Modeling and Simulating Computer Networks Using Formalized Data Flow Diagrams

Formalized Data Flow Diagrams (FDFD\u27s) provide simple and natural abstractions for specifying network behavior. We have augmented FDFD\u27s by providing (i) a notion of asynchronous timing of events, (ii) a convenient mechanism for describing node classes , and (iii) features for specifying network architecture. These extensions will facilitate the modeling of a large computer network (using the langauge NET-SPECS) and the direct generation of a simulator of that network

Modeling and Simulating Computer Networks Using Formalized Data Flow Diagrams

functions are simply parameterized assertions. All the abstract functions that appear in the firing rules will be explained and defined later in this section. Also note that "special symbols" in assertions are written with an ASCII representation to facilitate parsing and type checking. For example, the universal quantifier is written nforall and not 8, and the "and" operator is written /n, and not . The first firing rule listed sends a routing table to each neighbor when a token is present on the inflow from Timer. +T /" +ND: ---= ND' = ND /" "forall (IDType n) [n "elem neighbors(ND) =? OutPacket'n = (i,n,(i,rt(ND)))] The enabling condition requires that a signal be present on the inflow T from Timer and the inflow ND. In fact, every firing rule will contain +ND as part of the enabling condition, as there is always exactly one token on flow ND. The precondition is blank and assumed to be true, indicating that there are no other restrictions on the inflow value, other than those pro..