Research And Implementation Of Mechanism For Reliable Operation In Central Control Unit Of ACR

Large-scale Access Convergence Router (ACR) is a special network device which acts as a bridge between the backbone network and end users, and it is different from other routers. When failure happens, ACR can not be substituted by other routers for it works not only as a core router for backbone network but also as an end users switch. Therefore, it is very important to keep reliability of ACR. Based on the National 863 specialized research project" Research on system performance and key technologies of large-scale Access Convergence Router (ACR)", this paper mainly focuses on usability of ACR. Based on the two types of network buildup structures of ACR, this thesis presents the mechanism for reliable operation in central control unit of ACR.According to the mechanism, the main work of this dissertation is as follows:1. The design and implementation of main-standby switch mechanism based on NSR is proposed under single-shelf network buildup structures. It can be completed using main and standby main-boards. Through building a stochastic process mode, this paper analyzes the three ways of failure detection how to affect the performance of main-standby switch, and provides theory reference for the design of reliable operation on central control unit of ACR.2. A cooperated working mechanism is proposed to protect central control unit under the multi-shelf intra-connected network structure mode. This paper focuses on two key problems in this mode: the first is that there is a lot of direct-connection routing inside ACR, the second is how to manage the interface equipment without collision. Hash algorithm to keep the route table synchronized is provided, and a scheme is designed to keep the consistency of interface management.3. An improving OSPF graceful restart protocol is designed. In the improving scheme, the original restart mode which needs cooperation among neighbors is improved and simplified, and it can work on main and standby main-board complete independently.4. At the end of this paper, it is the realization of the main-standby switch based on NSR and improved OSPF extended protocol on ACR. Test results indicate that the mechanism of main-standby switch can satisfy the reliability requirement of the ACR.