RE: Spanning tree strange behaviou

STP selects just one root bridge per broadcast domain. I think I can
guarantee that these switches do not see each other's BPDUs. Two potential
explanations occur to me:
1. they are not in the same broadcast domain
2. BPDUs are being filtered

If you find some other cause, please let me know.

Best regards,

Bob Sinclair

> -----Original Message-----
> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
> CCIE
> Sent: Sunday, June 13, 2010 10:29 AM
> To: 'groupstudy'
> Subject: Spanning tree strange behaviou
>
> Hi experts,
>
>
>
> I have a strange case in which the two connected switches are working
> as a
> root for the same VLAN??
>
>
>
> SW1#sho spanning-tree vlan 1
>
>
>
> VLAN0001
>
> Spanning tree enabled protocol ieee
>
> Root ID Priority 32769
>
> Address ec30.91b7.b000
>
> This bridge is the root
>
> Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
>
>
>
> Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)
>
> Address ec30.91b7.b000
>
> Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
>
> Aging Time 300
>
>
>
> Interface Role Sts Cost Prio.Nbr Type
>
> ---------------- ---- --- --------- --------
> --------------------------------
>
> Fa0/5 Desg FWD 19 128.6 P2p
>
>
>
>
>
>
>
> SW2#sho spanning-tree vlan 1
>
>
>
> VLAN0001
>
> Spanning tree enabled protocol ieee
>
> Root ID Priority 32769
>
> Address ec30.91f9.7580
>
> This bridge is the root
>
> Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
>
>
>
> Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)
>
> Address ec30.91f9.7580
>
> Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
>
> Aging Time 300
>
>
>
> Interface Role Sts Cost Prio.Nbr Type
>
> ---------------- ---- --- --------- --------
> --------------------------------
>
> Fa0/6 Desg FWD 19 128.7 P2p
>
>
>
> Regards,
>
> Amin
>
>
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Received on Sun Jun 13 2010 - 11:31:50 ART