Design And Implementation Of The Ospf Protocol Software

The OSPF protocol was developed by the OSPF working group of the Internet Engineering Task Force. It is a dynamic routing protocol based on Link-State. OSPF is classified as an Interior Gateway Protocol (IGP), it only processes the routing information in an Autonomous System. The basic theory of the protocol is as follows: In Autonomous System each running OSPF router will accumulate the information of router's usable interfaces and reachable neighbors, which is called Link-State. The router distributes its local state throughout the Autonomous System by flooding, so each router maintains a same database describing the Autonomous System's topology. and from the topological database, each router constructs a tree of shortest paths with itself as root. This shortest-path tree gives the route to each destination in the Autonomous System. Externally derived routing information appears on the tree as leaves.First of all the basic theory of OSPF, some basic algorithm used by the protocol OSPF and some important packet structure are discussed in this thesis. Because of the Link-State's important role in OSPF, the whole second section is used to introduce the knowledge of Link-State, such as generating, advertising, flooding, updating etc are introduced. The detail of SPF algorithm and the generating of routing table are also mentioned in this section. Then we discuss the architecture of the OSPF routing protocol software and the portion I have done in it, which mainly contain the module of algorithm of SPF. Link-State database and the generation of route table. At last, At last, the software of the OSPF routing protocol is tested, and the conclusions are drawn.