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13-13
Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
OL-10101-02
Chapter 13 Configuring STP
Configuring Spanning-Tree Features
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.
Disabling Spanning Tree
Spanning tree is enabled by default on VLAN 1 and on all newly created VLANs up to the spanning-tree
limit specified in the
“Supported Spanning-Tree Instances” section on page 13-9. Disable spanning tree
only if you are sure there are no loops in the network topology.
Caution When spanning tree is disabled and loops are present in the topology, excessive traffic and indefinite
packet duplication can drastically reduce network performance.
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 14, “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 4094. 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 IEEE 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.