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Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
OL-10101-02
Chapter 14 Configuring MSTP
Displaying the MST Configuration and Status
To return the switch to its default setting, use the no spanning-tree link-type interface configuration
command.
Restarting the Protocol Migration Process
A switch running MSTP supports a built-in protocol migration mechanism that enables it to interoperate
with legacy IEEE 802.1D switches. If this switch receives a legacy IEEE 802.1D configuration BPDU
(a BPDU with the protocol version set to 0), it sends only IEEE 802.1D BPDUs on that port. An MSTP
switch can also detect that a port is at the boundary of a region when it receives a legacy BPDU, an MST
BPDU (version 3) associated with a different region, or an RST BPDU (version 2).
However, the switch does not automatically revert to the MSTP mode if it no longer receives IEEE
802.1D BPDUs because it cannot determine whether the legacy switch has been removed from the link
unless the legacy switch is the designated switch. A switch also might continue to assign a boundary role
to a port when the switch to which it is connected has joined the region.
To restart the protocol migration process (force the renegotiation with neighboring switches) on the
switch, use the clear spanning-tree detected-protocols privileged EXEC command.
To restart the protocol migration process on a specific interface, use the clear spanning-tree
detected-protocols interface interface-id privileged EXEC command.
Displaying the MST Configuration and Status
To display the spanning-tree status, use one or more of the privileged EXEC commands in Table 14-4:
For information about other keywords for the show spanning-tree privileged EXEC command, see the
command reference for this release.
Step 5
show spanning-tree mst interface interface-id Verify your entries.
Step 6
copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose
Ta b l e 14-4 Commands for Displaying MST Status
Command Purpose
show spanning-tree mst configuration Displays the MST region configuration.
show spanning-tree mst instance-id Displays MST information for the specified instance.
show spanning-tree mst interface interface-id Displays MST information for the specified interface. Valid interfaces
include physical ports, VLANs, and port channels. Valid VLAN IDs are 1
to 4094. The valid port-channel range is 1 to 6.