Virtual Router Redundancy Protocol (VRRP) Fabric Routing

Virtual Router Redundancy Protocol V(RRP) has one master router that does L3 routing and one or more backup routers that perform L2 forwarding of packets toward the master router, as per VRRP RFC specification. With this method, L3 routing capability of backup router goes unused. This also causes loss of bandwidth in the links that connect master and backup routers. This issue is present in any topology where host traffic is flowing using the backup routers. With multiple backup routers, traffic from hosts attached to some backup routers have to traverse multiple links to reach the master router. This causes loss of bandwidth in multiple links toward the master.

This feature allows backup routers to take part in L3 routing for the packets it receives with the destination address equal to VMAC. Backup routers enabled with this feature are called Fabric Routing Enabled Backup (FREB) routers. This feature allows
  • Load sharing of traffic between VRRP routers
  • Saves bandwidth on the links connecting master and backup routers
This solution is applicable for all topologies, such as MLAG, EAPS, or STP.


Summit X450-G2, X460-G2, X670-G2, X770, and ExtremeSwitching X620, X440-G2 series switches


  • Fabric Routing feature will not be supported for VRRP VR for which Virtual IP is same as interface IP (owned IP).
  • Traffic sent from host destined for VIP, will be L3 forwarded by FREB router if FREB router sits in between, even though both are in same subnet. VIP cannot be used to run protocols between host and VRRP router which will expect TTL value not be decremented, for example BFD.
  • PVLAN configuration will not be supported in this release.
  • VLAN Aggregation configuration will not be supported in this release.

New CLI Commands

configure vrrp {vlan vlan_name vr vr_id | all} fabric-route-mode [on | off]