Users Guide

NOTE: Dell EMC Networking recommends conguring the VLT MAC address manually on both the VLT peer switches. Use the
same MAC address on both peers.
Congure the delay restore timer
When the secondary VLT node boots, it waits for a pre-congured amount of time (delay restore) to restore the VLT port status. This delay
enables VLT peers to complete the control data information exchange.
If the peer VLT device was up at the time the VLTi link failed, the system delays bringing up the VLT ports after reload or peer-link
restoration between the VLT peer switches.
When both the VLT peers are up and running, and if the VLTi fails with the VLT heartbeat up, the secondary peer brings down the VLT
ports. When the VLTi comes up, the secondary peer does not bring up its VLT ports immediately. The VLT ports are brought up only after
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
Congure 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 dierent 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 dierentiate 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.
Congure 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 congured, when the VLTi link fails, the system checks for the heartbeat connection without waiting for the timed intervals,
thus allowing faster convergence.
Example conguration:
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 dierent cases where the VLT backup link is used:
In the following gure, the backup link is not congured:
1206
Virtual Link Trunking