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Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
78-17058-01
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 rapid PVST+ protocol on all NNIs.
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.
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
spanning-tree mode {pvst | mst |
rapid-pvst}
Configure a spanning-tree mode on NNIs on the switch.
• Select pvst to enable PVST+.
• Select mst to enable MSTP (and RSTP). For more configuration
steps, see Chapter 15, “Configuring MSTP.”
• Select rapid-pvst to enable rapid PVST+ (the default setting).
Step 3
interface interface-id (Recommended only for rapid-PVST+ mode) Specify an NNI to
configure, and enter interface configuration mode. Valid interfaces
include physical NNIs, VLANs, and NNI port channels. The VLAN ID
range is 1 to 4094. The port-channel range is 1 to 12.
Note If a physical interface is not an NNI, enter the port-type nni
interface configuration command before attempting to
configure it as a spanning-tree link.
If the interface is a VLAN, only NNIs in the VLAN will run
spanning tree.
If the interface is a port channel, all members of the port channel
must be NNIs.
Step 4
spanning-tree link-type point-to-point (Recommended only for rapid-PVST+ mode) Specify that the link type
for this port is point-to-point.
If you connect this NNI (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 changes the local
port to the forwarding state.
Step 5
end Return to privileged EXEC mode.
Step 6
clear spanning-tree detected-protocols (Recommended only for rapid-PVST+ mode) If any NNI 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 detects 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.