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In guaranteed-type applications the bandwidth planning and cost management are two important issues in deployment of optical core networks. A two-stage fuzzy-based approach is proposed for accommodating long-term demand uncertainties in dense wavelength division multiplexing optical networks. Here, the uncertainties are modelled using the Gaussian fuzzy membership functions. First, the forecasted part of demand matrix is introduced to Dijkstra shortest path-based routing algorithm. Then, the available wavelengths are assigned to demand uncertainties. Unlike existing algorithms, different bandwidth cost factors are assigned to the links of a lightpath according to network and links state information. The performance of proposed approach is evaluated on a typical optical link for uncertain traffic loads in Erlang mode. Simulation results show that the proposed fuzzy-based approach is up to 29% cost-effective for accommodating network demands in real-world applications comparing to existing algorithms. [ABSTRACT FROM AUTHOR]

Study the effects of concurrent voice connections on the performance metrics of communication network such as queue length, waiting time, packets service time and is very important. Mathematical analysis of such network especially with long-tail traffic will help us for a good capacity planning and also lead to an accurate admission control algorithms. In this study a mathematical model of a communication network supporting VoIP and back-ground traffic with long-tail service time is considered. Some problems of previous mathematical models are identified and a new queueing system is proposed in which specifically the coexisting of heavy-tail and voice flows is addressed. The long-tail service time is approximated via hyper-Erlang distribution and also to achieving an accurate performance model a Markov reward model is introduced. The available bandwidth for long-tail distribution varies according to the Markov chain, describing the utilisation factor of voice connection. Numerical results show a comparison between exponential and heavy-tail service time and finally the effects of concurrent voice connections on the service time of heavy-tailed back-ground packets is shown. [ABSTRACT FROM AUTHOR]