Noob question about QinQ

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Feb 9th, 2010
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As I understand it QinQ is an asymmetric setup i.e one end of a link is set to a dot1q-tunnel with an (outer) access vlan, and the other end is set to a dot1q trunk.  I think I may have misunderstood our service provider, but is there any circumstance where both ends would be configured as dotq1-tunnel?


TIA

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Giuseppe Larosa Wed, 02/10/2010 - 03:14
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Hello tf2-conky,


the usual scenario is:


L2 CE:L2 trunk ---- L2 PE 802.1Q tunnel -----   L2 ISP clould ----- L2 PE 802.1Q tunnel ---- L2 CE:L2 trunk


on the same link one side is a L2 trunk (Customer side), one side is 802.1Q tunnel.


so if you are a customer you should never need to configure QinQ on your side


Hope to help

Giuseppe

tf2-conky Wed, 02/10/2010 - 18:25
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Will this work if one end is set to QinQ, and the other end is set to an access port?  Will this strip the QinQ tagging, or will we be able to decapsulate the inner Vlan's later on in our network?

huangedmc Wed, 02/10/2010 - 22:00
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Not sure why you'd want to use an access port, since the whole point of QinQ is to be able to preserve all your VLAN tags through the provider cloud.

I don't know if trunk port is a requirement, but in theory the PE would just append a metro tag on packets coming out of your access port.

In the provider cloud, packets would only have one tag instead of two.

You should be able to lab this out w/ four 3560's.

tf2-conky Wed, 02/10/2010 - 22:28
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^^Thanks


As I understand it, a dot1q-tunnel is configured at one end, and a dot1q trunk to break the Vlan's configured out on the other.


For commercial reasons we are using a 'transit provider' to provide backhaul between the service provider and ourselves.  I suspect the transit provider can't break the VLAN's out with a dot1q trunk as they would likely conflict other Vlan's in their transit network.


As is currently setup a cisco compatible QinQ tunnel is set at the service provider edge, and is matched with a QinQ tunnel on what I believe is a Cisco switch on the transit provider edge.  I wasn't sure if this setup was compatible, which would appear to add yet another layer of tagging, hence my previous question on configuring the transit provider edge as an access port.


I'll try and lab it out, but if anyone could further comment on this it would be really appeciated.

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