Simulation of Signaling System No. 7, Message Transfer. Part 2

The objective of this work is to perform simulation modeling of the Signaling System No. 7 SS7 network with particular emphasis on modeling of the Message Transfer Part Level 2. The basics of common channel signaling using Signaling System No. 7 is initially outlined and discussed with reference to the ITU-T Q.7xx-Series Recommendations. This includes the protocol stack, signaling points, signaling links and typical network structure. In particular, the functionality of the Message Transfer Part, which provides the main mechanism to convey signaling messages, is discussed in detail. Subsequently the modeling of the Message Transfer Part, in particular MTP level 2, using the simulation tool OPNET from MIL3. Inc. is presented. The model uses a multi-layer modular approach, with each layer corresponding to the SS7 layer it is modeling. The functional blocks within each layer are thought of as processes. With their buffers and processors, these processes form a complex interlinked queuing model that is complicated to analyze but is readily simulated. In order to illustrate the use of the simulation model, the basic linkset delay between two signaling points under a heavy traffic load is simulated and compared with analysis based on MG1 queuing models.