14-13
Catalyst2950 and Catalyst2955 Switch Software Configuration Guide
78-11380-10
Chapter14 Configuring STP Configuring Spanning-Tree Features
Changing the Spanning-Tree Mode
The switch supports three spanning-tree modes: PVST+, rapid PVST+, o r MSTP. By default, the switch
runs the PVST+ protocol.
Beginning in privileged EXEC mode, follow these steps to change the spanning-tree mode. If y ou 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
Step1 configure terminal Enter global configuration mode.
Step2 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 Chapter15, “Configuring MSTP.”
Select rapid-pvst to enable rapid PVST+.
Step3 interface interface-id (Recommended for rapid-PVST+ mode only) Specify an interfac e t o
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.
Step4 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.
Step5 end Return to privileged EXEC mode.
Step6 clear spanning-tree detected-protocols (Recommended for rapid-PVST+ mode only) If any port on the sw itch
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+.
Step7 show spanning-tree summary
and
show spanning-tree interface
interface-id
Verify your entries.
Step8 copy running-config startup-config (Optional) Save your entries in the configuration file.