Spanning Problem with Unknown State

Unanswered Question
May 7th, 2010
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Hi All,

Currently, I am facing some STP issue need to know what is the problem for my STP? Anyone know?...thanks

SW#show spanning-tree vlan 360

  Spanning tree enabled protocol ieee
  Root ID    Priority    32768
             Address     0022.557c.5de8
             Cost        4
             Port        1669 (Port-channel30)
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32768
             Address     00d0.03e0.2d68
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time 300

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Gi9/18           Desg BKN*19        128.1042 P2p *LOOP_Inc
Po30             Root FWD 4         128.1669 P2p
Po31             Desg FWD 4         128.1670 P2p


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jonathanaxford Fri, 05/07/2010 - 06:45
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Hi there,

It looks like the port has put itself in "Loop Inconsistent" state. Are you running the Spanning Tree Loop Guard config on the port?

If so, and you are sure that the interface is functioning as it should be (i.e in full working order) I have heard that disabling and re-enabling Loop Guard on the port can sometimes clear errors...



alexloh83 Fri, 05/07/2010 - 07:39
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Hi Jonathan,

Thanks for your reply.

The port configuration just a normal trunk, no any Loop guard feature enable. But SW001 and SW004 have disabled STP gloablly.

SW001and SW004 only allowed vlan 350 - 359 but SW002 and SW003 only allowed vlan 350 - 360

swithport mode trunk

swithport allowed vlan 350-360

SW001 --> SW002 ---- SW003 <-- SW004


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