A Application Of MPLS VPN In WAN

Multi-Protocol Label Switching (MPLS) is a key enabling technology for next generation networks. It was originally conceived to combine the flexibility of IP hop-by-hop routing with the quality of service and traffic engineering benefits of connection-oriented protocols such as ATM. Today, it has become one of the central elements of next generation networks.MPLS does not replace IP routing, but will work alongside existing and future routing technologies to provide very high speed data forwarding between Label-Switched Routers (LSRs) together with reservation of bandwidth for traffic flows with differing Quality of Service (QoS) requirements. MPLS enhances the services that can be provided by IP networks, offering scope for Traffic Engineering, guaranteed QoS and Virtual Private Networks (VPNs).Virtual Private Networks (VPNs) are a method of interconnecting multiple sites belonging to a customer using a Service Provider (SP) backbone network in place of dedicated leased lines. Each customer site is directly connected to the SP backbone. The SP can offer a VPN service more economically than if dedicated private WANs are built by each individual customer because the SP can share the same backbone network resources (bandwidth, redundant links) between many customers. The customer also gains by outsourcing the complex task of planning, provisioning and managing a geographically distributed network to the SP.Unfortunately, existing VPN solutions are not all interoperable and may be tied to one equipment vendor and/or a single SP. This has created strong interest in IP-based VPNs running over the public Internet using standards-based interoperable implementations that work across multiple SPs.The new Internet technology, MPLS forwards data using labels that are attached to each data packet. Intermediate MPLS nodes do not need to look at the content of the data in each packet. In particular the destination IP addresses in the packets are not examined, which enables MPLS to offer an efficient encapsulation mechanism for private data traffic traversing the SP backbone. MPLS can, therefore, provide an excellent base technology for standards-based VPNs.The development of MPLS and VPN, which including the basicalgorithm of MPLS and VPN, the reason of using MPLS, the traditional model of VPN , etc. are introduced summarily at first. Then, the comparison of IP switching and MPLS switching architecture are given. Third, the technic of VPN based MPLS is investigated with much emphasis. By the end, representative case of DaLian CATV based MPLS VPN is presented, and some other using of MPLS is discussed briefly.