ABSTRACT
Wide acceptance of security standards in IP and deployment of quality-of-service mechanisms like Differentiated Services and Resource Reservation Protocol within multi-protocol label switching is increasing the feasibility of virtual private networks (VPNs). VPN management tools that allow improved control and views of VPN components and users are now being deployed, resulting in increased scalability and lower ongoing operational costs of VPNs. Service providers have responded by offering VPNs as a service using the differentiating capability of Multi-Protocol Label Switching (MPLS) as a competitive differentiator. Layer 2 MPLS-VPNs, based on the Internet Engineering Task Force’s Martini draft or Kompella draft, simply emulate layer 2 services such as Frame Relay, ATM, or Ethernet. Layer 2 MPLS-VPNs are transparent, from a user perspective, much in the same way the underlying ATM infrastructure is invisible to Frame Relay users. Most metropolitan area networks using MPLS-VPNs provision these ser-vices in layer 2 of the network and offer them over a high-bandwidth pipe.
