Enabling Fabric Routing Mode

A VRRP (Virtual Router Redundancy Protocol) router configured with fabric routing mode will be in backup state. There is some difference in behavior based on enabling sequence which is described below.

When enabling VRRP VR after configuring fabric routing mode, assume that fabric routing mode has already been configured for VRRP VR and VR is administratively enabled now. Initially the VRRP state machine will start from INIT state. It will move to backup state and wait for Master_Down_Interval duration to receive an advertisement from current master. Based on VRRP Master election (as described earlier in the sections), VRRP router will either become master or will assume forwarding responsibility while in backup state (i.e., FREB). Waiting in backup state avoids a burst of messages exchanged in software during the transition. This is useful in scaled setups.

Note

For the duration it waits in backup state, traffic will be forwarded to the VRRP master where it gets routed. This behavior is same as existing behavior without fabric routing.

When configuring fabric route mode when the VR is already in backup state, if the VR has received advertisements within the last advertisement interval, the router will take forwarding responsibility immediately.

The hold off timer will be applied before FREB starts IP forwarding. In case of reboot or process restart, the VR will wait for 60 seconds before taking forwarding responsibility. This will allow the routing protocols in the restarting system to converge.

To enable fabric routing, use the following command:

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

To configure a specific VRRP instance as FREB:

configure vrrp vlan v1 vrid 1 fabric-routing on

To configure all the VRRP instances as FREB:

configure vrrp all fabric-routing on

Configured fabric routing can be seen in the show command output of the show vrrp detail or show vrrp vlan vlan CLI command:

# sh vrrp detail
VLAN:  v1       VRID:  1        VRRP:  Disabled State:  Backup
Virtual Router:  VR-Default
Priority:  100(backup)  Advertisement Interval:  1 sec
Version: v2     Preempt:  Yes   Preempt Delay: 0 sec
 Virtual IP Addresses:
 Accept mode:  Off
 Host-Mobility:  Off
 Host-Mobility Exclude-Ports:
 Tracking mode:  ALL
 Tracked Pings:  -
 Tracked IP Routes:  -
 Tracked VLANs:  -
 Fabric Routing: On

  * indicates a tracking condition has failed

Published March 2020prev | next

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