SRv6 on Arista EOS¶
Arista EOS implements SRv6 with a uSID-first design: the forwarding model is built around micro-SIDs in the F3216 format (32-bit block, 16-bit uSIDs), starting with the uN node SID and adding static uA adjacency SIDs, IS-IS integration, counters, and hitless upgrade support over the 4.34 to 4.36 release trains. The authors of OpenAI's MRC AI-cluster transport collaborated with Arista to implement SRv6 in EOS on Broadcom Tomahawk 5 switches, and MRC runs in large-scale production — see AI/ML Networks.
Source scope
This page summarizes Arista's public EOS user manual (EOS 4.36.2F) and the titles/summaries of Arista's public SRv6 TOI (Transfer of Information) listings. Full TOI documents require an Arista login; check them and the release notes for your exact version before deploying.
Feature Timeline¶
| Feature | EOS release | Source |
|---|---|---|
| uN (End with uSID) | 4.34.2F | TOI: "SRv6 uN Support" |
| Static SRv6 adjacency segments (uA) | 4.35.2F | TOI: "Support for SRv6 static adjacency segments (uA)" |
| IS-IS SRv6 with micro-SID compression and Flex-Algo (7280R4 and 7800R4 series) | 4.36.1F | TOI: "Support for SRv6 in IS-IS"; user manual IS-IS chapter |
| Smart System Upgrade (SSU) with SRv6 uN | 4.36.1F | TOI: "SSU support for SRv6" |
| Per-endpoint counters (packets/bytes per endpoint operation, e.g. uN) | 4.36.2F | TOI: "Support for SRv6 Counters" |
Capabilities (EOS 4.36.2F user manual)¶
The show srv6 capabilities example in the user manual reports:
| Category | Supported | Not supported |
|---|---|---|
| Endpoint behaviors | End (uN when used with uSIDs), End.DT4, End.DT6 | End.X, End.DX4, End.DX6 |
| Flavors | PSP, USD, Next-CSID | USP |
| Headend behaviors | H.Encaps | H.Encaps.Red, H.Insert, H.Insert.Red |
| uSID formats | F3216 | — |
Note
Static uA support (an End.X-type adjacency micro-SID) arrived in EOS 4.35.2F and is configured per interface in the manual's IS-IS chapter (adjacency-segment srv6 locator <loc> usid <value> behavior end.x ...), even though the capabilities example still prints End.X as unsupported. Treat the capability table as a snapshot of the manual's example rather than a complete feature list. The IS-IS SRv6 TOI is also tagged TI-LFA, but its body requires a login and the manual documents TI-LFA for SR-MPLS only, so SRv6 TI-LFA on EOS is unverified.
Supported Platforms¶
| Family | Models listed in the user manual |
|---|---|
| 7060X6 | DCS-7060X6 |
| 7280R3 / R4 | DCS-7280R3, DCS-7280R4-32*, DCS-7280R4K-32*, DCS-7282R4* |
| 7500R3 | DCS-7500R3 |
| 7800R3 / R4 | DCS-7800R3, DCS-7800R4-*, DCS-7800R4K-36PE-LC, DCS-7800R4M-36PE-LC, DCS-DL-7700R4K-* |
On the R3/R4 (Jericho-family) platforms, SRv6 needs a TCAM profile with the feature srv usid f3216 feature; the 7060X6 is not listed for that requirement.
Configuration Model¶
The manual organizes SRv6 under router srv6:
| Command | Purpose |
|---|---|
router srv6 → vrf default | SRv6 configuration context |
micro-segment domain → block, usid length, gib range | Defines the uSID block, uSID length, and Global ID Block range |
locator → prefix micro-segment domain <d> end usid <v> | Allocates the node's uN from the domain |
igp algorithm flex-algo <name> | Associates a locator with a Flex-Algo |
adjacency-segment srv6 locator <loc> usid <value> behavior end.x (interface, IS-IS) | Static uA adjacency SID |
show srv6 capabilities / domain / locator / route | Verification |
ping srv6 sid … via segment-list …, traceroute srv6 sid … | SRv6 OAM |
See the user manual for complete configuration examples; exact syntax varies between EOS releases.
OAM gotcha
The manual notes that the target uN prefix (for example the /48) must be configured on a loopback for ping srv6 / traceroute srv6 to that uN to work.
Where It Fits¶
- AI back-end fabrics — static, source-routed uSID paths on Tomahawk 5 (7060X6 class) are what MRC uses; see AI/ML Networks and CLOS & Load Balancing.
- DC/WAN edge and spine — Jericho-based 7280R3/R4 and 7500R3/7800R3/R4 for uSID forwarding; IS-IS SRv6 and Flex-Algo are documented for the 7280R4 and 7800R4 series only.
- L3VPN and EVPN RT5 PE — not in Arista's public documentation, but 7280R3 (2025) and 7280R4 (2026) acted as SRv6 L3VPN and EVPN RT5 PEs in the EANTC interoperability tests. Ask Arista which EOS release supports it before planning a design around it.
Further Reading¶
- Implementations Overview
- SRv6 Support Matrix - EOS feature by feature next to IOS-XR, Junos, SR OS and open-source platforms
- MRC and SRv6 - EOS on Tomahawk 5 in OpenAI's and Microsoft's SRv6 AI fabrics
- uSID Compression - F3216 format and shift-and-forward
- AI/ML Networks - MRC: OpenAI's SRv6 static source routing in production
- TI-LFA - Fast reroute with SRv6 repair segments
References¶
- Arista EOS User Manual: Segment Routing over IPv6 (SRv6) - EOS 4.36.2F SRv6 chapter: platforms,
router srv6/micro-segment configuration, capabilities, OAM - Arista TOI: SRv6 tag listing - Index of SRv6 Technical Overviews (uA, IS-IS, SSU, counters) with release tags
- Arista TOI: Support for SRv6 static adjacency segments (uA) - EOS 4.35.2F static uA (login required)
- Arista TOI: SSU support for SRv6 - EOS 4.36.1F Smart System Upgrade with SRv6 uN (login required)
- Arista TOI: Support for SRv6 Counters - EOS 4.36.2F per-endpoint packet/byte counters (login required)
- Resilient AI Supercomputer Networking using MRC and SRv6 - OpenAI et al. paper; states SRv6 was implemented with Arista in EOS on Broadcom Tomahawk 5 switches for MRC
- Arista TOI: SRv6 uN Support - EOS 4.34.2F uN support (login required)
- Arista EOS User Manual: IS-IS (Configuring SRv6 for IS-IS) - IS-IS SRv6, Flex-Algo and static uA configuration; 7280R4/7800R4 platforms
- EANTC 2026 Interop Test Report: L3VPN over SRv6 - Independent multi-vendor test with an Arista 7280R4 as SRv6 L3VPN PE