Spanning Tree Loop

Unanswered Question
Oct 1st, 2007

What are the most obvious show commands, statistics and parameters to verify and check when you suspect you have a Spanning Tree Loop problem?

Are there any obvious pointers and what are the most common causes and solutions?


I have this problem too.
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rico_hao40 Mon, 10/01/2007 - 08:06

#show cdp nei

(Quick way shows if you have a loop)

# show spanning-tree vlan x

(check the status of ports, FWD or BLK)

balajitvk Mon, 10/01/2007 - 09:32


Usually you can see any switch port/vlan got blocked using,

show spanning-tree blockedports

If the show interface command is showing error-disabled, See whether it is due the BpduGuard,

spanning-tree bpduguard interface configuration command on the switch to put an interface in the error-disabled state when it receives a bridge protocol data unit (BPDU).

Rate if it does,



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