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joe Bronze

Convert HDLC T-1 to sub-if to configure multi-vrf CE

We are converting a small ISP to MPLS and have a quick question-

We have several sites connected using a basic HDLC T-1 from what is going to be the CE to the PE (all isr's running 12.4)

Over this one link we will have MPLS (with the PE's side being in a vrf), and we would like to continue bringing in internet from the PE's global routing table that we are doing now.

I know you can simply use frame relay with sub-interfaces to do this... only we cant provision frame-relay service to these CE's...

Any ideas how we could segment these HDLC's into 2 sub-interfaces (one with private addressing for the MPLS wan) and one with public ip addressing for the internet circuit.

I've been thinking about gre 2 tunnels between the PE/CE just to make this work, with one TUNNEL being in the PE's VRF for the customer, the other remaining in the global routing table.

Oh, and I know you can just route the internet into the VRF on the PE, but that is not desirable here.



New Member

Re: Convert HDLC T-1 to sub-if to configure multi-vrf CE

I would say you need to use VRF-lite in order to do this efficiently.

All other solutions will require tunnelling which is not efficient.

One possibility is to have a single site that has the routes to the Internet i.e. a central DC site. This would mean that a default route would take all internet bound traffic to the DC whereby it will be routed to an 'Internet' circuit. This is a common method and usually involves a MPLS L2Transport circuit into the DC site which terminates between an Internet router and a CE/Fw. This will require a L2 protocol that can deliver discreet L2 paths i.e. FR or Ethernet VLANs. The advantage is reduced tunnelling but introduces suboptimal/hairpin routing.

An alternative is L2TPv3 from each CE to an Internet CE