Research On Shanghai Metro Ring Network Optimization Based On Cisco REP Shanghai JiaoTong University

The construction of Shanghai metro began twenty years ago. Most of corresponding supporting facilities have also been out of work now.The information network built before can meet the demand of modern information no more, and also face a replacement.In order to solve the practical problems of information network of Shanghai metro.The data packages are forwarding from the core layer,the distribution,the access and the terminal layer.And so the upper layer device cannot be accessed once any link is down in this topology.So the information network of Shanghai metro requires to reach the telecommunication level and also without discontinuity and efficient communications standards.The research is based on the Cisco REP, in order to optimizing the information network of Shanghai metro.This paper introduces the various forms of the communication network links,with analyzing the advantages and disadvantages and also dissect the basic principle of STP and REP. This paper makes analysis deeply of situation of Shanghai metro and expounds actual problems of the information network of Shanghai metro before modification and make a strategic planning of Shanghai metro according to the REP.The advantages of technical principles are points out by the paper. A research on the REP shows that blocking the blocked port is aim to make the link a idle state and unblocking the blocked port to make the link a down state,and that is so called redundancy-backup. The research is focused on the link failure detection, the disorder of the Shanghai metro topology,such as protection switching of single-ring and single link failure,protection switching of single-ring and multi-point link failure, protection switching of multi-ring and multi-point link.Finally, this design makes the link possible to restore within 50 ms,and solves the problems of the information network of Shanghai metro by reaching the telecommunication level standard.At last,the paper shows an application and configuration on the program.The innovations of this paper are:The research is introducing into theconcept of below: the main-ring and sub-ring,main-ring with high priority and sub-ring with low priority. When the link is down, the main-ring link still works by using the sub-ring link. The research is introducing into the concept of the great transfer station. According to the situation of Shanghai metro,two or more lines usually have a transfer station called the great transfer station. So we make the great transfer station a core node that can be a tangent point in double loops.The redundant backup is based on double-ring and double link.