Concept Guide

Sample PVST+ Conguration
The following examples show the PVST+ conguration that you must perform on each peer switch to prevent forwarding loops.
Congure 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
Congure 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
Congure both ends of the VLT interconnect trunk with identical PVST+ congurations. 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
Interface Designated
Name PortID Prio Cost Sts Cost Bridge ID PortID
---------- -------- ---- ------ ----------- ------- -------------------- --------
Po 1 128.2 128 188
FWD(vltI) 0 0 90b1.1cf4.9b79 128.2
Po 2 128.3 128 2000 FWD(vlt) 0 0 90b1.1cf4.9b79 128.3
Te 1/10 128.230 128 2000 FWD 0 0 90b1.1cf4.9b79 128.230
Te 1/13 128.233 128 2000 FWD 0 0 90b1.1cf4.9b79 128.233
Interface
Name Role PortID Prio Cost Sts Cost Link-type Edge
---------- ------ -------- ---- ------- ----------- ------- --------- ----
Po 1 Desg 128.2 128 188 FWD 0
(vltI)P2P No
Po 2 Desg 128.3 128 2000 FWD 0 (vlt) P2P No
Gi 1/10 Desg 128.230 128 2000 FWD 0 P2P Yes
Gi 1/13 Desg 128.233 128 2000 FWD 0 P2P No
DellEMC#
Peer Routing Conguration Example
This section provides a detailed explanation of how to congure peer routing in a VLT domain.
In the following example, devices are congured as follows:
• Access switch A1 is connected to two VLT peers (Dell-1 and Dell-2).
• The two VLT peers are connected to an upstream switch R1.
• OSPF is congured in Dell-1, Dell-2, and R1 switches.
• Dell-1 is congured as the root bridge.
• Dell-1 is congured as the VLT primary.
• As the Router ID of Dell-1 is the highest in the topology (highest loopback address of 172.17.1.1), Dell-1 is the OSPF Designated Router.
• As the Router ID of Dell-2 is the second highest in the topology (172.16.1.1), Dell-2 is the OSPF Backup Designated Router.
Virtual Link Trunking (VLT)
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