Implementing MPLS over VLAN trunk

Unanswered Question
Jun 25th, 2007

We are investigation the options of running MPLS between our two core switches (C6509 with dual Sup720s) with the aim of introducing MPLS VPNs. These two core switches are linked via a Layer 2 trunk in a collapsed backbone topology.

Is it possible to create a point-to-point MPLS-enabled link between these switches on a VLAN interface between these switches, rather than an a dedicated physical port? It is anticipated that these two core switches will be PE routers (also acting as RRs, if required).

I have this problem too.
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swaroop.potdar Mon, 06/25/2007 - 06:49

Its possible to run MPLS on any media with IP configurable for it. So till you have IP reachbility on a media, you can run MPLS.

As in your case you can very well run MPLS on an SVI reachable both sides over a trunk.

But as a after thought, why do you want to do this, although its possible, why do you want to carry other vlans on the same trunk which also carrier the internconnect vlan for the PE's.



mmelbourne Mon, 06/25/2007 - 07:27

Thanks for that; I did think "mpls ip" on a SVI was possible - well, at least the commands are there in the CLI (though I've been caught out thinking like that before :-)

We have a Data Centre servers' VLAN which needs extending between the two switches, but yes, it should be possible to re-work the core over time to remove VLANs which span the core.

swaroop.potdar Mon, 06/25/2007 - 09:52

Just that as a best practice its good to use PE-PE link only to label switch the traffic, except multicast traffic.

If you have already planned and thought of it its safe and great.



mrcomm2000 Wed, 08/01/2007 - 00:02

but i think y need to adjust the mtu values coz u run mpls over Giga interfaces or vlans


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