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New Member

Dot1q tunnel question

hi guys,

just a qucik question.

i am planning to configure Dot1q tunnel in my network. becoz i need to hide some vlans. my concern is , when we configure Dot1q tunnel . what happens to the cos marking on the original dot1q packet ? are they coppied to the newly imposed tunnel tag ?


Cisco Employee

Re: Dot1q tunnel question

Hi Amit,

No the COS making is not imposed anutomatically to the new tunnel tag. You have to manaully define it on the port.

All packets entering through a tunnel port on an edge switch are treated as untagged packets, whether they are untagged or already tagged with IEEE 802.1Q headers.All the packets will be tagged with a Metro tag VLAn ID. This metro Tag has a priority field which carries the COS value asssinged on the port. If no value is configured it will bydefault take it a COS 0.

Here is the command that you need put on the interface :

l2protocol-tunnel cos value


-amit singh

New Member

Re: Dot1q tunnel question

Hi Amit,

thanks for your quick reply. i was under same impression. i just wanted to confirm that.

The problem is that we have multiple COS valused used in the network. and we have differentiated treatment for different COS vlaues.

now i need to find adifferent way to accomodate my COS requirements.

If i use this command all traffic will be marked with newly configured COS value in the metro tag.

Thanks for ur help.


amit batra.