ON THE IMPACT OF LINK/NODE FAILURES AND NETWORK APPLICATIONS ON THE LOAD AND CALL PROCESSING TIMES IN ATM NETWORKS

The beginning of the 1990s brought new technologies in the telecommunication networks. Asynchronous Transfer Mode (ATM) has been chosen as the transmission technology of broadband networks. The standardisation of ATM is practically finished today, the implementations are ready and the ATM equipment is largely introduced by users and service providers. At the end of the 1990s the Internet Protocol (IP) became the fastest growing network layer protocol that is applicable over any data link layer. The convergence of these two technologies became reality at the beginning of the year 2000, but a couple of months later the telecommunication market entered the deepest recession ever seen. In the current marketplace the service providers must improve network management to reduce operation costs. ATM network service providers offered mainly permanent virtual circuit connections to customers in the last years, but recently there is an increasing interest to offer switched virtual circuit (SVC) connections to end users. The SVC is based on the use of signalling protocols. Our paper focuses on the performance of call processing in ATM networks. Based on a series of measurements on four types of ATM switches we have established some generalised conclusions, which are switch invariant features of the ATM signalling flows. These results have a wide generality among ATM switches and they can be used to model and design large ATM signalling networks. Our new model is validated against the measurement results on the 7-node backbone of the TEN-155 Pan-European ATM network. The second part of the paper shows that a cascaded network is a good estimator for the signalling performance of an arbitrary network. In addition, it is demonstrated that the call density of the network is an important network parameter, which is closely related to the maximum network level call arrival rate. The impact of the link/node failures and network applications on the call establishment times are investigated in this article on a 35-node sample network. The case studies are extended from homogeneous networks to hybrid networks, where many types of switches are present