[c-nsp] Vlans and catalyst 2950

[Oliver Boehmer (oboehmer)]

Alban,

Did you enable vtp pruning? Can you send a "show trunk x/y" (CatOS) or
"show int xxx trunk" (IOS) on your Cat6k/core switch? It could be that
the 6k incorrectly pruned Vlan41 from the trunk. Workaround: disable vtp
pruning..

	oli
 
Alban Dani <> wrote on Wednesday, February 09, 2005 4:24 PM:

> Hi there,
> 
> we are using VTP. All the new Vlans are created on the 6509 which is
> the core. 
> 
> Here is the output of the show  vlan on the cat2950:
> 
> cat2950#sh vlan id 41
> VLAN Name                             Status    Ports
> ---- -------------------------------- ---------
> ------------------------------- 41   Stevens                       
> active    Fa0/6, Fa0/35, Fa0/46, Gi0/1 VLAN Type  SAID       MTU  
> Parent RingNo BridgeNo Stp  BrdgMode Trans1 Trans2 ---- -----
> ---------- ----- ------ ------ -------- ---- -------- ------ ------
> 41   enet  100041     1500  -      -      -        -    -        0   
> 0 Remote SPAN VLAN ----------------
> Disabled
> Primary Secondary Type              Ports
> 
> cat2950#sh spanning-tree vlan 41
> 
> VLAN0041
>   Spanning tree enabled protocol ieee
>   Root ID    Priority    24617
>              Address     0009.b799.a680
>              Cost        28
>              Port        49 (GigabitEthernet0/1)
>              Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
> 
>   Bridge ID  Priority    32809  (priority 32768 sys-id-ext 41)
>              Address     000b.fd53.9540
>              Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
>              Aging Time 300
> 
> Interface        Role Sts Cost      Prio.Nbr Type
> ---------------- ---- --- --------- --------
> -------------------------------- Fa0/35           Desg FWD 19       
> 128.35   P2p 
> Fa0/46           Desg FWD 19        128.46   P2p
> Gi0/1            Root FWD 4         128.49   P2p
> 
> Port Fa0/35 is trunked and Vlan 41 never makes it up this trunk unless
> as I have explained I put a port on cat2950 on that vlan and get  some
> traffic in it.
> 
> 
> Thanks,
> 
> Alban
> 
> On Wed, 09 Feb 2005 10:58:15 +0200, Adrian Pirciu
> <adrian.pirciu at rdsnet.ro> wrote:
>> Hello
>> 
>> Alban Dani wrote:
>>> Hello Matthew,
>>> 
>>> I also am having a very wierd issue with vlans and 2950-s.
>>> 
>>> We are running pst+.
>>> We have a 6509 in the core and everytime we try to get a new vlan
>>> passed through a chain  of switches( all connected via dot1q trunks)
>>> that has a 2950 in it, it does not work. The only workaround we
>>> found so far is to go to a port on the given 2950 , set the port on
>>> the requried vlan and connect a machine to it and through some
>>> traffic. That makes the 2950 aware of  that vlan.
>> 
>> a 2950 will not pass traffic for the vlans not defined in its table.
>> When you put a port in a vlan, it automatically adds this vlan to the
>> config (sh vlan) and it starts forwarding traffic for that vlan which
>> explains the behaviour you describe.
>> 
>> You can use VTP if you want to have a consistent vlan database
>> accross you network. Be careful though (there are some bat things
>> that can happen, read the documentation from www.cisco.com and they
>> are described). 
>> 
>> 
>>> 
>>> If this was not enough, if the vlan in question does not see traffic
>>> for a couple of days the 2950 totally forgets about it.
>> 
>> I am not aware of anything resembling this behaviour. Anybody ? Does
>> the vlan apper on "sh vlan" when this happens ?
>> 
>>> 
>>> I am wondering if you ever found a solution to your problem and if
>>> so what was it? 
>>> 
>>> I have upgraded to the latest IOS but it did not help.
>> 
>> i'm pretty sure it is not an IOS/switch related problem.
>> 
>>> 
>>> thanks,
>>> 
>>> Alban
>>> _______________________________________________
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>> 
>> --
>> adixor
>> 
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