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Spanning-tree loopback-detection – SMC Networks SMC Tiger 10/100 SMC6128PL2 User Manual

Page 521

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Spanning Tree Commands

4-213

4

Default Setting

auto

Command Mode

Interface Configuration (Ethernet, Port Channel)

Command Usage

• Specify a point-to-point link if the interface can only be connected to exactly

one other bridge, or a shared link if it can be connected to two or more bridges.

• When automatic detection is selected, the switch derives the link type from the

duplex mode. A full-duplex interface is considered a point-to-point link, while
a half-duplex interface is assumed to be on a shared link.

• RSTP only works on point-to-point links between two bridges. If you designate

a port as a shared link, RSTP is forbidden. Since MSTP is an extension of
RSTP, this same restriction applies.

Example

spanning-tree loopback-detection

This command enables the detection and response to Spanning Tree loopback
BPDU packets on the port. Use the no form to disable this feature.

Syntax

spanning-tree loopback-detection
no spanning-tree loopback-detection

Default Setting

Enabled

Command Mode

Interface Configuration (Ethernet, Port Channel)

Command Usage

• 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

.

Example

Console(config)#interface ethernet 1/5
Console(config-if)#spanning-tree link-type point-to-point

Console(config)#interface ethernet 1/5
Console(config-if)#spanning-tree loopback-detection