is this a spanning-tree issue or VTP pruning issue?

Unanswered Question

Hi,

I've run in to a problem i cant figure out. Its a live environment and I must be careful not to make things worse, things are working mostly.... I have a link between 2 switches, trunk - dot1q,  on one end everything looks fine on the opposite end things don't look right.  Things have been working until a couple of weeks ago no changes have been made.

The trunk  is NOT carrying all the Vlans (except Vlan 1), when I check spanning-tree it show s the port forwarding all the Vlans.  This switch is configured as VTP client, v2, prunning enabled and the down stream switch is transparent.

Any suggestions? thanks inadvance.

show trunk 4/1 detail

* - indicates vtp domain mismatch

# - indicates dot1q-all-tagged enabled on the port

$ - indicates non-default dot1q-ethertype value

Port      Mode         Encapsulation  Status        Native vlan

--------  -----------  -------------  ------------  -----------

4/1      nonegotiate  dot1q          trunking      1


Port      Peer-Port  Mode         Encapsulation  Status

--------  ---------  -----------  -------------  ------------

4/1      FastEther  unknown      unknown        unknown


Port      TrunkFramesTx         TrunkFramesRx         WrongEncap

--------  --------------------  --------------------  ----------

4/1                 119731770              63985591           0


Port      Vlans allowed on trunk

--------  ---------------------------------------------------------------------

4/1      1,34,157,166,172,175,178,190,194,504,637,652,804-805,864


Port      Vlans allowed and active in management domain

--------  ---------------------------------------------------------------------

4/1      1,34,157,166,172,175,178,190,194,504,637,652,804-805,864


Port      Vlans in spanning tree forwarding state and not pruned

--------  ---------------------------------------------------------------------

4/1      1

show spantree 4/1

Port                     Vlan Port-State    Cost      Prio Portfast Channel_id

------------------------ ---- ------------- --------- ---- -------- ----------

4/1                     1    forwarding           19   32 disabled 0

4/1                     34   forwarding           19   32 disabled 0

4/1                     157  forwarding           19   32 disabled 0

4/1                     166  forwarding           19   32 disabled 0

4/1                     172  forwarding           19   32 disabled 0

4/1                     175  forwarding           19   32 disabled 0

4/1                     178  forwarding           19   32 disabled 0

4/1                     190  forwarding           19   32 disabled 0

4/1                     194  forwarding           19   32 disabled 0

4/1                     504  forwarding           19   32 disabled 0

4/1                     637  forwarding           19   32 disabled 0

4/1                     652  forwarding           19   32 disabled 0

4/1                     804  forwarding           19   32 disabled 0

4/1                     805  forwarding           19   32 disabled 0

4/1                     864  forwarding           19   32 disabled 0

I have this problem too.
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This is the down stream switch, where everything looks fine. - Version 12.1(22)EA12, 2950

interface FastEthernet0/26

switchport trunk allowed vlan 1,34,157,166,172,175,178,190,194,504,637,652,804

switchport trunk allowed vlan add 805,864

switchport mode trunk

switchport nonegotiate

end

This is a 6509 with cat OS, Version NmpSW: 8.4(2a)
set trunk 4/1  nonegotiate dot1q 1,34,157,166,172,175,178,190,194,504,637,652,804-805,864
clear trunk 4/1  2-33,35-156,158-165,167-171,173-174,176-177,179-189,191-193,195-503,505-636,638-651,653-803,806-863,865-4094
If there is anything else please do not hesitate.
Regards.
Chetan Kumar Ress Thu, 07/08/2010 - 11:28

Hi Sean

I think that you had post the output of 6509 ( in intial post ) .

Can you try to configure your 2950 with encap dot1q ( switch port trunk encap dot1q ).

Note : Default it will use Dot1q but before configuring please check the output of 2950 with sh int fa0/26 trunk )

You supposed to see the encap dot1q .

Brelow output :

Port      Mode         Encapsulation  Status        Native vlan
fa0/20       on           802.1q         trunking      10

and also please check the log in 2950 switch.

Regards

Chetan Kumar

Sorry I should have posted this at the begining:

show int fa0/26 trunk

Port        Mode         Encapsulation  Status        Native vlan

Fa0/26      on           802.1q         trunking      1

Port      Vlans allowed on trunk

Fa0/26      1,34,157,166,172,175,178,190,194,504,637,652,804-805,864

Port        Vlans allowed and active in management domain

Fa0/26      1,34,157,166,172,175,178,190,194,504,637,652,804-805,864

Port        Vlans in spanning tree forwarding state and not pruned

Fa0/26      1,34,157,166,172,175,178,190,194,504,637,652,804-805,864

show spanning-tree int fa0/26

Vlan             Role Sts Cost      Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

VLAN0001         Root FWD 19        128.26   P2p

VLAN0034         Root FWD 19        128.26   P2p

VLAN0157         Root FWD 19        128.26   P2p

VLAN0166         Root FWD 19        128.26   P2p

VLAN0172         Root FWD 19        128.26   P2p

VLAN0175         Desg FWD 19        128.26   P2p

VLAN0178         Root FWD 19        128.26   P2p

VLAN0190         Root FWD 19        128.26   P2p

VLAN0194         Desg FWD 19        128.26   P2p

VLAN0504         Root FWD 19        128.26   P2p

VLAN0637         Root FWD 19        128.26   P2p

VLAN0652         Root FWD 19        128.26   P2p

VLAN0804         Root FWD 19        128.26   P2p

VLAN0805         Root FWD 19        128.26   P2p

VLAN0864         Desg FWD 19        128.26   P2p

As you can see the 2950 seems ready to go, it just seems that the 6509 is not forwarding the vlans!
I'm suspecting vtp pruning on the 6509, and the 2950 is transparent.
show vtp domain
Version      : running VTP2 (VTP3 capable)
Domain Name  : XXXXXX                           Password  : configured
Notifications: disabled                         Updater ID: ###.###.###.###
Feature        Mode           Revision
-------------- -------------- -----------
VLAN           Client         XXX
Pruning             : enabled
VLANs prune eligible: 2-1000
Chetan Kumar Ress Thu, 07/08/2010 - 12:04

Hi

I'm suspecting vtp pruning on the 6509, and the 2950 is transparent

===> As you mention 2950 is transparent but in output is it showing VTP Client.

Can you explain ?

Regrads

Chetan Kumar

Sorry my bad. I wasn't clear - 6509 is client and 2950 is transparent -

2950

show vtp status

VTP Version                     : 2

Configuration Revision          : 0

Maximum VLANs supported locally : 250

Number of existing VLANs        : 19

VTP Operating Mode              : Transparent

VTP Domain Name                 : XXXXX

VTP Pruning Mode                : Enabled

VTP V2 Mode                     : Enabled

VTP Traps Generation            : Disabled

MD5 digest                      : XXXXXXXXXXXXXXXXXXXXXXXXXXXX

Configuration last modified by ###.###.###.### at 6-21-10 18:29:17

ResTow>

6509

show vtp domain

Version      : running VTP2 (VTP3 capable)

Domain Name  : XXXXX                           Password  : configured

Notifications: disabled                         Updater ID: ###.###.###.###

Feature        Mode           Revision

-------------- -------------- -----------

VLAN           Client         146

Pruning             : enabled

VLANs prune eligible: 2-1000

That makes it a bit clearer - sorry

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