Users Guide

Verify VLT is up. Verify that the VLTi (ICL) link, backup link connectivity (heartbeat status), and VLT peer link (peer chassis) are all up.
Dell#show vlt br
VLT Domain Brief
------------------
Domain ID : 1
Role : Secondary
Role Priority : 32768
ICL Link Status : Up
HeartBeat Status : Up
VLT Peer Status : Up
Version : 6(3)
Local System MAC address : 00:01:e8:8a:e9:91
Remote System MAC address : 00:01:e8:8a:e9:76
Remote system version : 6(3)
Delay-Restore timer : 90 seconds
Delay-Restore Abort Threshold : 60 seconds
Peer-Routing : Disabled
Peer-Routing-Timeout timer : 0 seconds
Multicast peer-routing timeout : 150 seconds
Dell#
Verify that the VLT LAG is up in VLT peer unit.
Dell-2#show interfaces port-channel 2 brief
Codes: L - LACP Port-channel
LAG Mode Status Uptime Ports
L 2 L2L3 up 03:43:24 Te 1/4 (Up)
Dell-4#show interfaces port-channel 2 brief
Codes: L - LACP Port-channel
LAG Mode Status Uptime Ports
L 2 L2L3 up 03:33:31 Te 1/18 (Up)
PVST+ Configuration
PVST+ is supported in a VLT domain.
Before you configure VLT on peer switches, configure PVST+ in the network. PVST+ is required for initial loop prevention during the VLT
startup phase. You may also use PVST+ for loop prevention in the network outside of the VLT port channel.
Run PVST+ on both VLT peer switches. A PVST+ instance is created for every VLAN configured in the system. PVST+ instances running
in the Primary Peer control the VLT-LAGs on both Primary and Secondary peers. Only the Primary VLT switch determines the PVST+
roles and states on VLT ports and ensures that the VLT interconnect link is never blocked. The PVST+ instance in Primary peer sends the
role/state of VLT-LAGs for all VLANs to the Secondary peer. The Secondary peer uses this information to program the hardware. The
PVST+ instance running in Secondary peer does not control the VLT-LAGs.
Dell Networking recommends configuring the primary VLT peer as the primary root device for all the configured PVST+ Instances and
configuring the secondary VLT peer as the secondary root device for all the configured PVST+ Instances.
Sample PVST+ Configuration
The following examples show the PVST+ configuration that you must perform on each peer switch to prevent forwarding loops.
Configure PVST+ on VLT Peers to Prevent Forwarding Loops (VLT Peer 1)
Dell_VLTpeer1(conf)#protocol spanning-tree pvst
Dell_VLTpeer1(conf-pvst)#no disable
Dell_VLTpeer1(conf-pvst)#vlan 1000 bridge-priority 0
844
Virtual Link Trunking (VLT)