VLAN 80 not propagating to other swicthes

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Mar 9th, 2004
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Hello all,


I manage a small switch network compose of:


1. 3350-12G as Core and Distribution


2. (6) 2950-48G as access


Each 2950 connect to the core/distribution with Gig fiber. Those ports are in trunk mode with 802.1q


The 3550 is in server and all 2950 are in client mode. VTP v2 is running and pruning was configured.


There are a total of 30 VLAN's. Now the problem is that one vlan (80) is not propagating to other switches located on the 2nd. floor. While troubleshooting this the following appears when entering the sh int trunk command on the 3350:



Port Vlans in spanning tree forwarding state and not pruned

Gi0/2 1,5,10,20,30,40,130,140,160,180

Gi0/3 1,5,50,60

Gi0/4 1,5,15,80,130,150

Gi0/5 1,5,40,50,80,110,160


Gi0/2 port is connected to a 2950G in the 2nd. floor.

Gi0/3 is connected to a 2950 in the 3rd. floor.

Gi0/4 is connected to a 2950 in the 1st. floor.

Gi0/5 is connectef to a 2950 in the data center.


VLAN 80 does not appears in the forwarding state and as pruned.


But using the same command on the 2nd. floor swicth:


Port Vlans in spanning tree forwarding state and not pruned

Gi0/1 1,5,10,15,20,30,40,50,60,70,75,80,100,105,110,120,130,140,150,160,180

Gi0/2 1,5,10,20,30,130,140,180


Vlan 80 appears in the forwarding state on port Gi0/1 which connects to the 3550.


Port Gi0/2 which connects to amother 2950 in the same closet shows Vlan 80 as in not forwarding state.


Let's take a look at the switch connected to Gi0/2 port:


Port Vlans in spanning tree forwarding state and not pruned

Gi0/1 1,5,10,15,20,30,40,50,60,70,75,80,100,105,110,120,130,140,150,160,180

Gi0/2 1,5,10,30,130


Vlan 80 appears in the forwarding state on port Gi0/1 but not on port Gi0/2 which connects to the 3rd. 2950 same closet same floor.


Now on the 3rd. swicth:


Port Vlans in spanning tree forwarding state and not pruned

Gi0/1 1,5,10,15,20,30,40,50,60,70,75,80,100,105,110,120,130,140,150,160,180


Vlan 80 appears in the forwarding state


Now there is one port on the first 2950, second floor that belongs to VLAN 80. That PC cannot browse or connect to the network. I had to move that port to a different one so the person can browse and connects to the network.


Why does Vlan 80 does not appears on the 3550?


And on the 2nd. 2950 located on the 2nd. floor port Gi0/2?

Any ideas?



Regards,


Carlos Roque

Office Of Management And Budget

Commonwealth Of Puerto Rico


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milan.kulik Wed, 03/10/2004 - 00:08
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Hi,

your message is quite complicated, but I'd

1) check if VTP propagates VLAN80 to all switches correctly using

sh vtp status (should show the same VTP revision number)

and sh VLAN (VLAN80 should be present on all switches)

2) clarify which switch is the STP root in VLAN80 using

sh spanning-tree vlan 80

If your 3550 is not the root, change it's STP priority by

spanning-tree vlan 80 root primary

to become an STP root for VLAN80.

3) trace the VLAN80 STP tree per each trunk using

sh interfaces gi 0/x switchport

and sh spanning-tree vlan 80 active det

or sh spanning-tree vlan 80 int gi 0/1

4) it's also possible that VLAN80 is disabled on some trunk, the

sh interfaces gi 0/x switchport

should show this case.


Regards,

Milan


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