Segment Routing v6 Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

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Segment Routing v6 Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

SRv6 Provider Edge Lite support

Updated: September 8, 2026

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Explains how PE Lite provides VPN demultiplexing and SLA-based traffic transport across IP, SR-MPLS, and SRv6 domains and describes its processing and configuration.

SRv6 Provider Edge (PE) Lite support is an SRv6 feature that

  • provides VPN de-multiplexing-only behaviors (End.DT4/DT6/DT46) at an SRv6 PE node

  • allows for a lightweight-PE implementation by not supporting VPN encapsulation, and

  • allows for a lightweight-PE implementation (no VPN encapsulation), and

  • leverages SRv6 programmability to steer SRv6-encapsulated traffic across an SR-MPLS backbone after performing a VPN lookup.

Table 1. Feature History Table

Feature Name

Release

Description

SRv6 Provider Edge (PE) Lite

 Release 25.4.1

Introduced in this release on: Fixed Systems (8700 [ASIC: K100], 8010 [ASIC: A100])(select variants only*)

*This feature is supported on:

  • 8711-48Z-M

  • 8011-32Y8L2H2FH

  • 8011-12G12X4Y-A/D

SRv6 Provider Edge (PE) Lite

 Release 25.1.1

Introduced in this release on: Fixed Systems (8700 [ASIC: K100], 8010 [ASIC: A100])

This feature is now supported on:

  • 8712-MOD-M

  • 8011-4G24Y4H-I

SRv6 Provider Edge (PE) Lite

 Release 24.4.1

Introduced in this release on: Fixed Systems (8200 [ASIC: P100], 8700 [ASIC: P100])(select variants only*); Modular Systems (8800 [LC ASIC: P100])(select variants only*)

*This feature is supported on:

  • 8212-48FH-M

  • 8711-32FH-M

  • 88-LC1-36EH

  • 88-LC1-12TH24FH-E

  • 88-LC1-52Y8H-EM

SRv6 Provider Edge (PE) Lite

Release 7.5.3

This feature provides VPN de-multiplexing-only behaviors (End.DT4/DT6/DT46) at an SRv6 PE node. This allows for a lightweight-PE implementation (no VPN encapsulation) that steers SRv6-encapsulated traffic across an SR-MPLS backbone after performing a VPN lookup.

Benefits of SRv6 Provider Edge Lite support

  • Lightweight-PE implementation: It allows for a simplified PE role by only supporting VPN de-multiplexing behaviors and not VPN encapsulation.

  • Efficient traffic steering: It effectively steers SRv6-encapsulated traffic across an SR-MPLS backbone after performing a VPN lookup.

  • High availability: Achieved through the use of Anycast SRv6 locators, ensuring that traffic can still be handled by other nodes if a specific SRv6 PE lite node fails.

  • SLA-Driven transport: It enables the provision of desired transport Service Level Agreements (SLAs) to applications by leveraging BGP VPN overlay routes with color extended communities and SR-TE policies.

  • Interoperability: It facilitates the carrying of SRv6-encapsulated traffic over IP-only metro domains and SR-MPLS backbones, bridging different network technologies and domains.

How SRv6 Provider Edge Lite processes traffic

SRv6 Provider Edge (PE) Lite is a mechanism that leverages SRv6 programmability to seamlessly steer service traffic from an IPv6 domain across an SR MPLS (non-SRv6) backbone. This process ensures that traffic adheres to specified Service Level Agreements (SLAs) even when traversing heterogeneous network segments.

Summary

SRv6 Provider Edge (PE) Lite is a mechanism that leverages SRv6 programmability to seamlessly steer service traffic from an IPv6 domain across an SR MPLS (non-SRv6) backbone. This process ensures that traffic adheres to specified Service Level Agreements (SLAs) even when traversing heterogeneous network segments.

Workflow

These stages describe how SRv6 PE Lite steers traffic across an SR MPLS backbone:

  1. Control Plane Setup and Signaling:

    • SRv6 PE Lite nodes are configured with SRv6 locators and explicit service de-multiplexing end-point behaviors (e.g., End.DT46 functions).

    • Data center gateways advertise prefixes into the backbone via multiprotocol BGP, including color extended communities to indicate desired transport SLAs.

    • SRv6 PE Lite nodes acting as SR-TE head-ends establish SR policies associated with specific colors and egress PE end-points for steering.

  2. Ingress Data Center Gateway Encapsulation:

    • Data center gateways receive traffic destined for a remote data center.

    • The Data Center Gateway encapsulates this traffic into an outer IPv6 header, where the destination address is an SRv6 network program (e.g., FCBB:BB00:100:FE01::) determined by a gateway controller for a desired transport SLA.

  3. Metro Domain Transport:

    Transit nodes in the IP-only metro domain perform a longest-prefix-match lookup for the outer IPv6 destination address and forward the packet along the shortest path to the SRv6 PE Lite node.

  4. SRv6 PE Lite Decapsulation and VPN Lookup:

    • The SRv6 PE Lite node receives the encapsulated traffic.

    • The SRv6 PE Lite node removes the SRv6 encapsulation and performs a lookup of the original encapsulated packet's IP destination address in the routing table of the corresponding MPLS VPN (e.g., VRF 200).

  5. SRv6 PE Lite Label Imposition and Steering:

    • Based on the VPN lookup and associated SLA, the SRv6 PE Lite node imposes the necessary MPLS VPN label and additional transport labels/SIDs.

    • This steers the traffic over the native LSP path for best-effort traffic or over an SR policy path for SLA-specific traffic.

  6. SR MPLS Backbone Transport

    Transit nodes in the SR MPLS backbone forward the traffic based on the imposed MPLS labels or SIDs, directing it towards the egress PE.

  7. Egress PE Decapsulation and Delivery:

    • The Egress PE receives the traffic from the backbone.

    • The Egress PE performs final decapsulation and VPN table lookup, then delivers the original packet to its destination in the remote data center.

Configuration for SRv6 PE Lite Node

Procedure

  1. Configure SRv6.

    Example:

    segment-routing
 srv6
  locators
   locator myLoc1
    micro-segment behavior unode psp-usd
    prefix fcbb:bb00:11::/48
   !
   locator myLocAnycast
    anycast
    micro-segment behavior unode psp-usd
    prefix fcbb:bb00:100::/48
   !
  !
 !
!

  2. Configure IGP instance in core with SR MPLS enabled and prefix SID assigned to Loopback0.

    Example:

    router isis core
 address-family ipv4 unicast
  metric-style wide level 1
  router-id Loopback0
  segment-routing mpls
 !
 interface Loopback0
  address-family ipv4 unicast
   prefix-sid absolute 16011
  !
 !
!

  3. Configure interface Loopback0.

    Example:

    interface Loopback0
 ipv4 address 1.1.1.11 255.255.255.255
!

  4. Configure the SR policy.

    Example:

    segment-routing
 traffic-eng
  segment-list sample-SIDLIST
   index 10 mpls label 16050
   index 20 mpls label 16021
  !
  policy pol-sla-to_21
   color 1000 end-point ipv4 1.1.1.21
   candidate-paths
    preference 100
     explicit segment-list sample-SIDLIST
     !
    !
   !
  !
 !
!

  5. Configure the VRF (dual-stack IPv4/IPv6).

    Example:

    vrf VRF-200
 address-family ipv4 unicast
  import route-target
   1:200
  !
  export route-policy SET-COLOR-1000
  export route-target
   1:200
  !
 !
 address-family ipv6 unicast
  import route-target
   1:200
  !
  export route-policy SET-COLOR-1000
  export route-target
   1:200
  !
 !
!
!         
extcommunity-set opaque COLOR-1000
  1000
end-set
!
route-policy SET-COLOR-1000
  set extcommunity color COLOR-1000 
end-policy
!

  6. Configure BGP.

    Example:

    router bgp 100
 segment-routing srv6
  locator myLoc1
 !
 address-family vpnv4 unicast
 !
 neighbor 1.1.1.21
  remote-as 100
  address-family vpnv4 unicast
  !
 !
 vrf VRF-200
  rd 200:1
  address-family ipv4 unicast
  !
 !
!