Restarting the Protocol
An MST bridge can detect that a port is at the boundary of a region when it receives a legacy BPDU or an
MST BPDU that is associated with a different region. However, the STP protocol migration cannot determine
whether the legacy switch, which is a switch that runs only IEEE 802.1D, has been removed from the link
unless the legacy switch is the designated switch. Enter this command to restart the protocol negotiation (force
the renegotiation with neighboring switches) on the entire switch or on specified interfaces.
Procedure
Purpose
Command or Action
Restarts MST on the entire switch or
specified interfaces.
switch#
clear spanning-tree detected-protocol
[
interface interface
[
interface-num
|
port-channel
]]
Step 1
This example shows how to restart MST on the Ethernet interface on slot 2, port 8:
switch#
clear spanning-tree detected-protocol interface ethernet 2/8
Verifying the MST Configuration
Use the following commands to display MST configuration information.
Purpose
Command
Displays the current spanning tree configuration.
show running-config spanning-tree
[
all
]
Displays detailed information for the current MST
configuration.
show spanning-tree mst
[
options
]
This example shows how to display the current MST configuration:
switch#
show spanning-tree mst configuration
% Switch is not in mst mode
Name
[mist-attempt]
Revision
1
Instances configured 2
Instance
Vlans mapped
--------
---------------------------------------------------------------------
0
1-12,14-41,43-4094
1
13,42
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92
Configuring Multiple Spanning Tree
Restarting the Protocol