Reference Guide

Per-VLAN Spanning Tree Plus | 787
Enable PVST+
When you enable PVST+, FTOS instantiates STP on each active VLAN. To enable PVST+ globally:
Disable PVST+
Display your PVST+ configuration by entering the command show config from PROTOCOL PVST
context, as shown in fig.
FTOS_E600(conf-pvst)#show config verbose
!
protocol spanning-tree pvst
no disable
vlan 100 bridge-priority 4096
Influence PVST+ Root Selection
In Figure 43-1, all VLANs use the same forwarding topology because R2 is elected the root, and all
GigabitEthernet ports have the same cost. Figure 43-2 changes the bridge priority of each bridge so that a
different forwarding topology is generated for each VLAN. This behavior demonstrates how you can use
PVST+ to achieve load balancing.
Figure 43-2. Load Balancing with PVST+
Step Task Command Syntax Command Mode
1 Enter PVST context. protocol spanning-tree pvst PROTOCOL PVST
2 Enable PVST+. no disable PROTOCOL PVST
Task Command Syntax Command Mode
Disable PVST+ globally. disable PROTOCOL PVST
Disable PVST+ on an interface or remove a PVST+ parameter configuration. no spanning-tree pvst INTERFACE
R2
R3
R1
2/32
1/22
1/32
2/12
3/22
3/12
STI 3 root
STI 3: VLAN 300
STI 1: VLAN 100
STI 2: VLAN 200STI 2: VLAN 200
STI 1 root
Forwarding
X
X
X
X
X
X
STI 2 root
vlan 100 bridge-priority 4096
vlan 100 bridge-priority 4096
vlan 100 bridge-priority 409
6
Blocking