Tag :: IS-IS

The BGP-LS extension allows IGPs (OSPF/IS-IS) link state database information to be injected into BGP. This is typically used in deployments where some external component, (like a controller or Path Computation Engine) can do centralized path computations by learning the entire IGP topology through BGP-LS. The controller can then communicate the computed paths based on the BGP-LS updates to the head end device in the network. The mechanism used by the controller to communicate the computed TE paths is outside the scope of this document. Using BGP-LS instead of an IGP peering with the controller to distribute IGP link state information has the following advantages.

EOS 4.22.1F adds support for disabling the IS IS authentication check for received IS IS PDUs. By enabling this

Until EOS release 4.32.0F, EOS allows users to statically configure link min-delay and max-delay used for IS-IS FlexAlgo. This feature adds support for dynamic measurement of link delay using the TWAMP Light protocol described in RFC 8186 and provides it to IS-IS FlexAlgo dynamically.

This document describes how to configure and monitor this feature.

Administrative Groups (AG) provide a way to associate certain attributes or policies with links, enabling network administrators to control the routing decisions based on specific criteria. Extended Administrative Groups (EAG) are an extension of AG which allow a larger range of admin groups to be utilized for various Traffic Engineering (TE) purposes within a network. EAGs are defined in a new sub-TLV for IS-IS link attributes, separate to AGs, however they are considered as one within EOS. The EAG feature in EOS allows the range of administrative color to be increased from 0-31 to 0-127.

IGP shortcuts enable traffic to get forwarded along traffic engineered paths computed by RSVP using a modified SPF

This feature implements RFC6119, which allows the extension of IS IS protocol to carry IPv6 Traffic Engineering

EOS IS-IS implementation advertises interface-address TLVs for both passive and non-passive interfaces. IS-IS “advertise interface-address passive-only” feature is used to control the advertisement of interface address TLVs in LSP Advertisement. Once this feature is enabled on the device, IS-IS advertises interface address TLVs i,e. IP Interface Address TLV #132 and IPv6 Interface Address TLV #232 only for passive interfaces in the LSP Advertisement and stops advertising these TLVs for active or non-passive interfaces.

IS IS area proxy allows the creation of more scalable networks. IS IS already has hierarchical mechanisms for

The ‘clear isis instance’ command can be used to reset the ISIS instance that is running. All ISIS instance and interface states will be cleared and re-initialized from the configuration so that ISIS rediscovers neighbors and reconverges the different instances in the ISIS routing tables.

This feature introduces a way for IS-IS to advertise its IP reachability and SID for loopback interfaces only when routes matching an RCF function are present. One example use-case is to use IS-IS Segment Routing to attract traffic to a router only when routes towards the ultimate destination are present. The RCF function is matched against winning routes in the Unicast RIB (seen with 'show rib route …').

This feature allows configuration of the IS IS CSNP generation interval. The default CSNP interval is 10

IS-IS flexible algorithm (FlexAlgo) provides a lightweight, simplified mechanism for performing basic traffic engineering functions within a single IS-IS area. FlexAlgo requires the cooperation of all nodes within the IS-IS area but does not require an external controller. Paths are computed by each node within the area, resulting in an MPLS switched forwarding path to nodes that are advertising a node Segment Identifier (SID) for the algorithm. The results of the path computation are placed in the colored tunnel RIB or system tunnel RIB, which simplifies route resolution.

The IS IS maximum LSP size feature provides the ability to configure the maximum LSP size that the IS IS protocol will

Segment Routing provides mechanism to define end-to-end paths within a topology by encoding paths as sequences of sub-paths or instructions. These sub-paths or instructions are referred to as “segments”. IS-IS Segment Routing (henceforth referred to as IS-IS SR) provides means to advertise such segments through IS-IS protocol.

Level 1 2 routers set attached bit in their Level 1 LSPs to indicate their reachability to the rest of the network. A

Traffic Engineering (TE) provides a mechanism to network administrators to control the path that a data packet takes, bypassing the standard routing model which uses routes along the shortest path. Traffic engineered paths are generally computed on the head-end routers of the topology based on various constraints (e.g. minimum bandwidth, affinity) configured for those paths and attributes (e.g available bandwidth, color) received from devices in the network topology. IS-IS Traffic Engineering (IS-IS TE) feature extends IS-IS protocol in EOS to carry TE attributes as part of its Link State Protocol Data Units (LSPs).  Note that IS-IS in EOS only acts as a carrier for TE attributes and it is not used by any processing (e.g. SPF).

This feature allows a user to configure multiple static adjacency SIDs for an IS IS adjacency. This feature is an

IS IS adjacency is not formed between devices with different address families configured. For example,  a router

Traffic steering enables traffic for a specified set of prefixes to get forwarded along traffic engineered paths

IS-IS SR Stateful Switchover (SSO) support allows for a switchover from an active supervisor to a standby supervisor where MPLS traffic remains undisrupted during switchover. This involves reconciliation of all Segment Routing related information in the network using IS-IS Graceful Restart procedures. And also installing the same in forwarding hardware in a manner that does not disrupt the ongoing traffic.

This feature adds support for configuring multiple area addresses in an IS-IS instance.

Topology Independent Fast Reroute, or TI-LFA, uses IS-IS SR to build loop-free alternate paths along the post-convergence path. These loop-free alternates provide fast convergence.

EOS 4.23.0F adds support for redistributing DHCPv6 routes in IS IS when using the multi agent routing protocol mode.