The SPF Network Model Based On PLAN Network

Because of contraposing to serials of problems in the development of network (viz., the difficulty of importing new technologies and standards into current network, the decline of network performance because of redundancy operations by few net protocol layers, the difficulty of joinning new services in existing structure modules), the concept of AN(Active Networks) is presented by DARPA(Defense Advanced Research Projects Agency) in 1995.AN is compared to current network. Current network be named as Passive Networks because they don't compute or disposal message. Although the routers and the switchs can change the header of message in current network, they do nothing about the actual user data, and their tenet is transmiting user data without change. Even if changing the header of message and other route operation is independent of user disposal and applications which made these message. Compare to this, the routers and the switchs in AN can compute network message according to users' demands.PLAN(Programming Language for Active Network) implement the characters of AN via idea of integration. Program is integrated in each data packet, then be send to network. Every message or packet have a piece of program code, which explain whether it can embed data or not. Active node will explain these program, and send out data in program when the packet arrived.Current PLAN network use SLRP (SLRP-Service Level Routing Protocol) route protocol as its default route service. This protocol is a dynamic route protocol based on hops counting. Its arithmetic just based on hops counting is low efficiency and unilateralism when the network have complex link state.We presented an AN model in this article. It based on the current structure of PLAN network, which use cost to instead of the hops to compute network path length and realize the route rule of Shortest Path First (SPF). This model make full use of the programmable feature of AN, dynamicly install the route protocol as a service without reworking bottom protocol of network, and implement the route rule of the SPF by PLAN active packet.The model is written by Java and Pizza program language. It was installed and debugged by PLAN language, and analyzed and tested by Ping and Traceroute program which are common network utilities.