VTP Pruning -

From: Jason Cash (cash2001@swbell.net)
Date: Wed Jun 25 2003 - 19:06:11 GMT-3


i have a question about vtp pruning on 3550s. I have 2 switches:

 

3550-1

F3/5 vlan56

F3/23-24 Port Channeling to 3550-2

 

3550-2

F0/4 vlan4

F0/6 trunking vlan56,76

F0/7 vlan76

F0/8 vlan8

F0/9 vlan9

F0/23-24 Port Channeling to 3550-1

 

VTP pruning is enabled on both switches. 3550-1 has no ports in vlan 4,8,9
but when i do a 'sh vlan' on 3550-1, the vlans are being listed:

 

3550-1>sh vlan

VLAN Name Status Ports

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

1 default active Fa3/6

4 VLAN0004 active

8 VLAN0008 active

9 VLAN0009 active

56 VLAN0056 active Fa3/5

76 VLAN0076 active

1002 fddi-default active

1003 token-ring-default active

1004 fddinet-default active

1005 trnet-default active

 

Also, 'show int trunk' lists those vlans as not pruned:

3550-1#sh int trunk

  

Port Mode Encapsulation Status Native vlan

Po1 desirable n-isl trunking 1

  

Port Vlans allowed on trunk

Po1 1-4094

  

Port Vlans allowed and active in management domain

Po1 1,4,8-9,56,76,1002-1005

  

Port Vlans in spanning tree forwarding state and not pruned

Po1 1,4,8-9,56,76,1002-1005

 

Whereas on 3550-2, those ports are pruned:

3550-2#sh int trunk

 

Port Mode Encapsulation Status Native vlan

Fa0/6 on 802.1q trunking 1

Po1 desirable n-802.1q trunking 1

 

Port Vlans allowed on trunk

Fa0/6 1,56,76,1002-1005

Po1 1-4094

 

Port Vlans allowed and active in management domain

Fa0/6 1,56,76

Po1 1,4,8-9,56,76

 

Port Vlans in spanning tree forwarding state and not pruned

Fa0/6 1,56,76

Po1 1,56

 

Is this normal operation? My understanding of VTP pruning is that traffic
on ports that are prune eligible, would not be transmitted across the trunk
to a switch that has no ports in that vlan.



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