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Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
OL-8978-04
Chapter 7 Configuring Spanning Tree
Configuring PVST+ on the Switch
Console> (enable)
show config all
.
.
.
set spantree portcost 2/12,2/15 19
set spantree portcost 2/1-2,2/4-11,2/13-14,2/16-48 100
set spantree portcost 2/3 12
set spantree portpri 2/1-48 32
set spantree portvlanpri 2/1 0
set spantree portvlanpri 2/2 0
.
.
.
set spantree portvlanpri 2/48 0
set spantree portvlancost 2/1 cost 99
set spantree portvlancost 2/2 cost 99
set spantree portvlancost 2/3 cost 20000 1-5,12
Disabling the PVST+ Mode on a VLAN
When the switch is in PVST+ mode, you can disable spanning tree on individual VLANs or all VLANs.
When you disable spanning tree on a VLAN, the switch does not participate in spanning tree and any
BPDUs that are received in that VLAN are flooded on all ports.
Caution
We do not recommend disabling spanning tree, even in a topology that is free of physical loops. Spanning
tree serves as a safeguard against misconfigurations and cabling errors. Do not disable spanning tree in
a VLAN without ensuring that there are no physical loops present in the VLAN.
Caution
Do not disable spanning tree on a VLAN unless all switches or routers in the VLAN have spanning tree
disabled. You cannot disable spanning tree on some switches or routers in a VLAN and leave spanning
tree enabled on other switches or routers in the VLAN. If spanning tree remains enabled on the switches
and routers, they will have incomplete information about the physical topology of the network. This
situation may cause unexpected results.
To disable PVST+, perform this task in privileged mode:
This example shows how to disable PVST+ on a VLAN:
Console> (enable)
set spantree disable 4
Spantree 4 disabled.
Console> (enable)
Task
Command
Disable PVST+ mode on a VLAN.
set spantree disable
vlans
[
all
]