CLI Reference Guide-R07

Chapter 19 | Spanning Tree Commands
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spanning-tree
loopback-detection
release-mode
This command configures the release mode for a port that was placed in the
discarding state because a loopback BPDU was received. Use the no form to restore
the default.
Syntax
spanning-tree loopback-detection release-mode {auto | manual}
no spanning-tree loopback-detection release-mode
auto - Allows a port to automatically be released from the discarding state
when the loopback state ends.
manual - The port can only be released from the discarding state manually.
Default Setting
auto
Command Mode
Interface Configuration (Ethernet, Port Channel)
Command Usage
◆ If the port is configured for automatic loopback release, the port will be
returned to the forwarding state when the interval for the parameter
“spanning-tree loopback-detection action shutdown duration” has expired.
◆ If Port Loopback Detection is not enabled and a port receives it’s own BPDU,
then the port will drop the loopback BPDU according to IEEE Standard 802.1W-
2001 9.3.4 (Note 1).
◆ Port Loopback Detection will not be active if Spanning Tree is disabled on the
switch.
◆ When configured for manual release mode, then a link down / up event will not
release the port from the discarding state. It can only be released using the
spanning-tree loopback-detection release command.
Example
Console(config)#interface ethernet 1/5
Console(config-if)#spanning-tree loopback-detection release-mode manual
Console(config-if)#