgp)#neighbor 1.0.0.2 export-localpref 201
    switch(config-router-bgp)#show ip bgp neighbors 1.0.0.2 advertised-routes
    BGP routing table information for VRF default
    Router identifier 192.168.201.37, local AS number 1
    Route status codes: s - suppressed, * -valid, > - active, E - ECMP head, e - ECMP, b - backup
    S - Stale, c - Contributing to ECMP,q - Queued for advertisement
    Origin codes: i - IGP, e - EGP, ? - incomplete
    AS Path Attributes: Or-ID - Originator ID, C-LST -Cluster List, LL Nexthop - Link Local Nexthop
    
    Network Next HopMetricLocPref Weight Path
     * >1.0.4.0/241.0.0.1 - 201 - i
     * >1.0.6.0/241.0.1.2 - 201 - i
    switch(config-router-bgp)#
  • The following command configures the switch to preserve the local preference of the reflected route 1.0.6.0.
    switch(config-router-bgp)#bgp route-reflector preserve-attributes
    switch(config-router-bgp)#show ip bgp neighbors 1.0.0.2 advertised-routes
    BGP routing table information for VRF default
    Router identifier 192.168.201.37, local AS number 1
    Route status codes: s - suppressed, * -valid, > - active, E - ECMP head, e - ECMP, b - backup
    S - Stale, c - Contributing to ECMP,q - Queued for advertisement
    Origin codes: i - IGP, e - EGP, ? - incomplete
    AS Path Attributes: Or-ID - Originator ID, C-LST -Cluster List, LL Nexthop - Link Local Nexthop
    
    Network Next HopMetricLocPref Weight Path
     * >1.0.4.0/241.0.0.1 - 201 - i
     * >1.0.6.0/241.0.1.2 - 100 - i
    switch(config-router-bgp)#
  • The following command changes the local preference of 1.0.0.2 to 200.
    switch(config-router-bgp)#neighbor 1.0.0.2 route-map rm1 out
    switch(config-router-bgp)#show ip bgp neighbors 1.0.0.2 advertised-routes
    BGP routing table information for VRF default
    Router identifier 192.168.201.37, local AS number 1
    Route status codes: s - suppressed, * -valid, > - active, E - ECMP head, e - ECMP, b - backup
    S - Stale, c - Contributing to ECMP,q - Queued for advertisement
    Origin codes: i - IGP, e - EGP, ? - incomplete
    AS Path Attributes: Or-ID - Originator ID, C-LST -Cluster List, LL Nexthop - Link Local Nexthop
    
    Network Next HopMetricLocPref Weight Path
     * >1.0.4.0/241.0.0.1 - 200 - i
     * >1.0.6.0/241.0.1.2 - 200 - i
    switch(config-router-bgp)#
  • The following command includes the always option to prevent the local preference from being changed by a route map.
    switch(config-router-bgp)#bgp route-reflector preserve-attributes always
    switch(config-router-bgp)#show ip bgp neighbors 1.0.0.2 advertised-routes
    BGP routing table information for VRF default
    Router identifier 192.168.201.37, local AS number 1
    Route status codes: s - suppressed, * -valid, > - active, E - ECMP head, e - ECMP, b - backup
    S - Stale, c - Contributing to ECMP,q - Queued for advertisement
    Origin codes: i - IGP, e - EGP, ? - incomplete
    AS Path Attributes: Or-ID - Originator ID, C-LST -Cluster List, LL Nexthop - Link Local Nexthop
    
    Network Next HopMetricLocPref Weight Path
     * >1.0.4.0/241.0.0.1 - 200 - i
     * >1.0.6.0/241.0.1.2 - 100 - i
    switch(config-router-bgp)#

Displaying Route Reflector Information

The show bgp instance command display the route reflector information.

Note: The value of the “Attributes of reflected routes” can be preserved, always preserved, or not preserved.
Example
  • This command displays the global BGP status for the default VRF.
    switch#show bgp instance
    BGP instance information for VRF default
    BGP Local AS: 64512, Router ID: 1.1.4.1
    Total peers:14
    Configured peers: 14
    UnConfigured peers: 0
    Disabled peers: 4
    Established peers:9
    Graceful restart helper mode enabled
    Attributes of reflected routes are preserved
    End of rib timer timeout: 00:05:00
    BGP Convergence timer is inactive
    BGP Convergence information:
    BGP has converged: yes, Time taken to converge: 00:05:44
    Outstanding EORs:0, Outstanding Keepalives: 0
    Convergence timeout: 00:10:00
    switch#

Configuring BGP Confederations

BGP confederations allow you to break an autonomous system (AS) into multiple sub-ASs, and then to group the sub-ASs as a confederation. The sub-ASs exchange iBGP routing information (next-hop, local-preference and MED), but communicate via eBGP.

To configure a BGP confederation, complete the following tasks on each BGP device in the confederation.

  • Configure the local AS number: the local AS number is the membership number in a sub-AS. BGP devices with the same local AS number are identified as members of the same sub-AS. BGP devices always use the local AS number when communicating with other BGP4 devices in the confederation.
  • Configure the confederation ID: the confederation ID is the AS number for those BGP devices that are outside of the confederation. A BGP device outside the confederation is not aware that BGP devices are in multiple sub-ASs. The confederation ID must differ from the sub-AS numbers.
  • Configure the list of sub-AS numbers that are confederation members: devices in a sub-AS exchange information via iBGP, while devices in different sub-ASs use eBGP.
Figure 1. BGP Confederation Example

Example

  • The router bgp command enables BGP and configures the router in sub-autonomous system 65050. The bgp confederation identifier command specifies that confederation 65050 belongs to autonomous system 100.

    The neighbors from other autonomous systems within the confederation are treated as special eBGP peers when using the bgp confederation peers command.

    switch(config)#router bgp 65050
    switch(config-router-bgp)#bgp confederation identifier 100
    switch(config-router-bgp)#bgp confederation peers 65060
    switch(config-router-bgp)#
  • The Arista eos will group the maximum ranges together. In this example, peers 65032 and 65036 are not included in BGP confederation 100.
    switch(config)#router bgp 65050
    switch(config-router-bgp)#bgp confederation identifier 100
    switch(config-router-bgp)#bgp confederation peers 65060
    switch(config-router-bgp)#no bgp confederation peers 65032, 65036
    switch(config-router-bgp)#

BGP Operational Commands

Shutdown

The shutdown (BGP) command disables BGP operations without disrupting the BGP configuration. The no router bgp command disables BGP and removes the BGP configuration.

The no shutdown (BGP) command resumes BGP activity.

Examples
  • This command disables BGP activity on the switch.
    switch(config-router-bgp)#shutdown
    switch(config-router-bgp)#
  • This command resumes BGP activity on the switch.
    switch(config-router-bgp)#no shutdown
    switch(config-router-bgp)#

Clearing the Routing Table and Resetting BGP Sessions

When entered without parameters, the clear ip bgp command clears all BGP learned routes from the routing table, reads routes from designated peers, and sends routes required by those peers. Routes that are read or sent are processed through any modified route map or AS-path access list.

Followed by an asterisk (*), it clears the BGP sessions with all BGP peers. To reset the session with a specific peer, enter the peer’s IP address at the end of the command.

Example
  • This command removes all BGP learned routes from the routing table.
    switch#clear ip bgp
    switch#

BGP Examples

This section shows example configurations and topologies for iBGP (Example 1) and eBGP (s).

BGP Example 1

Example 1 features an internal BGP (iBGP) link that connects peers in AS 100.

 

BGP Example 1 Diagram

Figure 2displays an iBGP connection, linking neighbors within AS 100. Each switch advertises two subnets. In UPDATE packets sent by Switch A, the LOCAL_PREF field is 150. In UPDATE packets sent by Switch B, the LOCAL_PREF field is 75.

Figure 2. BGP Example 1

BGP Example 1 Code

This code configures the Example 1 BGP instance on both switches.

  1. Configure the neighbor addresses.
    1. Specify the neighbor to Switch A.
      switchA(config)#router bgp 100
      switchA(config-router-bgp)#neighbor 10.100.100.2 remote-as 100
    2. Specify the neighbor to Switch B.
      switchB(config)#router bgp 100
      switchB(config-router-bgp)#neighbor 10.100.100.1 remote-as 100
  2. Configure the routes to be advertised.
    1. Advertise Switch A’s routes.
      switchA(config-router-bgp)#network 10.10.1.0/24
      switchA(config-router-bgp)#network 10.10.2.0/24
    2. Advertise Switch B’s routes.
      switchB(config-router-bgp)#network 10.10.3.0/24
      switchB(config-router-bgp)#network 10.10.4.0/24
  3. Configure the LOCAL_PREF.
    1. Configure LOCAL_PREF on Switch A.
      switchA(config-router-bgp)#neighbor 10.100.100.2 export-localpref 150
    2. Configure LOCAL_PREF on Switch B.
      switchB(config-router-bgp)#neighbor 10.100.100.2 export-localpref 75
  4. Modify the hold time and keepalive interval.
    1. Configure timers on Switch A.
      switchA(config-router-bgp)#timer bgp 30 90
    2. Configure timers on Switch B.
      switchB(config-router-bgp)#timer bgp 30 90

BGP Example 2

Example 2 creates an external BGP (eBGP) link that connects routers in AS 100 and AS 200.

 

BGP Example 2 Diagram

Figure 3 displays an eBGP connection, linking Switch A in AS 100 to Switch B in AS 200. Each switch advertises two subnets.

Switch A assigns a local preference of 150 to networks advertised by Switch B. Switch B assigns a local preference of 75 to networks advertised by Switch A.

Figure 3. BGP Example 2

BGP Example 2 Code

This code configures the Example 2 BGP instance on both switches.

  1. Configure the neighbor addresses.
    1. Specify the neighbor to Switch A.
      switchA(config)#router bgp 100
      switchA(config-router-bgp)#neighbor 10.100.100.2 remote-as 100
    2. Specify the neighbor to Switch B.
      switchB(config)#router bgp 100
      switchB(config-router-bgp)#neighbor 10.100.100.1 remote-as 100
  2. Configure the routes to be advertised.
    1. Advertise Switch A’s routes.
      switchA(config-router-bgp)#network 10.10.1.0/24
      switchA(config-router-bgp)#network 10.10.2.0/24
    2. Advertise Switch B’s routes.
      switchB(config-router-bgp)#network 10.10.3.0/24
      switchB(config-router-bgp)#network 10.10.4.0/24
  3. Configure the LOCAL_PREF.
    1. Configure LOCAL_PREF on Switch A.
      switchA(config-router-bgp)#neighbor 10.100.100.2 import-localpref 150
    2. Configure LOCAL_PREF on Switch B.
      switchB(config-router-bgp)#neighbor 10.100.100.2 import-localpref 75
  4. Modify the hold time and keepalive interval.
    1. Configure timers on Switch A.
      switchA(config-router-bgp)#timer bgp 30 90
    2. Configure timers on Switch B.
      switchB(config-router-bgp)#timer bgp 30 90

BGP Commands

Global Configuration Commands

Router-BGP Configuration Mode (Includes Address-Family Mode)

Route Map Configuration Mode

Clear CommandsPrivileged EXEC Mode

Display Commands EXEC Mode

address-family

The address-family command places the switch in address-family configuration mode to configure the address family setting of addresses configured as BGP neighbors. Address-family configuration mode is not a group change mode; running-config is changed immediately after commands are executed. The exit command does not affect the configuration.

The switch supports these address families:

  • ipv4-unicast
  • ipv6-unicast

Running-config displays address-family commands in sub-blocks of the BGP configuration. The following commands are available in address family configuration mode:

The no address-family and default address-family commands delete the specified address family from running-config by removing all commands previously configured in the corresponding address-family mode.

The exit command returns the switch to router-BGP configuration mode.

Command Mode

Router-BGP Configuration

Command Syntax

bgp ipv4|ipv6

no bgp ipv4|ipv6

default bgp ipv4|ipv6

Parameters

  • ipv4 subsequent commands are applied to the IPv4 unicast address family.
  • ipv6 subsequent commands are applied to the IPv6 unicast address family.

Example

  • These commands enter address family mode for IPv6-unicast, insert a command, then exit the mode:
    switch(config)#router bgp 1
    switch(config-router-bgp)#address-family ipv6
    switch(config-router-bgp-af)#neighbor 172.10.1.1 activate
    switch(config-router-bgp-af)#exit
    switch(config-router-bgp)#

aggregate-address

The aggregate-address command creates an aggregate route in the Border Gateway Protocol (BGP) database. Aggregate routes combine the characteristics of multiple routes into a single route that the switch advertises. Aggregation can reduce the amount of information that a BGP speaker is required to store and transmit when advertising routes to other BGP speakers. Aggregate routes are advertised only after they are redistributed.

The advertised address of the aggregate is entered as an IP subnet; any routes configured on the switch that lie within that subnet then become contributors to the aggregate. Note that on Arista switches the BGP aggregate route will become active if there are any available contributor routes on the switch, regardless of the originating protocol. This includes routes configured statically.

Note: Aggregate routes are redistributed automatically, and their redistribution cannot be disabled.

Command options affect the attributes associated with the aggregated route, the advertisement of the contributor routes that comprise the aggregate, and which contributor routes are included.

Command options affect the following aggregate routing attributes:

  • AS_PATH attribute inclusion: the as-set option controls the aggregate route’s AS_PATH and ATOMIC_AGGREGATE attribute contents. AS_PATH identifies the autonomous systems through which UPDATE message routing information passes. ATOMIC_AGGREGATE indicates that the route is an aggregate or summary of more specific routes.

    When the command includes as-set, the aggregate route’s AS_SET attribute contains the AS numbers of contributor routes. This can help BGP neighbors to prevent loops by rejecting aggregate routes that include their AS number in the AS_SET.

    When the command does not include as-set, the aggregate route’s ATOMIC_AGGREGATE attribute is set and the aggregate route AS_PATH will include the longest leading PATH_SEQ of the AS_PATH which is common to all contributor routes. For example, for the aggregate 1.0.0.0/16 with two contributors present, the AS_PATH for the aggregate is “100 200” as shown.

    Aggregate

    1.0.0.0/16 as-path ??

    Contributors

    1.0.1.0/24 as-path “100 200 400 500”

    1.0.2.0/24 as-path “100 200 300”

  • Attribute assignment: the attribute-map option assigns attributes contained in set commands in a specified route map’s lowest sequence with any set command to the aggregated route, overriding the automatic determination of the aggregate route’s attributes by the switch.
  • Route suppression: the summary-only option suppresses the advertisement of the contributor routes that comprise the aggregate.
  • Contributor filtering: the match-map option uses a route map to filter out contributor routes that would otherwise be included in the aggregate.

The no aggregate-address and default aggregate-address commands remove the corresponding aggregate-address command from running-config.

Command Mode

Router-BGP Configuration

Command Syntax

aggregate-address AGGREGATE_NET [AS_SET][SUMMARY][ATTRIBUTE_MAP][MATCH_MAP]

no aggregate-address AGGREGATE_NET

default aggregate-address AGGREGATE_NET

Parameters

  • AGGREGATE_NET aggregate route IP address. Options include:
    • netv4_addr IPv4 subnet address (CIDR or address-mask notation).
    • netv6_addr IPv6 subnet address (CIDR notation).
  • AS_SET controls AS_PATH attribute values associated with aggregate route. Options include:
    • <no parameter> ATOMIC_AGGREGATE attribute is set. Route contains no AS_PATH data.
    • as-set route includes AS_PATH information from contributor routes as AS_SET attributes.
  • SUMMARY controls advertisement of contributor routes. Options include:
    • <no parameter> contributor and aggregate routes are advertised.
    • summary-only contributor routes are not advertised.
  • ATTRIBUTE_MAP controls attribute assignments to the aggregate route. Options include:
    • <no parameter> attribute values are not assigned to route.
    • attribute-map map_name assigns attribute values in set commands of the map’s permit clauses. Deny clauses and match commands in permit clauses are ignored.
  • MATCH_MAP filters contributors to the aggregate route. Options include:
    • <no parameter> no contributors are filtered.
    • match-map map_name filters contributor routes using the named match-map.

Examples

  • These commands create an aggregate route (10.16.48.0/20) from the contributor routes 10.16.48.0/23, 10.16.50.0/23, 10.16.52.0/23, and 10.16.54.0/23. The aggregate route includes the AS_PATH information from the contributor routes.
    switch(config)#router bgp 1
    switch(config-router-bgp)#aggregate-address 10.16.48.0/20 as-set
    switch(config-router-bgp)#exit
    switch(config)#
  • These commands create an aggregate route and use a route map to add a local-preference attribute to the route.
    switch(config)#route-map map1 permit 10
    switch(config-route-map-map1)#set community 45
    switch(config-route-map-map1)#exit
    switch(config)#router bgp 1
    switch(config-router-bgp)#aggregate-address 10.16.48.0/20 attribute-map map1
    switch(config-router-bgp)#exit
    switch(config)#
  • These commands create an aggregate route and use a route map to allow only those contributors which match a specified prefix list to be included in the aggregate route.
    switch(config)#route-map matchmap permit 10
    switch(config-route-map-matchmap)#match ip address prefix-list agglist
    switch(config-route-map-matchmap)#exit
    switch(config)#router bgp 1
    switch(config-router-bgp)#aggregate-address 1.1.0.0/16 match-map matchmap
    switch(config-router-bgp)#

bgp advertise-inactive

By default, BGP will advertise only those routes that are active in the switch’s RIB. This can contribute to dropped traffic. If a preferred route is available through another protocol (like OSPF), the BGP route will become inactive and not be advertised; if the preferred route is lost, there is no available route to the affected peers. Advertising inactive BGP routes minimizes traffic loss by providing alternative routes.

The bgp advertise-inactive command configures BGP to advertise inactive routes to BGP neighbors. Inactive route advertisement is configured globally, but the global setting can be overridden on a per-VRF basis.

The no bgp advertise-inactive and default bgp advertise-inactive commands restore the default BGP behavior (advertising only active routes) by removing the corresponding bgp advertise-inactive command from running-config.

Command Mode

Router-BGP Configuration

Command Syntax

bgp advertise-inactive

no bgp advertise-inactive

default bgp advertise-inactive

Example

  • These commands configure BGP to advertise inactive routes.
    switch(config)#router bgp 64500
    switch(config-router-bgp)#bgp advertise-inactive
    switch(config-router-bgp)#

bgp always-compare-med

The bgp always-compare-med command configures the switch to always consider multi-exit discriminator (MED) values (also known as “metric”) in best-path selection. By default, this function is disabled, and MED values are compared only if two paths have the same neighbor AS.

When there are two or more links between autonomous systems, MED values may be set by a router in the originating AS to give preferences to certain routes. In comparing MED values, the lower value is preferred.

The no bgp always-compare-med and default bgp always-compare-med commands restore the default behavior of comparing MED values only on paths with the same neighbor AS.

Command Mode

Router-BGP Configuration

Command Syntax

bgp always-compare-med

no bgp always-compare-med

default bgp always-compare-med

Related Commands

Example

  • These commands configure BGP to always consider MED values in best-path comparisons.
    switch(config)#router bgp 64500
    switch(config-router-bgp)#bgp always-compare-med
    switch(config-router-bgp)#

bgp bestpath as-path ignore

The bgp bestpath as-path ignore command configures BGP to ignore the length of the autonomous system (AS) path when comparing routes. This behavior is disabled by default. Normally, the switch compares AS paths as the third step in the best-path selection process (see Best-Path Selection), preferring the route with the shorter AS path.

The no bgp bestpath as-path ignore and default bgp bestpath as-path ignore commands restore the default behavior of considering AS path length in route comparisons.

Command Mode

Router-BGP Configuration

Command Syntax

bgp bestpath as-path ignore

no bgp bestpath as-path ignore

default bgp bestpath as-path ignore

Related Commands

Example

  • These commands configure BGP to ignore AS path lengths when comparing routes.
    switch(config)#router bgp 64500
    switch(config-router-bgp)#bgp bestpath as-path ignore
    switch(config-router-bgp)#

bgp bestpath as-path multipath-relax

The bgp bestpath as-path multipath-relax command allows multiple eBGP routes to a destination to be considered equal in ECMP if their AS paths are the same length despite having different autonomous systems in those paths. The no bgp bestpath as-path multipath-relax command configures best-path selection to consider two paths unequal if their AS path contents are different, and prefers the first path received.

Multipath-relax is enabled by default. The bgp bestpath as-path multipath-relax and default bgp bestpath as-path multipath-relax commands restore the default behavior by removing the corresponding no bgp bestpath as-path multipath-relax command from running-config.

For BGP to support equal cost multipath (ECMP) routing, the maximum paths (BGP) command must be issued in router-BGP configuration mode.

Command Mode

Router-BGP Configuration

Command Syntax

bgp bestpath as-path multipath-relax

no bgp bestpath as-path multipath-relax

default bgp bestpath as-path multipath-relax

Related Commands

Example

  • These commands configure BGP best-path selection to consider routes unequal if the contents of their AS paths differ.
    switch(config)#router bgp 64500
    switch(config-router-bgp)#no bgp bestpath as-path multipath-relax
    switch(config-router-bgp)#

bgp bestpath ecmp-fast

By default, within an ECMP group the BGP best-path selection process prefers the active path (the first path received by the switch) unless a relevant tie-breaker is enabled. The no bgp bestpath ecmp-fast command causes the best-path selection process to ignore order of arrival and continue evaluating paths on other criteria.

The bgp bestpath ecmp-fast and default bgp bestpath ecmp-fast commands restore the default behavior by removing the corresponding no bgp bestpath ecmp-fast command from running-config.

Command Mode

Router-BGP Configuration

Command Syntax

bgp bestpath ecmp-fast

no bgp bestpath ecmp-fast

default bgp bestpath ecmp-fast

Related Commands

Example

  • These commands configure BGP to ignore order of arrival in best-path comparisons of paths within an ECMP group.
    switch(config)#router bgp 64500
    switch(config-router-bgp)#no bgp bestpath ecmp-fast
    switch(config-router-bgp)#

bgp bestpath med confed

By default, paths originating within the same confederation as the switch and received from confederation peers do not have their multi-exit discriminator (MED) values compared as part of the best-path selection process. The bgp bestpath med confed command causes comparison of MED values in such routes. To ensure that MED values are considered in the best-path selection process for all routes received, use the bgp always-compare-med command.

The no bgp bestpath med confed and default bgp bestpath med confed commands restore the default behavior by removing the corresponding bgp bestpath ecmp-fast command from running-config.

Command Mode

Router-BGP Configuration

Command Syntax

bgp bestpath med confed [missing-as-worst]

no bgp bestpath med confed [missing-as-worst]

default bgp bestpath med confed [missing-as-worst]

Related Commands

Parameters

  • missing as worst By default, best-path selection considers a missing MED value to be 0, so paths with missing MED values will be preferred. This option reverses the behavior in comparisons of routes originating within the same confederation as the switch, treating a missing MED as having the highest (least preferred) value.
Note: The bgp bestpath med missing-as-worst command controls how best-path selection treats missing MED values for all routes received, and, if configured, overrides the missing-as-worst option of this command.

Example

  • These commands configure the BGP best-path selection process to consider MED values in comparisons between routes originating within the same confederation as the switch.
    switch(config)#router bgp 64500
    switch(config-router-bgp)#bgp bestpath med confed
    switch(config-router-bgp)#

bgp bestpath med missing-as-worst

By default, BGP best-path selection considers a missing MED value to be 0, so paths with missing MED values will be preferred. The bgp bestpath med missing-as-worst command reverses the behavior, treating a missing MED as having the highest (least preferred) value.

The no bgp bestpath med missing-as-worst and default bgp bestpath med missing-as-worst commands restore the default behavior (giving preference to missing MED values) by removing the corresponding bgp bestpath med missing-as-worst command from running-config.

Note: This command overrides the missing-as-worst setting of the bgp bestpath med confed command.

Command Mode

Router-BGP Configuration

Command Syntax

bgp bestpath med missing-as-worst

no bgp bestpath med missing-as-worst

default bgp bestpath med missing-as-worst

Related Commands

Example

  • These commands configure the BGP best-path selection process to consider a missing MED value to be considered highest (least preferred) in MED comparisons for all routes received.

    switch(config)#router bgp 64500
    switch(config-router-bgp)#bgp bestpath med missing-as-worst
    switch(config-router-bgp)#
    

bgp bestpath tie-break cluster-list-length

The bgp bestpath tie-break cluster-list-length command causes the best-path selection process to prefer the multipath route with the shortest CLUSTER_LIST length in case of a tie in step 10. The cluster list length is assumed to be 0 if the route doesn’t carry a CLUSTER_LIST attribute.

The no bgp bestpath tie-break cluster-list-length and default bgp bestpath tie-break cluster-list-length commands restore the default behavior by removing the associated bgp bestpath tie-break cluster-list-length command from running-config.

Command Mode

Router-BGP Configuration

Command Syntax

bgp bestpath tie-break cluster-list-length

no bgp bestpath tie-break cluster-list-length

default bgp bestpath tie-break cluster-list-length

Related Commands

Example

  • These commands configure the BGP selection process to prefer the multipath route with the shortest CLUSTER_LIST length in case of a tie.e
    switch(config)#router bgp 64500
    switch(config-router-bgp)#bgp bestpath tie-break cluster-list-length
    switch(config-router-bgp)#

bgp bestpath tie-break router-id

The bgp bestpath tie-break router-id command causes the best-path selection process to prefer the multipath route with the lowest ROUTER_ID in case of a tie in step 10. If the route is a reflected route (i.e., if it contains route reflector attributes), the process will use the ORIGINATOR_ID as the ROUTER_ID for comparison. This behavior is disabled by default.

The no bgp bestpath tie-break router-id and default bgp bestpath tie-break router-id commands restore the default behavior by removing the associated bgp bestpath tie-break router-id command from running-config.

Command Mode

Router-BGP Configuration

Command Syntax

bgp bestpath tie-break router-id

no bgp bestpath tie-break router-id

default bgp bestpath tie-break router-id

Related Commands

Example

  • These commands configure the best-path selection process to prefer the multipath route with the lowest ROUTER_ID in case of a tie.
    switch(config)#router bgp 64500
    switch(config-router-bgp)#bgp bestpath tie-break router-id
    switch(config-router-bgp)#

bgp client-to-client reflection

By default, routes received from a route reflector client and selected as best routes are propagated to all BGP peers, including other route reflector clients. If the clients are fully meshed, however, routes received from a client do not need to be mirrored to other clients. In this case, client-to-client reflection should be disabled.

The no bgp client-to-client reflection command disables client-to-client reflection.

The bgp client-to-client reflection and default bgp client-to-client reflection commands restore the default behavior by removing the no bgp client-to-client reflection command from running-config.

Command Mode

Router-BGP Configuration

Command Syntax

bgp client-to-client reflection

no bgp client-to-client reflection

default bgp client-to-client reflection

Example

  • These commands disable client-to-client reflection on the switch.
    switch(config)#router bgp 1
    switch(config-router-bgp)#no bgp client-to-client reflection
    switch(config-router-bgp)#

bgp cluster-id

When using route reflectors, an AS is divided into clusters. A cluster consists of one or more route reflectors and a group of clients to which they re-advertise route information, and for redundancy a single cluster may contain multiple route reflectors. Each route reflector has a cluster ID. If the cluster has only one route reflector the cluster ID is its router ID, but if a cluster has multiple route reflectors a 4-byte cluster ID must be assigned to all route reflectors in the cluster. All must be configured with the same cluster ID to allow them to identify updates from the cluster’s other route reflectors.

The bgp cluster-id command configures the cluster ID in a cluster with multiple route reflectors.

The no bgp cluster-id and default bgp cluster-id commands remove the cluster ID by removing the corresponding bgp cluster-id command from running-config. Do not remove the cluster ID if there are multiple route reflectors in the cluster.

Command Mode

Router-BGP Configuration

Command Syntax

bgp cluster-id ID_NUM

no bgp cluster-id

default bgp cluster-id

Parameters

  • ID_NUM cluster ID shared by all route reflectors in the cluster (32-bit dotted-decimal notation). Options include:
    • 0.0.0.1 to 255.255.255.255 valid cluster ID number.
    • 0.0.0.0 removes the cluster-ID from the switch. Equivalent to no bgp cluster-id command.

Example

  • This command sets the cluster ID for the switch to 172.22.30.101.

    switch(config)#router bgp 1
    switch(config-router-bgp)#bgp cluster-id 172.22.30.101
    switch(config-router-bgp)#

bgp confederation identifier

The bgp confederation identifier command configures the confederation identifier. Confederation can reduce the number of iBGP connections in a large AS domain. The AS domain is divided into several smaller sub-ASs, and each sub-AS remains fully connected. Devices in a sub-AS exchange information via iBGP, while devices in different sub-ASs use eBGP

The no bgp confederation identifier and default bgp confederation identifier commands remove the bgp confederation identifier command from running-config.

Command Mode

Router-BGP Configuration

Command Syntax

bgp confederation identifier as_number

no bgp confederation identifier

default bgp confederation identifier

Parameters

  • as_number the ID of BGP AS confederation. Values range from 1 to 4294967295.

Example

  • This command sets the BGP confederation identifier to 9.
    switch(config)#router bgp 1
    switch(config-router-bgp)#bgp confederation identifier 9
    switch(config-router-bgp)#

bgp confederation peers

The bgp confederation peers command configures a confederation consisting of sub-ASs.

Before this command is executed, the confederation ID should be configured using the bgp confederation identifier command. Otherwise this configuration is invalid. The configured ASs in this command are inside the confederation and each AS uses a fully meshed network. The confederation appears as a single AS to the devices outside it.

The no bgp confederation peers and default bgp confederation peers commands delete the specified sub-AS from the confederation by removing the corresponding bgp confederation peers command from running-config.

Command Mode

Router-BGP Configuration

Command Syntax

bgp confederation peers as_range

no bgp confederation peers as_range

default bgp confederation peers as_range

Parameters
  • as_range the sub-AS number. Formats include number (from 1 to 4294967295), number range, or comma-delimited list of numbers and ranges.

Example

  • This command configures the confederation that contains AS 1000 and AS 1002.
    switch(config)#router bgp 1
    switch(config-router-bgp)#bgp confederation peers 1000 1002
    switch(config-router-bgp)#

bgp convergence slow-peer time

The bgp convergence slow-peer time command configures the idle peer time to wait for the slow peers to establish a session in a BGP convergence state.

The no bgp convergence slow-peer time command disables the inheritance of the configuration from the global BGP configuration mode. The default bgp convergence slow-peer time command sets the timeout value to the default value.

Command Mode

Router-BGP Configuration

Command Syntax

bgp convergence slow-peer time timeout

no bgp convergence slow-peer time

default bgp convergence slow-peer time

Parameters

  • timeout the maximum time to wait for the slow peers to establish a session connection. Values range from 1 to 3600 seconds. The default value is 90 seconds.

Example

  • This command configures an idle peer timeout of 40 seconds to wait before establishing a session.
    switch(config)#router bgp 1
    switch(config-router-bgp)#bgp convergence slow-peer time 40
    switch(config-router-bgp)#

bgp convergence time

The bgp convergence time command configures the time to wait before the BGP convergence starts in a session.

The no bgp convergence time command removes the configured convergence time to wait. The default bgp convergence time command sets the timeout value to the default value.

Command Mode

Router-BGP Configuration

Command Syntax

bgp convergence time timeout_range

no bgp convergence time

default bgp convergence time

Parameters

  • timeout_range the maximum time to wait for the BGP convergence. Values range from 1 to 3600 seconds. The default value is 300 seconds.

Example

  • This command configures a convergence time of 200 seconds to wait before establishing a session.
    switch(config)#router bgp 1
    switch(config-router-bgp)#bgp convergence time 200
    switch(config-router-bgp)#

bgp default

The bgp default command configures the default address family activation level of all addresses configured as BGP neighbors. The switch sends the following announcements to addresses active in an address family:

  • IPv4 address family: IPv4 capability and all network advertisements with IPv4 prefixes.
  • IPv6 address family: IPv6 capability and all network advertisements with IPv6 prefixes.

The following commands configure default address family activation levels for addresses configured as BGP neighbors:

  • bgp default ipv4-unicast: all addresses are IPv4 address family active.
  • no bgp default ipv4-unicast: all addresses are not IPv4 address family active.
  • bgp default ipv6-unicast: all addresses are IPv6 address family active
  • no bgp default ipv6-unicast: all addresses are not IPv6 address family active.
  • bgp default ipv4-unicast transport ipv6: all BGP neighbor addresses are IPv4 address family active and IPv6 neighbors can receive IPv4 NLRIs.
Note: If it is necessary to exchange IPv4 NLRIs over an IPv6 connection, the IPv4 address family must be activated on the IPv6 neighbor. To do this for all IPv6 neighbors, use the command bgp default ipv4-unicast transport ipv6. For an individual neighbor, use the neighbor activate command for the IPv6 neighbor in the IPv4 address-family configuration mode as described below.

The activation state of an individual BGP neighbor address is configured by the neighbor activate command. The neighbor activate command overrides the address’s default activation state for the address family configuration mode in which the command is issued:

  • neighbor activate: the specified address is active.
  • no neighbor activate: the specified address is not active.

The default-default address family activation state defines the address family activation level of all addresses configured as BGP neighbors when running-config does not contain any bgp default commands. The default state of the BGP default activation level varies by address family.

  • IPv4 address family: all BGP addresses are IPv4 address family active.
  • IPv6 address family: all BGP addresses are not IPv6 address family active.

The default bgp default command restores the default-default activation setting for BGP neighbor addresses in the specified address family:

  • default bgp ipv4-unicast is equivalent to bgp ipv4-unicast
  • default bgp ipv6-unicast is equivalent to no bgp ipv6-unicast

Command Mode

Router-BGP Configuration

Command Syntax

bgp default ADDRESS_FAMILY

no bgp default ADDRESS_FAMILY

default bgp default ADDRESS_FAMILY

Parameters

  • ADDRESS_FAMILY BGP address family. Options include:
    • ipv4-unicast IPv4-unicast peering sessions.
    • ipv6-unicast IPv6-unicast peering sessions.

Example

  • These commands configure the switch to configure all BGP neighbor addresses as IPv4 address-family active and IPv6 address-family active.

    switch(config)#router bgp 1
    switch(config-router-bgp)#bgp default ipv4-unicast
    switch(config-router-bgp)#bgp default ipv6-unicast
    switch(config-router-bgp)#show active
    router bgp 65533
     bgp log-neighbor-changes
     distance bgp 20 200 200
     neighbor 172.23.254.2 remote-as 65533
     neighbor 172.41.254.78 remote-as 65534
     neighbor 2001:0DB8:52a4:fe01::2 remote-as 65533
     neighbor 2001:0DB8:52a4:fe4c::1 out-delay 10
    switch(config-router-bgp)#

The show active command does not display the bgp default ipv4-unicast command because it is the default setting for IPv4 peering sessions.

bgp enforce-first-as

The bgp enforce-first-as command causes a forced comparison of the first autonomous system (AS) in the AS path of eBGP routes received from BGP neighbors to the configured remote external peer autonomous system number (ASN). Updates from eBGP peers that do not include that ASN as the first item in the AS path (in the AS_PATH attribute) are discarded.

This behavior is enabled by default upon BGP configuration, and disabled globally by the no form of this command. To configure first-AS enforcement for an individual neighbor or peer group, use the neighbor enforce-first-as command.

Command Mode

Router-BGP Configuration

Command Syntax

bgp enforce-first-as

default bgp enforce-first-as

no bgp enforce-first-as

Example

  • This command configures BGP to enforce the first AS globally.
    switch(config-router-bgp)#bgp enforce-first-as
    switch(config-router-bgp)#

bgp listen range

The bgp listen range command identifies the BGP peering request from a range of IPv4 or IPv6 address, and names the dynamic peer group to which those peers belong to. To create a static peer group, use the neighbor peer group (create) command.

The request can be from a single AS number or from a range of AS numbers configured. To accept the peering request from single ASN use the remote-as option, and to accept request from multiple ASNs use the peer-filter option.

Members of a dynamic peer group are configured in groups and not as individuals. Once a new peer group is created with a group name, the group name is then used as an argument by the following neighbor commands:

The no bgp listen range and default bgp listen range commands remove the dynamic peer group by deleting the corresponding command from running-config. To remove a static peer group, use the no neighbor command. All peering relationships with group members are terminated when the dynamic peer group is deleted.

Command Mode

Router-BGP Configuration

Command Syntax

bgp listen range NET_ADDRESS peer-group group_name [remote-as as_number | peer-filter filter_name]

no bgp listen range NET_ADDRESS peer-group group_name

default bgp listen range NET_ADDRESS peer-group group_name

Parameters

  • NET_ADDRESS IP address range. Options include:
    • IPv4_subnet IPv4 subnet (CIDR notation).
    • IPv4_address mask subnet IPv4 subnet (dotted decimal notation).
    • IPv6_prefix IPv6 subnet (dotted decimal notation).
  • group_name name of the peer group.
  • as_number the autonomous system number, ranges from 1 to 4294967295.
  • filter_name name of the peer filter.

Examples

  • These commands create a dynamic peer group called “brazil” in AS 5 which accepts peering requests from the 192.168.6.0/24 subnet.
    switch(config)#router bgp 1
    switch(config-router-bgp)#bgp listen range 192.168.6.0/24 peer-group brazil remote-as 5
    switch(config-router-bgp)#
  • These commands create a dynamic peer group called “brazil” in a range of AS numbers, which accepts peering requests from the 192.0.2.0/24 subnet. The range of AS numbers is defined by peer filter option.
    switch(config)#router bgp 1
    switch(config-router-bgp)#bgp listen range 192.0.2.0/24 peer-group brazil peer-filter group-1
    switch(config-router-bgp)#

bgp log-neighbor-changes

The bgp log-neighbor-changes command configures the switch to generate a log message when a BGP peer enters or exits the established state. This is the default behavior.

The no bgp log-neighbor-changes command disables the generation of these log messages. The default bgp log-neighbor-changes command enables the generation of these log messages.

Command Mode

Router-BGP Configuration

Command Syntax

bgp log-neighbor-changes

no bgp log-neighbor-changes

default bgp log-neighbor-changes

Example

  • These commands configure the switch to generate a message when a BGP peer enters or exits the established state.
    switch(config)#router bgp 1
    switch(config-router-bgp)#bgp log-neighbor-changes
    switch(config-router-bgp)#

bgp redistribute-internal (BGP)

The bgp redistribute-internal command enables the redistribution of iBGP routes into an interior gateway protocol (IGP).

The no bgp redistribute-internal and default bgp redistribute-internal commands disable route redistribution from the specified domain by removing the corresponding bgp redistribute-internal command from running-config.

Command Mode

Router-BGP Configuration Router-BGP Address-Family Configuration

Command Syntax

bgp redistribute internal

no bgp redistribute internal

default bgp redistribute internal

Example
  • This command redistributes internal BGP routes.
    switch(config)#router bgp 9
    switch(config-router-bgp)#bgp redistribute-internal
    switch(config-router-bgp)#

bgp route install-map

The bgp route install-map command enables BGP Selective Route Download on the switch and allows the learning and advertising of the BGP routes without installing them in hardware.

The no bgp route install-map and default bgp route install-map commands delete the BGP Selective Route Download instance.

The exit command returns the switch to global configuration mode.

Command Mode

BGP Configuration

Command Syntax

bgp route install-map map_name

Parameter

  • map_name The name of the route map configured.

Example

  • These commands configure BGP Selective Route Download for test_BGP map.
    switch(config)#router bgp 100
    switch(config-router-bgp)#bgp route install-map test_BGP
    switch(config-router-bgp)#

bgp route-reflector preserve-attributes

The bgp route-reflector preserve-attributes command configures the switch as a BGP route reflector. By default, BGP route reflector is disabled.

The no bgp route-reflector preserve-attributes and default bgp route-reflector preserve-attributes commands disable BGP route reflector on the switch.

The exit command returns the switch to global configuration mode.

Command Mode

Router-BGP Configuration

Command Syntax

bgp route-reflector preserve-attributes [always]

no bgp route-reflector preserve-attributes [always]

default bgp route-reflector preserve-attributes [always]

Parameter

  • always Always preserve route attributes, overwriting route map changes.

Example

  • The following commands configure the switch as BGP route reflector.
    switch(config)#router bgp 10
    switch(config-router-bgp)#bgp route-reflector preserve-attributes always
    switch(config-router-bgp)#

clear ip bgp counters

The clear ip bgp counters command resets general statistics of peers. These statistics primarily consist of message-related counts.

Command Mode

Privileged EXEC

Command Syntax

clear ip bgp [PEERS] counters [VRF_INSTANCES]

Parameters

  • PEERS specifies targeted BGP peers. Options include:
    • <no parameters> all IPv4 and IPv6 peers.
    • * all IPv4 and IPv6 peers.
    • ipv4_addr the IPv4 peer with the specified IPv4 address.
    • ipv6_addr the IPv6 peer with the specified IPv6 address.
    • intrf_ipv6_addr the peer using the specified IPv6 link-local address.
    • peer-group peer_grp_name the peers using the specified BGP peer group.
  • VRF_INSTANCES specifies the VRF(s) examined for BGP peers. Options include:
    • <no parameters> resets matching peers in the context-active VRF.
    • vrf_name resets matching peers in the specified VRF.
    • all resets matching peers in all VRFs.
    • default resets matching peers in the default VRF.

Related Commands

Example

  • This command resets general statistics of all IPv4 and IPv6 peers in the context-active VRF.
    switch#clear ip bgp counters
    ! Clearing all IPv4 and IPv6 peering sessions
    switch#

clear ip bgp errors

The clear ip bgp errors command resets the error statistics and history of peers. Peer general statistics primarily consist of notification errors, socket errors, and update errors.

Command Mode

Privileged EXEC

Command Syntax

clear ip bgp [PEERS] errors [VRF_INSTANCES]

Parameters

  • PEERS specifies targeted BGP peers. Options include:
    • <no parameters> all IPv4 and IPv6 peers.
    • * all IPv4 and IPv6 peers.
    • ipv4_addr the IPv4 peer with the specified IPv4 address.
    • ipv6_addr the IPv6 peer with the specified IPv6 address.
    • intrf_ipv6_addr the peer using the specified IPv6 link-local address.
    • peer-group peer_grp_name the peers using the specified BGP peer group.
  • VRF_INSTANCES specifies the VRF(s) examined for BGP peers. Options include:
    • <no parameters> resets matching peers in the context-active VRF.
    • vrf_name resets matching peers in the specified VRF.
    • all resets matching peers in all VRFs.
    • default resets matching peers in the default VRF.

Related Commands

Example

  • This command resets the error statistics of all IPv4 and IPv6 peers in the context-active VRF.
    switch#clear ip bgp errors
    ! Clearing all IPv4 and IPv6 peering sessions
    switch#

clear ip bgp neighbor *

The clear ip bgp neighbor * command clears BGP neighbors belonging to the IPv4 transport address family. To clear BGP neighbors in the IPv6 transport address family, use the clear ipv6 bgp neighbor * command.

Command Mode

Privileged EXEC

Command Syntax

clear ip bgp neighbor * [VRF_INSTANCE]

Parameters

  • VRF_INSTANCE specifies VRF instance for which IPv4 transport address family BGP neighbors will be cleared. Options include:
    • <no parameter> clears IPv4 BGP neighbors in the context-active VRF.
    • vrf vrf_name clears IPv4 BGP neighbors in the specified VRF.
    • vrf all clears IPv4 BGP neighbors in the all VRFs.
    • vrf default clears IPv4 BGP neighbors in the default VRF.

Related Commands

Examples

  • This command clears all IPv4 BGP neighbors in the context-active VRF.
    switch#clear ip bgp neighbor *
    switch#
  • This command clears all IPv4 BGP neighbors in VRF “purple.”
    switch#clear ip bgp neighbor * vrf purple
    switch#

clear ip bgp

The clear ip bgp command removes learned BGP routes from the routing table, reads all routes from designated peers, and sends routes to those peers as required. This command can also clear the switch’s BGP sessions with its peers.

Routes that are read or sent are processed through modified route maps or AS-path access lists.

Command Mode

Privileged EXEC

Command Syntax

clear ip bgp [PEERS] [RESET_TYPE] [DATA_FLOW] [VRF_INSTANCE]

Parameters

  • PEERS specifies targeted BGP peers. Options include:
    • <no parameters> all IPv4 and IPv6 peers.
    • * all IPv4 and IPv6 peers.
    • ipv4_addr the IPv4 peer with the specified IPv4 address.
    • ipv6_addr the IPv6 peer with the specified IPv6 address.
    • intrf_ipv6_addr the peer using the specified IPv6 link-local address.
    • peer-group peer_grp_name the peers using the specified BGP peer group.
  • RESET_TYPE specifies the method used to reset routes. Options include:
    • <no parameters> performs a hard reset that terminates current BGP sessions and recreates the local routing information base.
    • soft performs a soft reset that maintains current BGP sessions and reconfigures the local routing information base using stored routes.
  • DATA_FLOW restricts soft reset to inbound or outbound routes. Hard reset is bidirectional. Options include:

    • <no parameters> resets inbound and outbound routes.
    • in resets inbound peer routes.
    • out resets outbound peer routes.
  • VRF_INSTANCES specifies the VRF(s) examined for BGP peers. Options include:

    • <no parameters> resets matching peers in the context-active VRF.
    • vrf_name resets matching peers in the specified VRF.
    • all resets matching peers in all VRFs.
    • default resets matching peers in the default VRF.

Related Commands

Guidelines

Use the clear ip bgp command after changing any of the following BGP attributes:

  • weights
  • distribution lists
  • timers
  • administrative distance

Examples

  • This command performs a hard reset of all IPv4 and IPv6 peers in the context-active VRF.
    switch#clear ip bgp
    switch#
  • This command has the same behavior as the above clear ip bgp command.
    switch#clear ip bgp *
    switch#

clear ipv6 bgp counters

The clear ipv6 bgp counters command resets general statistics of peers. These statistics primarily consist of message-related counts.

Command Mode

Privileged EXEC

Command Syntax

clear ipv6 bgp [PEERS] counters [VRF_INSTANCES]

Parameters

  • PEERS specifies targeted BGP peers. Options include:
    • <no parameters> all IPv4 and IPv6 peers.
    • * all IPv4 and IPv6 peers.
    • ipv4_addr the IPv4 peer with the specified IPv4 address.
    • ipv6_addr the IPv6 peer with the specified IPv6 address.
    • intrf_ipv6_addr the peer using the specified IPv6 link-local address.
    • peer-group peer_grp_name the peers using the specified BGP peer group.
  • VRF_INSTANCES specifies the VRF(s) examined for BGP peers. Options include:
    • <no parameters> resets matching peers in the context-active VRF.
    • vrf_name resets matching peers in the specified VRF.
    • all resets matching peers in all VRFs.
    • default resets matching peers in the default VRF.

Related Commands

Example

  • This command resets general statistics of all IPv4 and IPv6 peers in the context-active VRF.
    switch#clear ipv6 bgp counters
    ! Clearing all IPv4 and IPv6 peering sessions
    switch#

clear ipv6 bgp errors

The clear ipv6 bgp errors command resets the error statistics and history of peers. Peer general statistics primarily consist of notification errors, socket errors, and update errors.

Command Mode

Privileged EXEC

Command Syntax

clear ipv6s bgp [PEERS] errors [VRF_INSTANCES]

Parameters

  • PEERS specifies targeted BGP peers. Options include:
    • <no parameters> all IPv4 and IPv6 peers.
    • * all IPv4 and IPv6 peers.
    • ipv4_addr the IPv4 peer with the specified IPv4 address.
    • ipv6_addr the IPv6 peer with the specified IPv6 address.
    • intrf_ipv6_addr the peer using the specified IPv6 link-local address.
    • peer-group peer_grp_name the peers using the specified BGP peer group.
  • VRF_INSTANCES specifies the VRF(s) examined for BGP peers. Options include:
    • <no parameters> resets matching peers in the context-active VRF.
    • vrf_name resets matching peers in the specified VRF.
    • all resets matching peers in all VRFs.
    • default resets matching peers in the default VRF.

Related Commands

Example

  • This command resets the error statistics of all IPv4 and IPv6 peers in the context-active VRF.
    switch#clear ipv6 bgp errors
    ! Clearing all IPv4 and IPv6 peering sessions
    switch#

clear ipv6 bgp neighbor *

The clear ipv6 bgp neighbor * command clears BGP neighbors belonging to the IPv4 transport address family. To clear BGP neighbors in the IPv4 transport address family, use the clear ip bgp neighbor * command.

Command Mode

Privileged EXEC

Command Syntax

clear ipv6 bgp neighbor * [VRF_INSTANCE]

Parameters

  • VRF_INSTANCE specifies VRF instance for which IPv6 transport address family BGP neighbors will be cleared. Options include:
    • <no parameter> clears IPv6 BGP neighbors in the context-active VRF.
    • vrf vrf_name clears IPv6 BGP neighbors in the specified VRF.
    • vrf all clears IPv6 BGP neighbors in the all VRFs.
    • vrf default clears IPv6 BGP neighbors in the default VRF.

Related Commands

Examples

  • This command clears all IPv4 BGP neighbors in the context-active VRF.
    switch#clear ip bgp neighbor *
    switch#
  • This command clears all IPv4 BGP neighbors in VRF “purple.”
    switch#clear ip bgp neighbor * vrf purple
    switch#

clear ipv6 bgp

The clear ipv6 bgp command removes learned BGP routes from the routing table, reads all routes from designated peers, and sends routes to those peers as required. This command can also clear the switch’s BGP sessions with its peers.

Routes that are read or sent are processed through modified route maps or AS-path access lists.

Command Mode

Privileged EXEC

Command Syntax

clear ipv6 bgp [PEERS] [RESET_TYPE] [DATA_FLOW] [VRF_INSTANCE]

Parameters

  • PEERS specifies targeted BGP peers. Options include:
    • <no parameters> all IPv4 and IPv6 peers.
    • * all IPv4 and IPv6 peers.
    • ipv4_addr the IPv4 peer with the specified IPv4 address.
    • ipv6_addr the IPv6 peer with the specified IPv6 address.
    • intrf_ipv6_addr the peer using the specified IPv6 link-local address.
    • peer-group peer_grp_name the peers using the specified BGP peer group.
  • RESET_TYPE specifies the method used to reset routes. Options include:
    • <no parameters> performs a hard reset that terminates current BGP sessions and recreates the local routing information base.
    • soft performs a soft reset that maintains current BGP sessions and reconfigures the local routing information base using stored routes.
  • DATA_FLOW restricts soft reset to inbound or outbound routes. Hard reset is bidirectional. Options include:
    • <no parameters> resets inbound and outbound routes.
    • in resets inbound peer routes.
    • out resets outbound peer routes.
  • VRF_INSTANCES specifies the VRF(s) examined for BGP peers. Options include:
    • <no parameters> resets matching peers in the context-active VRF.
    • vrf_name resets matching peers in the specified VRF.
    • all resets matching peers in all VRFs.
    • default resets matching peers in the default VRF.

Related Commands

Guidelines

Use the clear ipv6 bgp command after changing any of the following BGP attributes:

  • weights
  • distribution lists
  • timers
  • administrative distance

Examples

  • This command performs a hard reset of all IPv4 and IPv6 peers in the context-active VRF.
    switch#clear ipv6 bgp
    switch#
  • This command has the same behavior as the above clear ip bgp command.
    switch#clear ipv6 bgp *
    switch#

distance bgp

The distance bgp command assigns an administrative distance to routes that the switch learns through BGP. Routers use administrative distances to select a route when two protocols provide routing information to the same destination. Distance values range from 1 to 255; lower distance values correspond to higher reliability. BGP routing tables do not include routes with a distance of 255.

The distance command assigns distance values to external, internal, and local BGP routes:

  • external: Best-path routes learned from a neighbor external to the autonomous system. Default distance is 200.
  • internal: Internal routes are routes learned from a BGP entity within the same autonomous system. Default distance is 200.
  • local: Local routes are networks listed with a network router configuration command for that router or for networks that are redistributed from another process. Default distance is 200.

The no distance bgp and default distance bgp commands restore the default administrative distances by removing the distance bgp command from running-config.

Command Mode

Router-BGP Configuration

Command Syntax

distance bgp external_dist [INTERNAL_LOCAL]

no distance bgp

default distance bgp

Parameters

  • external_dist distance assigned to external routes. Values range from 1 to 255.
  • INTERNAL_LOCAL distance assigned to internal and local routes. Values for both routes range from 1 to 255. Options include:
    • <no parameter> the external_dist value is also assigned to internal and local routes.
    • internal_dist local_dist values assigned to internal and local routes.

Example

  • This command assigns an administrative distance of 150 to external routes, 200 to internal, and 150 to local routes.
    switch(config)#router bgp 1
    switch(config-router-bgp)#distance bgp 150 200 150
    switch(config-router-bgp)#

dynamic peer max

The dynamic peer max command limits the number of dynamic BGP peers allowed on the switch.

The no dynamic peer max and default dynamic peer max commands restore the default limit of dynamic BGP peers by removing the dynamic peer max command from running-config.

Command Mode

Router-BGP Configuration

Command Syntax

dynamic peer max maximum

no dynamic peer max

default dynamic peer max

Parameters

  • maximum the maximum number of dynamic BGP peers to be allowed on the switch. Values range from 1 to 1000; default value is 100.

Example

  • This command sets the maximum number of dynamic BGP peers allowed on the switch to 200.
    switch(config)#router bgp 1
    switch(config-router-bgp)#dynamic peer max 200
    switch(config-router-bgp)#

graceful-restart stalepath-time

The graceful-restart stalepath-time command specifies the maximum time that stale routes from a restarting BGP neighbor will be retained after a BGP session is re-established with that peer.

The no graceful-restart stalepath-time and default graceful-restart stalepath-time commands restore the default value of 300 seconds by deleting the graceful-restart stalepath-time statement from running-config.

Command Mode

Router-BGP Configuration

Command Syntax

graceful-restart stalepath-time interval

no graceful-restart stalepath-time

default graceful-restart stalepath-time

Parameters

  • interval Maximum period (in seconds) that stale routes from a restarting BGP neighbor will be retained after the BGP session is re-established. Values range from 1 to 3600 (60 minutes). Default is 300.

Example

  • These commands configure the stale path retention interval to 15 minutes.
    switch(config)#router bgp 1
    switch(config-router-bgp)#graceful-restart stalepath-time 900
    switch(config-router-bgp)#

graceful-restart-helper

The graceful-restart helper command enables BGP graceful restart helper mode on the switch for all BGP neighbors. When graceful restart helper mode is enabled, the switch will retain routes from neighbors which are capable of graceful restart while those neighbors are restarting BGP. Graceful restart is enabled by default. To configure graceful restart helper mode for a specific neighbor or peer group, use the neighbor graceful-restart-helper command. Individual neighbor configuration takes precedence over the global configuration.

The no graceful-restart helper command disables graceful restart helper mode on the switch. The default graceful-restart helper command enables graceful restart helper mode by removing the corresponding no graceful-restart helper command from running-config.

Command Mode

Router-BGP Configuration

Command Syntax

graceful-restart helper

no graceful-restart helper

default graceful-restart helper

Example

  • These commands disable graceful restart helper mode on the switch.
    switch(config)#router bgp 1
    switch(config-router-bgp)#no graceful-restart-helper
    switch(config-router-bgp)#

ip as-path access-list

The ip as-path access-list command creates an access list to filter BGP route updates. If access list list_name does not exist, this command creates it. If it already exists, this command appends statements to the list.

The no ip as-path access-list and default ip as-path access-list commands delete the named access list.

Command Mode

Global Configuration

Command Syntax

ip as-path access-list list_name FILTER_TYPE regex ORIGIN

no ip as-path access-list list_name

default ip as-path access-list list_name

Parameters

  • list_name the name of the AS path access list.
  • FILTER_TYPE access resolution of the specified AS path. Options include:
    • permit access is permitted.
    • deny access is denied.
  • regex a regular expression describing the AS path being filtered. Regular expressions are pattern-matching strings that are composed of text characters and operators.
  • ORIGIN the origin of the path information. Values include:
    • <no parameter> sets the origin to any.
    • any any BGP origin.
    • egp EGP origin.
    • igp IGP origin.
    • incomplete incomplete origin.

Example

  • These commands create an AS path access list named “list1” which allows all BGP routes except those originating in AS 3.
    switch(config)#ip as-path access-list list1 deny _3$
    switch(config)#ip as-path access-list list1 permit .*
    switch(config)#

ip as-path regex-mode

The ip as-path regex-mode command specifies how the switch will evaluate regular expressions describing AS paths in ACLs. When the regex mode is set to asn, AS numbers in the ACL are interpreted as AS numbers; only complete AS number matches in the AS path return a match. When it is set to string, AS numbers in the ACL are interpreted as strings; both complete AS number matches and longer AS numbers that include the target string return a match. The default mode is asn.

For example, asn mode will return “false” and string mode will return “true” when searching for “10” in an AS path of “100 200.”

The no ip as-path regex-mode and default ip as-path regex-mode commands restore the regex mode to asn by removing the ip as-path regex-mode command from running-config.

Command Mode

Global Configuration

Command Syntax

ip as-path regex-mode MODE_SETTING

no ip as-path regex-mode

default ip as-path regex-mode

Parameters

  • MODE_SETTING Specifies how regular expressions describing AS paths in AS path ACLs will be evaluated. Options include:
    • asn AS numbers in the ACL are interpreted as AS numbers; only complete AS number matches in the AS path return a match.
    • string AS numbers in the ACL are interpreted as strings; both complete AS number matches and longer AS numbers that include the target string return a match.

Example

  • This command sets the regex mode to string.
    switch(config)#ip as-path regex-mode string
    switch(config)#

ip community-list regexp

The ip community-list regexp command creates and configures a BGP access list based on BGP communities. A BGP community access list filters prefixes based on their BGP communities. The command uses regular expressions to identify the communities specified by the list. To create a community list by explicitly specifying one or more communities, use the ip community-list command.

The no ip community-list regexp and default ip community-list regexp commands delete the specified community list. To delete a specific community-list entry, specify the entry in the no ip community-list regexp command.

Command Mode

Global Configuration

Command Syntax

ip community-list regexp list_name {deny | permit} reg_exp

no ip community-list regexp list_name {deny | permit} reg_exp

default ip community-list regexp list_name

Parameters

  • list_name name of the community list. Valid input is text.
  • permit access is permitted for the specified community.
  • deny access is denied for the specified community.
  • reg_exp list of communities, formatted as a regular expression. Regular expressions are pattern-matching strings that are composed of text characters and operators.
    Note: When using the no form of the command, a regular expression can be used to specify a single entry to be removed from the list, leaving the rest of the list intact. If no entry is specified, the no form of the command removes the entire list.

Related Commands

Guideline

The ip community-list regexp command with the permit internet option permits access to only those routes that carry the community value of 0.

Examples

  • This command creates a BGP community list that permits routes from networks 20-24 and 30-34 in autonomous system 10.
    switch(config)#ip community-list regexp list_2 permit 10:[2-3][0-4]_
    switch(config)#
  • This command removes the above statement from the community list named “list_2,” leaving any other statements in the list intact.
    switch(config)#no ip community-list regexp list_2 permit 10:[2-3][0-4]_
    switch(config)#
  • This command deletes the community list named “list_2” entirely.
    switch(config)#no ip community-list regexp list_2 
    switch(config)#
  • This command permits access to all routes associated with the BGP community list (CLIST1) that carry the community value 0.
    switch(config)#ip community-list regexp CLIST1 permit internet
    switch(config)#

ip community-list

The ip community-list command creates and configures a BGP access list based on BGP communities.

The no ip community-list and default ip community-list commands delete the specified community list by removing the corresponding ip community-list command from running-config.

Command Mode

Global Configuration

Command Syntax

ip community-list list_name [permit | deny] [GSHUT | aa:nn | internet | local-as | no-advertise | no-export | number]

no ip community-list list_name

default ip community-list list_name

Parameters

  • list_name name of the community list. Valid input is text.
  • permit permits access to the specified community.
  • deny denies access to the specified community.
  • GSHUT well-known graceful shutdown community.
  • aa:nn AA is 65535 and NN specifies the community number (0-65535) within the AS.
  • internet advertises route to the Internet community.
  • local-as advertises route only to local peers.
  • no-advertise does not advertise route to any peer.
  • no-export advertises route only within BGP AS boundary.
  • number community number. Values ranges from 0 to 4294967040.

Related Commands

Guideline

eos does not support disabling the process of graceful shutdown community.

Note: The ip community-list command with the permit internet option permits access to all routes associated with any community.

Examples

  • This command creates a BGP community list (named “list_9”) that does not match members of route maps configured with AS-network number 100:250.
    switch(config)#ip community-list list_9 deny 100:250
    switch(config)#
  • These commands create a BGP community list that permits the graceful shutdown community, then use that list it in a route map to permit routes with that community.
    switch(config)#ip community-list gshut_list permit GSHUT
    switch(config)#route-map map1
    switch(config-route-map-map1)#match community gshut_list
    switch(config-route-map-map1)#exit
    switch(config)#show route-map map1
    route-map map1 permit 10
    Description:
    Match clauses:
    match community gshut_list
    SubRouteMap:
    Set clauses:
    switch(config)#
  • This command permits access to all routes associated with the BGP community list (CLIST1).
    switch(config)#ip community-list CLIST1 permit internet
    switch(config)#

ip extcommunity-list regexp

The ip extcommunity-list regexp command creates an extended community list to filter VRF routes or for link bandwidth (LBW) advertisement. The command uses regular expressions to define the extended communities specified by the list. To specify particular values, use the ip extcommunity-list command.

The following extcommunity-list types are supported:

  • Route Target (rt) identifies sites that may receive appropriately tagged routes.
  • Site of Origin (soo) identifies sites where the switch learned the route.
  • Link Bandwidth (lbw) advertises BGP link bandwidth.

The no ip extcommunity-list regexp and default ip extcommunity-list regexp commands delete the specified extended community list by removing the corresponding ip extcommunity-list regexp statement from running-config.

Command Mode

Global Configuration

Command Syntax

ip extcommunity-list regexp list_name {deny | permit} reg_exp

no ip extcommunity-list regexp list_name {deny | permit} reg_exp

default ip extcommunity-list regexp list_name

Parameters

  • list_name name of the extended community list. Valid input is text.
  • permit access is permitted for the specified extended community list.
  • deny access is denied for the specified extended community list.
  • reg_exp list of communities, formatted as a regular expression. Regular expressions are pattern-matching strings that are composed of text characters and operators.
    • Expressions beginning with RT: match the route target extended community attribute option.
    • Expressions beginning with SoO: match the site of origin extended community attribute option.

Related Commands

Example

  • This command creates a BGP extended community list that denies routes from route target networks 20-24 and 30-34 in autonomous system 10.
    switch(config)#ip extcommunity-list regexp list_1 deny RT:10:[2-3][0-4]_
    switch(config)#

ip extcommunity-list

The ip extcommunity-list command creates an extended community list to filter VRF routes or for link bandwidth (LBW) advertisement.

The following extcommunity-list types are supported:

  • Route Target (rt) identifies sites that may receive appropriately tagged routes.
  • Site of Origin (soo) identifies sites where the switch learned the route.
  • Link Bandwidth (lbw) advertises BGP link bandwidth.

The no ip extcommunity-list and default ip extcommunity-list commands delete the specified extended community list by removing the corresponding ip extcommunity-list statement from running-config.

Command Mode

Global Configuration

Command Syntax

ip extcommunity-list list_name {deny | permit} COMM_1 [COMM_2...COMM_n]

no ip extcommunity-list list_name

default ip extcommunity-list list_name

Parameters

  • list_name name of the extended community list.
  • permit access is permitted for the specified community.
  • deny access is denied for the specified community.
  • COMM_x extended community attribute. Options include:
    • rt aa:nn route target, as specified by autonomous system:network number.
    • rt ip_addr:nn route target, as specified by ip address:network number.
    • soo aa:nn Site of Origin, as specified by autonomous system:network number.
    • soo ip_addr:nn site of origin, as specified by ip address:network number.
    • lbw link bandwidth in bits per second.

Related Commands

Example

  • This command creates a BGP extended community list that denies routes from route target 100:250.

    switch(config)#ip extcommunity-list list_9 deny rt 100:250
    switch(config)#

ip large-community-list regexp

The ip large-community-list regexp command creates and configures a BGP access list based on BGP large communities. A BGP large-community access list filters prefixes based on their BGP large community values. The command uses regular expressions to match large communities. Multiple large-community lists with the same name may be specified. To create a large-community list by explicitly specifying one or more communities, use the ip large-community-list command.

Large-communities are represented as follows: [ASN]:local-part1:local-part2.

The no ip large-community-list regexp and default ip large-community-list regexp commands delete the specified large community list. To delete a specific community-list entry, specify the entry in the no ip large-community-list regexp command.

Command Mode

Global Configuration

Command Syntax

ip large-community-list regexp list_name {deny | permit} reg_exp

no ip large-community-list regexp list_name {deny | permit} reg_exp

default ip large-community-list regexp list_name

Parameters
  • list_name name of the community list. Valid input is text.
  • permit access is permitted for the specified community.
  • deny access is denied for the specified community.
  • reg_exp list of communities, formatted as a regular expression. Regular expressions are pattern-matching strings that are composed of text characters and operators.
    Note: When using the no form of the command, a regular expression can be used to specify a single entry to be removed from the list, leaving the rest of the list intact. If no entry is specified, the no form of the command removes the entire list.

Related Commands

Examples

  • This command creates a BGP large community list that permits routes from autonomous system 10 with local-part1 value of 20-24 or 30-34.
    switch(config)#ip large-community-list regexp list_2 permit 10:[2-3][0-4]:_
    switch(config)#
  • This command removes the above statement from the large community list named “list_2,” leaving any other statements in the list intact.
    switch(config)#no ip large-community-list regexp list_2 permit 10:[2-3]:[0-4]_
    switch(config)#
  • This command deletes the large community list named “list_2” entirely.
    switch(config)#no ip large-community-list regexp list_2
    switch(config)#

match as-range

The match as-range command defines the match statement for the peer-filter, based on the match statement the peer-filter accept or reject the incoming peer request. The match statement includes a sequence number, AS number range and a match condition to accept or reject a peer by comparing its remote AS number to the specified range. A peer filter can consist of a single match statement or multiple match statements. The match statement for the peer filter is configured under peer-filter configuration mode.

The no match as-range or default match as-range command deletes the peer-filter condition for the group from running-config.

Command Mode

Peer-Filter Configuration

Command Syntax

[sequence_number] match as-range [as_number1] [- as_number2] result {accept | reject} group_name

no[as_number1] [- as_number2] result {accept | reject} group_name

default[as_number1] [- as_number2] result {accept | reject} group_name

Parameters

  • sequence_number optional sequence number for the match statement; one is automatically created if not assigned. Values range from 0 to 65535.
  • group_name name of the peer filter group.
  • as_number the autonomous system number, values range from 1 to 4294967295.

Example

  • These commands define a peer filter that accepts any AS number.
    switch(config)#peer-filter group1
    switch(config-peer-filter-group1)#10 match as-range 1-4294967295 result accept
    switch(config-peer-filter-group1)#
  • These commands define a peer filter that accepts any AS number within 65000 and 65100 (inclusive) except 65008 and 65009.
    switch(config)#peer-filter group2
    switch(config-peer-filter-group2)#10 match as-range 65008-65009 result reject
    switch(config-peer-filter-group2)#20 match as-range 65000-651000 result accept
    switch(config-peer-filter-group2)#
  • These commands define a peer filter that accepts 3 specific remote AS numbers.
    switch(config)#peer-filter group3
    eswitch(config-peer-filter-group3)#10 match as-range 65003 result accept
    switch(config-peer-filter-group3)#20 match as-range 65007 result accept
    switch(config-peer-filter-group3)#30 match as-range 65009 result accept
    switch(config-peer-filter-group3)#

maximum paths (BGP)

The maximum-paths command controls the maximum number of parallel eBGP routes that the switch supports. The default maximum is one route. The command provides an ECMP (equal cost multiple paths) parameter that controls the number of equal-cost paths that the switch stores in the routing table for each route.

For paths to be consider equal, they must have the same weight, local preference, AS-path length, and origin. To require that they also have the same multi-exit discriminator (MED) value, use the bgp always-compare-med command. To require that their AS paths have the same contents, use the no bgp bestpath as-path multipath-relax command.

The no maximum-paths and default maximum-paths commands restore the default values of the maximum number of parallel routes and the maximum number of ECMP paths by removing the corresponding maximum paths command from running-config.

Command Mode

Router-BGP Configuration

Command Syntax

maximum-paths paths [ecmp ecmp_paths]

no maximum-paths

default maximum-paths

Parameters
  • paths maximum number of parallel routes. Default value is 1. Value must be less than or equal to the maximum number of ECMP paths.
  • ecmp_paths maximum number of ECMP paths for each route. Default is maximum value as defined belows.

    Value for each parameter ranges from 1 to the number of interfaces available per ECMP group, which is platform dependent.

    • Arad: Values range from 1 to 128. Default value is 128.
    • FM6000: Values range from 1 to 32. Default value is 32.
    • PetraA: Values range from 1 to 16. Default value is 16.
    • Trident: Values range from 1 to 32. Default value is 32.
    • Trident II: Values range from 1 to 128. Default value is 128.

Examples

  • These commands configure the maximum number of BGP parallel paths to 12 without changing the default ECMP value.
    switch(config)#router bgp 1
    switch(config-router-bgp)#maximum-paths 12
    switch(config-router-bgp)#
  • These commands configure the maximum number of eBGP parallel routes to 2, with a maximum of 4 equal cost multipath (ECMP) paths for each route.
    switch(config)#router bgp 1
    switch(config-router-bgp)#maximum-paths 2 ecmp 4
    switch(config-router-bgp)#

neighbor activate

The neighbor activate command defines the configuration mode address family activation state of a specified address that is configured as a BGP neighbor. The switch sends the following announcements to addresses active in an address family:

  • IPv4 address family: IPv4 capability and all network advertisements with IPv4 prefixes.
  • IPv6 address family: IPv6 capability and all network advertisements with IPv6 prefixes.

The bgp default command configures the default address family activation state of addresses configured as BGP neighbors. The neighbor activate and no neighbor activate commands override the neighbor’s default activation state within the configuration mode address family.

  • neighbor activate: the specified address is active in the address family.
  • no neighbor activate: the specified address is not active in the address family.

The default neighbor activate command removes the corresponding neighbor activate or no neighbor activate command from running-config, restoring the default address family activation state for the specified neighbor address.

Command Mode

Router-BGP Address-Family Configuration

Command Syntax

neighbor neighbor_ID activate

no neighbor neighbor_ID activate

default neighbor neighbor_ID activate

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.

Limitations

The switch supports the advertisement of networks with IPv6 prefixes to IPv4 transport neighbors. The switch does not support the advertisement of networks with IPv4 prefixes to IPv6 transport neighbors.

Example

  • These commands activate the advertising of specified neighbors during IPv4 peering sessions, then display the result.
    switch(config)#router bgp 1
    switch(config-router-bgp)#no address-family ipv4
    switch(config-router-bgp-af)#neighbor 172.41.18.15 activate
    switch(config-router-bgp-af)#neighbor 172.49.22.6 activate
    switch(config-router-bgp-af)#no neighbor 172.15.21.18 activate
    switch(config-router-bgp-af)#show active
     address-family ipv4
    no neighbor 172.15.21.18 activate
    neighbor 172.49.22.6 activate
    neighbor 172.41.18.15 activate
    switch(config-router-bgp-af)#exit
    switch(config-router-bgp)#

neighbor allowas-in

By default, BGP drops received routes if their autonomous system (AS) paths contain the AS number (ASN) of the switch. The neighbor allowas-in command configures the switch to accept routes from the specified BGP neighbor even if their AS paths contain the ASN of the switch itself. Optionally, the command can also configure the maximum number of times that the switch’s ASN can appear in a route before it is dropped.

The no neighbor allowas-in command configures the default behavior (dropping BGP routes that contain the ASN of the switch).

The default neighbor allowas-in command applies the system default configuration for individual neighbors and applies the peer group’s setting for neighbors that are members of a peer group.

The no neighbor command removes all configuration commands for the BGP neighbor at the specified address.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID allowas-in [asn_quantity]

no neighbor neighbor_ID allowas-in

default neighbor neighbor_ID allowas-in

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.
  • asn_quantity number of repetitions of the switch’s ASN allowed in the AS path of routes received from the specified BGP neighbor. Values range from 1 to 10. Default is 3.

Related Commands

This command is used on a customer edge router that is part of a split AS; to address the problem at the provider end, use the neighbor as-path remote-as replace out command.

Example

  • These commands configure the switch to accept routes from the BGP neighbor at 192.168.1.30 which contain the switch’s ASN in their AS paths as many as 3 times.
    switch(config)#router bgp 1
    switch(config-router-bgp)#neighbor 192.168.1.30 allowas-in
    switch(config-router-bgp)#

neighbor as-path remote-as replace out

By default, BGP drops received routes if their autonomous system (AS) paths contain the AS number (ASN) of the switch. In a split AS sharing route advertisements through a provider network, this can result in valid routes being dropped. The neighbor as-path remote-as replace out command configures a provider edge switch to replace the customer’s AS with its own in route advertisements sent to neighbors in that AS.

The no neighbor as-path remote-as replace out command configures the default behavior (leaving the customer’s AS in the AS path attribute of routes advertised to the specified neighbor).

The default neighbor as-path remote-as replace out command applies the system default configuration for individual neighbors and applies the peer group’s setting for neighbors that are members of a peer group.

The no neighbor command removes all configuration commands for the BGP neighbor at the specified address.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID as-path remote-as replace out

no neighbor neighbor_ID as-path remote-as replace out

default neighbor neighbor_ID as-path remote-as replace out

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.

Related Commands

This command is used on a provider edge router forwarding BGP routes to a customer in a split AS; to address the problem at the customer end, use the neighbor allowas-in command.

Example

  • These commands configure the switch to substitute its local ASN for the ASN of the BGP neighbor at 192.168.2.15 in BGP routes advertised to that neighbor.
    switch(config)#router bgp 1
    switch(config-router-bgp)#neighbor 192.168.2.15 as-path remote-as replace out
    switch(config-router-bgp)#

neighbor auto-local-addr

The neighbor auto-local-addr command configures the switch to automatically determine the local address to be used for the non-transport address family in NLRIs sent to the specified neighbor or peer group. This allows IPv4 NLRIs to be carried over IPv6 transport, or IPv6 NLRIs to be carried over IPv4 transport.

The no neighbor auto-local-addr command applies the system default configuration.

The default neighbor auto-local-addr command applies the system default configuration for individual neighbors, and applies the peer group’s setting for neighbors that are members of a peer group.

Note: While this feature works well in eBGP deployments in which the pairing routers are directly connected and have matching IP address configurations, multi-hop eBGP or iBGP deployments may require manual local address configuration.

To explicitly configure a local address for the non-transport address family for a specific neighbor or peer group, use the neighbor local-v4-addr command for IPv6 neighbors, or the neighbor local-v6-addr for IPv4 neighbors.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID auto-local-addr

no neighbor neighbor_ID auto-local-addr

default neighbor neighbor_ID auto-local-addr

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.

Example

  • For the IPv6 neighbor at 2001:0DB8:c2a4:1761::2, these commands configure the switch to automatically determine the IPv4 NLRI value to be sent during peering sessions.
    switch(config)#router bgp 1
    switch(config-router-bgp)#neighbor 2001:0DB8:c2a4:1761::2 auto-local-addr
    switch(config-router-bgp)#

neighbor default-originate

The neighbor default-originate command advertises a default route to a BGP neighbor or peer group. This default route overrides the default route advertised by any other means to the specified neighbor or peer group. However, the update generated by neighbor default-originate is not processed by neighbor route map out policies.

If a route map is specified in this command, its set clauses are used to modify attributes of the exported default route, but its match clauses are not used to conditionally advertise the route. The default route is always advertised to the specified neighbor.

The no neighbor default-originate command applies the system default configuration.

The default neighbor default-originate command applies the system default configuration for individual neighbors and applies the peer group’s setting for neighbors that are members of a peer group.

The no neighbor command removes all configuration commands for the neighbor at the specified address.

Command Mode

Router-BGP Configuration Router-BGP Address-Family Configuration

Command Syntax

neighbor neighbor_ID default-originate [MAP]

no neighbor neighbor_ID default-originate

default neighbor neighbor_ID default-originate

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.
  • MAP specifies route map that modifies attributes of the exported default route. Options include:
    • <no parameter> attributes are not modified by a route map.
    • route-map map_name attributes set by specified route map are assigned to the exported default route.

Example

  • These commands advertise a default route to the BGP neighbor at 192.168.14.5.
    switch(config)#router bgp 9
    switch(config-router-bgp)#neighbor 192.168.14.5 default-originate
    switch(config-router-bgp)#

neighbor description

The neighbor description command associates descriptive text with the specified peer or peer group.

The no neighbor description command removes the text association from the specified peer or peer group.

The default neighbor description command removes the text association from the specified peer for individual neighbors, and applies the peer group’s description to neighbors that are members of a peer group.

The no neighbor command removes all configuration commands for the neighbor at the specified address or for the specified peer group.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID description description_string

no neighbor neighbor_ID description

default neighbor neighbor_ID description

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.
  • description_string text string to be associated with the neighbor or peer group.

Example

  • These commands associate the string “PEER_1” with the peer located at 192.168.1.30.
    switch(config)#router bgp 1
    switch(config-router-bgp)#neighbor 192.168.1.30 description PEER_1
    switch(config-router-bgp)#

neighbor ebgp-multihop

The neighbor ebgp-multihop command programs the switch to accept and attempt BGP connections to the external peers residing on networks not directly connected to the switch. The command does not establish the multihop if the only route to the peer is the default route (0.0.0.0).

The no neighbor ebgp-multihop command applies the system default configuration.

The default neighbor ebgp-multihop command applies the system default configuration for individual neighbors, and applies the peer group’s setting for neighbors that are members of a peer group.

The no neighbor command removes all configuration commands for the neighbor at the specified address.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID ebgp-multihop [hop_number]

no neighbor neighbor_ID ebgp-multihop

default neighbor neighbor_ID ebgp-multihop

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.
  • hop_number time-to-live (hops). Values range from 1 to 255. Default value is 255.

Example

  • These commands configure the switch to accept and attempt BGP connections to the external peer located at 192.168.1.30, setting the hop limit to 32.
    switch(config)#router bgp 1
    switch(config-router-bgp)#neighbor 192.168.1.30 ebgp-multihop 32
    switch(config-router-bgp)#

neighbor enforce-first-as

The neighbor enforce-first-as command causes a forced comparison of the first autonomous system (AS) in the AS path of eBGP routes received from a specified BGP peer or peer group to the configured remote external peer autonomous system number (ASN). Updates from the specified eBGP peers that do not include an ASN as first AS path (in the AS_PATH attribute) are discarded.

This behavior is enabled globally by default upon BGP configuration, and disabled for the specified neighbor or peer group by the no form of the command. To configure first AS enforcement globally, use the bgp enforce-first-as command.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID enforce-first-as

no neighbor neighbor_ID enforce-first-as

default neighbor neighbor_ID enforce-first-as

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.

Example

  • This command disables enforcement of the first BGP AS for the neighbors in peer group “region-3.”
    switch(config-router-bgp)#no neighbor region-3 enforce-first-as
    switch(config-router-bgp)#

neighbor export-localpref

The neighbor export-localpref command determines the LOCAL_PREF value that is sent in BGP UPDATE packets to the specified peer or peer group. This command has no effect on external peers.

The no neighbor export-localpref command resets the LOCAL_PREF value to the system default of 100 in packets sent to the specified peer or peer group.

The default neighbor export-localpref command resets the LOCAL_PREF value to the system default of 100 for individual neighbors, and applies the peer groups’s setting for neighbors that are members of a peer group.

The no neighbor command removes all configuration commands for the neighbor at the specified address or the specified peer group.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID export-localpref preference

no neighbor neighbor_ID export-localpref

default neighbor neighbor_ID export-localpref

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.
  • preference preference value. Values range from 0 to 4294967295.

Example

  • This command configures the switch to fill the LOCAL_PREF field with 200 in UPDATE packets that it sends to the peer located at 10.1.1.45.
    switch(config)#router bgp 1
    switch(config-router-bgp)#neighbor 10.1.1.45 export-localpref 200
    switch(config-router-bgp)#

neighbor graceful-restart

The neighbor graceful-restart command enables the BGP graceful restart mode for a specified BGP neighbor or peer group. When graceful restart mode is enabled, the switch retains routes from neighbors that are capable of graceful restart. By default, graceful restart is enabled for all BGP neighbors. Individual neighbor configuration takes precedence over the global configuration.

The no neighbor graceful-restart and default neighbor graceful-restart commands disable graceful restart mode for the specified BGP neighbor or peer group by removing the corresponding no neighbor graceful-restart command from running-config.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID graceful-restart

no neighbor neighbor_ID graceful-restart

default neighbor neighbor_ID graceful-restart

Parameters

  • neighbor_ID neighbors’s IPv4 or IPv6 address or peer group name.

Example

  • This command enables BGP graceful restart mode for the neighbor with the IP address192.168.12.1.
    switch(config)#router bgp 1
    switch(config-router-bgp)#neighbor 192.168.12.1 graceful-restart
    switch(config-router-bgp)#

neighbor graceful-restart-helper

The neighbor graceful-restart helper command enables BGP graceful restart helper mode for the specified BGP neighbor or peer group. When graceful restart helper mode is enabled, the switch will retain routes from neighbors which are capable of graceful restart while those neighbors are restarting BGP. Graceful restart is enabled by default for all BGP neighbors. To configure graceful restart helper mode for all BGP neighbors, use the graceful-restart-helper command. Individual neighbor configuration takes precedence over the global configuration.

The no neighbor graceful-restart helper command disables graceful restart helper mode for the specified BGP neighbor or peer group. The default neighbor graceful-restart helper command enables graceful restart helper mode for the specified BGP neighbor or peer group by removing the corresponding no neighbor graceful-restart helper command from running-config.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID graceful-restart helper

no neighbor neighbor_ID graceful-restart helper

default neighbor neighbor_ID graceful-restart helper

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.

Example

  • These commands disable graceful restart helper mode for the neighbor at 192.168.12.1.
    switch(config)#router bgp 1
    switch(config-router-bgp)#no neighbor 192.168.12.1 graceful-restart-helper
    switch(config-router-bgp)#

neighbor import-localpref

The neighbor import-localpref command determines the local preference assigned to routes received from the specified external peer or peer group. This command has no effect on routes received from internal peers.no neighbor import-localpref

Thecommand resets the local preference to the default of 100 for routes received from the specified peer or peer group.

The default neighbor import-localpref command resets the local preference to the default of 100 for individual neighbors, and applies the peer group’s setting for neighbors that are members of a peer group.

The no neighbor command removes all configuration commands for the neighbor at the specified address.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID import-localpref preference

no neighbor neighbor_ID import-localpref

default neighbor neighbor_ID import-localpref

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.
  • preference preference value. Values range from 0 to 4294967295.

Example

  • These commands configure the switch to assign a local preference of 50 to routes received from the peer located at 192.168.1.30.
    switch(config)#router bgp 1
    switch(config-router-bgp)#neighbor 192.168.1.30 import-localpref 50
    switch(config-router-bgp)#

neighbor local-as

The neighbor local-as command enables AS_PATH attribute modification for received eBGP routes, allowing the switch to appear as a member of a different AS to external peers. Arista switches do not prepend the local AS number to routes received from the eBGP neighbor; currently, we implement the command only as neighbor local-as no-prepend replace-as.

The no neighbor local-as command disables AS_PATH modification for the specified peer or peer group. The default neighbor local-as command disables AS_PATH modification for individual neighbors, and applies the peer groups setting for neighbors that are members of a peer group.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID local-as as_id no-prepend replace-as

no neighbor neighbor_ID local-as

default neighbor neighbor_ID local-as

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.
  • as_id AS number that is sent in outbound routing updates in place of the actual AS of the switch. Values range from 1 to 4294967295.

    This parameter cannot be set to the switch’s AS number or to any AS number in the peer’s network.

Example

  • For the neighbor at 10.13.64.1, these commands remove AS 300 from outbound routing updates and replace it with AS 600.
    switch(config)#router bgp 300
    switch(config-router-bgp)#neighbor 10.13.64.1 local-as 600 no-prepend replace-as
    switch(config-router-bgp)#

neighbor local-v4-addr

The neighbor local-v4-addr command specifies the next-hop value that the switch sends as the IPv4 NLRI value to neighbors with whom IPv6 transport peering is established.

The no neighbor local-v4-addr command applies the system default configuration.

The default neighbor local-v4-addr command applies the system default configuration for individual neighbors, and applies the peer group’s setting for neighbors that are members of a peer group.

To configure the switch to automatically determine the IPv4 address to be sent as the next-hop in IPv4 NLRIs to an IPv6 neighbor, use the neighbor auto-local-addr command.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID local-v4-addr ipv4_local

no neighbor neighbor_ID local-v4-addr

default neighbor neighbor_ID local-v4-addr

Parameters

  • neighbor_ID neighbor’s IPv6 address or peer group name.
  • ipv4_local next hop address.

Example

  • For the neighbor at 2001:0DB8:c2a4:1761::2, these commands specify an IPv4 NLRI value of 10.7.5.11 to be sent during IPv6 transport peering sessions.
    switch(config)#router bgp 1
    switch(config-router-bgp)#neighbor 2001:0DB8:c2a4:1761::2 local-v4-addr 
    10.7.5.11
    switch(config-router-bgp)#

neighbor local-v6-addr

The neighbor local-v6-addr command specifies the next-hop value that the switch sends as the IPv6 NLRI value to neighbors with which IPv4 transport peering is established.

In IPv6 peering sessions, the switch sends the global IPv6 address of the interface that is used to transmit BGP updates.

The no neighbor local-v6-addr command applies the system default configuration.

The default neighbor local-v6-addr command applies the system default configuration for individual neighbors, and applies the peer group’s setting for neighbors that are members of a peer group.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID local-v6-addr ipv6_local

no neighbor neighbor_ID local-v6-addr

default neighbor neighbor_ID local-v6-addr

Parameters

  • neighbor_ID neighbor’s IPv4 address or peer group name.
  • ipv6_local next hop address (A:B:C:D:E:F:G:H).

Example

  • For the neighbor at 10.7.5.11, these commands specify an IPv6 NLRI value that is sent during IPv4 transport peering sessions.
    switch(config)#router bgp 1
    switch(config-router-bgp)#neighbor 10.7.5.11 local-v6-addr 2001:0DB8:c2a4:1761::2
    switch(config-router-bgp)#show active
    router bgp 1
     bgp log-neighbor-changes
     bgp default ipv6-unicast
     neighbor 10.7.5.11 local-v6-addr 2001:0DB8:c2a4:1761::2
    switch(config-router-bgp)#

neighbor maximum-routes

The neighbor maximum-routes command determines the number of BGP routes the switch accepts from a specified neighbor and defines an action when the limit is exceeded. The default value is 12,000. To remove the maximum routes limit, select a limit of zero.

When the number of routes received from a peer exceeds the limit, the switch generates an error message. This command can also configure the switch to disable peering with the neighbor. In this case, the neighbor state is reset only through a clear ip bgp command.

The no neighbor maximum-routes command applies the system default maximum-routes value of 12,000 for the specified peer.

The default neighbor maximum-routes command applies the system default value for individual neighbors, and applies the peer group’s setting for neighbors that are members of a peer group.

The no neighbor command removes all configuration commands for the neighbor at the specified address.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID maximum-routes quantity [ACTION]

no neighbor neighbor_ID maximum-routes

default neighbor neighbor_ID maximum-routes

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.
  • quantity maximum number of routes. Values include:
    • 0 the switch does not define a route limit.
    • 1 to 4294967294 maximum number of routes.
  • ACTION switch action when the route limit is exceeded. Values include:
    • <no parameter> peering is disabled and an error message is generated.
    • warning-only peering is not disabled, but an error message is generated.

Example

  • This command configures the switch to accept 15000 routes for the neighbor at 10.3.16.210. If the neighbor exceeds 15000 routes, the switch disables peering with the neighbor.
    switch(config)#router bgp 1
    switch(config-router-bgp)#neighbor 110.3.16.210 maximum-routes 15000
    switch(config-router-bgp)#

neighbor next-hop-peer

The neighbor next-hop-peer command configures the switch to list the peer address as the next hop in routes that it receives from the specified peer BGP-speaking neighbor or members of the specified peer group. This command overrides the next hop for all routes received from this neighbor or peer group.

The no neighbor next-hop-peer command applies the system default (no next-hop override) for the specified peer.

The default neighbor next-hop-peer command applies the system default for individual neighbors and applies the peer group’s setting for neighbors that are members of a peer group.

The no neighbor command removes all configuration commands for the neighbor at the specified address or the specified peer group.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID next-hop-peer

no neighbor neighbor_ID next-hop-peer

default neighbor neighbor_ID next-hop-peer

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.

Example

  • This command configures the peer address of 10.3.2.24 as the next hop for routes advertised to the switch from the peer BGP neighbor.
    switch(config)#router bgp 9
    switch(config-router-bgp)#neighbor 10.3.2.24 next-hop-peer
    switch(config-router-bgp)#

neighbor next-hop-self

The neighbor next-hop-self command configures the switch to list its address as the next hop in routes that it advertises to the specified BGP-speaking neighbor or neighbors in the specified peer group. This is used in networks where BGP neighbors do not directly access all other neighbors on the same subnet.

The no neighbor next-hop-self command applies the system default (no next-hop override) for the specified peer.

The default neighbor next-hop-self command applies the system default for individual neighbors and applies the peer group’s setting for neighbors that are members of a peer group.

The no neighbor command removes all configuration commands for the neighbor at the specified address or for the specified peer group.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID next-hop-self

no neighbor neighbor_ID next-hop-self

default neighbor neighbor_ID next-hop-self

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.

Example

  • This command configures the switch as the next hop for the peer at 10.4.1.30.
    switch(config)#router bgp 1
    switch(config-router-bgp)#neighbor 10.4.1.30 next-hop-self
    switch(config-router-bgp)#

neighbor out-delay

The neighbor out-delay command sets the period of time that a route update for the specified neighbor must be in the routing table before the switch exports it to BGP. The out delay interval is used for bundling routing updates.

The no neighbor out-delay command applies the system default (out-delay value of zero) for the specified peer.

The default neighbor out-delay command applies the system default for individual neighbors and applies the peer group’s setting for neighbors that are members of a peer group.

The no neighbor command removes all configuration commands for the specified neighbor.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID out-delay delay_time

no neighbor neighbor_ID out-delay delay_time

default neighbor neighbor_ID out-delay delay_time

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.
  • delay_time the out delay period (seconds). Values range from 0 to 600. Default value is 0.

Example

  • These commands set the out delay period to 5 seconds for the connection with the peer at 10.24.15.9.
    switch(config)#router bgp 1
    switch(config-router-bgp)#neighbor 10.24.15.9 out-delay 5
    switch(config-router-bgp)#

neighbor passive

The neighbor passive command sets the TCP connection for the specified BGP neighbor or peer group to passive mode. When the peer’s transport connection mode is set to passive, it accepts TCP connections for BGP but does not initiate them.

The no neighbor passive command sets the specified BGP neighbor or peer group to active connection mode. BGP peers in active mode can both accept and initiate TCP connections for BGP. This is the default behavior.

The default neighbor passive command restores the default connection mode. The default mode is active for individual BGP peers, or the mode inherited from the peer group for peer group members.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID passive

no neighbor neighbor_ID passive

default neighbor neighbor_ID passive

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.

Example

  • These commands configure the neighbor at IP address 10.2.2.14 to not initiate TCP connections for BGP peering.
    switch(config)#router bgp 300
    switch(config-router-bgp)#neighbor 10.2.2.14 passive
    switch(config-router-bgp)#

neighbor password

The neighbor password command enables authentication on a TCP connection with a BGP peer. The plain-text version of the password is a string, up to 8 bytes in length. Peers must use the same password to ensure proper communication.

Running-config displays the encrypted version of the password. The encryption scheme is not strong by cryptographic standards; encrypted passwords should be treated in the same manner as plain-text passwords.

The no neighbor password command applies the system default for the specified peer, removing the neighbor password from the configuration and disabling authentication with the specified peer.

The default neighbor password command applies the system default for individual neighbors and applies the peer group’s setting for neighbors that are members of a peer group.

The no neighbor password and default neighbor password commands remove the neighbor password from the configuration, disabling authentication with the specified peer.

The no neighbor command removes all configuration commands for the neighbor at the specified address.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID password [ENCRYPT_LEVEL] key_text

no neighbor neighbor_ID password

default neighbor neighbor_ID password

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.
  • ENCRYPT_LEVEL the encryption level of the key_text parameter. Values include:
    • <no parameter> the key_text is in clear text.
    • 0 the key_text is in clear text. Equivalent to the <no parameter> case.
    • 7 the key_text is MD5-encrypted.
  • key_text the password.

Example

  • This command specifies a password in clear text.
    switch(config)#router bgp 1
    switch(config-router-bgp)#neighbor 10.25.25.13 password 0 code123
    switch(config-router-bgp)#

    Running-config stores the password as an encrypted string.

neighbor peer group (create)

Peer groups allow the user to apply settings to a group of BGP neighbors simultaneously. Once a peer group is created, the group name can be used as a parameter in neighbor configuration commands, and the configuration will be applied to all members of the group. Settings applied to an individual neighbor in the peer group override group settings.

The neighbor peer group (create) command is used to create static BGP peer groups. Static peer groups are peer groups whose members are added manually. To assign BGP neighbors to a static peer group, use the neighbor peer-group (neighbor assignment) command. To create a dynamic peer group, use the bgp listen range command.

The no neighbor peer group (create) and default neighbor peer group (create) commands remove the specified static peer group from running-config. When a static peer group is deleted, the neighbors that were members of that peer group lose any configuration that was inherited from the peer group. The no form of the bgp listen range command removes a dynamic peer group.

The no neighbor command removes all configuration commands for the specified neighbor.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor group_name peer group

no neighbor group_name peer group

default neighbor group_name peer group

Parameters

  • group_name peer group name.

Examples

  • These commands create a BGP peer group called “bgpgroup1,” assign several neighbors to the group, apply a route map, and adjust the configuration for one group member.
    switch(config)#router bgp 9
    switch(config-router-bgp)#neighbor bgpgroup1 peer group
    switch(config-router-bgp)#neighbor 10.1.1.1 peer group bgpgroup1
    switch(config-router-bgp)#neighbor 10.2.2.2 peer group bgpgroup1
    switch(config-router-bgp)#neighbor 10.3.3.3 peer group bgpgroup1
    switch(config-router-bgp)#neighbor bgpgroup1 route-map corporate in
    switch(config-router-bgp)#neighbor 10.3.3.3 maximum-routes 5000
    switch(config-router-bgp)#show active
    router bgp 9
    bgp log-neighbor-changes
     neighbor bgpgroup1 peer-group
     neighbor bgpgroup1 route-map corporate in
     neighbor bgpgroup1 maximum-routes 12000
     neighbor 10.1.1.1 peer-group bgpgroup1
     neighbor 10.2.2.2 peer-group bgpgroup1
     neighbor 10.3.3.3 peer-group bgpgroup1
     neighbor 10.3.3.3 maximum-routes 5000
    switch(config-router-bgp)#
  • This command removes peer group “bgpgroup1” from running-config. The group members remain, but all settings that group members inherited from the peer group are removed.
    switch(config-router-bgp)#no neighbor bgpgroup1 peer-group
    switch(config-router-bgp)#show active
    router bgp 9
    bgp log-neighbor-changes
     neighbor 10.1.1.1 maximum-routes 12000
     neighbor 10.2.2.2 maximum-routes 12000
     neighbor 10.3.3.3 maximum-routes 5000
    switch(config-router-bgp)#

neighbor peer-group (neighbor assignment)

Peer groups allow the user to apply settings to a group of BGP neighbors simultaneously. Once a peer group is created, the group name can be used as a parameter in neighbor configuration commands, and the configuration will be applied to all members of the group. Settings applied to an individual neighbor in the peer group override group settings.

The neighbor peer-group (neighbor assignment) command is used to assign BGP neighbors to an existing static peer group. To create a static peer group, use the neighbor peer group (create) command. A neighbor can only belong to one peer group, so issuing this command for a neighbor that is already a member of another group will remove it from that group.

The no neighbor peer-group and default neighbor peer-group commands remove the specified neighbor from all peer groups. When a neighbor is removed from a peer group, the neighbor retains the configuration inherited from the peer group.

The no neighbor command removes all configuration commands for the specified neighbor.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor NEIGHBOR_ADDR peer-group group_name

no neighbor NEIGHBOR_ADDR peer-group

default neighbor NEIGHBOR_ADDR peer-group

Parameters

  • NEIGHBOR_ADDR address of a neighbor being added to peer group. Values include:
    • ipv4_addr neighbor’s IPv4 address.
    • ipv6_addr neighbor’s IPv6 address.
  • group_name peer group name.

Examples

  • These commands create a BGP peer group called “bgpgroup1,” assign several neighbors to the group, and apply a route map.
    switch(config)#router bgp 9
    switch(config-router-bgp)#neighbor bgpgroup1 peer-group
    switch(config-router-bgp)#neighbor 10.1.1.1 peer-group bgpgroup1
    switch(config-router-bgp)#neighbor 10.2.2.2 peer-group bgpgroup1
    switch(config-router-bgp)#neighbor 10.3.3.3 peer-group bgpgroup1
    switch(config-router-bgp)#neighbor bgpgroup1 route-map corporate in
    switch(config-router-bgp)#
  • This command removes the neighbor at 1.1.1.1 from the peer group. All settings that neighbor 10.1.1.1 inherited from the peer group are maintained.
    switch(config-router-bgp)#no neighbor 10.1.1.1 peer-group
    switch(config-router-bgp)#

neighbor remote-as

The neighbor remote-as command configures the expected AS number for a neighbor (peer). This configuration is required to establish a neighbor connection. Internal neighbors have the same AS number; external neighbors have different AS numbers.

Note: To establish a BGP session, there must be an IPv4 router ID configured in the same VRF or at least one L3 interface with an IPv4 address in the same VRF. If the VRF contains no L3 interfaces with IPv4 addresses (e.g., in an IPv6-only environment), configure an appropriate router ID using the router-id (BGP) command.

The no neighbor remote-as command applies the system default for the specified peer or peer group.

The default neighbor remote-as command applies the system default for individual neighbors and applies the peer group’s setting for neighbors that are members of a peer group.

The no neighbor command removes all configuration commands for the neighbor at the specified address.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID remote-as as_id

no neighbor neighbor_ID remote-as

default neighbor neighbor_ID remote-as

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.
  • as_id autonomous system (AS) of the peer. Values range from 1 to 4294967295.

Example

  • These commands establish a BGP connection with the router at 10.4.3.10 in AS 300.
    switch(config)#router bgp 9
    switch(config-router-bgp)#neighbor 10.4.3.10 remote-as 300
    switch(config-router-bgp)#

neighbor remove-private-as

The neighbor remove-private-as command removes private autonomous system numbers from outbound routing updates for external BGP (eBGP) neighbors. When the autonomous system path includes only private autonomous system numbers, the REMOVAL parameter specifies how the private autonomous system number is removed.

The no neighbor remove-private-as command applies the system default (preserves private AS numbers) for the specified peer.

The default neighbor remove-private-as command applies the system default for individual neighbors and applies the peer group’s setting for neighbors that are members of a peer group.

The no neighbor command removes all configuration commands for the neighbor at the specified address.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID remove-private-as [REMOVAL]

no neighbor neighbor_ID remove-private-as

default neighbor neighbor_ID remove-private-as

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.
  • REMOVAL specifies removal of all private AS numbers when the AS path contains only private AS numbers. Values include:
    • all removes all private AS numbers from AS path in outbound updates.
    • all replace-as all private AS numbers in AS path are replaced with router’s local AS number.
Note: This command does not support a mix of public and private AS numbers.

Example

  • These commands program the switch to remove all private AS numbers from outbound routing updates for the eBGP neighbor at 10.5.2.11 only if the AS path does not contain any public AS number.
    switch(config)#router bgp 9
    switch(config-router-bgp)#neighbor 10.5.2.11 remove-private-as
    switch(config-router-bgp)#
  • This command replaces all private AS numbers in the AS path with the switch’s local AS number.
    switch(config)#router bgp 9
    switch(config-router-bgp)#neighbor 10.5.2.11 remove-private-as all replace-as
    switch(config-router-bgp)#

neighbor rib-in pre-policy retain

By default, inbound BGP routes that are filtered out by the import policy are still stored on the switch. Because all routes are retained, this allows policies to be changed without resetting BGP sessions. It also allows the switch to display all advertised routes when the show ip bgp neighbor advertised-routes command is issued.

The no neighbor rib-in pre-policy retain command configures the switch to discard information about routes received from the specified neighbor or group that fail the import policy.

The neighbor rib-in pre-policy retain command restores the system default behavior (retaining routes from the specified neighbor or group regardless of import policy).

The default neighbor rib-in pre-policy retain command applies the system default (retaining all routes) for individual neighbors and applies the peer group’s setting for neighbors that are members of a peer group.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID rib-in pre-policy retain inbound [SCOPE]

no neighbor neighbor_ID rib-in pre-policy retain inbound

default neighbor neighbor_ID rib-in pre-policy retain inbound

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.
  • SCOPE determines how routes including the switch’s AS number are handled. Values include:
    • <no parameter> routes including the switch’s AS number are discarded.
    • all routes including the switch’s AS number are retained.

Example

  • These commands configure the switch to discard information about routes from the neighbor at 10.5.2.23 which are filtered out by the switch’s import policies.
    switch(config)#router bgp 9
    switch(config-router-bgp)#no neighbor 10.5.2.23 rib-in pre-policy retain inbound
    switch(config-router-bgp)#

neighbor route-map (BGP)

The neighbor route-map command applies a route map to inbound or outbound BGP routes. When a route map is applied to outbound routes, the switch will advertise only routes matching at least one section of the route map. Only one outbound route map and one inbound route map can be applied to a given neighbor. A new route map applied to a neighbor will replace the previous route map.

The command is available in Router-BGP and Router-BGP-Address-Family configuration modes. The mode in which the command is executed determines the scope of the command:

  • In Router-BGP mode, the route map is applied to the specified neighbor in all peering sessions where it is advertised.
  • In Router-BGP-Address-Family mode, the route map is applied to the neighbors only in peering sessions corresponding to the configuration-mode address family.

The no neighbor route-map command discontinues the application of the specified route map for the specified neighbor and direction. Removing a route map from one direction does not remove it from the other if it has been applied to both.

The default neighbor route-map command applies the system default (no route map) for individual neighbors, and applies the peer group’s setting for neighbors that are members of a peer group.

Command Mode

Router-BGP Configuration

Router-BGP Address-Family Configuration

Command Syntax

neighbor neighbor_ID route-map map_name DIRECTION

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.
  • map_name name of a route map.
  • DIRECTION routes to which the route map is applied. Options include:
    • in route map is applied to inbound routes.
    • out route map is applied to outbound routes.

Example

  • This command applies a route map named “inner-map” to a BGP inbound route from 10.5.2.11.
    switch(config)#router bgp 9
    switch(config-router-bgp)#neighbor 10.5.2.11 route-map inner-map in
    switch(config-router-bgp)#

neighbor route-reflector-client

Participating BGP routers within an AS communicate eBGP-learned routes to all of their peers, but to prevent routing loops they must not re-advertise iBGP-learned routes within the AS. To ensure that all members of the AS share the same routing information, a fully meshed network topology (in which each member router of the AS is connected to every other member) can be used, but this topology can result in high volumes of iBGP messages when it is scaled. Instead, in larger networks one or more routers can be configured as route reflectors.

A route reflector is configured to re-advertise routes learned through iBGP to a group of BGP neighbors within the AS (its clients), eliminating the need for a fully meshed topology.

The neighbor route-reflector-client command configures the switch to act as a route reflector and configures the specified neighbor as one of its clients. Additional clients are specified by re-issuing the command.

The no neighbor route-reflector-client and default neighbor route-reflector-client commands disable route reflection by deleting the neighbor route-reflector-client command from running-config.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID route-reflector-client

no neighbor neighbor_ID route-reflector-client

default neighbor neighbor_ID route-reflector-client

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.

Related Commands

Example

  • This command configures the switch as a route reflector and the neighbor at 10.5.2.1 as one of its clients.
    switch(config)#router bgp 9
    switch(config-router-bgp)#neighbor 10.5.2.11 route-reflector-client
    switch(config-router-bgp)#

neighbor route-to-peer

The neighbor route-to-peer command allows BGP to establish a connection to reach the specified peer using kernel routing table information. By default, route-to-peer configuration is enabled for a peer or a peer group.

The no neighbor route-to-peer command prevents BGP from using kernel routing table information to establish a BGP connection to reach a peer and the default neighbor route-to-peer command enables route-to-peer configuration for a peer or a peer group by removing the corresponding no neighbor route-to-peer command from the running-config.

If the peer is directly connected, BGP instead uses ARP table or neighbor table information to establish a BGP connection to reach the peer.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID route-to-peer

no neighbor neighbor_ID route-to-peer

default neighbor neighbor_ID route-to-peer

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or the peer group name.

Example

  • These commands establish a connection between the switch and the BGP peer located at IP address 172.16.1.1, and prevent BGP from using kernel routing table information to establish a route to that peer.
    switch(config)#router bgp 64496
    switch(config-router-bgp)#no neighbor 172.16.1.1 route-to-peer
    switch(config-router-bgp)#neighbor 172.16.1.1 remote-as 100
    switch(config-router-bgp)#

neighbor send-community add / remove

The neighbor send-community add / remove command modifies the types of community path attributes included for routes in the UPDATE messages advertised to the specified BGP neighbor without having to issue the no neighbor send-community command.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID send-community {add | remove} {extended | large | standard}

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.
  • add appends the specified community path attribute type to the list of community path attribute types sent to the specified neighbor.
  • remove removes the specified community path attribute type from the list of community path attribute types sent to the specified neighbor.
  • extended enables (or disables) sending of the extended community path attribute to the specified neighbor.
  • large enables (or disables) sending of the large community path attribute to the specified neighbor.
  • standard enables (or disables) sending of the standard community path attribute to the specified neighbor.
  • link-bandwidth see neighbor send-community link-bandwidth for a description of this parameter.

Guidelines

  • If the neighbor send-community command has been issued for the neighbor without specifying any community types, that neighbor will receive all community attributes in the routes advertised to it. Using the neighbor send-community add command then to add an attribute will cause the switch to send only the specified community types in advertised routes. This will result in the other community path attributes no longer being advertised to that BGP peer.
  • If all community types are removed using the neighbor send-community remove command, the switch will then send routes with all community types. (This behavior is maintained for backward compatibility.) To remove all community path attributes from routes sent to the specified neighbor, use the no neighbor send-community command.
  • After using this command, issue the show active command in Router-BGP Configuration Mode to ensure that the intended attributes are being sent to the specified neighbor.

Examples

  • These commands configure the switch to send large community attributes in the routes sent to the neighbor at address 10.5.2.24, then add extended community attributes as well.
    switch(config)#router bgp 9
    switch(config-router-bgp)#neighbor 10.5.2.24 send-community large
    switch(config-router-bgp)#neighbor 10.5.2.24 send-community add extended
    switch(config-router-bgp)#show active
    switch(config-router-bgp)#neighbor 10.5.2.24 send-community add extended
    switch(config-router-bgp)#show active
    router bgp 9
     neighbor 10.5.2.24 send-community extended large
     neighbor 10.5.2.24 maximum-routes 12000
    switch(config-router-bgp)#
  • These commands configure the switch to include extended and large community attributes in the routes sent to the neighbor at address 10.5.2.27, then remove the large attribute from the list of community types to be included.
    switch(config)#router bgp 9
    switch(config-router-bgp)#neighbor 10.5.2.27 send-community extended large
    switch(config-router-bgp)#neighbor 10.5.2.27 send-community remove large
    switch(config-router-bgp)#show active
    router bgp 600
     neighbor 10.5.2.27 send-community extended
     neighbor 10.5.2.27 maximum-routes 12000
    switch(config-router-bgp)#
  • These commands attempt to configure the switch to remove large community attributes from routes sent to the neighbor at address 10.5.2.28, but send all others. However, because the original command did not specify a list of attributes, the remove command has no effect, and all community path attributes are still included.
    switch(config)#router bgp 9
    switch(config-router-bgp)#neighbor 10.5.2.28 send-community
    switch(config-router-bgp)#neighbor 10.5.2.28 send-community remove large
    switch(config-router-bgp)#show active
    router bgp 600
     neighbor 10.5.2.28 send-community
     neighbor 10.5.2.28 maximum-routes 12000
    switch(config-router-bgp)#
  • These commands configure the switch to send only large community attributes in routes sent to the neighbor at address 10.5.2.29, then attempt to remove the large attribute from sent routes. However, because this removes the last specified attribute, all community path attributes (including large) will now be included.
    switch(config)#router bgp 9
    switch(config-router-bgp)#neighbor 10.5.2.29 send-community large
    switch(config-router-bgp)#neighbor 10.5.2.28 send-community remove large
    switch(config-router-bgp)#show active
    router bgp 600
     neighbor 10.5.2.29 send-community
     neighbor 10.5.2.29 maximum-routes 12000
    switch(config-router-bgp)#

neighbor send-community link-bandwidth

The neighbor send-community link-bandwidth command is used to locally regenerate the link-bandwidth value to be advertised to a specific BGP neighbor or peer group. When this command is configured the regenerated link-bandwidth value is included in the extended community path attribute in UPDATE messages.

This command is used specifically for local regeneration of the link-bandwidth value. To send an explictly-configured link-bandwidth value, add an extended community to a route map instead. (see set extcommunity (route-map)) and include extended community attributes in UPDATE messages sent to that neighbor.

Note: The neighbor send-community command will override this command and vice-versa.

The no neighbor send-community command applies the system default (not sending community attributes in BGP UPDATE messages) for the specified peer.

The default neighbor send-community command applies the system default for individual neighbors and applies the peer group’s setting for neighbors that are members of a peer group.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID send-community link-bandwidth {aggregate [reference_speed] | divide {equal | ratio}

no neighbor neighbor_ID send-community

default neighbor neighbor_ID send-community

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.
  • aggregate sends the sum of all link-bandwidth values for all paths toward a prefix to the specified neighbor or to each member of the specified peer group.
    • reference_speed optional value to specify a reference link speed in bits/second. Values range from 0.0 to 4294967295.0; larger values can also be expressed using the multiplier K (*10^3), M (*10^6), or G (*10^9). The link speed of the connection to the peer is divided by this value, and the resulting ratio is used to scale down the link-bandwidth advertised to the peer. If the result is >1, the multiplier is ignored and the full aggregate value is advertised.
  • divide divides the cumulative link-bandwidth value described above among the peers in an Adj-RIB-Out either equally or proportionally.
    • equal divides the cumulative total link-bandwidth value equally among all peers in the same Adj-RIB-Out.
    • ratio divides the cumulative total link-bandwidth value among peers proportionally according to the speed of the connection to each peer in the Adj-RIB-Out.

Examples

  • These commands configure the switch to locally regenerate the link-bandwidth value, dividing the bandwidth proportionally and including it in UPDATE messages to all peers in the peer group “idaho.”
    switch(config)#router bgp 9
    switch(config-router-bgp)#neighbor idaho send-community link-bandwidth divide ratio
    switch(config-router-bgp)#
  • These commands configure the switch to locally regenerate the link-bandwidth value, scale it down with a reference link speed of 20 gigabits/second, and include it in UPDATE messages to the neighbor at address 10.5.2.24.
    switch(config)#router bgp 9
    switch(config-router-bgp)#neighbor 10.5.2.24 send-community link-bandwidth aggregate 20G
    switch(config-router-bgp)#

neighbor send-community

The neighbor send-community command configures the switch to include community path attributes for routes in the UPDATE messages advertised to the specified BGP neighbor. By default, the command enables the switch to send all community attributes: standard, extended, and large. To advertise only a subset of community attributes, use the keyword(s) for the community attribute(s) to be included. To add additional community attributes in a separate command, or to remove specific community attributes from advertised routes, use the neighbor send-community add / remove command.

Note: The neighbor send-community link-bandwidth command will override this command and vice-versa.

The no neighbor send-community command applies the system default (not sending community attributes in BGP UPDATE messages) for the specified peer.

The default neighbor send-community command applies the system default for individual neighbors and applies the peer group’s setting for neighbors that are members of a peer group.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID send-community [extended] [large] [standard]

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.
  • extended includes extended community attributes.
  • large includes large community attributes.
  • standard includes standard community attributes.

Examples

  • These commands configure the switch to send all community attributes to the neighbor at address 10.5.2.23.
    switch(config)#router bgp 9
    switch(config-router-bgp)#neighbor 10.5.2.23 send-community
    switch(config-router-bgp)#
  • These commands configure the switch to include only large community attributes in the routes sent to the neighbor at address 10.5.2.24.
    switch(config)#router bgp 9
    switch(config-router-bgp)#neighbor 10.5.2.24 send-community large
    switch(config-router-bgp)#
  • These commands configure the switch to send only standard and large community attributes to the neighbor at address 10.5.2.25.
    switch(config)#router bgp 9
    switch(config-router-bgp)#neighbor 10.5.2.25 send-community standard large
    switch(config-router-bgp)#

neighbor shutdown

The neighbor shutdown command disables the specified neighbor. Disabling a neighbor also terminates all of its active sessions and removes associated routing information.

The no neighbor shutdown command enables the specified peer.

The default neighbor shutdown command enables individual neighbors and applies the peer group’s setting for neighbors that are members of a peer group.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID shutdown

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.

Example

  • This command disables the neighbor at 10.5.2.23.
    switch(config)#router bgp 9
    switch(config-router-bgp)#neighbor 10.5.2.23 shutdown
    switch(config-router-bgp)#

neighbor timers

The neighbor timers command configures the BGP keepalive and hold times for a specified peer connection. The timers bgp command configures the times on all peer connections for which an individual command is not specified.

  • Keepalive time is the period between the transmission of consecutive keepalive messages.
  • Hold time is the period the switch waits for a KEEPALIVE or UPDATE message before it disables peering.

The hold time must be at least 3 seconds and should be three times longer than the keepalive setting.

The no neighbor timers command applies the system default for the specified peer or group (the timers specified by the timers bgp command).

The default neighbor timers command applies the system default for individual neighbors and applies the peer group’s setting for neighbors that are members of a peer group.

The no neighbor command removes all configuration commands for the neighbor at the specified address.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID timers keep_alive hold_time

no neighbor neighbor_ID timers

default neighbor neighbor_ID timers

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.
  • keep_alivekeepalive period, in seconds. Values include
    • 0 keepalive messages are not sent.
    • 1 to 3600 keepalive time (seconds).
  • hold_time hold time. Values include:
    • 0 peering is not disabled by timeout expiry; keepalive packets are not sent.
    • 3 to 7200 hold time (seconds).

Example

  • This command sets the keepalive time to 30 seconds and the hold time to 90 seconds for the connection with the peer at 10.24.15.9.
    switch(config)#router bgp 9
    switch(config-router-bgp)#neighbor 10.24.15.9 timers 30 90
    switch(config-router-bgp)#

neighbor ttl maximum-hops

The neighbor ttl maximum-hops command configures the Generalized TTL Security Mechanism (GTSM) for the specified neighbor(s).

The no neighbor ttl maximum-hops command disables the GTSM configuration in the specified neighbor.

The default neighbor ttl maximum-hops command applies the system default configuration for individual neighbors; and applies the peer group’s setting for neighbors that are members of a peer group.

Command-Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID ttl maximum-hops hop_number

no sneighbor neighbor_ID ttl maximum-hops

default neighbor neighbor_ID ttl maximum-hops

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.
  • hop_number maximum count of hops from a BGP peer. Values range from 0 to 254.

Example

  • This command configures the TTL security for 10.20.20.30 with a maximum of four hops.
    switch(config)#router bgp 9
    switch(config-router-bgp)#neighbor 10.20.20.30 ttl maximum-hops 4
    switch(config-router-bgp)#

neighbor update-source

The neighbor update-source command specifies the interface that BGP sessions use for TCP connections. By default, BGP sessions use the neighbor’s closest interface (also known as the best local address).

The no neighbor update-source command applies the system default (using best local address for TCP connections) for the specified peer or group.

The default neighbor update-source command applies the system default for individual neighbors and applies the peer group’s setting for neighbors that are members of a peer group.

The no neighbor command removes all configuration commands for the neighbor at the specified address.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID update-source INTERFACE

no neighbor neighbor_ID update-source

default neighbor neighbor_ID update-source

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.
  • INTERFACE interface type and number. Options include:
    • ethernet e_num Ethernet interface specified by e_num.
    • loopback l_num loopback interface specified by l_num.
    • management m_num management interface specified by m_num.
    • port-channel p_num port-channel interface specified by p_num.
    • vlan v_num VLAN interface specified by v_num.

Example

  • This command configures the switch to use Ethernet interface 10 for TCP connections for the neighbor at 10.2.2.14.
    switch(config)#router bgp 9
    switch(config-router-bgp)#neighbor 10.2.2.14 update-source ethernet 10
    switch(config-router-bgp)#

neighbor weight

The neighbor weight command assigns a weight attribute value to paths from the specified neighbor. Weight is the first parameter that the BGP best-path selection algorithm considers. When multiple paths to a destination prefix exist, the best-path selection algorithm prefers the path with the highest weight. Other attributes are used only when all paths to the prefix have the same weight.

Weight values range from 0 to 65535 and are not propagated to other switches through route updates. The default weight for paths that the router originates is 32768; the default weight for routes received through BGP is 0.

A path’s BGP weight is also configurable through route maps. Weight values set through route-map commands have precedence over neighbor weight command values.

The no neighbor weight command applies the system default (32768 for router-originated paths, 0 for routes received through BGP) for the specified peer or group.

The default neighbor weight command applies the system default for individual neighbors, and applies the peer group’s setting for neighbors that are members of a peer group.

The no neighbor command removes all configuration commands for the neighbor at the specified address.

Command Mode

Router-BGP Configuration

Command Syntax

neighbor neighbor_ID weight weight_value

no neighbor neighbor_ID weight

default neighbor neighbor_ID weight

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address or peer group name.
  • weight_value weight value. Values range from 1 to 65535.

Example

  • This command specifies a weight of 4000 for all paths from the neighbor at 10.1.2.5.
    switch(config)#router bgp 9
    eswitch(config-router-bgp)#neighbor 10.1.2.5 weight 4000
    switch(config-router-bgp)#

network (BGP)

The network command specifies a network for advertisement through UPDATE packets to BGP peers. The configuration zeros the host portion of the specified network address; for example, 192.0.2.4/24 is stored as 192.0.2.0/24. A route map option is available for assigning attributes to the network.

The command is available in Router-BGP and Router-BGP-Address-Family configuration modes. The mode in which the command is issued does not affect the command. The scope of the command depends on the specified network address:

  • commands with an IPv4 address are advertised to peers activated in the IPv4 address family.
  • commands with an IPv6 address are advertised to peers activated in the IPv6 address family.

The no network and default network commands remove the network from the routing table, preventing its advertisement.

Command Mode

Router-BGP Configuration

Router-BGP Address-Family Configuration

Command Syntax

network NET_ADDRESS [ROUTE_MAP]

no network NET_ADDRESS

default network NET_ADDRESS

Parameters

  • NET_ADDRESS IP address range. Entry options include:
    • ipv4_subnet IPv4 subnet (CIDR notation).
    • ipv4_addr mask subnet IPv4 subnet (address-mask notation).
    • ipv6_prefix neighbor’s IPv6 prefix (CIDR notation).
  • ROUTE_MAP specifies route map that assigns attribute values to the network. Options include:
    • <no parameter> attributes are not assigned through a route map.
    • route-map map_name attributes listed by specified route map are assigned to the network.

Example

  • This command enables BGP advertising for the network located at 10.1.2.5. The configuration stores the network as 10.1.2.5.
    switch(config)#router bgp 9
    switch(config-router-bgp)#network 10.1.2.5/24
    switch(config-router-bgp)#

no neighbor

The no neighbor command removes all neighbor configuration commands for the specified neighbor.

Neighbor settings can also be removed individually; refer to the command description page of the desired command for details. Neighbor settings for a peer group must be removed individually.

Command Mode

Router-BGP Configuration

Command Syntax

no neighbor neighbor_ID

default neighbor neighbor_ID

Parameters

  • neighbor_ID neighbor’s IPv4 or IPv6 address.This command does not accept a peer group name as an argument; peer group settings must be removed individually.

Example

  • This command removes all neighbor configuration commands for the neighbor at 10.1.1.1.
    switch(config)#router bgp 9
    switch(config-router-bgp)#no neighbor 10.1.1.1
    switch(config-router-bgp)#

rd (Router-BGP VRF and VNI Configuration Modes)

The rd command adds a route distinguisher (RD) to VRF and VNI configuration modes. RDs internally identify routes belonging to a VRF or VNI to distinguish overlapping or duplicate IP address ranges. This allows the creation of distinct routes to the same IP address for different VPNs. The RD is a 64-bit number made up of an AS number or IPv4 address followed by a user-selected ID number.

If the switch is not running EVPN, an RD is not required for a VRF or VNI to function. Use no or default command forms to remove an RD from a VRF or VNI.

Note: Legacy RDs that were assigned in VRF Configuration Mode appear in show vrf outputs if an RD has not been configured using this command, but they no longer have an effect on the system. RDs assigned in the VNI Configuration Mode are displayed in the output of show bgp evpn command.

Command Modes

Router-BGP VRF Configuration

Router-BGP VNI Configuration

Command Syntax

rd admin_ID:local_assignment

no rd

default rd

Parameters

  • admin_ID an AS number or globally assigned IPv4 address identifying the entity assigning the RD. This should be an IANA-assigned identifying number.
  • local_assignment a locally assigned number distinguishing the VRF. Values range from 0-65535 if the admin_ID is an IPv4 address, or from 0-4,294,967,295 if the admin_ID is an AS number. If the admin_ID is an AS number, the local_assignment can also be entered in the form of an IPv4 address.

Examples

  • These commands identify the administrator of the VRF called “purple” as AS 530 and assign 12 as its local number.
    switch(config)#router bgp 50
    switch(config-router-bgp)#vrf purple
    switch(config-router-bgp-vrf-purple)#rd 530:12
    switch(config-router-bgp-vrf-purple)#
  • These commands identify the administrator of the MAC-VRF called “bundle1” as AS 530 and assign 12 as its local number.
    cvx(config)#router bgp 100
    cvx(config-router-bgp)#vni-aware-bundle bundle1
    cvx(config-macvrf-bundle1)#rd 530:12
    cvx(config-macvrf-bundle1)#

redistribute (BGP)

The redistribute command enables the redistribution of specified routes to the BGP domain.

The no redistribute and default redistribute commands disable route redistribution from the specified domain by removing the corresponding redistribute command from running-config.

Note: Aggregate routes are redistributed automatically, and their redistribution cannot be disabled.

Command Mode

Router-BGP Configuration

Command Syntax

redistribute ROUTE_TYPE [ROUTE_MAP]

no redistribute ROUTE_TYPE

default redistribute ROUTE_TYPE

Parameters

  • ROUTE_TYPE source from which routes are redistributed. Options include:
    • connected routes that are established when IP is enabled on an interface.
    • match nssa-external all OSPF NSSA external routes.
    • match nssa-external 1 type 1 OSPF NSSA external routes.
    • match nssa-external 2 type 2 OSPF NSSA external routes.
    • ospf routes from an OSPF domain.
    • ospf match external routes external to the AS, but imported from OSPF.
    • ospf match internal OSPF routes that are internal to the AS.
    • ospf match nssa-external all OSPF NSSA external routes.
    • ospf match nssa-external 1 type 1 OSPF NSSA external routes.
    • ospf match nssa-external 2 type 2 OSPF NSSA external routes.
    • ospf3 routes from an OSPFv3 domain.
    • ospf3 match external routes external to the AS, but imported from OSPFv3.
    • ospf3 match internal OSPFv3 routes that are internal to the AS.
    • rip routes from a RIP domain.
    • static IP static routes.
    • isis IS-IS routes. Sub-options include.
      • level-1 redistribute IS-IS level-1 routes.
      • level-1-2 redistribute IS-IS level-1 and level-2 routes.
      • level-2 redistribute IS-IS level-2 routes.
      • route-map route map reference.
        Note: While redistributing IS-IS routes into BGP, the level-1 or level-2 keyword can be used to selectively redistribute level-1 routes or level-2 routes into BGP. The level-1 or level-2 keyword is optional, and the command defaults to level-2 when it is not configured.
  • ROUTE_MAP route map that determines the routes that are redistributed. Options include:
    • <no parameter> all routes are redistributed.
    • route-map map_name only routes in the specified route map are redistributed.

Example

  • These commands redistribute OSPF routes into the BGP domain.
    switch(config)#router bgp 1
    switch(config-router-bgp)#redistribute OSPF
    switch(config-router-bgp)#
  • These commands redistribute ISIS routes into the BGP domain in address-family mode.
    Switch(config)#router bgp 1
    switch(config-router-bgp)#address-family ipv4
    switch(config-router-bgp-af)#redistribute isis level-1 route-map isis-to-bgp-v4
    switch(config-router-bgp-af)#
  • These commands redistribute ISIS routes into the BGP domain in router-bgp mode.
    switch(config)#router bgp 1
    switch(config-router-bgp)#redistribute isis level-1 route-map isis-to-bgp
    switch(config)#

router bgp

The router bgp command places the switch in router-BGP configuration mode. If BGP was not previously instantiated, this command creates a BGP instance with the specified AS number. Router-BGP configuration mode is not a group-change mode; running-config is changed immediately after commands are executed. The exit command does not affect the configuration.

When a BGP instance exists, the command must include the AS number of the existing BGP instance. Running this command with a different AS number generates an error message.

The no router bgp and default router bgp commands delete the BGP instance.

The exit command returns the switch to global configuration mode.

Command Mode

Global Configuration

Command Syntax

router bgp as_id

no router bgp

default router bgp

Parameters

  • as_id autonomous system (AS) number. Values range from 1 to 4294967295.

Examples

  • This command creates a BGP instance with AS number 64500.
    switch(config)#router bgp 64500
    switch(config-router-bgp)#
  • This command attempts to open a BGP instance with a different AS number from that of the existing instance. The switch displays an error and stays in global configuration mode.
    switch(config)#router bgp 64501
    % BGP is already running with AS number 64500
    switch(config)#
  • This command exits BGP configuration mode.
    switch(config-router-bgp)#exit
    switch(config)#
  • This command deletes the BGP instance.
    switch(config)#no router bgp
    switch(config)#

router-id (BGP)

The router-id command sets the local router BGP router ID.

When no ID has been specified, the local router ID is set to the following:

  • the loopback IP address when a single loopback interface is configured.
  • the loopback with the highest IP address when multiple loopback interfaces are configured.
  • the highest IP address on a physical interface when no loopback interfaces are configured.
    Note: The router ID must be specified if the switch has no IPv4 addresses configured.

The no router-id and default router-id commands remove the router-id command from running-config.

Command Mode

Router-BGP Configuration

Command Syntax

router-id id_num

no router-id [id_num]

default router-id [id_num]

Parameters

  • id_num router ID number (32-bit dotted decimal notation).

Example

  • This command configures the fixed router ID address of 10.10.4.11.
    switch(config)#router bgp 9
    switch(config-router-bgp)#router-id 10.10.4.11
    switch(config-router-bgp)#

show bgp convergence

The show bgp convergence command displays information about the Border Gateway Protocol (BGP) convergence state and other statistics about the BGP instance in the specified VRF or in all VRFs.

Command Mode

EXEC

Command Syntax

show bgp convergence [VRF_INSTANCE]

Parameters

  • VRF_INSTANCE specifies VRF instances. Options include:
    • <no parameter> displays BGP information for the context-active VRF.
    • vrf vrf_name displays BGP information for the specified VRF.
    • vrf all displays BGP information for all VRFs.
    • vrf default displays BGP information for the default VRF.

Examples

  • This command displays the output when no peers have joined before convergence.
    switch#show bgp convergence
    BGP Convergence information for VRF: default
    Configured convergence timeout: 00:02:30
    Configured convergence slow peer timeout: 00:00:55
    Convergence based update synchronization is enabled
    Last Bgp convergence event : None
    Bgp convergence state : Not Initiated (Waiting for the first peer to join)
     Convergence timer is not running
     Convergence timeout in use: 00:02:30
     Convergence slow peer timeout in use: 00:00:55
     First peer is not up yet
     All the expected peers are up: no
     All IGP protocols have converged: yes
     Outstanding EORs: 0, Outstanding Keepalives: 0
     Pending Peers: 2
     Total Peers: 2
     Established Peers: 0
     Disabled Peers: 0
     Peers that have not converged yet:
     IPv4 peers:
     201.1.1.1 (Session : Connect)
     202.1.1.1 (Session : Connect)
     IPv6 peers:
     None
    switch#
  • This command displays the output when the first peer has joined before convergence.
    switch#show bgp convergence
    BGP Convergence information for VRF: default
    Configured convergence timeout: 00:02:30
    Configured convergence slow peer timeout: 00:00:55
    Convergence based update synchronization is enabled
    Last Bgp convergence event 00:00:40 ago
    Bgp convergence state : Pending (Waiting for EORs/Keepalives from peer(s) and IGP 
    convergence)
     Convergence timer running, will expire in 00:01:50
     Convergence timeout in use: 00:02:30
     Convergence slow peer timeout in use: 00:00:55
     First peer came up 00:00:13 ago
     All the expected peers are up: no
     All IGP protocols have converged: yes
     Outstanding EORs: 0, Outstanding Keepalives: 0
     Pending Peers: 1
     Total Peers: 2
     Established Peers: 1
     Disabled Peers: 0
     Peers that have not converged yet:
     IPv4 peers:
     201.1.1.1 (Session : Active)
     IPv6 peers:
     None
    switch#
  • This command displays the output when the convergence timeout value is reached.
    switch#show bgp convergence
    BGP Convergence information for VRF: default
    Configured convergence timeout: 00:02:30
    Configured convergence slow peer timeout: 00:00:55
    Convergence based update synchronization is enabled
    Last Bgp convergence event 00:02:44 ago
    Bgp convergence state : Timeout reached
     Time taken to converge 00:02:30
     Pending Peers: 1
     Total Peers: 2
     Established Peers: 1
     Disabled Peers: 0
     Peers that did not converge before local bgp convergence:
     IPv4 peers:
     201.1.1.1 (Session : Active)
     202.1.1.1 (Session : Established)
     IPv6 peers:
     None
    switch#
  • This command displays the output during the converged state.
    switch#show bgp convergence
    BGP Convergence information for VRF: default
    Configured convergence timeout: 00:05:00
    Configured convergence slow peer timeout: 00:01:30
    Convergence based update synchronization is enabled
    Last Bgp convergence event 00:00:05 ago
    Bgp convergence state : Converged
     Time taken to converge 00:00:02
     First peer came up 00:00:05 ago
     Pending Peers: 0
     Total Peers: 3
     Established Peers: 3
     Disabled Peers: 0
     Peers that did not converge before local bgp convergence:
     IPv4 peers:
     None
     IPv6 peers:
     None
    switch#

show bgp instance

The show bgp instance command displays summary Border Gateway Protocol (BGP) information about the BGP instance in the specified VRF or in all VRFs.

Command Mode

EXEC

Command Syntax

show bgp instance [VRF_INSTANCE]

Parameters

  • VRF_INSTANCE specifies VRF instances. Options include:
    • <no parameter> displays BGP information for the context-active VRF.
    • vrf vrf_name displays BGP information for the specified VRF.
    • vrf all displays BGP information for all VRFs.
    • vrf default displays BGP information for the default VRF.

Examples

  • This command displays information about the BGP instance in the context-active VRF.
    switch#show bgp instance
    BGP instance information for VRF purple
    BGP Local AS:64497, Router ID: 1.2.3.5
    Total peers:5
    Configured peers: 3
    UnConfigured peers: 2
    Disabled peers: 0
    Established peers:3
    Graceful restart helper mode enabled
    End of rib timer timeout: 00:05:00
    BGP Convergence timer is inactive
    BGP Convergence information:
    BGP has converged:no
    Outstanding EORs:0,Outstanding Keepalives: 0
    Convergence timeout: 00:10:00
    switch#
  • This command displays information about the BGP instance in the default VRF.
    switch#show bgp instance vrf default
    BGP instance information for VRF default
    BGP Local AS:64503, Router ID: 1.2.3.5
    Total peers:1
    Configured peers: 1
    UnConfigured peers: 0
    Disabled peers: 0
    Established peers:0
    Graceful restart helper mode enabled
    End of rib timer timeout: 00:05:00
    BGP Convergence timer is inactive
    BGP Convergence information:
    BGP has converged:no
    Outstanding EORs:0,Outstanding Keepalives: 0
    Convergence timeout: 00:10:00
    switch#

show bgp labeled-unicast tunnel

The show bgp labeled-unicast tunnel command displays the contents of the BGP labeled-unicast (LU) tunnel table. The user can optionally specify a tunnel index parameter to view the specific single tunnel information.

Command Mode

EXEC

Command Syntax

show bgp labeled-unicast tunnel tunnel_index

Parameters

  • tunnel_index index to view single tunnel information.

Example

  • This command displays the BGP LU tunnel table.
    switch#show bgp labeled-unicast tunnel
    Index Endpoint NexthopInterface LabelsContributing Metric Metric 2 Pref Pref 2
    ----- ---------- -------- ----------- --------------- ------------ ------ -------- ---- ------
    5 2.0.0.0/24 10.1.1.2 'Ethernet3' [ 123 899 900 ] Yes01002000
    6 2.0.1.0/24 10.1.1.2 'Ethernet3' [ 400 500 600 ] Yes01002000
    7 2.0.2.0/24 10.1.1.2 'Ethernet3' [ 400 500 600 ] Yes01002000
    switch#
  • This command displays the BGP LU tunnel table for tunnel index 4.
    switch#show bgp labeled-unicast tunnel 4
    Index EndpointNexthop/Tunnel Index Interface Labels Contributing Metric Metric 2PrefPref 2
    --------------------- ---------------------- --------------- -------- ------------ ------ --------- ----- ------
    4 10.253.0.10/3210.1.0.0 Port-Channel111 [ 3 ] Yes002000
    
    switch#

show ip as-path access-list

The show ip as-path access-list command displays BGP filters on the switch. Specifying an access list displays the statements from that access list. Entering the command without parameters displays the statements from all access lists on the switch.

Command Mode

EXEC

Command Syntax

show ip as-path access-list [list_name]

Parameters

  • list_name the name of an AS path access list.

Example

  • This command displays the contents of the AS path access list named “list1.”
    switch#show ip as-path access-list list1
    ip as-path access-list list1 deny _3$
    ip as-path access-list list1 permit .*
    switch#

show ip bgp community

The show ip bgp community command displays Border Gateway Protocol (BGP) routing table entries, filtered by community.

Command Mode

EXEC

Command Syntax

show ip bgp community COMM_1 [COMM_2... COMM_n] [MATCH_TYPE] [DATA_OPTION] [VRF_INSTANCE]

Parameters

  • COMM_x community number or name, as specified in the route map that sets the community list number.
    • GSHUT well-known graceful shutdown community.
    • aa:nn AS and network number, separated by colon. Each value ranges from 1 to 4294967295.
    • comm_num community number. Values range from 1 to 4294967040.
    • internet advertises route to Internet community.
    • local-as advertises route only to local peers.
    • no-advertise does not advertise the route to any peer.
    • no-export advertises route only within BGP AS boundary.
  • MATCH_TYPE routes are filtered based on their communities. Options include:
    • <no parameter> routes must match at least one community in the list.
    • exact route must match all communities and include no other communities.
    • regex display routes matching the regular expression of communities.
  • DATA_OPTION type of information the command displays. Options include:
    • <no parameter> displays table of the routing entry line items.
    • detail displays data block for each routing table entry.
  • VRF_INSTANCE specifies VRF instances. Options include:
    • <no parameter> displays routing table for context-active VRF.
    • vrf vrf_name displays routing table for the specified VRF.
    • vrf all displays routing table for all VRFs.
    • vrf default displays routing table for default VRF.

Guidelines

The interpretation of regular expressions is always based on string mode but not on the ACL configuration.

Example

  • This command displays the BGP routing table entries with the community 64496:1000.
    switch#show ip bgp community 64496:1000 detail
    BGP routing table information for VRF default
    Router identifier 10.0.0.102, local AS number 64500
    BGP routing table entry for 10.100.1.0/24
     Paths: 1 available
    64496 64497 65536
    10.1.0.100 from 10.1.0.100 (10.0.0.100)
    Origin IGP, metric 0, localpref 100, IGP metric 1, weight 0, received 00:03:16 ago, valid, external, best
    Community: 655:23590 64496:1000
    Rx SAFI: Unicast
    switch#

show ip bgp installed

The show ip bgp installed command displays the list of installed routes in the RIB.

Command Mode

EXEC

Command Syntax

show ip bgp installed

Example

  • This command displays the list of installed routes in the RIB.
    switch#show ip bgp installed 
    BGP routing table information for VRF default
    Router identifier 1.0.0.2, local AS number 100
    Route status codes: s - suppressed, * - valid, > - active, # - not installed, E 
    - ECMP head, e - ECMP
    S - Stale, c - Contributing to ECMP, b - backup
    Origin codes: i - IGP, e - EGP, ? - incomplete
    AS Path Attributes: Or-ID - Originator ID, C-LST - Cluster List, LL Nexthop - 
    Link Local Nexthop
    
    Network Next Hop MetricLocPref Weight Path
     * >6.0.0.0/241.0.0.10 100 0?
    switch#

show ip bgp neighbors (route type)

The show ip bgp neighbors (route type) command displays information for next-hop routes to a specified IPv4 neighbor. The show ip bgp neighbors (route-type) community command displays the same information for routes filtered by communities.

The output format depends on the selected FILTER parameter:

  • data-block format displays comprehensive information for each specified route.
  • tabular format displays routing table entries in tabular format for the specified IP addresses.

Commands that do not include a route type revert to the show ip bgp neighbors command.

Command Mode

EXEC

Command Syntax

show ip bgp neighbors neighbor_addr HOPDIRECT [FILTER] [VRF_INSTANCE]

show ip bgp neighbors neighbor_addr [ROUTE_TYPE] HOPDIRECT [detail]

Related Commands

Parameters

  • neighbor_addr location of the neighbor.
  • ROUTE_TYPE filters route on route type. Options include:
    • ipv4 unicast displays IPv4 unicast routes.
    • ipv6 unicast displays IPv6 unicast routes.
  • HOPDIRECT filters route on the basis of direction from neighbor. Options include:
    • advertised-routes displays routes advertised to the specified neighbor.
    • received-routes displays routes received from the specified neighbor (accepted and rejected).
    • routes displays routes received and accepted from specified neighbor.
  • FILTER routing table entries that the command displays. Values include:
    • <no parameter> displays all routing table entries in tabular format.
    • detail displays all routing table entries in data-block format.
    • ipv4_addr displays IPv4 host address in data-block format.
    • ipv4_prefix displays the route information of specified IPv4 prefix in data-block format. Option includes:
      • longer-prefixes displays the route information of IPv4 prefix in data-block format.
  • VRF_INSTANCE specifies VRF instances. Options include:
    • <no parameter> displays routing table for context-active VRF.
    • vrf vrf_name displays routing table for the specified VRF.
    • vrf all displays routing table for all VRFs.
    • vrf default displays routing table for default VRF.

Example

  • This command displays information for routes advertised to the neighbor at 10.3.0.103.
    switch#show ip bgp neighbors 10.3.0.103 advertised-routes
    BGP routing table information for VRF default
    Router identifier 10.0.0.102, local AS number 64500
    Route status codes: s - suppressed, * - valid, > - active, # - not installed, E - ECMP head, e - ECMP
    S - Stale, c - Contributing to ECMP, b - backup, L - labeled-unicast
    Origin codes: i - IGP, e - EGP, ? - incomplete
    AS Path Attributes: Or-ID - Originator ID, C-LST - Cluster List, LL Nexthop - Link Local Nexthop
    
     NetworkNext HopMetricLocPref WeightPath
     * > 10.1.0.0/2410.3.0.102- 100 - i
     * > 10.2.0.0/2410.3.0.102- 100 - i
     * > 10.3.0.0/2410.3.0.102- 100 - i
     * > 10.100.0.0/2410.1.0.100200 100 - 64496 i
     * > 10.100.1.0/2410.1.0.100- 100 - 64496 64497 65536 i
     * > 10.100.2.0/2410.1.0.10042100 - 64496 ?
     * > 10.101.0.0/2410.2.0.101- 100 - 64510 i
     * > 10.101.1.0/2410.2.0.101- 100 - 64510 i
     * > 10.101.2.0/2410.2.0.101- 100 - 64510 i
    switch#

show ip bgp neighbors (route-type) community

The show ip bgp neighbors (route type) community command displays information for next-hop routes to a specified neighbor. Routes are filtered by community.

The show ip bgp neighbors (route type) command displays the same information for routes filtered by IP addresses and subnets.

Command Mode

EXEC

Command Syntax

show ip bgp neighbors addr RTE community CM_1 [CM_2...CM_n] [MATCH] [INFO] [VRF_INST]

Related Commands

Parameters

  • addr location of the neighbor.
  • RTE type of route that the command displays. Options include:
    • advertised-routes displays routes advertised to the specified neighbor.
    • received-routes displays routes received from the specified neighbor (accepted and rejected).
    • routes displays routes received and accepted from specified neighbor.
  • CM_x community number or name, as specified in the route map that sets the community list number. The command must list at least one of the following community identifiers:
    • GSHUT well-known graceful shutdown community.
    • aa:nn AS and network number, separated by colon. Each value ranges from 1 to 4294967295.
    • comm_num community number. Values range from 1 to 4294967040.
    • internet advertises route to Internet community.
    • local-as advertises route only to local peers.
    • no-advertise does not advertise route to any peer.
    • no-export advertises route only within BGP AS boundary.
  • MATCH routes are filtered based on their communities.
    • <no parameter> routes must match at least one community in the list.
    • exact route must match all communities and include no other communities.
  • INFO type of information the command displays. Values include:
    • <no parameter> displays table of routing entry line items.
    • detail displays data block for each routing table entry.
  • VRF_INST specifies VRF instances. Options include:
    • <no parameter> displays routing table for context-active VRF.
    • vrf vrf_name displays routing table for the specified VRF.
    • vrf all displays routing table for all VRFs.
    • vrf default displays routing table for default VRF.

Example

  • This command lists the routes advertised to the neighbor at 10.3.0.103 with community 655:23590.
    switch#show ip bgp neighbors 10.3.0.103 advertised-routes community 655:23590
    BGP routing table information for VRF default
    Router identifier 10.0.0.102, local AS number 64500
    Route status codes: s - suppressed, * - valid, > - active, # - not installed, E - ECMP head, e - ECMP
    S - Stale, c - Contributing to ECMP, b - backup, L - labeled-unicast
    Origin codes: i - IGP, e - EGP, ? - incomplete
    AS Path Attributes: Or-ID - Originator ID, C-LST - Cluster List, LL Nexthop - Link Local Nexthop
    
     NetworkNext HopMetricLocPref WeightPath
     * > 10.100.1.0/2410.1.0.100- 100 - 64496 64497 65536 i
    switch#

show ip bgp neighbors regexp

The show ip bgp neighbors regexp command displays information for next-hop routes to a specified IPv4 neighbor that match the AS path attributes specified in the given regular expression.

Command Mode

EXEC

Command Syntax

show ip bgp neighbors addr RTE regexp as_paths [VRF_INST]

Related Commands

Parameters

  • addr location of the neighbor.
  • RTE type of route that the command displays. Options include:
    • advertised-routes displays routes advertised to the specified neighbor.
    • received-routes displays routes received from the specified neighbor (accepted and rejected).
    • routes displays routes received and accepted from specified neighbor.
  • as_paths list of AS paths, formatted as a regular expression. Regular expressions are pattern-matching strings that are composed of text characters and operators.
  • VRF_INST specifies VRF instances. Options include:
    • <no parameter> displays routing table for context-active VRF.
    • vrf vrf_name displays routing table for the specified VRF.
    • vrf all displays routing table for all VRFs.
    • vrf default displays routing table for default VRF.

Example

  • This command lists the routes advertised to the neighbor at 10.3.0.103 where the AS path is 64496.
    switch#show ip bgp neighbors 10.3.0.103 advertised-routes regex ^64496$
    BGP routing table information for VRF default
    Router identifier 10.0.0.102, local AS number 64500
    Route status codes: s - suppressed, * - valid, > - active, # - not installed, E - ECMP head, e - ECMP
    S - Stale, c - Contributing to ECMP,b - backup, L = labeled-unicast
    % - Pending BGP convergence
    Origin codes: i - IGP, e - EGP, ? - incomplete
    AS Path Attributes: Or-ID - Originator ID, C-LST -Cluster List, LL Nexthop - Link Local Nexthop
    
    NetworkNext Hop MetricLocPref WeightPath
     * > 10.100.0.0/24 10.1.0.100 200 100 - 64496 i
     * > 10.100.2.0/24 10.1.0.100 42100 - 64496 ?
    switch#

show ip bgp neighbors

The show ip bgp neighbors command displays Border Gateway Protocol (BGP) and TCP-session data for a specified IPv4 BGP neighbor, or for all IPv4 BGP neighbors if an address is not specified.

Command Mode

EXEC

Command Syntax

show ip bgp neighbors [NEIGHBOR_ADDR] [VRF_INSTANCE]

Parameters

  • NEIGHBOR_ADDR location of the neighbors. Options include:
    • <no parameter> command displays information for all IPv4 BGP neighbors.
    • ipv4_addr command displays information for specified neighbor.
  • VRF_INSTANCE specifies VRF instances. Options include:

    • <no parameter> displays routing table for context-active VRF.
    • vrf vrf_name displays routing table for the specified VRF.
    • vrf all displays routing table for all VRFs.
    • vrf default displays routing table for the default VRF.

Related Command

Example

  • This command displays information of the neighbor at 10.1.0.100.
    switch#show ip bgp neighbors 10.1.0.100
    BGP neighbor is 10.1.0.100, remote AS 64496, external link
    BGP version 4, remote router ID 10.0.0.100, VRF default
    Inherits configuration from and member of peer-group EXTERNAL
    Negotiated BGP version 4
    Member of update group 3
    Last read 00:00:17, last write 00:00:18
    Hold time is 180, keepalive interval is 60 seconds
    Configured hold time is 180, keepalive interval is 60 seconds
    Connect timer is inactive
    Idle-restart timer is inactive
    BGP state is Established, up for 00:05:17
    Number of transitions to established: 1
    Last state was OpenConfirm
    Last event was RecvKeepAlive
    Neighbor Capabilities:
    Multiprotocol IPv4 Unicast: advertised and received and negotiated
    Four Octet ASN: advertised and received and negotiated
    Route Refresh: advertised and received and negotiated
    Send End-of-RIB messages: advertised and received and negotiated
    Additional-paths recv capability:
    IPv4 Unicast: advertised
    Additional-paths send capability:
    IPv4 Unicast: received
    Restart timer is inactive
    End of rib timer is inactive
    Message Statistics:
    InQ depth is 0
    OutQ depth is 0
     SentRcvd
    Opens:1 1
    Notifications:0 0
    Updates:4 4
    Keepalives: 7 7
    Route-Refresh:0 0
    Total messages:1212
    Prefix Statistics:
     SentRcvd
    IPv4 Unicast: 9 4
    IPv6 Unicast: 0 0
    IPv4 SR-TE: 0 0
    IPv6 SR-TE: 0 0
    Inbound updates dropped by reason:
    AS path loop detection: 0
    Enforced First AS: 0
    Originator ID matches local router ID: 0
    Nexthop matches local IP address: 0
    Unexpected IPv6 nexthop for IPv4 routes: 0
    Nexthop invalid for single hop eBGP: 0
    Inbound updates with attribute errors:
    Resulting in removal of all paths in update (treat-as-withdraw): 0
    Resulting in AFI/SAFI disable: 0
    Resulting in attribute ignore: 0
    Inbound paths dropped by reason:
    IPv4 labeled-unicast NLRIs dropped due to excessive labels: 0
    IPv6 labeled-unicast NLRIs dropped due to excessive labels: 0
    Outbound paths dropped by reason:
    IPv4 local address not available: 0
    IPv6 local address not available: 0
    Local AS is 64500, local router ID 10.0.0.102
    TTL is 255, BGP neighbor may be upto 1 hops away
    Local TCP address is 10.1.0.102, local port is 179
    Remote TCP address is 10.1.0.100, remote port is 33171
    Auto-Local-Addr is disabled
    TCP Socket Information:
    TCP state is ESTABLISHED
    Recv-Q: 0/32768
    Send-Q: 0/32768
    Outgoing Maximum Segment Size (MSS): 1448
    Total Number of TCP retransmissions: 0
    Options:
    Timestamps enabled: yes
    Selective Acknowledgments enabled: yes
    Window Scale enabled: yes
    Explicit Congestion Notification (ECN) enabled: no
    Socket Statistics:
    Window Scale (wscale): 9,9
    Retransmission Timeout (rto): 204.0ms
    Round-trip Time (rtt/rtvar): 3.0ms/5.4ms
    Delayed Ack Timeout (ato): 40.0ms
    Congestion Window (cwnd): 10
    TCP Throughput: 39.20 Mbps
    Advertised Recv Window (rcv_space): 28960
    switch#
  • This command displays neighbor information for all neighbors.
    switch#show ip bgp neighbors
    BGP neighbor is 172.24.77.5, remote AS 100, external link
    BGP version 4, remote router ID 172.24.77.5, VRF default
    ...
    Neighbor Capabilities:
    Multiprotocol IPv4 Unicast: advertised
    Multiprotocol IPv4 Labeled Unicast: advertised and received and negotiated
    Four Octet ASN: advertised and received
    Route Refresh: advertised
    Send End-of-RIB messages: advertised
    Additional-paths Receive:
    IPv4 Unicast: advertised
    IPv4 Labeled Unicast: advertised
    ...
    Inbound updates dropped by reason:
    AS path loop detection: 0
    Enforced First AS: 0
    Malformed MPBGP routes: 0
    Originator ID matches local router ID: 0
    Nexthop matches local IP address: 0
    Unexpected IPv6 nexthop for IPv4 routes: 0
    Inbound paths dropped by reason:
    IPv4 labeled-unicast NLRIs dropped due to excessive labels: 0
    switch#

show ip bgp not-installed

The show ip bgp not-installed command displays the list of non-installed routes in the RIB.

Command Mode

EXEC

Command Syntax

show ip bgp not-installed

Example

  • This command displays the list of non-installed routes in the RIB.
    switch#show ip bgp not-installed 
    BGP routing table information for VRF default
    Router identifier 1.0.0.2, local AS number 100
    Route status codes: s - suppressed, * - valid, > - active, # - not installed, E 
    - ECMP head, e - ECMP
    S - Stale, c - Contributing to ECMP, b - backup
    Origin codes: i - IGP, e - EGP, ? - incomplete
    AS Path Attributes: Or-ID - Originator ID, C-LST - Cluster List, LL Nexthop - 
    Link Local Nexthop
    
    Network Next Hop MetricLocPref Weight Path
     * #7.0.0.0/241.0.0.10 100 0?
    switch#

show ip bgp paths

The show ip bgp paths command displays all BGP AS paths in the database.

Command Mode

EXEC

Command Syntax

show ip bgp paths [VRF_INSTANCE]

Parameters

  • VRF_INSTANCE specifies VRF instances.
    • <no parameter> displays routing table for context-active VRF.
    • vrf vrf_name displays routing table for the specified VRF.
    • vrf all displays routing table for all VRFs.
    • vrf default displays routing table for default VRF.

Display Values

  • Refcount: number of routes using a listed path.
  • Metric: the path’s Multi Exit Discriminator (MED).
  • Path: the route’s AS path and its origin code.

    The MED (the path’s external metric) provides information to external neighbors about the preferred path into an AS that has multiple entry points. Lower MED values are preferred.

Example

  • This command displays all BGP AS paths in the switch’s database.
    switch#show ip bgp paths
    Refcount Metric Path
    6064510 64505 64506 64507 i (HashID 9)
    6064510 ? (HashID 8)
    12 065530 65531 65532 e (HashID 5)
    12 0i (HashID 6)
    6064100 64200 i (HashID 4)
    28 0i (HashID 1)
    70? (HashID 2)
    40 064510 i (HashID 10)
    19 064510 i (HashID 7)
    20i (HashID 3)
    switch#

show ip bgp peer-group

The show ip bgp peer-group command displays the BGP version, address family, and group members for all BGP peer groups defined on the switch.

Command Mode

EXEC

Command Syntax

show ip bgp peer-group [GROUP] [VRF_INSTANCE]

Parameters

  • GROUP peer group for which command displays information. Options include:
    • <no parameter> command displays information for all peer groups.
    • group_name name of peer group for which command displays information.
  • VRF_INSTANCE specifies VRF instances.
    • <no parameter> displays routing table for context-active VRF.
    • vrf vrf_name displays routing table for the specified VRF.
    • vrf all displays routing table for all VRFs.
    • vrf default displays routing table for default VRF.

Example

  • This command displays BGP peer group information for all peer groups on the switch.
    switch#show ip bgp peer-group
    BGP peer-group is EXTERNAL
    BGP version 4
    Static peer-group members:
    VRF default:
    10.1.0.100, state: Connect
    Negotiated MP Capabilities:
    IPv4 Unicast: No
    IPv6 Unicast: No
    IPv4 SR-TE: No
    IPv6 SR-TE: No
    10.2.0.101, state: Connect
    Negotiated MP Capabilities:
    IPv4 Unicast: No
    IPv6 Unicast: No
    IPv4 SR-TE: No
    IPv6 SR-TE: No
    BGP peer-group is INTERNAL
    BGP version 4
    Listen-range subnets:
    VRF default:
    10.3.0.0/24, remote AS 64500
    Dynamic peer-group members:
    VRF default:
    switch#

show ip bgp regexp

The show ip bgp regexp command displays Border Gateway Protocol (BGP) IPv4 routing-table entries that match the AS path attributes specified in the given regular expression.

Command Mode

EXEC

Command Syntax

show ip bgp regexp as_paths [VRF_INSTANCE]

Parameters

  • as_paths list of AS paths, formatted as a regular expression. Regular expressions are pattern matching strings that are composed of text characters and operators.
  • VRF_INSTANCE specifies the VRF instance of the BGP routing table to be displayed.Options include:
    • <no parameter> displays routing table for context-active VRF.
    • vrf vrf_name displays routing table for the specified VRF.
    • vrf all displays routing table for all VRFs.
    • vrf default displays routing table for default VRF.

Example

  • This command displays information about the BGP IPv4 routes in the context-active VRF where the AS path is 64510.
    switch#show ip bgp regex ^64510$
    BGP routing table information for VRF default
    Router identifier 10.0.0.102, local AS number 64500
    Route status codes: s - suppressed, * - valid, > - active, # - not installed, E - ECMP head, e - ECMP
    S - Stale, c - Contributing to ECMP,b - backup, L = labeled-unicast
    % - Pending BGP convergence
    Origin codes: i - IGP, e - EGP, ? - incomplete
    AS Path Attributes: Or-ID - Originator ID, C-LST -Cluster List, LL Nexthop - Link Local Nexthop
    
    NetworkNext Hop MetricLocPref WeightPath
     * 10.2.0.0/24 10.2.0.101 0 100 0 64510 i
     * > 10.101.0.0/24 10.2.0.101 0 100 0 64510 i
     * > 10.101.1.0/24 10.2.0.101 0 100 0 64510 i
     * > 10.101.2.0/24 10.2.0.101 0 100 0 64510 i
    switch#

show ip bgp summary

The show ip bgp summary command displays the summary of all IPv4 and IPv6 BGP neighbors based on exchanged Address Family Identifiers (AFI) and Subsequent Address Family Identifiers (SAFI) negotiations where AFI is “IP” and SAFI is “unicast” information.

Command Mode

EXEC

Command Syntax

show ip bgp summary [VRF_INSTANCE]

Parameters

  • VRF_INSTANCE specifies VRF instances. Options include:
    • <no parameter> displays routing table for context-active VRF.
    • vrf vrf_name displays routing table for the specified VRF.
    • vrf all displays routing table for all VRFs.
    • vrf default displays routing table for default VRF.

Display Values

Header Row

  • BGP router identifier: the router identifier loopback address or highest IP address.
  • Local AS Number: AS number assigned to the switch.

Neighbor Table Columns

  • (First) Neighbor: neighbor’s IP address.
  • (Second) V: BGP version number.
  • (Third) AS: neighbor's AS number.
  • (Fourth) MsgRcvd: messages received from the neighbor.
  • (Fifth) MsgSent: messages sent to neighbor.
  • (Sixth) InQ: messages queued from neighbor.
  • (Seventh) OutQ: messages queued to send neighbor.
  • (Eighth) Up/Down: period the BGP session has been Established, or its current status.
  • (Ninth) State: State of the BGP session and the number of routes received from a neighbor.

After the maximum number of routes are received, the ninth field displays PfxRcd, and the connection becomes Idle. Maximum number of routes is set using the maximum paths (BGP) command.

Related Command

Example

  • This command displays the status of the switch’s BGP connections.
    switch#show ip bgp summary
    BGP summary information for VRF default
    Router identifier 10.0.0.102, local AS number 64500
    Neighbor Status Codes: m - Under maintenance
    Neighbor VAS MsgRcvd MsgSentInQ OutQUp/Down State PfxRcd PfxAcc
    10.1.0.100 464496 1075108300 00:04:04 Connect
    10.2.0.101 464510 1079108800 00:04:14 Connect
    switch#

show ip bgp

The show ip bgp command displays Border Gateway Protocol (BGP) IPv4 routing table entries. The output format depends on the command parameters:

  • data-block format displays comprehensive information for each specified BGP routing-table entry.
  • tabular format displays routing-table entries for the specified IPv4 addresses.

Command Mode

EXEC

Command Syntax

show ip bgp [FILTER] [VRF_INSTANCE]

Parameters

  • FILTER routing-table entries to display. Options include:
    • <no parameter> displays all routing-table entries in tabular format.
    • detail displays all routing-table entries in data-block format.
    • ipv4_addr displays IPv4 host address in data-block format.
    • PREFIX displays the route information of the specified IPv4 prefix in data block format. Options include:
      • detail ipv4_prefixdisplays the detailed route information of specified IPv4 prefix in data block format.
      • longer-prefixes ipv4_prefix displays the route information of IPv4 prefix in tabular block format.
      • longer-prefixes detail ipv4_prefix displays the detailed route information of specified IPv4 prefix in data block format.
    • community-list cmnty_list_name displays BGP routes filtered by the specified community list.
    • installed displays the information of installed BGP routes.
    • labeled-unicast displays the information of labeled-unicast BGP routes only.
    • not-installed displays the information of BGP routes that are not installed.
  • VRF_INSTANCE specifies VRF instances. Options include:
    • <no parameter> displays routing table for context-active VRF.
    • vrf vrf_name displays routing table for the specified VRF.
    • vrf all displays routing table for all VRFs.
    • vrf default displays routing table for default VRF.

Guidelines

You must provide the IPv4 prefix in CIDR notation.

Examples

  • This command displays the BGP routing table with prefix “L” flag for all BGP LU route entries.
    switch#show ip bgp
    BGP routing table information for VRF default
    Router identifier 0.0.0.1, local AS number 100
    Route status codes: s - suppressed, * - valid, > - active, # - not installed, E 
    - ECMP head, e - ECMP
    S - Stale, c - Contributing to ECMP, b - backup, L - labeled-unicast
    Origin codes: i - IGP, e - EGP, ? - incomplete
    AS Path Attributes: Or-ID - Originator ID, C-LST - Cluster List, LL Nexthop - 
    Link Local Nexthop
    
    NetworkNext Hop Metric LocPref Weight Path
    * > L 2.0.0.1/32 1.1.1.20100 0300 i
    * # 2.0.0.1/32 1.0.0.20100 0200 ?
    * > L 2.0.0.2/32 1.1.1.20100 0300 i
    * # 2.0.0.2/32 1.0.0.20100 0200 ?
    * > L 2.0.0.3/32 1.1.1.20100 0300 i
    * # 2.0.0.3/32 1.0.0.20100 0200 ?
    * > L 2.0.0.4/32 1.1.1.20100 0300 i
    * # 2.0.0.4/32 1.0.0.20100 0200 ?
    * > L 2.0.0.5/32 1.1.1.20100 0300 i
    * # 2.0.0.5/32 1.0.0.20100 0200 ?
    switch#
  • This command displays the routing-table information of unicast routes for a default VRF.
    switch#show ip bgp
    BGP routing table information for VRF default
    Router identifier 0.0.0.1, local AS number 100
    BGP routing table entry for 2.0.0.1/32
    Paths: 2 available
    300
    1.1.1.2 labels [ 101 102 103 104 ] from 1.1.1.2 (1.1.1.2)
    Origin IGP, metric 0, localpref 100, weight 0, valid, external, best
    Rx path id: 0x0
    200
    1.0.0.2 from 1.0.0.2 (0.0.1.1)
    Origin INCOMPLETE, metric 0, localpref 100, weight 0, valid, external, 
    not installed (labeled-route present)
    switch#
  • This command displays the BGP routing-table entry for the 10.100.1.0/24 network.
    switch#show ip bgp 10.100.1.0/24
    BGP routing table information for VRF default
    Router identifier 10.0.0.102, local AS number 64500
    BGP routing table entry for 10.100.1.0/24
     Paths: 1 available
    64496 64497 65536
    10.1.0.100 from 10.1.0.100 (10.0.0.100)
    Origin IGP, metric 0, localpref 100, IGP metric 1, weight 0, received 
    01:57:33 ago, valid, external, best
    Community: 655:23590 64496:1000
    Rx SAFI: Unicast
    switch#
  • This command displays the label stack associated with the route for a default VRF.
    switch#show ip bgp detail
    BGP routing table information for VRF default
    Router identifier 0.0.0.1, local AS number 100
    BGP routing table entry for 2.0.0.1/32
    Paths: 2 available
    200
    1.0.0.2 from 1.0.0.2 (0.0.1.1)
    Origin INCOMPLETE, metric 0, localpref 100, weight 0, valid, external, best
    300
    1.1.1.2 labels [ 101 102 103 104 ] from 1.1.1.2 (1.1.1.2)
    Origin IGP, metric 0, localpref 100, weight 0, valid, external
    Rx path id: 0x0
    Rx SAFI: Labels
    Tunnel RIB eligible
    switch#
  • This command displays the BGP routing-table entry for the 10.105.1.1/24 network, including the reason why the route was discarded by the best-path algorithm. The reason for discarding a route is preceded by the label “Not best:”.
    switch#show ip bgp 10.105.1.1/24 detail
    BGP routing table information for VRF default
    Router identifier 10.0.0.102, local AS number 64500
    Route status: [a.b.c.d] - Route isqueued for advertisement to peer.
    BGP routing table entry for 10.105.1.0/24
     Paths: 2 available
    64510
    10.2.0.101 from 10.2.0.101 (12.0.0.101)
    Origin IGP, metric 0, localpref 100, IGP metric 1, weight 0, received 
    00:00:58 ago, valid, external, best
    Rx SAFI: Unicast
    64496
    10.1.0.100 from 10.1.0.100 (10.0.0.100)
    Origin INCOMPLETE, metric 42, localpref 100, IGP metric 1, weight 0, received 
    00:00:33 ago, valid, external
    Rx SAFI: Unicast
    Not best: Origin
     Advertised to 2 peers:
    peer-group EXTERNAL:
    10.1.0.100
    peer-group INTERNAL:
    10.3.0.103
    switch#

show ip community-list

The show ip community-list command displays the BGP community lists configured on the switch.

Command Mode

EXEC

Command Syntax

show ip community-list [COMMUNITY_LIST]

Parameters

  • COMMUNITY_LIST community list for which command displays information. Options include:
    • <no parameter> command displays information for all community lists.
    • listname name of the community list (text string).

Example

  • This command displays the BGP paths in the switch’s database.
    switch#show ip community-list hs-comm-list
    ip community-list hs-comm-list permit 0:10
    switch#

show ip extcommunity-list

The show ip extcommunity-list command displays the BGP extended community lists configured on the switch.

Command Mode

EXEC

Command Syntax

show ip extcommunity-list [COMMUNITY_LIST]

Parameters

  • COMMUNITY_LIST extended community list for which command displays information. Options include:
    • <no parameter> command displays information for all extended community lists.
    • listname command displays information for the specified extended community list.

Example

  • This command displays information for all extended extcommunity lists on the switch.
    switch#show ip extcommunity-list
    ip extcommunity-list hs-extcomm-list permit rt 3050:20
    ip extcommunity-list hs-extcomm-list permit soo 172.17.52.2:30
    ip extcommunity-list hs-extcomm-list permit rt 3050:70000
    switch#

show ipv6 bgp match community

The show ipv6 bgp match community command displays IPv6 Border Gateway Protocol (BGP) routing-table entries, filtered by community.

Command Mode

EXEC

Command Syntax

show ipv6 bgp match community [COMM_1 ... COMM_n] [MATCH_TYPE] [INFO] [VRF_INSTANCE]

Parameters

  • COMM_x community number or name, as specified in the route map that sets the community-list number. Options include:
    • aa:nn AS and network number, separated by colon. Each value ranges from 1 to 4294967295.
    • comm_num community number. Values range from 1 to 4294967040.
    • internet advertises route to Internet community.
    • local-as advertises route only to local peers.
    • no-advertise does not advertise route to any peer.
    • no-export advertises route only within BGP AS boundary.
  • MATCH_TYPE routes are filtered based on their communities. Options include:
    • <no parameter> routes must match at least one community in the list.
    • exact route must match all communities and include no other communities.
  • INFO type of information the command displays. Options include:
    • <no parameter> displays table of the routing entry-line items.
    • detail displays data block for each routing-table entry.
  • VRF_INSTANCE specifies VRF instances. Options include:
    • <no parameter> displays routing-table for context-active VRF.
    • vrf vrf_name displays routing table for the specified VRF.
    • vrf all displays routing table for all VRFs.
    • vrf default displays routing table for default VRF.

Example

  • This command displays information in data-block format for each routing-table entry with community 655:23590.
    switch(config)#show ipv6 bgp match community 655:23590 detail
    BGP routing table information for VRF default
    Router identifier 10.0.0.102, local AS number 64500
    BGP routing table entry for 2001:10:100:1::/64
     Paths: 1 available
    64496 64497 65536
    2001:10:1::100 from 2001:10:1::100 (10.0.0.100)
    Origin IGP, metric 0, localpref 100, IGP metric 1, weight 0, received 01:09:29 ago, valid, external, best
    Community: 655:23590 64496:1000
    Rx SAFI: Unicast
    switch(config)#

show ipv6 bgp peers (route type) community

The show ipv6 bgp peers (route type) community command displays information about the routes either advertised to or received from a specified IPv6 BGP neighbor. The routes are filtered by community.

The show ipv6 bgp peers (route type) command displays the same information for routes filtered by IP addresses and prefixes.

Command Mode

EXEC

Command Syntax

show ipv6 bgp peers addr RTE community CM_1 [CM_2...CM_n] [MATCH] [INFO] [VRF_INST]

Parameters

  • addr neighbor location (IPv6 address).
  • RTE type of route that the command displays. Options include:
    • advertised-routes displays routes advertised to the specified neighbor.
    • received-routes displays routes received from the specified neighbor (accepted and rejected).
    • routes displays routes received and accepted from specified neighbor.
  • CM_x community number or name, as specified in the route map that sets the community list number. The command must list at least one of the following community identifiers:
    • GSHUT well-known graceful shutdown community.
    • aa:nn AS and network number, separated by colon. Each value ranges from 1 to 4294967295.
    • comm_num community number. Values range from 1 to 4294967040.
    • internet advertises route to Internet community.
    • local-as advertises route only to local peers.
    • no-advertise does not advertise route to any peer.
    • no-export advertises route only within BGP AS boundary.
  • MATCH routes are filtered based on their communities. Options include:
    • <no parameter> routes must match at least one community in the list
    • exact route must match all communities and include no other communities.
  • INFO type of information the command displays. Values include:
    • <no parameter> displays table of the routing entry line items.
    • detail displays data block for each routing table entry.
  • VRF_INST specifies VRF instances. Options include:
    • <no parameter> displays routing table for context-active VRF.
    • vrf vrf_name displays routing table for the specified VRF.
    • vrf all displays routing table for all VRFs.
    • vrf default displays routing table for default VRF.

Related Command

Example

  • This command lists the routes advertised to the neighbor at 2001:10:1:0::102 with the community 64496:1000.
    switch#show ipv6 bgp peers 2001:10:1:0::102 advertised-routes community 64496:1000
    BGP routing table information for VRF default
    Router identifier 10.0.0.100, local AS number 64496
    Route status codes: s - suppressed, * - valid, > - active, # - not installed, E - ECMP head, e - ECMP
    S - Stale, c - Contributing to ECMP, b - backup, L - labeled-unicast
    Origin codes: i - IGP, e - EGP, ? - incomplete
    AS Path Attributes: Or-ID - Originator ID, C-LST - Cluster List, LL Nexthop - Link Local Nexthop
    
     NetworkNext HopMetricLocPref WeightPath
     * > 2001:10:100:1::/64 2001:10:1::100- - - 64496 64497 65536 i
    switch#

show ipv6 bgp peers (route type)

The show ipv6 bgp peers (route type) command displays information about the routes either advertised to or received from a specified IPv6 BGP neighbor. The show ipv6 bgp peers (route type) community command displays the same information for routes filtered by communities. Commands that do not include a route type revert to the show ipv6 bgp peers command.

The output format depends on the selected FILTER parameter:

  • data-block format displays comprehensive information for each specified route.
  • tabular format displays routing table entries in tabular format for the specified IP addresses.

Output produced by the longer-prefixes option includes the specified route and all more specific routes.

Command Mode

EXEC

Command Syntax

show ipv6 bgp peers neighbor_addr HOPDIRECT [FILTER] [VRF_INSTANCE]

show ipv6 bgp peers neighbor_addr [ROUTE_TYPE] HOPDIRECT [detail]

Parameters

  • neighbor_addr location of the neighbor.
  • ROUTE_TYPE filters route on route type. Options include:
    • ipv4 unicast displays IPv4 unicast routes.
    • ipv6 unicast displays IPv6 unicast routes.
  • HOPDIRECT filters route on the basis of direction from neighbor. Options include:
    • advertised-routes displays routes advertised to the specified neighbor.
    • received-routes displays routes received from the specified neighbor (accepted and rejected).
    • routes displays routes received and accepted from specified neighbor.
  • FILTER routing table entries that the command displays. Options include:
    • <no parameter> displays all routing table entries in tabular format.
    • detail displays all routing table entries in data-block format.
    • ipv6_addr displays the IPv6 host address in data-block format.
    • ipv6_prefix displays the route information of specified IPv6 prefix in data-block format. Additional option:
      • longer-prefixes displays the route information of IPv4 prefix in data-block format.
  • VRF_INSTANCE specifies VRF instances. Options include:
    • <no parameter> displays routing table for context-active VRF.
    • vrf vrf_name displays routing table for the specified VRF.
    • vrf all displays routing table for all VRFs.
    • vrf default displays routing table for default VRF.

Related Commands

Example

  • This command displays information of all routes advertised to the neighbor at 2001:10:1:0::100.
    switch#show ipv6 bgp peers 2001:10:1:0::100 advertised-routes
    BGP routing table information for VRF default
    Router identifier 10.0.0.102, local AS number 64500
    Route status codes: s - suppressed, * - valid, > - active, # - not installed, E - ECMP head, e - ECMP
    S - Stale, c - Contributing to ECMP, b - backup, L - labeled-unicast
    Origin codes: i - IGP, e - EGP, ? - incomplete
    AS Path Attributes: Or-ID - Originator ID, C-LST - Cluster List, LL Nexthop - Link Local Nexthop
    
     NetworkNext HopMetricLocPref WeightPath
     * > 2001:10:1::/64 2001:10:1::102- - - 64500 i
     * > 2001:10:2::/64 2001:10:1::102- - - 64500 i
     * > 2001:10:3::/64 2001:10:1::102- - - 64500 i
     * > 2001:10:101::/64 2001:10:1::102- - - 64500 64510 i
     * > 2001:10:101:1::/64 2001:10:1::102- - - 64500 64510 i
     * > 2001:10:101:2::/64 2001:10:1::102- - - 64500 64510 i
    switch#

show ipv6 bgp peers regexp

The show ipv6 bgp peers regexp command displays information about routes (advertised or received) from a specified IPv6 neighbor that match the AS-path attributes specified in the given regular expression.

Command Mode

EXEC

Command Syntax

show ipv6 bgp peers addr ROUTE regexp as_paths [VRF_INST]

Parameters

  • addr neighbor location (IPv6 address).
  • ROUTE type of route that the command displays. Options include:
    • advertised-routes displays routes advertised to the specified neighbor.
    • received-routes displays routes received from the specified neighbor (accepted and rejected).
    • routes displays routes received and accepted from specified neighbor.
  • as_paths list of AS paths, formatted as a regular expression. Regular expressions are pattern-smatching strings that are composed of text characters and operators.
  • VRF_INST specifies VRF instances. Options include:
    • <no parameter> displays routing table for context-active VRF.
    • vrf vrf_name displays routing table for the specified VRF.
    • vrf all displays routing table for all VRFs.
    • vrf default displays routing table for default VRF.

Related Commands

Examples

  • This command displays information for routes received from the neighbor at 2001:10:1:0::100 which include AS number 64496 in their AS paths.
    switch#show ipv6 bgp peers 2001:10:1:0::100 received-routes regex 64496
    BGP routing table information for VRF default
    Router identifier 10.0.0.102, local AS number 64500
    Route status codes: s - suppressed, * - valid, > - active, # - not installed, E - ECMP head, e - ECMP
    S - Stale, c - Contributing to ECMP, b - backup, L - labeled-unicast
    Origin codes: i - IGP, e - EGP, ? - incomplete
    AS Path Attributes: Or-ID - Originator ID, C-LST - Cluster List, LL Nexthop - Link Local Nexthop
    
     NetworkNext HopMetricLocPref Weight Path
     * 2001:10:1::/64 2001:10:1::10042- -64496 ?
     * > 2001:10:100::/64 2001:10:1::100200 - -64496 i
     * > 2001:10:100:1::/64 2001:10:1::100- - -64496 64497 65536 i
     * > 2001:10:100:2::/64 2001:10:1::10042- -64496 ?
    switch#

show ipv6 bgp peers

The show ipv6 bgp peers command displays IPv6 Border Gateway Protocol (BGP) and TCP session data for a specified neighbor. Command displays data for all neighbors if an address is not included.

Command Mode

EXEC

Command Syntax

show ipv6 bgp peers [NEIGHBOR_ADDR] [VRF_INSTANCE]

Parameters

  • NEIGHBOR_ADDR location of the neighbors. Options include:
    • <no parameter> command displays information for all neighbors.
    • ipv6_addr command displays information for the specified neighbor.
  • VRF_INSTANCE specifies VRF instances. Options include:
    • <no parameter> displays routing table for the context-active VRF.
    • vrf vrf_name displays routing table for the specified VRF.
    • vrf all displays routing table for all VRFs.
    • vrf default displays routing table for the default VRF.

Related Command

Example

  • This command displays information for the neighbor at 2001:10:1:0::100.
    switch#show ipv6 bgp peers 2001:10:1:0::100
    BGP neighbor is 2001:10:1::100, remote AS 64496, external link
    BGP version 4, remote router ID 10.0.0.100, VRF default
    Inherits configuration from and member of peer-group EXTERNAL
    Negotiated BGP version 4
    Member of update group 3
    Last read 00:00:01, last write 00:00:01
    Hold time is 180, keepalive interval is 60 seconds
    Configured hold time is 180, keepalive interval is 60 seconds
    Connect timer is inactive
    Idle-restart timer is inactive
    BGP state is Established, up for 00:12:01
    Number of transitions to established: 1
    Last state was OpenConfirm
    Last event was RecvKeepAlive
    Neighbor Capabilities:
    Multiprotocol IPv6 Unicast: advertised and received and negotiated
    Four Octet ASN: advertised and received and negotiated
    Route Refresh: advertised and received and negotiated
    Send End-of-RIB messages: advertised and received and negotiated
    Additional-paths recv capability:
    IPv6 Unicast: advertised
    Additional-paths send capability:
    IPv6 Unicast: received
    Restart timer is inactive
    End of rib timer is inactive
    Message Statistics:
    InQ depth is 0
    OutQ depth is 0
     SentRcvd
    Opens:1 1
    Notifications:0 0
    Updates:4 5
    Keepalives:1414
    Route-Refresh:0 0
    Total messages:1920
    Prefix Statistics:
     SentRcvd
    IPv4 Unicast: 0 0
    IPv6 Unicast: 6 4
    IPv4 SR-TE: 0 0
    IPv6 SR-TE: 0 0
    Inbound updates dropped by reason:
    AS path loop detection: 0
    Enforced First AS: 0
    Originator ID matches local router ID: 0
    Nexthop matches local IP address: 0
    Unexpected IPv6 nexthop for IPv4 routes: 0
    Nexthop invalid for single hop eBGP: 0
    Inbound updates with attribute errors:
    Resulting in removal of all paths in update (treat-as-withdraw): 0
    Resulting in AFI/SAFI disable: 0
    Resulting in attribute ignore: 0
    Inbound paths dropped by reason:
    IPv4 labeled-unicast NLRIs dropped due to excessive labels: 0
    IPv6 labeled-unicast NLRIs dropped due to excessive labels: 0
    Outbound paths dropped by reason:
    IPv4 local address not available: 0
    IPv6 local address not available: 0
    Local AS is 64500, local router ID 10.0.0.102
    TTL is 1
    Local TCP address is 2001:10:1::102, local port is 45983
    Remote TCP address is 2001:10:1::100, remote port is 179
    Auto-Local-Addr is disabled
    TCP Socket Information:
    TCP state is ESTABLISHED
    Recv-Q: 0/32768
    Send-Q: 0/32768
    Outgoing Maximum Segment Size (MSS): 1428
    Total Number of TCP retransmissions: 0
    Options:
    Timestamps enabled: yes
    Selective Acknowledgments enabled: yes
    Window Scale enabled: yes
    Explicit Congestion Notification (ECN) enabled: no
    Socket Statistics:
    Window Scale (wscale): 9,9
    Retransmission Timeout (rto): 204.0ms
    Round-trip Time (rtt/rtvar): 1.4ms/2.7ms
    Delayed Ack Timeout (ato): 40.0ms
    Congestion Window (cwnd): 10
    TCP Throughput: 80.00 Mbps
    Advertised Recv Window (rcv_space): 28800
    switch#

show ipv6 bgp regexp

The show ipv6 bgp regexp command displays Border Gateway Protocol (BGP) IPv6 routing-table entries that match the AS-path attributes specified in the given regular expression.

Command Mode

EXEC

Command Syntax

show ipv6 bgp regexp as_paths [VRF_INSTANCE]

Parameters

  • as_paths slist of AS paths, formatted as a regular expression. Regular expressions are pattern matching strings that are composed of text characters and operators.
  • VRF_INSTANCE specifies the VRF instance of the BGP routing table to be displayed. Options include:
    • <no parameter> displays routing table for context-active VRF.
    • vrf vrf_name displays routing table for the specified VRF.
    • vrf all displays routing table for all VRFs.
    • vrf default displays routing table for default VRF.

Related Command

Examples

  • This command displays information about the BGP IPv6 routes in the context-active VRF that pass through AS 64496.
    switch#show ipv6 bgp regex _64496_
    BGP routing table information for VRF default
    Router identifier 10.0.0.102, local AS number 64500
    Route status codes: s - suppressed, * - valid, > - active, # - not installed, E - ECMP head, e - ECMP
    S - Stale, c - Contributing to ECMP,b - backup, L = labeled-unicast
    % - Pending BGP convergence
    Origin codes: i - IGP, e - EGP, ? - incomplete
    AS Path Attributes: Or-ID - Originator ID, C-LST -Cluster List, LL Nexthop - Link Local Nexthop
    
    NetworkNext Hop MetricLocPref WeightPath
     * 2001:10:1::/642001:10:1::100 42100 0 64496 ?
     * > 2001:10:100::/642001:10:1::100 200 100 0 64496 i
     * > 2001:10:100:1::/642001:10:1::100 0 100 0 64496 64497 65536 i
     * > 2001:10:100:2::/642001:10:1::100 42100 0 64496 ?
    switch#

show ipv6 bgp summary

The show ipv6 bgp summary command displays the summary of all IPv4 and IPv6 BGP neighbors based on Address Family Identifier (AFI) and Subsequent Address Family Identifier (SAFI) negotiations where AFI is “IPv6” and SAFI is “Unicast” information.

Command Mode

EXEC

Command Syntax

show ipv6 bgp summary [VRF_INSTANCE]

Parameters

  • VRF_INSTANCE specifies VRF instances. Options include:
    • <no parameter> displays routing table for context-active VRF.
    • vrf vrf_name displays routing table for the specified VRF.
    • vrf all displays routing table for all VRFs.
    • vrf default displays routing table for default VRF.

Display Values

Header Row

  • BGP router identifier: the router identifier; sloopback address or highest IP address.
  • Local AS number: AS number assigned to switch.

Neighbor Table Columns

  • (First) Neighbor: neighbor’s IP address.
  • (Second) V: BGP version number.
  • (Third) AS: neighbor’s AS number.
  • (Fourth) MsgRcvd: messages received from the neighbor.
  • (Fifth) MsgSent: messages sent to neighbor.
  • (Sixth) InQ: messages queued from neighbor.
  • (Seventh) OutQ: messages queued to send neighbor.
  • (Eighth) Up/Down: period the BGP session has been Established, or its current status.
  • (Ninth) State: state of the BGP session and the number of routes received from a neighbor.
  • (Tenth) PfxRcd: the count of prefixes received by BGP per neighbor.
  • (Eleventh) PfxAcc: the count of prefixes added to the BGP RIB among all received prefixes.

Related Command

Example

  • This command displays the status of the switch’s BGP connections.
    switch#show ipv6 bgp summary
    BGP summary information for VRF default
    Router identifier 10.0.0.102, local AS number 64500
    Neighbor Status Codes: m - Under maintenance
    Neighbor VAS MsgRcvd MsgSentInQ OutQUp/Down State PfxRcd PfxAcc
    2001:10:1::100 464496 373600 00:29:33 Estab 44
    2001:10:2::101 464510 353800 00:29:37 Estab 44
    switch#

show ipv6 bgp

The show ipv6 bgp command displays IPv6 Border Gateway Protocol (BGP) routing-table entries. The output format depends on the command parameters:

  • data-block format displays comprehensive information for each specified BGP routing-table entry.
  • tabular format displays routing-table entries for specified IPv6 addresses.

Command Mode

EXEC

Command Syntax

show ipv6 bgp [FILTER] [VRF_INSTANCE]

Parameters

  • FILTER routing table entries that the command displays. Options include:
    • <no parameter> displays all routing-table entries in tabular format.
    • detail displays all routing-table entries in data-block format.
    • ipv6_addr displays IPv6 host address in data-block format.
    • ipv6_prefix displays the route information of specified IPv6 prefix address in data-block format. Options include:
      • detail displays the detailed route information of specified IPv6 prefix address in data-block format.
      • longer-prefixes displays the route information of IPv6 prefix in data-block format.
      • longer-prefixes detail displays detailed route information of specified IPv6 prefix in data-block format.
    • community-list cmnty_list_name displays BGP routes filtered by the specified community list.
    • installed displays the information of installed BGP routes.
    • labeled-unicast displays the information of labeled-unicast BGP routes only.
    • not-installed displays the information of BGP routes that are not installed.
  • VRF_INSTANCE specifies VRF instances. Options include:
    • <no parameter> displays routing table for context-active VRF.
    • vrf vrf_name displays routing table for the specified VRF.
    • vrf all displays routing table for all VRFs.
    • vrf default displays routing table for default VRF.

Guidelines

You must provide the IPv6 prefix in CIDR notation.

Related Command

Examples

  • This command displays the route information of 2001:10:1:0::102/64 in data-block format.
    switch#show ipv6 bgp 2001:10:1:0::102/64
    BGP routing table information for VRF default
    Router identifier 10.0.0.102, local AS number 64500
    BGP routing table entry for 2001:10:1::/64
     Paths: 2 available
    Local
    - from - (10.0.0.102)
    Origin IGP, metric 1, localpref 0, IGP metric -, weight -, received 00:16:27 ago, valid, local, best, 
    redistributed (Connected)
    Rx SAFI: Unicast
    64496
    2001:10:1::100 from 2001:10:1::100 (10.0.0.100)
    Origin INCOMPLETE, metric 42, localpref 100, IGP metric 1, weight 0, received 00:10:09 ago, valid, 
    external
    Rx SAFI: Unicast
    switch#

show peer-filter

The show peer-filter command displays the definition of a peer filter.

Command Mode

EXEC

Command Syntax

show peer-filter filter_name

Parameters

  • filter_name name of the peer-filter group.

Example

  • This command displays the peer-filter group information for “group3.”
    switch#show peer-filter group3
    peer-filter group3
     10 match as-range 65003 result accept
     20 match as-range 65007 result accept
     30 match as-range 65009 result accept
    switch#

show tunnel rib brief

The show tunnel rib brief command displays the preferred tunnels for various IP endpoints, optionally filtered by endpoint. Each tunnel RIB entry in the output displays the type of the tunnel (such as BGP LU) and a numerical index uniquely identifying that tunnel within the type-specific tunnel table.

Command Mode

EXEC

Command Syntax

show bgp tunnel rib brief

Example

  • This command displays the tunnel type and the index value.
    switch#show tunnel rib brief
    EndpointTunnel Type Indexes
    ----------------- ----------------- -------
    10.1.1.0/32 BGP LU2
    11.1.1.0/32 BGP LU1, 3
    switch#

shutdown (BGP)

The shutdown command disables BGP on the switch without modifying the BGP configuration.

The no shutdown and default shutdown commands enable the BGP instance by removing the shutdown command from running-config.

Command Mode

Router-BGP Configuration

Command Syntax

shutdown

no shutdown

default shutdown

Examples

  • These commands disable BGP on the switch.
    switch(config)#router bgp 9
    switch(config-router-bgp)#shutdown
    switch(config-router-bgp)#
  • These commands enable BGP on the switch.
    switch(config)#router bgp 9
    switch(config-router-bgp)#no shutdown
    switch(config-router-bgp)#

peer-filter

The peer-filter command creates a peer filter group and places the switch in peer-filter configuration mode for that group. The peer-filter group parameters are defined using the match as-range command.

The no peer-filter and default peer-filter commands remove the peer-filter group from running-config.

Command Mode

Router-BGP Configuration

Command Syntax

peer-filter filter_name

no peer-filter filter_name

default peer-filter filter_name

Parameters

  • filter_name name of the peer filter.

Example

  • This command creates a peer filter called “group1” and places the switch in peer-filter configuration mode for that filter.
    switch(config-router-bgp)#peer-filter group1
    switch(config-peer-filter-group1)#

timers bgp

The timers bgp command configures the BGP keepalive and hold times.Timer settings apply to each peer connection. The neighbor timers command configures the times on a specified peer connection.

  • Keepalive time: period between the transmission of consecutive keepalive messages.
  • Hold time: period the switch waits for a keepalive or UPDATE message before it disables peering.

The hold time must be at least 3 seconds and should be three times longer than the keepalive setting.

The no timers bgp and default timers bgp commands return the time settings to their default values by removing the timers bgp command from running-config. The default values are:

  • keepalive: 60 seconds.
  • hold time: 180 seconds.

Command Mode

Router-BGP Configuration

Command Syntax

Parameters

timers bgp keep_alive hold_time

no timers bgp

default timers bgp

  • keep_alive keepalive period, in seconds. Values include:
    • 0 keepalive messages are not sent.
    • 1 to 3600 keepalive time (seconds).
  • hold_time hold time. Values include:
    • 0 peering is not disabled by timeout expiry; keepalive packets are not sent.
    • 3 to 7200 hold time (seconds).

Example

  • This command sets the keepalive time to 30 seconds and the hold time to 90 seconds.
    switch(config)#router bgp 9
    switch(config-router-bgp)#timers bgp 30 90
    switch(config-router-bgp)#

update wait-for-convergence

The update wait-for-convergence command disables FIB updates and route advertisement when the BGP instance is initiated until the BGP convergence state is reached.

The no update wait-for-convergence command allows FIB updates and route advertisement irrespective of the BGP convergence state.

Command Mode

Router-BGP Configuration

Command Syntax

update wait-for-convergence

no update wait-for-convergence

default update wait-for-convergence

Related Commands

  • clear ip bgp removes learned BGP routes from the routing table, reads all routes from designated peers, and sends routes to those peers as required.
  • bgp convergence slow-peer time configures the BGP convergence idle peer timeout value.
  • bgp convergence time configures the BGP convergence timeout value.
  • show bgp convergence displays information about the BGP convergence state; and other statistics about the BGP instance in either the specified VRF or all VRFs.

Guidelines

The initiation of BGP instance includes the following scenarios:

  • the BGP instance starts for the first time after a switch is reloaded.
  • the BGP instance restarts.
  • all sessions are cleared by using the clear ip bgp * command.

Configuration changes made by using this command are effective from the next initiation of a BGP instance.

Example

  • This command disables FIB updates and route advertisement when the BGP instance is initiated until the BGP convergence state is reached.
    switch(config)#router bgp 9
    switch(config-router-bgp)#update wait-for-convergence
    switch(config-router-bgp)#

vrf

The vrf command places the switch in BGP VRF configuration mode for the specified VRF. Commands issued in this mode will override global BGP configuration for the specified VRF.

Command Mode

Router-BGP Configuration

Command Syntax

vrf vrf_instance

Parameters

  • vrf_instance VRF to be configured.

Example

  • These commands place the switch in BGP VRF configuration mode for VRF “purple.”
    switch(config)#router bgp 9
    switch(config-router-bgp)#vrf purple
    switch(config-router-bgp-vrf-purple)#