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

IPv4 L3VPN active-active redundancy using port-active mode

Updated: September 8, 2026

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Explains how redundant PEs provide active-active customer connectivity and use EVPN route synchronization to preserve reachability when bundle hashing distributes control traffic unevenly.

An IPv4 L3VPN active-active redundancy using port-active mode is an SRv6 service that

  • provides active-active connectivity to a CE device in a Layer 3 VPN (L3VPN) deployment

  • allows the CE device, whether Layer 2 or Layer 3, to connect to redundant PE routers over a single Link Aggregation Control Protocol (LACP) link aggregation group (LAG) port, and

  • augments Layer 3 local route learning with remote route-synchronization programming to ensure complete route awareness across redundant PEs despite bundle hashing distributing ARP or IPv6 Network Discovery packets unevenly

Key concepts

Table 1. Feature History Table

Feature Name

Release Information

Feature Description

IPv4 L3VPN active-active redundancy using port-active mode

 Release 25.4.1

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

This feature enables active-active redundancy for IPv4 L3VPN using port-active mode with SRv6, allowing a CE device to connect to redundant PE routers through a single LAG port.

It supports both Layer 2 and Layer 3 CE connections and ensures complete route awareness by synchronizing routing information between redundant PEs, even when bundle hashing distributes packets unevenly.

This capability augments local route learning with remote route-synchronization programming and operates seamlessly in L3VPN deployments.

This feature is now supported on:

  • 8711-48Z-M

  • Bundle hashing: A method that distributes traffic across multiple links in a LAG based on packet header fields, which can cause packets like ARP or IPv6 ND to be sent to different redundant routers.

  • Remote route-synchronization programming: A mechanism that synchronizes Layer 3 routing information between redundant PEs to provide full route awareness

Route synchronization between service PEs

Route synchronization between service PE devices is essential to minimize service interruptions for both unicast and multicast traffic following a failure on a redundant service PE. The synchronization process uses specific EVPN route types for Layer 3 route synchronization:

  • EVPN route-type 2: Synchronizes ARP tables.

  • EVPN route-type 7/8: Synchronizes IGMP JOIN and LEAVE messages.

In scenarios where a Layer 3 CE router connects to redundant PEs, it may establish an IGP adjacency on the bundle port. This adjacency forms with only one of the redundant PEs, meaning that IGP customer routes are present only on that PE. To synchronize Layer-3 customer subnet routes (IP prefixes) across redundant PEs, EVPN route-type 5 is used. This route type carries the ESI, Ethernet Tag (ETAG), and the gateway address (prefix next-hop address) to ensure consistent routing information.

This synchronization mechanism ensures seamless failover and continuity of Layer 3 services in redundant PE environments

Consistent route synchronization across VRFs and Ethernet segments

Consistent route synchronization across Virtual Routing and Forwarding instances (VRFs) and Ethernet segments ensures optimized redundancy and efficient route management in the network. This synchronization maintains uniform routing information, which enhances network stability and simplifies the management of redundant paths and failover mechanisms.

  • Synchronization across VRFs prevents routing inconsistencies between isolated routing domains.

  • Ethernet segment synchronization supports redundancy by coordinating route updates among connected devices.

  • The approach optimizes route management by reducing conflicts and improving convergence times.

  • Gratuitous ARP (GARP) and IPv6 Network Advertisement (NA) replay are not necessary for CE devices connected to redundant PE devices through a single Link LAG port.

  • This configuration example enables Layer 3 route synchronization for routes learned on Ethernet segment subinterfaces:

    evpn
 route-sync vrf default
!
vrf RED
 evi route-sync 10
!
vrf BLUE
 evi route-sync 20
!
    Note

    EVPN does not support untagged interfaces.