- Written by Kamala R
- Posted on September 30, 2015
- Updated on July 20, 2023
- 11245 Views
The difference between the two forms of authentication is in the level of security provided. In case of clear text authentication, the password is specified as text in the authentication TLV, making it possible for an attacker to break the authentication by sniffing and capturing IS-IS PDUs on the network.
- Written by Nikhil Goyal
- Posted on November 22, 2017
- Updated on December 23, 2021
- 11463 Views
IS IS Graceful Restart adds support for Restart Signaling for IS IS, IETF RFC 5306. When IS IS is used
- Written by Nandan Saha
- Posted on September 30, 2015
- Updated on September 30, 2015
- 10554 Views
By default if there's a hostname configured on the switch, it is used as the IS IS hostname. It is also possible to
- Written by Arpit Bansal
- Posted on September 30, 2015
- Updated on September 30, 2015
- 10590 Views
An IS IS router can be configured as Level 1 2 which can form adjacencies and exchange routing information with both
- Written by Subham Burnwal
- Posted on January 5, 2026
- Updated on January 5, 2026
- 1100 Views
IS-IS LSP out-delay is a feature implemented to mitigate transient micro-loops that can occur during topology changes in an IS-IS network.When a topology change occurs (e.g., a link state or metric change), different routers in the network receive and process the updated Link State PDUs (LSPs) at slightly different times. This can lead to a transient state where some routers have updated their Forwarding Information Base (FIB) based on new LSPs, while others have not, causing traffic to be incorrectly forwarded and forming micro-loops.
- Written by Arunprakash Sekar
- Posted on September 30, 2015
- Updated on September 30, 2015
- 10687 Views
IS IS Multi Topology support enables an IS IS router to compute a separate topology for IPv4 and IPv6 links in the
- Written by Navneet Sinha
- Posted on June 29, 2016
- Updated on June 29, 2016
- 11092 Views
This feature enables an Arista switch to run the IS IS routing protocol over a tunnel interface to another IS IS
- Written by Navneet Sinha
- Posted on June 29, 2016
- Updated on September 9, 2025
- 22429 Views
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.
- Written by Arpit Bansal
- Posted on September 30, 2015
- Updated on April 22, 2020
- 11097 Views
Level 1 2 routers set attached bit in their Level 1 LSPs to indicate their reachability to the rest of the network. A
- Written by Przemyslaw Jacak
- Posted on April 18, 2018
- Updated on January 20, 2026
- 10786 Views
This document describes two features that allow dynamic metric change for IS-IS based on interface speed.
- Written by Bharath Somayaji
- Posted on September 30, 2015
- Updated on March 7, 2024
- 11071 Views
SPF Timers can be used in IS-IS to throttle the frequency of shortest-path-first (SPF) computations. In networks with a lot of churn, using these timers will help in containing the effect of network disruptions arising out of frequent SPF runs.
- Written by Ashish Yadav
- Posted on February 8, 2017
- Updated on February 9, 2017
- 10373 Views
The default behavior of a level 1 router running IS IS is to install a default route to a level 1 2 router present in a
- Written by Aditya Gujral
- Posted on September 30, 2015
- Updated on September 30, 2015
- 10401 Views
This feature adds Intermediate System to Intermediate System (IS IS) support for IP version 6 (IPv6) address family
- Written by Weichen Zhao
- Posted on August 25, 2016
- Updated on August 25, 2016
- 10786 Views
This feature provides a way to export non ISIS routes into level 1, level 2 or both by using route map's set clause. The
- Written by Aditya Gujral
- Posted on September 30, 2015
- Updated on February 7, 2022
- 10503 Views
This feature extends the IS IS set overload bit command to support wait for BGP option. In scenarios
- Written by Liam Smyth
- Posted on August 29, 2025
- Updated on August 29, 2025
- 1976 Views
Data entries from journald can be viewed through the CLI and the REST API. If the REST API is used the data is returned to the user in the form of a list of structured entries. This API is only for viewing journal data contained on the node being queried. The user is given the option to pass parameters to the API that can be used for pagination and for filtering the data that gets returned, e.g. only returning entries that were written by a specific application or after a specific start time.
- Written by Patrycja Kochmanska
- Posted on October 10, 2025
- Updated on October 10, 2025
- 1816 Views
The routing table is not available on the standby supervisor in EOS, hence running any diagnostics or scripts that talk to the standby supervisor through the forwarding plane is not possible. This feature adds a new Cli command that configures a default route on a standby supervisor. This default route will offload routing to the forwarding plane. Therefore it behaves the same way as the routing table on the active supervisor. The default route is installed on all VRFs.
- Written by Zeyad Tamimi
- Posted on March 3, 2023
- Updated on April 1, 2026
- 15204 Views
At a high level, L1 profiles are a set of configurations which allow EOS users to change the numbering scheme and default L1 configurations of all front panel interfaces across their network switch. On Arista network switches, front panel transceiver cages are exposed as ports which are numbered sequentially: 1, 2, 3, 4, etc. These identifiers are usually marked on the front panel to allow for easier identification.
- Written by Yiming Pan
- Posted on April 18, 2024
- Updated on April 1, 2025
- 8148 Views
Arista’s 7135 Connect Series of Layer 1+ switches are powerful network devices that allow for dynamic connections between various layer 1 components on the system, such as the front panel and FPGA. These connections are driven by an underlying CLOS network of crossbar switches. The following commands provide the ability to configure middle stage crossbar switches within the system to create dynamic layer 1 connections.
- Written by Shriprama Rao
- Posted on March 17, 2025
- Updated on March 17, 2025
- 3726 Views
This feature allows transport of multicast frames to an endpoint across an IP network by tunneling them through MPLSoGRE or MPLSoGUE. The tunneling of multicast frames is achieved with a traffic policy applied on the ingress interface which will match on all packets destined to a multicast IP address and redirect that traffic to a MoG nexthop group. The traffic policy will also specify “forced routing” in order to set the fwd_layer_index to 1 so that the L2 header is removed before encapsulation.
- Written by Prakrati Vidyarthi
- Posted on August 16, 2018
- Updated on May 5, 2026
- 24168 Views
Normally, a switch traps L2 protocol frames to the CPU. However, certain use-cases may require these frames to be forwarded or dropped. And in cases where the L2 protocol frames are forwarded (eg: Pseudowire), we may require the frames to be trapped to the CPU or dropped. The L2 Protocol Forwarding feature provides a mechanism to control the behavior of L2 protocol frames received on a port or subinterface.
- Written by Ajay Chhatwal
- Posted on May 15, 2020
- Updated on May 5, 2026
- 12355 Views
L2 protocol frames - LLDP, LACP and STP are trapped to the CPU by default. This feature allows for disabling the per protocol trap on a given set of interfaces.
- Written by Ravi Krishnamurthy
- Posted on January 7, 2026
- Updated on January 7, 2026
- 1255 Views
L2 support for CloudEOS and AWE is added.
- Written by Mihyar Baroudi
- Posted on December 8, 2015
- Updated on December 21, 2015
- 10782 Views
In our current implementation, on a switch with default startup config or no config, all ports come up in access
- Written by Sarah Chen
- Posted on October 17, 2024
- Updated on October 17, 2024
- 5743 Views
This feature is used to connect a Layer 3 EVPN VXLAN network to an Adaptive Virtual Topology (AVT) WAN network using dynamic path selection (DPS) tunnels. One or a pair of WAN routers are configured to serve as the VXLAN gateway. On the control plane, the configured VXLAN gateway handles EVPN IP-PREFIX route exchanges between the VXLAN network and the WAN network. On the data plane, the configured VXLAN gateway decapsulates the VXLAN packets received from the VXLAN network and encapsulates them into the DPS tunnels and sends them to the AVT WAN network.
- Written by Isidor Kouvelas
- Posted on December 22, 2017
- Updated on December 9, 2020
- 13403 Views
This feature is available when configuring BGP in the multi agent routing protocol model. Ethernet
- Written by Lavanya Conjeevaram
- Posted on June 29, 2016
- Updated on April 25, 2018
- 11833 Views
L3 interface ingress counters can be used to count routable traffic coming into the box on sub interfaces and vlan
- Written by Manuel Mendez
- Posted on September 30, 2019
- Updated on April 21, 2026
- 13709 Views
Subinterfaces divide a single ethernet or port channel interface into multiple logical L3 interfaces based on the 802.1q tag (VLAN ID) of incoming traffic. Subinterfaces are commonly used in the L2/L3 boundary device, but they can also be used to isolate traffic with 802.1q tags between L3 peers by assigning each subinterface to a different VRF. L3 subinterface shaping + VRF is also supported.
- Written by Jayden Navarro
- Posted on February 8, 2017
- Updated on February 15, 2017
- 10718 Views
LACP on Loopback Interfaces allows for Active Port Channels on one or more interfaces whose link endpoints terminate
- Written by Jayden Navarro
- Posted on February 8, 2017
- Updated on February 9, 2017
- 11794 Views
LACP State Transition Event Monitoring on Arista switches allows for quick and filterable viewing of LACP state
- Written by Nathan Wolfe
- Posted on February 15, 2018
- Updated on July 15, 2025
- 18538 Views
Introduced in EOS-4.20.1F, “selectable hashing fields” feature controls whether a certain header’s field is used in the hash calculation for LAG and ECMP.
- Written by Mihyar Baroudi
- Posted on February 1, 2016
- Updated on September 29, 2025
- 12191 Views
LAGs are allocated hardware resources on transition from one member (software LAG) to two members (hardware LAG) and deallocated hardware resources on transition from two member to one member. This allocation/deallocation causes some traffic disruption. Starting with EOS4.15.4F, the option to configure all LAGs to use hardware resources is supported on the 7500E platform.
- Written by Yuta Higuchi
- Posted on April 23, 2025
- Updated on April 23, 2025
- 3118 Views
This document addresses LAG hashing improvements across different platforms. In DANZ Monitoring Fabric (DMF) 8.7, the Controller applies the default hash configuration if no hash fields are configured or the configuration contains an error. If the Controller detects any hash error, DMF reports it as a fabric error.
- Written by Piotr Nowakowski
- Posted on December 20, 2024
- Updated on December 20, 2024
- 4491 Views
Switches can now use two LAG partitions (A and B) to support double the number of available Port Channels dictated by the chosen LAG mode. This is useful if the selected LAG mode does not allow the creation of the desired number of Port Channels on a single partition.
- Written by Greg Poloczek
- Posted on September 11, 2017
- Updated on September 11, 2017
- 11697 Views
Arista switches use the hashing algorithm to load balance traffic among LAG (Link Aggregation Group) members
- Written by Dawon Lee
- Posted on August 17, 2018
- Updated on October 16, 2025
- 14079 Views
LANZ Mirroring feature allows users to automatically mirror traffic queued as a result of congestion to either CPU or a different interface.
- Written by Stefan Rebaud
- Posted on March 31, 2017
- Updated on January 11, 2022
- 11477 Views
This document describes the current status of LANZ on DCS 7500R, DCS 7280R and DCS 7020R, for both polling and
- Written by Pinky Agrawal
- Posted on November 22, 2017
- Updated on December 22, 2017
- 10499 Views
LANZ on 7160S 32CQ, 7160 48YC6 and 7160 48TC6 adds support for monitoring congestion on front panel ports with Start,
- Written by Zackary Ayoun
- Posted on May 23, 2022
- Updated on February 5, 2026
- 16432 Views
LANZ is the EOS Latency and congestion ANalyZer. On DCS-7280, DCS-7020, DCS-7500 and DCS-7800 series, it allows monitoring congestion and transmit latencies on both front panel and CPU ports.
- Written by Tanuj Kumar Jhamb
- Posted on July 2, 2024
- Updated on November 4, 2025
- 6987 Views
ECN (Explicit Congestion Notification) is a mechanism of notifying network congestion without dropping the packets. The ECN based network congestion notification can be done in two ways: queue-length based ECN, latency based ECN. The queue-length based ECN marks the ECN-Capable Transport (ECT) packets when the average VOQ length exceeds the configured ECN threshold value whereas latency based ECN notify the congestion by marking the ECT packets, if packets take longer than the configured threshold to get dequeued from the VOQ. Both result in the egress marking of the packet if the congestion experienced is beyond the threshold.
- Written by Dhruba Jyoti Pokhrel
- Posted on May 28, 2026
- Updated on May 28, 2026
- 45 Views
Configure latency thresholds for DHCP, DNS, AAA, WAN, and Gateway while creating a Client Connectivity Test (CCT) profile. When the latency exceeds the defined threshold, the CCT result is displayed as a partial failure.
- Written by Andrei Dvornic
- Posted on April 2, 2015
- Updated on May 15, 2026
- 18595 Views
NAT peer state synchronization feature provides redundancy and resiliency for dynamic NAT across a pair of devices in an attempt to mitigate the risk of single NAT device failure. The main motivation is that since the NAT state is shared between two switches, the failure of one switch can be tolerated since the other switch will retain the translations.
- Written by Diksha Mahajan
- Posted on March 3, 2023
- Updated on January 8, 2026
- 11090 Views
A layer 3 subinterface is a logical endpoint associated with traffic on an interface distinguished by 802.1Q tags, where each interface, 802.1Q tag tuple, is treated as a routing interface.
- Written by Navneet Sinha
- Posted on June 29, 2016
- Updated on April 20, 2026
- 12824 Views
E-Tree is an L2 EVPN service (defined in RFC8317) in which each attachment circuit (AC) is assigned the role of Root or Leaf. Root ACs can communicate with leaf ACs and other root ACs. Leaf ACs can only communicate with root ACs. Leaf AC to leaf AC traffic is blocked. In this implementation, ACs are configured at the VLAN level, and the forwarding rules are enforced using a combination of local configuration of leaf VLANs (for local hosts), and asymmetric route targets (for remote hosts).
- Written by Shyam Kota
- Posted on June 5, 2020
- Updated on August 20, 2025
- 12296 Views
This feature implements RFC 3478. It allows devices to preserve the MPLS LDP LFIB entries in the forwarding plane if the TCP connection is lost or LDP agent restarts.
- Written by Pedro Coutinho
- Posted on December 22, 2020
- Updated on April 30, 2025
- 17370 Views
The LDP pseudowire feature provides support for emulating Ethernet connections over a Multiprotocol Label Switching (MPLS) network using the extension of the MPLS Label Distribution Protocol (LDP)
- Written by Xin Guang (Tony) Du
- Posted on August 25, 2016
- Updated on November 23, 2020
- 15887 Views
The LDP pseudowire feature provides support for emulating Ethernet connections over a Multiprotocol Label
- Written by Peter Lam
- Posted on September 30, 2015
- Updated on May 29, 2026
- 21699 Views
Leaf Smart System Upgrade (SSU) provides the ability to upgrade the EOS image with minimal traffic disruption.
- Written by Pavan Narasimhaprasad
- Posted on June 27, 2024
- Updated on September 4, 2025
- 6377 Views
Leaf Smart System Upgrade (SSU) provides the ability to upgrade the EOS image with minimal traffic disruption.Note: It is possible that SSU shutdown and bootup are not supported in the same image. If a product has shutdown support in image A and bootup support in a later image B, then SSU upgrade cannot be performed from image A to any images earlier than image B, including image A itself. However, upgrading from image A to image B onwards is allowed.
- Written by Girish Dasari
- Posted on April 30, 2025
- Updated on April 30, 2025
- 3387 Views
At a transit router when multiple LSP are available for a given destination from different protocols EOS does stitching based on hard coded preferences. LFIB stitching preferences give a provision to stitch together different LSPs based on configurable preferences. For each protocol(destination) preference can be configured for a given source protocol.
