Performability, reliability, and survivability of communication networks: system of methods and models for evaluation

This paper presents a system of methods and models for evaluating the performability, reliability, and survivability of a communication network. All proposed models and methods are shown to be interdependent by way of indexes and parameters of the basic network properties. Indexes for these network properties are found for each message-exchanging terminal pair and for the entire network. Steady-state availability, MTBF (mean time between failures), and MTTR (mean time to repair) are computed for reliability analysis of the network with limited repair. Survivability indexes are found for the network exposed to multiple external (adverse) influences that cause a gradual structural degradation of the network. Models are proposed for the performability evaluation of unreliable virtual circuit network X.25/X.75 with routing adapted to network element failures. Some numerical results of comparative analysis of network performability for adaptive and static routings are presented