Study On The ISPF Algorithm And Its Application In OSPF Protocols

The Open Shortest Path First (OSPF) is the most popular routing protocol in network which is a link state based protocol. However,it has some shortcomings i.e. every time link status changed, the Shortest Path Function (SPF) algorithm used in OSPF will re-calculate all the route no matter whether the node is on the Shortest Path Tree (SPT) or not,The Incremental Shortest Path First (ISPF) only need calculating impacted partial route which can accelerate network convergence rate and reduce calculating time. Thus, the real time performance of network is improved. This thesis presents a comprehensive and deep analysis of OSPF protocol which supporting ISPF.Firstly,this thesis presents the fundamental principles of OSPF, SPF algorithm and the part to be improved. Then ISPF and Partial Route Calculation (PRC) algorithms are studied in detail to improve the disadvantages of traditional OSPF protocols. Two OSPF supporting ISPF are introduced and compared. Finally,the design and testing cases of actual OSPF system supporting ISPF are given which proving the validity of theoretical analysis.