Sub-second convergence for EVPN with BGP PIC-edge

Updated: June 10, 2026

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Explains sub-second convergence for EVPN with BGP PIC-edge, focusing on network resiliency improvements, supported deployment scenarios, benefits, limitations, operational process, and configuration steps for rapid failover.

Sub-second convergence for EVPN with BGP PIC-edge is a network functionality that

maintains uninterrupted service during network failures
delivers rapid convergence for active-active EVPN ELAN and E-Line services, and
enables immediate switchover to backup nexthop path for user traffic when a preferred path becomes unavailable.

Table 1. Feature History Table
Feature Name	Release Information	Feature Description
Sub-second convergence for EVPN with BGP PIC-edge	Release 25.4.1	Introduced in this release on: Fixed Systems (8700 [ASIC: K100])(select variants only) This feature is supported on Cisco 8711-48Z-M routers.
Sub-second convergence for EVPN with BGP PIC-edge	Release 25.3.1	Introduced in this release on: Fixed Systems (8010 [ASIC: A100], 8200 [ASIC: P100], 8700 [ASIC: P100, K100]); Modular Systems (8800 [LC ASIC: P100]) You can maintain continuous service in multihomed EVPN deployments using sub-second convergence for EVPN with BGP PIC-edge. This functionality rapidly switches traffic to a backup nexthop path when the preferred nexthop fails, delivering fast convergence and high availability for active-active EVPN E-LAN and E-Line services.

EVPN network resiliency with sub-second BGP PIC-edge convergence

Sub-second convergence for EVPN with BGP PIC-edge enhances network availability and reliability by minimizing service disruptions in large-scale environments where even brief outages affect users and business operations.

Key features include:

Preprogrammed primary and backup paths: Both active and standby routes are configured in advance to maintain service continuity during failures.
Automatic traffic redirection: The system reroutes traffic seamlessly to backup paths upon primary path failure and restores normal operation quickly when the primary path is available.
Rapid convergence for active-active EVPN E-LAN and E-Line services: Multihomed deployments achieve sub-second recovery times independent of the underlying BGP and EVPN prefixes.

Supported deployment scenarios for sub-second EVPN convergence

The sub-second EVPN convergence supports these deployment scenarios:


When...	and remote PE is reachable through...	the feature provides...
the remote PE is within the same IGP domain	IGP	sub-second EVPN convergence for node failure in active-active Multihoming scenarios.
the remote PE is in a different IGP domain	BGP-LU	sub-second EVPN convergence in inter-IGP domain scenarios.

Benefits of sub-second convergence for EVPN with BGP PIC-edge

These are some of the benefits of sub-second convergence for EVPN with BGP PIC-edge:

Rapid traffic recovery: Enables sub-second failover when a primary path or node fails, minimizing traffic disruption for end users.
Improved network resiliency: Enhances the ability of the network to quickly recover from failures, supporting high-availability services.
Prefix-Independent Convergence (PIC): Pre-programs backup paths in hardware, allowing instant traffic switching without software re-programming of each prefix.
Optimized for active-active multihoming: Provides seamless traffic redirection in active-active multihoming scenarios.
Scales efficiently for large EVPN deployments.

Limitations of sub-second convergence for EVPN with BGP PIC-edge

Sub-second convergence applies only to unicast EVPN traffic. Backup paths can be pre-programmed in hardware only for unicast prefixes.
Fast convergence for BUM traffic is not supported.
Sub-second convergence is supported only when a single EVPN nexthop path goes down at a time. Multiple simultaneous failures or mass flaps may not achieve sub-second recovery.
Use the preferred-nexthop {[highest-ip] [lowest-ip]} command to enable sub-second convergence.
Backup path pre-programming relies on hardware capabilities.

How sub-second convergence for EVPN with BGP PIC-edge works

Sub-second EVPN convergence features minimize traffic interruption during network failures by switching to a pre-programmed backup nexthop path without control-plane delay.

Summary

The key components involved in the process are:

Primary path: The main route used for forwarding EVPN service traffic.
Backup path: An alternate route pre-programmed in hardware to take over if the primary path fails.
Forwarding Information Base (FIB): A table that manages path selection and failover.

Workflow

These stages describe how the sub-second EVPN convergence works.

When the preferred path is operational, all traffic is sent using the primary path.
If the primary path fails because of a node failure, link failure, or IGP event, the hardware immediately switches forwarding to the backup path without waiting for the control plane to reconverge.
The system continues forwarding over the backup path until the primary path is restored or a new preferred path is configured.
If the primary path is not restored, the control plane later reconverges and programs the backup path as the sole forwarding path.

Result

Service interruption is minimized, and traffic switchover occurs in less than one second in supported scenarios.

Configure sub-second convergence for EVPN with BGP PIC-edge

Achieve sub-second EVPN convergence by enabling rapid failover through preferred next-hop configuration.

This task applies when you want to optimize EVPN path selection to ensure fast failover between primary and backup paths.

Before you begin

Ensure you have access to the router CLI and necessary privileges to configure EVPN.

Procedure

Configure the preferred next-hop for the EVPN instance to optimize path selection for rapid failover.

Example:

Router# configure
Router(config)# evpn
Router(config-evpn)# evi 100
Router(config-evpn-instance)# preferred-nexthop highest-ip
Router(config-evpn-instance)# commit

Run the show running-config evpn command to ensure the configuration is active.

Example:

Router#show running-config evpn
evpn
 evi 100
  preferred-nexthop highest-ip
 !
!

The router is configured for sub-second EVPN convergence, with both primary and backup paths pre-programmed to provide rapid and automatic failover.

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