The VLT peer liveliness mechanism checks for the availability of the peer node. The system sends periodic keep-alive messages to detect the liveliness of the peer node. Use a different link, other than the VLTi, for the peer liveliness check. This link is referred to as the VLT backup link. Dell Technologies recommends using the OOB management network connection for the VLT backup link.
If the VLTi goes down, the backup link helps differentiate the VLTi link failure from a peer node failure. If all links in the VLTi fail, the VLT nodes exchange node liveliness information through the backup link.
Based on the node liveliness information:
- If only the VLTi link fails, but the peer is alive, the secondary VLT peer shuts down its VLT ports.
- If the primary VLT node fails, then both the VLTi and heartbeat fail, and the current secondary peer takes over the primary role.
Configure the VLT backup link using the backup destination {ip-address | ipv6 ipv6–address} [vrf management] [interval interval-time]
. The interval range is from 1 to 30 seconds. The default interval is 30 seconds. Irrespective of the configured interval, when the VLTi link fails, the system checks for the heartbeat connection without waiting for the timed intervals, thus allowing faster convergence.
OS10(config)# vlt-domain 1
OS10(conf-vlt-1)# backup destination 10.16.151.110 vrf management interval 20