MPLS Handling of Aggregated ADSL-connected sites

Question

I'm familiar with serially-connected sites entering an MPLS core, where there is a physical connection associated with each site, and so the site is simply identifiable to the MPLS PE by virtue of a physical port. However, I'm trying to get my head round how to handle ADSL connections, where many sites' traffic is aggregated into one bearer. How does the MPLS network associate the right traffic with the right site under these conditions? Sorry if this is a bit of a "dumb newbie" question, but I've googled extensively, and just haven't got to the stage where I feel confident in my understanding.
Jim

Answer 1

Hi Jim,
When using DSL most architectures use PPPoA/PPPoE (you could just bridge at the dslam and use no PPP but that would result in a subinterface a VRF could be configured on).
PPP will create a virtual-access interface per PPP authentication (username).
When the virtual interface is being created the provider router (LNS) will ask a radius server if the user can be granted access. If yes, the radius can also give the router configuration information which can include IP address and VRF.
Ultimately the traffic is kept separate because point to point logical sessions can be built on top of a multi access network (PPPoE).
Hope this helps,
Matt Ayre