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Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
78-11380-10
Chapter 14 Configuring STP
Configuring Spanning-Tree Features
Changing the Spanning-Tree Mode
The switch supports three spanning-tree modes: PVST+, rapid PVST+, or MSTP. By default, the switch
runs the PVST+ protocol.
Beginning in privileged EXEC mode, follow these steps to change the spanning-tree mode. If you want
to enable a mode that is different from the default mode, this procedure is required.
To return to the default setting, use the no spanning-tree mode global configuration command. To return
the port to its default setting, use the no spanning-tree link-type interface configuration command.
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
spanning-tree mode {pvst | mst |
rapid-pvst}
Configure a spanning-tree mode.
• Select pvst to enable PVST+ (the default setting).
• Select mst to enable MSTP (and RSTP). For more configuration
steps, see Chapter 15, “Configuring MSTP.”
• Select rapid-pvst to enable rapid PVST+.
Step 3
interface interface-id (Recommended for rapid-PVST+ mode only) Specify an interface to
configure, and enter interface configuration mode. Valid interfaces
include physical ports, VLANs, and port channels. Valid VLAN IDs are
1 to 1005 when the SI is installed and 1 to 4094 when the EI is installed.
The port-channel range is 1 to 6.
Step 4
spanning-tree link-type point-to-point (Recommended for rapid-PVST+ mode only) Specify that the link type
for this port is point-to-point.
If you connect this port (local port) to a remote port through a
point-to-point link and the local port becomes a designated port, the
switch negotiates with the remote port and rapidly transitions the local
port to the forwarding state.
Step 5
end Return to privileged EXEC mode.
Step 6
clear spanning-tree detected-protocols (Recommended for rapid-PVST+ mode only) If any port on the switch
is connected to a port on a legacy 802.1D switch, restart the protocol
migration process on the entire switch.
This step is optional if the designated switch determines that this switch
is running rapid PVST+.
Step 7
show spanning-tree summary
and
show spanning-tree interface
interface-id
Verify your entries.
Step 8
copy running-config startup-config (Optional) Save your entries in the configuration file.