Ever gone to try and terminate a cisco L2TPv3 xconnect on an SVI on  Cisco 6500 and wondered why the hell it wouldn’t come up?  You run the following:

switch# sh mpl l2transport vc

and find that the output is always down no matter what.  Well, cleverly Cisco decided you’re not allowed to do that.  A useful technology introduced to improve things actually ends up making things a little more difficult.  It *is* possible if you have a SIP line card (ES20) for example, but if you’re reading this it’s doubtful you have one of these.

There is a possible workaround to achieve what you’re probably after.  Although you cannot terminate the xconnect on an SVI you can, however, terminate the xconnect on a sub interface and in turn sub interface’s can be placed into a vlan.  It’s not an ideal work around and in some cases it’s probably not very practical – nonetheless it is a sometimes feasible workaround if required.  All that you should need to do is create a sub interface on the upstream facing link with the xconnect configuration and place the sub interface into a dot1q vlan – et voila

Hope this helps people:)

Also  see the follow up article for another workaround: Xconnects on SVIs Part 2

James Greig