Suppressing VLAN information on a trunk port

Unanswered Question
Feb 1st, 2008

Can the VLAN information be suppressed on a trunk port on a Catalyst 6513?

I have this problem too.
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Jon Marshall Fri, 02/01/2008 - 08:51


What exactly do you mean by suppressed. You can

1) clear a vlan off a trunk link in which case no traffic for that vlan will traverse the trunk

2) Use VTP pruning which stops most traffic for a vlan going across the trunk if there are no ports in that vlan at the other end but STP will still run across the trunk for that vlan.



cfolkerts Fri, 02/01/2008 - 09:00

Or you can do manual suppression of vlans on the interface with the command below.

switchport trunk allowed vlan


JJeremic Fri, 02/01/2008 - 09:03

Hi Jon,

Thanks for the promp response.

Here is what I mean:

I have to connect my customer's 3750 switch, over a trunk port, to my 6513 switch, on which I have othe VLANs, I don't want the customer to see my other VLANs on his swich, only the one that he will be using.

He is running his traffic on VLAN xx and I will create the same VLAN on my switch and allow only that VLAN on the trunk. However, this doesn't prevent the VLAN information from getting across the trunk?

Jon Marshall Fri, 02/01/2008 - 09:37


Yes you are correct, unless your switch is set to be VTP transparent it will propogate the vlan information to the customer. You could ask them to use VTP transparent on their switch but you may or may not trust them.

As far as i know there is no way to use VTP transparent on some trunk links and VTP server on others so unless you can set your switch to VTP transparent then you will have to rely on manually only allowing the customer vlan traffic on the trunk.



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