Disabling The Pvst+ Mode On A Vlan; Using Rapid Pvst - Cisco WS-C2950SX-48-SI Configuration Manual

Using Rapid PVST+

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.
Do not disable spanning tree on a VLAN unless all switches and bridges in the VLAN have spanning
Caution
tree disabled. You cannot disable spanning tree on some switches or bridges in a VLAN and leave it
enabled on other switches or bridges in the VLAN. Doing so can have unexpected results because
switches and bridges with spanning tree enabled will have incomplete information regarding the
physical topology of the network.
We do not recommend disabling spanning tree, even in a topology that is free of physical loops.
Caution
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.
To disable PVST+ mode, perform this task in privileged mode:
Task
Disable PVST+ mode on a VLAN.
This example shows how to disable PVST+ on a VLAN:
Console> (enable) set spantree disable 4
Spantree 4 disabled.
Console> (enable)
Using Rapid PVST+
To configure Rapid PVST+, you need to also configure PVST+ on your switch. You can configure
PVST+ either before or after you enable Rapid PVST+.
To configure Rapid PVST+, perform this task in privileged mode:
Task
Step 1 Enable Rapid PVST+.
Step 2
Set the link type to point-to-point mode for
the port.
Step 3
If any port on the switch is connected to a
port on a PVST+ switch, check for any
legacy bridges on the port.
Step 4
Verify the Rapid PVST+ configuration.
Catalyst 4500 Series, Catalyst 2948G, Catalyst 2980G Switches Software Configuration Guide
7-28
Chapter 7
Command
set spantree disable vlans [all]
Command
set spantree mode rapid-pvst+
set spantree link-type mod/port point-to-point
clear spantree detected-protocols mod/port
show spantree vlan
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Release 8.1
Configuring Spanning Tree
78-15486-01