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

L3VPN active-standby redundancy with port-active mode

Updated: September 8, 2026

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Explains the Segment Routing IPv6 (SRv6) Services: L3VPN VPNv4 Active-Standby Redundancy using Port-Active Mode feature provides all-active per-port load balancing for multihoming. The forwarding of traffic is determined based on a specific interface rather than per-flow across multiple Provider.

A SRv6 L3VPN active-standby redundancy with port-active mode is a network feature that

  • provides all-active, per-port load balancing for multihomed connections,

  • determines traffic forwarding based on a specific interface rather than per-flow across multiple provider edge routers, and

  • enables efficient load balancing and faster convergence in failover scenarios.

Table 1. Table 1. Feature History Table

Feature Name

Release Information

Feature Description

SRv6 L3VPN VPNv4 Active-Standby Redundancy using Port-Active Mode

Release 25.4.1

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

*This feature is supported on:

  • 8011-32Y8L2H2FH

  • 8011-12G12X4Y-A/D

SRv6 L3VPN VPNv4 Active-Standby Redundancy using Port-Active Mode

 Release 25.1.1

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

This feature is now supported on Cisco 8011-4G24Y4H-I routers.

SRv6 L3VPN VPNv4 Active-Standby Redundancy using Port-Active Mode

Release 24.4.1

Introduced in this release on: Fixed Systems (8200 [ASIC: P100], 8700 [ASIC: P100, K100])(select variants only*); Modular Systems (8800 [LC ASIC: P100])(select variants only*)

This feature enables interface-based traffic forwarding, ensuring efficient load-balancing and faster convergence for multihoming. In active-standby scenarios, the active PE router is identified through a designated forwarder (DF) election using byte 10 of the Ethernet Segment Identifier (ESI), and the standby PE router interface is then brought down.

*This feature is supported on:

  • 8212-48FH-M

  • 8711-32FH-M

  • 8712-MOD-M

  • 88-LC1-36EH

  • 88-LC1-12TH24FH-E

  • 88-LC1-52Y8H-EM

In active-standby scenarios, the active Provider Edge (PE) router is identified using a Designated Forwarder (DF) election based on a modulo calculation of byte 10 of the Ethernet Segment Identifier (ESI). The interface of the standby PE router is brought down automatically to ensure rapid and seamless failover.

L3VPN active-standby redundancy restrictions

The following restrictions apply to L3VPN active-standby redundancy using port-active mode:

  • This feature can only be configured for bundle interfaces.

  • When an EVPN Ethernet Segment (ES) is configured with port-active load-balancing mode, you cannot configure the attachment circuits (ACs) of that bundle on bridge-domains with a configured EVPN instance (EVI); EVPN Layer 2 bridging service is not compatible with port-active load-balancing mode.

  • SRv6 services for L3VPN active-standby redundancy can be used with port-active mode if all other restrictions are observed. For more information, see:

L3VPN active-standby redundancy operation

Summary

L3VPN active-standby redundancy ensures service continuity by enabling routers (Provider Edge, or PE routers) to elect a Designated Forwarder (DF) for multihomed Ethernet Segments (ES) using EVPN and BGP routing. This process maintains traffic flow and handles failover when a link or port failure occurs.

The key components involved in the process are:

  • PE routers: Exchange EVPN ES routes, build an ordered list of peer PEs, and participate in DF election.

  • BGP protocol: Facilitates communication and route exchange between participating PE routers.

  • DF: The elected PE router that actively forwards traffic for a given ES.

Workflow

The process involves the following stages:

  1. Under port-active operational mode, each PE router exchanges EVPN ES routes across BGP with other routers servicing the same multihomed ES.

  2. Each PE router builds an ordered list of all connected PE IP addresses (including its own) and assigns itself an ordinal representing its position in this list.
  3. Using a modulo calculation and the ordinal values, each PE determines which router will be the Designated Forwarder for the ES. The chosen DF actively forwards the traffic.
  4. All non-DF PEs transition to standby mode and take their respective interface bundles out of service for that ES, preventing traffic duplication.
  5. In the event of a link or port failure, the active DF PE withdraws its ES route, which triggers a new DF election among the remaining PEs. Another eligible PE becomes the DF and forwards traffic.

Result

L3VPN active-standby redundancy provides seamless failover by ensuring that traffic is always forwarded by a single active PE (the DF). When failures occur, the election process rapidly selects a new DF to maintain uninterrupted service.

Configure L3VPN active-standby redundancy with port-active mode

Provide step-by-step instructions to establish L3VPN active-standby redundancy with port-active mode using SRv6 on Cisco IOS XR Series devices.

Use this procedure when deploying L3VPN services over SRv6 where you require fast failover and service resilience using active-standby links configured in port-active mode. These steps combine essential configuration, best practices, and verification.

Before you begin

  • Ensure all participating devices are running a compatible Cisco IOS XR release supporting SRv6 and L3VPN active-standby with port-active mode.

  • Plan unique interface numbering, BGP ASN, and EVI/ESI identifiers.

  • Collect required IP addressing for interfaces, bundles, and BGP neighbors.

  • Confirm administrative access to the device CLI ("enable" and "configure" modes).

  • Review the intended network topology (e.g., which devices/ports are active vs. standby) and have failover testing planned.

The following steps help to configure L3VPN active-standby redundancy with port-active mode:

Procedure

  1. Configure SRv6 services L3VPN active-standby redundancy using port-active mode under an ES.

    
/* Configure Ethernet Link Bundles */
Router# configure
Router(config)# interface Bundle-Ether10
Router(config-if)# ipv4 address 10.0.0.2 255.255.255.0
Router(config-if)# ipv6 address 2001:DB8::1
Router(config-if)# lacp period short
Router(config-if)# mac-address 1.2.3
Router(config-if)# bundle wait-while 0
Router(config-if)# exit
Router(config)# interface GigabitEthernet 0/2/0/5
Router(config-if)# bundle id 14 mode active
Router(config-if)# commit

/* Configure load balancing. */
Router# configure
Router(config)# evpn
Router(config-evpn)# interface Bundle-Ether10
Router(config-evpn-ac)# ethernet-segment
Router(config-evpn-ac-es)# identifier type 0 11.11.11.11.11.11.11.11.14
Router(config-evpn-ac-es)# load-balancing-mode port-active
Router(config-evpn-ac-es)# commit
!
/* Configure address family session in BGP. */
Router# configure
Router(config)# router bgp 100
Router(config-bgp)# bgp router-id 192.168.0.2
Router(config-bgp)# address-family l2vpn evpn
Router(config-bgp)# neighbor 192.168.0.3
Router(config-bgp-nbr)# remote-as 200
Router(config-bgp-nbr)# update-source Loopback 0
Router(config-bgp-nbr)# address-family l2vpn evpn
Router(config-bgp-nbr)# commit

    Running configuration

    
interface Bundle-Ether14
 ipv4 address 14.0.0.2 255.255.255.0
 ipv6 address 14::2/64
 lacp period short
 mac-address 1.2.3
 bundle wait-while 0
!
interface GigabitEthernet0/2/0/5
 bundle id 14 mode active
!
evpn
 interface Bundle-Ether14
  ethernet-segment
   identifier type 0 11.11.11.11.11.11.11.11.14
   load-balancing-mode port-active
  !
 !
!
router bgp 100
 bgp router-id 192.168.0.2
 address-family l2vpn evpn
 !
 neighbor 192.168.0.3
  remote-as 100
  update-source Loopback0
  address-family l2vpn evpn
  !
 !
!

  2. Verify the SRv6 services L3VPN active-standby redundancy using port-active mode configuration.

    Example:

    
/* Verify ethernet-segment details on active DF router */
Router# show evpn ethernet-segment interface Bundle-Ether14 detail 
Ethernet Segment Id      Interface                          Nexthops            
------------------------ ---------------------------------- --------------------
0011.1111.1111.1111.1114 BE14                               192.168.0.2
                                                            192.168.0.3
    ES to BGP Gates   : Ready
  ES to L2FIB Gates : Ready
  Main port         :
     Interface name : Bundle-Ether14
     Interface MAC  : 0001.0002.0003
     IfHandle       : 0x000041d0
     State          : Up
     Redundancy     : Not Defined
  ESI type          : 0
     Value          : 11.1111.1111.1111.1114
  ES Import RT      : 1111.1111.1111 (from ESI)
  Source MAC        : 0000.0000.0000 (N/A)
  Topology          :
     Operational    : MH
     Configured     : Port-Active
  Service Carving   : Auto-selection
     Multicast      : Disabled
  Peering Details   :
     192.168.0.2 [MOD:P:00]
     192.168.0.3 [MOD:P:00]

  Service Carving Results:
     Forwarders     : 0
     Permanent      : 0
     Elected        : 0
     Not Elected    : 0
  MAC Flushing mode : STP-TCN
  Peering timer     : 3 sec [not running]
  Recovery timer    : 30 sec [not running]
  Carving timer     : 0 sec [not running]
  Local SHG label   : None
  Remote SHG labels : 0


/* Verify bundle Ethernet configuration on active DF router */
Router# show bundle bundle-ether 14 
Bundle-Ether14
  Status:                                    Up
  Local links <active/standby/configured>:   1 / 0 / 1
  Local bandwidth <effective/available>:     1000000 (1000000) kbps
  MAC address (source):                      0001.0002.0003 (Configured)
  Inter-chassis link:                        No
  Minimum active links / bandwidth:          1 / 1 kbps
  Maximum active links:                      64
  Wait while timer:                          Off
  Load balancing:                            
    Link order signaling:                    Not configured
    Hash type:                               Default
    Locality threshold:                      None
  LACP:                                      Operational
    Flap suppression timer:                  Off
    Cisco extensions:                        Disabled
    Non-revertive:                           Disabled
  mLACP:                                     Not configured
  IPv4 BFD:                                  Not configured
  IPv6 BFD:                                  Not configured

  Port                  Device           State        Port ID         B/W, kbps
  --------------------  ---------------  -----------  --------------  ----------
  Gi0/2/0/5             Local            Active       0x8000, 0x0003     1000000
      Link is Active
	  


/*  Verify ethernet-segment details on standby DF router */
Router# show evpn ethernet-segment interface bundle-ether 10 detail

Router# show evpn ethernet-segment interface Bundle-Ether24 detail
Ethernet Segment Id      Interface                          Nexthops            
------------------------ ---------------------------------- --------------------
0011.1111.1111.1111.1114 BE24                               192.168.0.2
                                                            192.168.0.3
  ES to BGP Gates   : Ready
  ES to L2FIB Gates : Ready
  Main port         :
     Interface name : Bundle-Ether24
     Interface MAC  : 0001.0002.0003
     IfHandle       : 0x000041b0
     State          : Standby
     Redundancy     : Not Defined
  ESI type          : 0
     Value          : 11.1111.1111.1111.1114
  ES Import RT      : 1111.1111.1111 (from ESI)
  Source MAC        : 0000.0000.0000 (N/A)
  Topology          :
     Operational    : MH
     Configured     : Port-Active
  Service Carving   : Auto-selection
     Multicast      : Disabled
  Peering Details   :
     192.168.0.2 [MOD:P:00]
     192.168.0.3 [MOD:P:00]

  Service Carving Results:
     Forwarders     : 0
     Permanent      : 0
     Elected        : 0
     Not Elected    : 0
  MAC Flushing mode : STP-TCN
  Peering timer     : 3 sec [not running]
  Recovery timer    : 30 sec [not running]
  Carving timer     : 0 sec [not running]
  Local SHG label   : None
  Remote SHG labels : 0

/* Verify bundle configuration on standby DF router */
Router# show bundle bundle-ether 24 
 
Bundle-Ether24
  Status:                                    LACP OOS (out of service)
  Local links <active/standby/configured>:   0 / 1 / 1
  Local bandwidth <effective/available>:     0 (0) kbps
  MAC address (source):                      0001.0002.0003 (Configured)
  Inter-chassis link:                        No
  Minimum active links / bandwidth:          1 / 1 kbps
  Maximum active links:                      64
  Wait while timer:                          Off
  Load balancing:                            
    Link order signaling:                    Not configured
    Hash type:                               Default
    Locality threshold:                      None
  LACP:                                      Operational
    Flap suppression timer:                  Off
    Cisco extensions:                        Disabled
    Non-revertive:                           Disabled
  mLACP:                                     Not configured
  IPv4 BFD:                                  Not configured
  IPv6 BFD:                                  Not configured

  Port                  Device           State        Port ID         B/W, kbps
  --------------------  ---------------  -----------  --------------  ----------
  Gi0/0/0/4             Local            Standby      0x8000, 0x0002     1000000
      Link is in standby due to bundle out of service state

L3VPN active-standby redundancy is established using port-active mode. The active router carries traffic over its bundle; the standby remains ready for failover. Verification commands confirm the correct operational and standby states.