Chapter 18
| Spanning Tree Commands
– 448 –
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, then the port will only
be returned to the forwarding state if one of the following conditions is
satisfied:
■
The port receives any other BPDU except for it’s own, or;
■
The port’s link status changes to link down and then link up again, or;
■
The port ceases to receive it’s own BPDUs in a forward delay interval.
◆
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)#
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