MPLS Virtual Private Networks
Historically, private WANs were provisioned using dedicated leased line connections, each line providing a point-to-point connection between two customer sites.  Such networks are expensive to put in place, especially if the connections between sites need to support some level of redundancy.

Migrating to IPVPN
With the emergence of converged IP services, medium-to-large businesses are demanding greater performance from their enterprise networks than ever before. To meet the evolving needs of these five to 50-site companies and their mediarich applications, enterprise networks are challenged to evolve in lockstep with those demands.