802.1q Tunneling/dot1q tunnel - ?

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Jul 11th, 2008
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What is the most common implementation with SP's regarding this?

Do SP's commonly use dot1q tunnel + l2pt on the ce intf and q-in-q on the intf to other PE's?

It would be nice to know the practical implementation.


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francisco_1 Fri, 07/11/2008 - 08:05
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to extending vlans beyond WAN boundaries. allow SP to preserve 802.1Q VLAN tags across a WAN service. by doing so, VLANs actually span multiple geographically dispersed sites.

swaroop.potdar Fri, 07/11/2008 - 08:29
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Typically Dot1Q tunnelling is used in Metro-E Core based setups where the chances of vlan overlaps between customers and SP's is high.

In a MPLS based Core, this might be done when the customer has a requirement to transport multiple vlans, and the SP would like to preserve his vlan space or use a single VC to transport it to the other end.

In both above cases function of the feature is the same, but the necessity is different or extended.

Dot1Q Tunn and QinQ are the same.



francisco_1 Fri, 07/11/2008 - 08:29
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vlan5 (client vlan) Vlan6 (SP Vlan) Vlan5 (Client vlan)

so for the customer vlan 5 to traverse the WAN and still preserve it original 802.1Q vlan tag, the SP will encapsulate the client vlan 5 with additional 802.1Q-in-Q header and forward it across the WAN to ClientSW2 and will then remove the 802.1Q-in-Q header leaving the original 802.1Q header for vlan 5.

hope it make sense.


amin.amor Tue, 07/15/2008 - 03:42
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Dear all,

I would like to compare Q-in-Q with the others alternatives:





all provides L2 solutions, to extend the customer LAN to the WAN.

When? and Why?



santos.alberto Tue, 07/15/2008 - 05:25
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I've seen a combination of QinQ and MPLS, QinQ as a access metro network and with a VPLS on the core, also it is the ISP topology recommened by Cisco.

look for VPLS and you will this example




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