VRRP Fabric Routing

Prior to ExtremeXOS 16.2, VRRP had one master router which would do L3 routing and one or more backup routers which would do L2 forwarding of packets to the master router. This caused loss of bandwidth in the links that connect the master and backup routers. This issue is present in any topology wherein host traffic is flowing via backup router. In case of multiple backup routers, traffic from hosts attached to some backup routers would have to traverse multiple links to reach the master router. This caused loss of bandwidth in multiple links towards the master.

The VRRP fabric routing feature introduced in ExtremeXOS 16.2 allows the backup router to take part in L3 routing for the packets it receives with DA=VMAC. A backup router enabled with this feature is called a Fabric Routing Enabled Backup (FREB) router. This feature allows load sharing of traffic between VRRP routers and saves the bandwidth of links connecting the master and backup. This bandwidth saved can be used to provide better connectivity between the segments of the network wherein each segment is connected to only one VRRP router directly. This solution is applicable for all topologies such as MLAG, EAPS, or STP.

The VRRP FREB router receives and processes VRRP advertisements from the master, but does not generate advertisements. Broadcast ARP requests and multicast neighbor solicitations to resolve the virtual IP are responded to by the master router. The Fabric Routing Enabled Backup router behaves as mentioned in RFC 5798 with the following exceptions:
  • The backup router performs forwarding functionality, similar to the master.
  • The backup router responds to unicast ARP/Neighbor Solicitation requests it receives.

Configuring VRRP Fabric Routing

To configure the fabric routing feature, enter the following command:

configure vrrp vlan vlan_name vrid vridval fabric-routing [on | off]

This configuration can be present on all VRRP routers, regardless of VRRP state of the router. Fabric routing will be enabled only when the VRRP router is in backup state.