Spanning Tree Loop

mikedelafield · ‎10-01-2007

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?

Thanks.

rico_hao40 · ‎10-01-2007

#show cdp nei

(Quick way shows if you have a loop)

# show spanning-tree vlan x

(check the status of ports, FWD or BLK)

Francois Tallet · ‎10-01-2007

This link is a little bit old, but the information there is still valid:

http://www.cisco.com/warp/public/473/16.html#stp_fail

regards,

Francois

balajitvk · ‎10-01-2007

Hi,

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,

Rgs