Application of Modified Predicate Transition Nets to Modeling and Simulation of Communication Protocols

The use of modified predicate transition nets for the modeling of computer communication protocols is investigated in this paper. The lower three layers of the OS! architecture are of primary concern. On the Network Layer (Layer 3), fragmentation and reassembly, routing, store and forward buffering and congestion control mechanisms are treared. The Data-Link Layer (Layer 2) leads to window-flow control, time-out retransmission and transmission error recovery models. These mechanisms may repeatedly dealt with in the different layers of the computer communication architecture. Non-prime transitions can be embedded into the modified predicate transition ners hence a top-down modeling is possible. The present paper uses a hierarchical modeling approach to describe complex communication mechanisms in tenns of simpler constructs. Models developed using the modified predicate transition nelS can be automatically translated into simulation programs. The paper presents the translation of a computer communication model into a program, using a process oriented simulation language, ASPOL.