Implementation Research Of MPLS L2VPN Service In PTN System

Traditional VPN technology has met the needs of many large enterprises for setting up an enterprise private network in some extent.However,the VPN technology which is based on ATM or Frame Relay is overwhelming dependent on special transmission medium,its deployment is very complex and the cost of network construction is very high.These reasons cause it can't meet the requirements of the enterprise for the flexibility,scalability and economy of the network.Therefore,the MPLS VPN based on the MPLS technology is gradually gaining popularity.Among them,MPLS L2 VPN technology has become the new highlight of VPN technology due to its simple network topology,strong scalability and relatively low operation cost.Along with the trend that the mobile network is gradually developing into the Packet Transport Network,major equipment providers are beginning to compete with each other to research and produce the PTN equipments which can transmit MPLS L2 VPN service.Therefore,this thesis selected the implementation of MPLS L2 VPN service on PTN equipment as the research topic,designed a forwarding model that can support MPLS L2 VPN service at the forwarding level of a centralized PTN equipment.The whole thesis focused on how to complete the transparent transmission of user data,and the MPLS label processing,such as addition,deletion and substitution.The major contents can be summarized as the following:(1)This thesis described the frame structure and software architecture of a PTN equipment,and introduced the functions would be implemented when the two basic types of MPLS L2 VPN services are forwarded on this equipment.(2)A forwarding model of MPLS L2 VPN service is designed.Based on the functions,the model is divided into several modules such as L2 VPN creation,data accessing and forwarding,and MPLS label processing.The thesis described the composition of each module,and their respective functions,and introduced the function interfaces designed for creating each part and the detailed encoding process.At the same time,the interfaces of the related functions such as the MAC address learning,linear 1: 1 protection,also were introduced.(3)The actual network topologies of two basic types of MPLS L2 VPN services were simulated,and the overall test scheme is designed in this thesis.The verification results show that the PTN equipment which used this forwarding model is able to process the user datagram on layer 2,and can complete the MPLS label processing correspond to the label forwarding process,also,it can complete the protection of MPLS L2 VPN services via the linear protection technologies such as LSP1: 1 and PW1: 1.The software implementation of the MPLS L2 VPN service forwarding model designed in this thesis is completed by the C language based on the Linux operating system.The experimental results show that,the PTN equipment which used this forwarding model can meet the industry requirements which are proposed by metropolitan area network for this type of equipment when carrying MPLS L2 VPN services.