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New Member

Excluded VLAN on Trunk

looking  at the picture, If I do the pruning and exclude VLAN 30 from allowed  VLAN list but allow every other vlans on Trunk port (g1) on switch B  because I don’t have any other VLAN 30 members anywhere in my network,  does this affect VLAN 30’s inter-vlan routing and/or internet  connection?

In other word, what does the switch do in terms of tagging frames when

1. receives an inter-vlan frame

2. receives internet frame

pruning.jpg

8 REPLIES
New Member

Excluded VLAN on Trunk

By the way am I following a correct logic ine the following? :

There is not any other VLAN 30 members in my network except these access ports on my switch B. So I would allow every VLANs on its g1 trunk port except VLAN 30 by using the following command:

switchport trunk allowed vlan 10,20,40

New Member

Excluded VLAN on Trunk

Hey Saman,

I believe you are asking about vlan autostate. Take a look at this:

http://www.cisco.com/en/US/products/hw/switches/ps700/products_tech_note09186a0080160b14.shtml

It may answer your question... otherwise please get back to the forum with more information about vlan 30.

Cheers,

Fabio

New Member

Excluded VLAN on Trunk

Hey if you have L2 connectivity either from access or trunk port it should be fine.

Cheers,

Fabio

New Member

Re: Excluded VLAN on Trunk

Just to double-check and make sure my configuration is clear, please take a look at the following picture:

So I won't have any inter-vlan routing or internet connecting problem from SW1 via switches and router behind SW2?

New Member

Re: Excluded VLAN on Trunk

Saman,

From this diagram there is no vlans 20,30, 40, 50 in SW1 therefore no need to allow those vlan in the trunk.

I take that vlan 10 is also on SW2 right?

Make sure that you allow only vlan 10 on the trunk.

Cheers,

Fabio

New Member

Re: Excluded VLAN on Trunk

Fabio,

VLAN 10 does not exist on SW2 or anywhere esle other than SW1 itself, so there is no need to allow it on g1 port on SW1 right? So I excluded VLAN 10 and allowed everything else.

Also since just VLAN 10 exists in "front" of the g2 port and nothing else, the only VLAN that needs to be allowed on trunk port is VLAN 10. So I excluded everything and just allowed VLAN 10.

This was my logic.

New Member

Re: Excluded VLAN on Trunk

Hey Saman,

Trunks are used to carry multiple vlans which isn't the case above.... Why don't you make a port in SW2 a layer 3 port and assign an IP address in the same range as vlan 10? (considering that we are dealing with L3 switches..)

If you can't do that your second option is to create a vlan 10 in SW2 and assign the interface that connects to SW1 to vlan 10.

HTH

Fabio

New Member

Re: Excluded VLAN on Trunk

They are L2 switches. In regards to the second option, actually those VLANs are wireless VLANs created on a WLC, not the wired ones, And what connect to SW1 ports are actually lightweight APs!

Btw seems you are right. There is no need of trunking if there is just one single vlan on SW1. And seems I can configure g1 and g2 as Access Ports and put them in VLAN 100 which is my wired VLAN for connecting APs to the management interface of the WLC.

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