Glossary

Table Of Contents
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
DellEMC#
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 EMC 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
Configure PVST+ on VLT Peers to Prevent Forwarding Loops (VLT Peer 2)
Dell_VLTpeer2(conf)#protocol spanning-tree pvst
Dell_VLTpeer2(conf-pvst)#no disable
Dell_VLTpeer2(conf-pvst)#vlan 1000 bridge-priority 4096
Configure both ends of the VLT interconnect trunk with identical PVST+ configurations. When you enable VLT, the show
spanning-tree pvst brief command output displays VLT information.
DellEMC#show spanning-tree pvst vlan 1000 brief
VLAN 1000
Executing IEEE compatible Spanning Tree Protocol
Root ID Priority 0, Address 90b1.1cf4.9b79
Root Bridge hello time 2, max age 20, forward delay 15
Bridge ID Priority 0, Address 90b1.1cf4.9b79
We are the root of Vlan 1000
Configured hello time 2, max age 20, forward delay 15
Virtual Link Trunking (VLT)
1001