Hello,
though agreeing with the previous post I still would like to add some info:
Multi-VRF aka VRF-lite will require a WAN encapsulation allowing subinterfaces like frame relay.
VRF lite will allow you to implement separate control planes i.e. routing tables and routing contexts. You still will need data plane separation of the traffic. In a MPLS environment data plane separation will be achieved through the VPN label. With VRF lite you need a separate FR PVC (or VLAN or ...) for global routing table and each VRF between your PE routers.
In case you can not use FR or dot1Q then your choice will be MPLS.
From a scalability point of view subinterfaces are posing more operational overhead than MPLS, which does not require WAN reconfiguration for each additional VRF.
Also QoS wise MPLS seems more simple than different FR PVCs or VLANs, as there will be one policy on the WAN link instead of a sparate policy for each PVC.
Finally overlapping VPNs and central service VPNs or the like will be much simpler with MPLS in place.
As already mentioned with the requirements given each solution will be solving your issues.
Hope this helps!
Regards, Martin
