Restarting The Protocol Migration Process; Displaying The Mst Configuration And Status - Cisco Catalyst 2960 Software Configuration Manual

Chapter 17 Configuring MSTP

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 also can 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 detect 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 17-5 Commands for Displaying MST Status
Command
show spanning-tree mst configuration
show spanning-tree mst configuration digest Displays the MD5 digest included in the current MSTCI.
show spanning-tree mst instance-id
show spanning-tree mst interface interface-id Displays MST information for the specified interface.
For information about other keywords for the show spanning-tree privileged EXEC command, see the
command reference for this release.
OL-26520-01
Purpose
Displays the MST region configuration.
Displays MST information for the specified instance.
Catalyst 2960 and 2960-S Switches Software Configuration Guide, Release 15.0(1)SE
Displaying the MST Configuration and Status
Table 17-5:
17-27