[c-nsp] Vlans and catalyst 2950

[Alban Dani]

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
> > _______________________________________________
> > cisco-nsp mailing list  cisco-nsp at puck.nether.net
> > https://puck.nether.net/mailman/listinfo/cisco-nsp
> > archive at http://puck.nether.net/pipermail/cisco-nsp/
> 
> --
> adixor
>