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SRv6 on Cisco IOS-XR

Cisco IOS-XR has supported SRv6 since Release 6.6.1 (full-length SIDs, IS-IS, TI-LFA, L3VPN and OAM on NCS 5500 and ASR 9000). SRv6 uSID (F3216, the NEXT-C-SID flavor of RFC 9800) arrived in 7.3.1 and is what Cisco has built most later features on: EVPN-VPWS (7.3.2), EVPN E-LAN (7.5.2), End.DT46 (7.8.1), path MTU discovery and traffic accounting. Full-length SIDs are still documented in the 26.x guides, but only one SID format can be used per network. Per-platform release numbers for every feature are in the SRv6 Support Matrix.

Supported Platforms

Platform SRv6 notes
NCS 5500 / 5700 First-generation NCS 5500 (Jericho) needs hw-module profile segment-routing srv6 mode micro-segment format f3216 and a reload before uSID works; NCS 5700 sets the format under segment-routing srv6
NCS 540 uSID L3VPN and transport, as in the XRdocs tutorial series
ASR 9000 3rd-, 4th- and 5th-generation line cards and IOS XRv 9000
Cisco 8000 (Silicon One) Q200-based systems and later only; "SRv6 is not supported on Q100-based line cards and fixed-port routers"

Documented gaps worth knowing before a design review: SRv6 Tree-SID / P2MP multicast is not supported (Tree-SID is SR-MPLS only), per-CE uDX4/uDX6 allocation is not supported with uSID, PCE-initiated SRv6 policies are listed as unsupported, and the BGP SR Policy SAFI does not carry SRv6 segments.

Basic Configuration

!! Enable SRv6
segment-routing
 srv6
  locators
   locator MAIN
    micro-segment behavior unode psp-usd
    prefix fc00:0:1::/48
   !
  !
 !
!

!! Enable SRv6 in IS-IS
router isis CORE
 address-family ipv6 unicast
  segment-routing srv6
   locator MAIN
  !
 !
!

!! SRv6-based L3VPN
vrf CUSTOMER-A
 address-family ipv4 unicast
  import route-target 100:1
  export route-target 100:1
 !
!

router bgp 65000
 vrf CUSTOMER-A
  rd auto
  address-family ipv4 unicast
   segment-routing srv6
    locator MAIN
    alloc mode per-vrf
   !
  !
 !
!

Verification Commands

show segment-routing srv6 locator
show segment-routing srv6 sid
show segment-routing srv6 manager
show isis segment-routing srv6 locators
show bgp vpnv4 unicast vrf CUSTOMER-A

Further Reading

References

  1. Segment Routing Configuration Guide for Cisco NCS 5500 Series Routers - Official Cisco IOS-XR SRv6 micro-SID configuration guide for NCS 5500
  2. SRv6 Transport on NCS 5500/500 - Part 1 (XRdocs) - XRdocs tutorial series on SRv6 transport configuration
  3. Implementing Layer 3 VPN over SRv6 Transport on NCS 5500/500 (XRdocs) - XRdocs tutorial on L3VPN services over SRv6
  4. Cisco Converged SDN Transport SRv6 High Level Design (XRdocs) - SRv6 transport design guide for converged SDN networks
  5. Cisco NCS 5500 Series Product Page - NCS 5500 platform support portal with SRv6-capable hardware information
  6. Cisco NCS 5500 Release Notes for IOS XR 6.6.1 - First SRv6 release: SRv6 base, IS-IS, TI-LFA, L3VPN and OAM
  7. Cisco 8000 SRv6 Configuration Guide: Limitations of SRv6 - Q200-only support on Cisco 8000 and other restrictions
  8. Cisco 8000 Segment Routing Configuration Guide 26.x: Tree-SID - Tree-SID is SR-MPLS only; SRv6 Tree-SID is not supported