VLAN tags over Pseudowire

Unanswered Question

I have an existing MPLS Pseudowire connection that I need to rework to be able to carry vlan tags instead of just plain L2 frames.

Existing setup:

ME3400 <-> 7206VXR <-> 7206VXR <-> ME3400

The ME3400's customer facing int tags incoming frames, which go over a trunk interface to a 7206VXR subint. The subint is conf'd for pseudowire p2p to the remote 7206VXR which has an identical setup. Subint on a trunk int to a ME3400, cust facing int tied to a matching vlan.

My thought is use QinQ on the switches, with the question being will the 7206s correctly strip off one vlan tag layer, encapsulate the remaining vlan tagged L2 frame for psuedowire, and on the remote end take the pesuedowire packet, decapsulate it, add on the QinQ tag, and shove it back out to the switch? I won't know ahead of time what vlan tags the customer will be looking to pass, so I need to be able to support whatever they try to throw across this link.

I have this problem too.
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Mohamed Sobair Mon, 02/23/2009 - 12:44

Hi,

You can definitely do that, The pseudowire has 2 labels , the outer label represent the (tunnel label), the inner label represent the (Vc label).

The egress 7206Vxr performs lookup at Vc label and forward the frames un labeled to the ME3400.

On the other hand, with QinQ, the customer vlan access port is tunneled across the Service provider Network, this has no affect in your MPLS Forwarding which done at the vxr7206, The outer vlan tag(tagged by the service provider) is stripped out when the frames forwarded firstly unlabeled to the ME3400 at the egress tunnel interface , the inner vlan tag (customer tag) is forwarded untouched (preserved) to the ingress ME3400 interface.

So, from different point,the MPLS provider is transparent for the Customer Vlan traffic even within the MPLS forwarding LSRs, The Only vlan that is binded to the inner label (Vc label) is the service provider access vlan provided to each customer.

HTH

Mohamed

shivlu jain Mon, 02/23/2009 - 22:09

I have implemented the scenario in MPLS domain with ME ring. You can use Q-In-Q per vpn in a ME ring and the same subinterface will be configured on the router. A l2vpn will create from 7200 to 7200 and again the tag will be entitled on the 7200 and from ME SP tag will be removed and customer will able to receive his tag.

regards

shivlu jain

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