C
HAPTER
32
| Spanning Tree Commands
– 812 –
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
â—† 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:
â–
The port receives any other BPDU except for it’s own, or;
â–
The port’s link status changes to link down and then link up again,
or;
â–
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).
â—† Port Loopback Detection will not be active if Spanning Tree is disabled
on the switch.
â—† 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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