Layer 3 route synchronization for EVPN multihoming

Updated: June 17, 2026

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Introduces Layer 3 route synchronization for EVPN multihoming, highlighting its benefits, detailing VRF configuration requirements on subinterfaces, and explaining operational workflows for effective route synchronization.

Layer 3 route synchronization for EVPN multihoming is a Layer 3 service function that

enhances resilience and load balancing for Layer 3 services in multihoming environments
keeps routing information consistent across redundant PE routers
synchronizes ARP, ND, and multicast route information using BGP-EVPN to enable seamless traffic forwarding and consistent multicast behavior.

Feature history

The feature history table lists release support for this feature.

Table 1. Feature History Table
Feature Name	Release Information	Feature Description
Layer-3 route synchronization for EVPN multi-homing	Release 25.4.1	Introduced in this release on: Fixed Systems (8010 [ASIC: A100], 8700 [ASIC: K100])(select variants only) This feature is supported on: 8711-48Z-M 8011-32Y8L2H2FH 8011-12G12X4Y-A/D
Layer-3 route synchronization for EVPN multi-homing	Release 25.3.1	Introduced in this release on: Fixed Systems(8200, 8700, 8011)(select variants only); Modular Systems (8800 [LC ASIC: P100]) With Layer 3 route synchronization, you can ensure seamless failover and optimal traffic distribution in multihoming environments by synchronizing critical Layer 3 routing information, such as ARP/ND entries and multicast routes, across redundant Provider Edge (PE) routers. This feature leverages the BGP-EVPN route synchronization mechanism to maintain consistent routing states and accelerate convergence across your network. This feature is supported on: 8212-48FH-M 8711-32FH-M 8712-MOD-M 8011-4G24Y4H-I

Route synchronization behavior

Layer 3 route synchronization is a functionality that

enhances the resilience and load-balancing capabilities of Layer 3 services in multihoming environments,
addresses challenges of maintaining consistent routing information across redundant PE routers, and
ensures synchronized Layer 3 routing information (ARP/ND, multicast routes) on backup or standby PEs.

In multihoming setups, traffic can arrive at any redundant PE. However, Layer 3 routing information, such as ARP/ND entries for hosts and multicast routes for PIM Designated Routers (DRs), might only be learned by the primary or active PE. This can lead to traffic drops on backup or standby PEs until these entries are resolved. Additionally, PIM DR election might not always align with the currently active service PE, causing inconsistencies in multicast routing.

Layer 3 route synchronization eliminates these issues by proactively synchronizing ARP/ND entries and multicast routes across all redundant PEs using BGP-EVPN. This capability ensures that all PEs possess the necessary routing information, enabling seamless traffic forwarding and consistent multicast behavior, even on backup or standby devices.

Layer 3 route synchronization benefits

Layer 3 route synchronization offers several benefits for redundant PE designs that use EVPN multihoming for Layer 3 services:

Enhanced resilience: Ensures backup or standby PEs have synchronized Layer 3 routing information (such as ARP/ND and multicast routes), enabling seamless failover and minimizing traffic loss during link or node failures.
Optimal load balancing: Facilitates efficient traffic distribution by ensuring all eligible PEs are prepared to forward Layer 3 traffic without delays caused by missing routing entries.
Consistent routing: Leverages BGP-EVPN for control-plane synchronization of Layer 3 routes, providing a unified and consistent view of network reachability across redundant PEs.
Faster convergence: Reduces convergence time by pre-populating ARP/ND tables and synchronizing multicast states, eliminating the need for on-demand learning after a failover.

Configure VRF only on subinterfaces in EVPN multihoming deployments

For EVPN multihoming deployments, configure the VRF only on subinterfaces to enable Layer 3 route synchronization. Configuring the VRF on interfaces other than subinterfaces is not supported.

How Layer 3 route synchronization works

Layer 3 route synchronization is critical in EVPN networks to ensure high availability and prevent service interruptions. By coordinating routing information across multiple Provider Edge routers, the network maintains seamless traffic flow, even during failovers or topology changes.

Summary

The key components involved in the process are:

BGP-EVPN: The underlying protocol for route synchronization.
Service PEs: The Provider Edge routers that participate in route learning and synchronization.
Route types: Specific EVPN route types (MAC-IP route type, IP Prefixes route type, Multicast Report route types) used for different types of Layer 3 information.
Synchronization attributes: EVPN attributes (EVI, L2-Route-Target, ESI, ETAG, ES Import, EVI-Route-Target) that tag routes for targeted distribution.
Connected switches: Devices that update their MAC tables during failover events.

Layer 3 route synchronization ensures consistent routing information across redundant service Provider Edge (PE) routers by leveraging BGP-EVPN to propagate and install Layer 3 routing information.

Workflow

These stages describe how Layer 3 route synchronization works:

Information learning and propagation: A service PE learns Layer 3 routing information (such as ARP/ND entries and multicast routes) and propagates it to other redundant service PEs by using BGP-EVPN.
Targeted route distribution: BGP imports Layer 3 synchronization routes based on matching ES Import route-policy filters and EVI route targets, ensuring distribution to relevant PEs.
Scenario application: The synchronization mechanism applies to Layer 3 gateway multihoming, L3VPN active-active bundles, and L3VPN port-active bundles, providing resilient services and efficient traffic handling.
If a PE fails or receives a route delete, the new primary service PE triggers a gratuitous ARP (GARP) or Neighbor Advertisement (NA) replay. Connected switches update their MAC tables, redirecting traffic to the new primary PE.

Result

Layer 3 route synchronization keeps redundant service PEs ready to forward traffic and respond to failover events with consistent routing state.

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