Users Guide

Configure the VLT peer liveliness check
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. You must use a different link other than the VLTi for the peer liveliness check. This link
is referred to as the VLT backup link.
NOTE: Dell EMC Networking recommends using the OOB management network connection for the VLT backup link.
If the VLTi goes down, the backup link helps to 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, 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 interval that is configured, when the VLTi link fails, the system checks for the heartbeat connection
without waiting for the timed intervals, thus allowing faster convergence.
Example configuration:
OS10(config)# vlt-domain 1
OS10(conf-vlt-1)# backup destination 10.16.151.110 vrf management interval 20
OS10(config)# vlt-domain 1
OS10(conf-vlt-1)# backup destination ipv6 1::1 vrf management interval 20
The following examples describe different cases where the VLT backup link is used:
In the following figure, the backup link is not configured:
Virtual Link Trunking
1627