Split protocol stack network simulations using the dynamic simulation backplane

We introduce and discuss a methodology for heterogeneous simulations of computer networks using the dynamic simulation backplane. This methodology allows for exchanging of protocol information between simulators across layers of the protocol stack. For example, the simulationist may wish to construct a simulation using the rich set of TCP models found in the ns network simulator, and at the same time using the highly detailed wireless MAC models found in the GloMoSim simulator. The backplane provides an interface between heterogeneous simulators which allows these simulators to exchange meaningful information across layers of the protocol stack, without detailed knowledge of internal representation in the foreign simulator. With this method of heterogeneous simulation, new and experimental protocols can be validated and tested in conjunction with existing and accepted simulations of lower protocol layers. We discuss the particular problems presented by the split protocol stack model, and present our solutions. We give results of our implementation of the split protocol backplane, using the ns simulator for the higher protocol stack layers, and the GloMoSim simulator for the lower layers.