Representation of data communication processes

Due to the complexities of data communication systems, there arises a need for suitable methods of representation which may be used for analysis and in aiding the understanding of particular procedures used to ensure proper functioning of the system. This paper is concerned with four methods of representation of a data transfer protocol operating over a packet switching network. A narrative description, PASCAL programs, Processing State Transition Diagrams (PSTDs) and Numerical Petri Nets (NPNs) comprise the four methods. Attention is drawn to the value of PSTDs and NPNs as pictorial and graphical representations and a brief comparison of the methods is presented.