Network/service survivability is increasingly becoming important to customers, as well as telecommunication service providers and network operators. So survivability is an important problem demanding prompt solution in design and planning of new telecommunications networks (e.g., SDH networks and ATM networks). In the past a few years, different restoration mechanisms for SDH and ATM networks have been developed [5-14]. The previous literature comparing and evaluating the res toration mechanisms only uses a simple method. In order to overcome the shortcomings in the traditional method, this paper proposed the customer-oriented and network engineer-oriented definitions of restoration mechanism availability. In the second definition, the extra spare capacity requirement in the network is taken into account in the availability analysis. Because an exact measurement of the availability is in-feasible due to the large number of failure states in the network, an ORDER algorithm[16] to get a reasonable subset to approximately measure the availability is recommended. Then, applications of the definitions are given. One application is how this definition is used by network planner/engineer to construct a cost-effective survivable network. Another application is that a new group of parameters- survivability quality of service (SQoS) is defined and added to CAC (Connection Admission Control) of ATM survivable network. Finally, the simulation using two definitions has done. The simulation results prove that two availability's can evaluate restoration mechanisms more sufficient and more meaningful.
展开▼
