Research And Implementation Of MPLS Pseudowire Fault Detection And Recovery Technology Based On VCCV

Pseudo-Wire Emulation Edge-to-Edge(PWE3) is a solution which is provided for the convergence of traditional communication network and existing Packet Switched Network(PSN).so as to achieve the sharing of resources and extension of networks. PWE3 is intended to provide only the minimum necessary functionality to emulate the service with the required degree of faithfulness for the given service definition.With the deployment of PWE3, the need for the correspondent OAM mechanism is intensifying day by day. In order to enhance the operability and maintainability of PWE3, the PWE3 Working Group of Internet Engineering Task Force defined the protocol of Virtual Circuit Connectivity Verification (VCCV). VCCV is an exclusive OAM mechanism of PWE3. A control channel can be established between the endpoints of the pseudowire by VCCV, and then it transmits OAM messages between the two Provider Edge routers through that control channel.Therefore, the end-to-end fault detection could be achieved along the pseudowire's forwarding path.Service Provider(SP) should guarantee high reliability for the pseudowire service. The Bidirectional Forwarding Detection(BFD) connectivity verification message type of VCCV provides a fast and continuous fault detection mechanism for pseudowire,the combination of this mechanism and pseudowire redundancy network organization can achieve Protection Switching for pseudowire at milliseconds level, so that the reliability of pseudowire service could be effectively guaranteed.Due to the fact that Multi-Protocol Label Switching(MPLS) network is the priority PSN type chosen by the SP when implementing PWE3, so this paper mainly focused on the fault detection and redundancy protection technology for dynamic MPLS single segment pseudowire based on VCCV. Firstly, the four components of VCCV were taken as the unit to research and analyse the technical principles of VCCV profoundly. After that, the VCCV module has been designed and implemented based on existing MPLS, LDP, MPLS OAM and BFD modules, it provides a simple and efficient pseudowire fault detection tool for network managers.Redundancy protection technology for dynamic MPLS single segment pseudowire based on VCCV is another research emphases of this paper. After detailed analysis about two solutions of pseudowire redundancy network organization, the pseudowire redundancy protection module has been designed and implemented based on aforementioned VCCV module. This module sets up pseudowire redundancy protection group beforehand on the main processing unit, conducts fault detection for pseudowire with distributed BFD VCCV on line processing unit, and conducts OAM mapping among the pseudowire and Attachment Circuits. Further, according to the pseudowire connectivity status reported by BFD VCCV. the module will conduct protection switching for pseudowire. After been tested in a real experimental network, the fault detection and recovery time of this solution reached the millisecond level, which is able to meet the requirement of practical application.