Users Guide

the VLT port restoration timer expires. The delay restore timer enables both VLT peers to synchronize the control information with each
other.
The default timer is 90 seconds. You can use the delay-restore seconds command to modify the duration of the timer.
Example:
OS10(config)# vlt-domain 1
OS10(conf-vlt-1)# delay-restore 100
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.
NOTE:
The VLT domain and the backup parameters are auto-configured in the SmartFabric Services mode from release
10.5.0 onwards.
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:
1180
Virtual Link Trunking