[c-nsp] quick spanning tree question

[Billy Guthrie]

Cord,

You are not providing enough details to help you troubleshoot the issue.With 
the information
you have provided is unfortunately not enough. We can only make assumptions 
at this point.
How many switches are involved in this STP Domain, what is the status of all 
links to the Root
Bridge. Assuming you have you have 3 switches, 2 (sw01/sw02) at the top and 
one (sw03) at the bottom.
The port from the top right switch connecting to sw03 port gi1/46 would have 
to be in
a blocking state as sw03 port 1/46 is desg FWD; however, if the link between 
the top left and
right switch (sw01/sw02) was down(or blocking/Disabled), gi1/46 would be in 
Desg FWD.

Maybe the link between sw01 and sw02 has been disable for some violation, 
port could be in
a STP inconsistent state.


Good luck
Billy

----- Original Message ----- 
From: "Tassos Chatzithomaoglou" <achatz at forthnet.gr>
To: <cisco-nsp at puck.nether.net>
Sent: Saturday, March 27, 2010 3:51 AM
Subject: Re: [c-nsp] quick spanning tree question


> Unless the other side of Gi0/46 is blocked, i don't think it's an issue to 
> see traffic on a designated port.
> On the other hand, if this switch has dual uplinks to the pri/sec root 
> switches, then somewhere else there must be a blocked port.
>
> -- 
> Tassos
>
>
> Cord MacLeod wrote on 27/03/2010 08:47:
>> 3 days ago traffic started showing up on the trunk port connecting my top 
>> of rack switches.  Each of these switches has it's own better trunk path 
>> to the root bridge.  I can't see why any traffic at all would traverse 
>> these links unless the other trunk on g0/45 was down, which it isn't. 
>> Also, spanning tree doesn't claim any topology changes.
>>
>> switch3#sh spanning-tree root port
>> VLAN0001         GigabitEthernet0/45
>> VLAN0100         GigabitEthernet0/45
>> VLAN0101         GigabitEthernet0/45
>> VLAN0102         GigabitEthernet0/45
>> VLAN0120         GigabitEthernet0/45
>> VLAN0200         GigabitEthernet0/45
>> VLAN0231         GigabitEthernet0/45
>> VLAN0250         GigabitEthernet0/45
>> VLAN0321         GigabitEthernet0/45
>> VLAN0450         GigabitEthernet0/45
>> VLAN0777         GigabitEthernet0/45
>> VLAN0888         GigabitEthernet0/45
>> switch3#
>>
>> All vlans read same the Root and Desg port.
>>
>> VLAN0101
>>    Spanning tree enabled protocol ieee
>>    Root ID    Priority    24677
>>               Address     0017.e1d6.e111
>>               Cost        4
>>               Port        45 (GigabitEthernet0/45)
>>               Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
>>
>>    Bridge ID  Priority    32869  (priority 32768 sys-id-ext 101)
>>               Address     001e.1494.4000
>>               Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
>>               Aging Time 300
>>
>> Interface        Role Sts Cost      Prio.Nbr Type
>> ---------------- ---- --- --------- -------- --------------------------------
>> Gi0/45           Root FWD 4         128.45   P2p
>> Gi0/46           Desg FWD 4         128.46   P2p
>>
>> Any ideas?
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