Distributed dynamic QoS-aware routing in WDM optical networks

As the WDM technology matures and the demand for bandwidth increases, dynamic provisioning of lightpaths at the WDM layer becomes an important and challenging problem. Any distributed algorithm for routing dynamic traffic should be simple, efficient, and also scalable. Most of the multimedia and real-time applications require specific quality of service (QoS), hence it is important that the routing algorithm should provide lightpaths which satisfy the required QoS. The QoS also includes fault-tolerance besides guarantees on different metrics such as bandwidth, bit-error-rate, and reliability. In this paper, we propose distributed dynamic routing algorithms for QoS constrained routing and survivable routing, based on preferred link routing approach. For QoS constrained routing, we provide a common framework for routing connections with constraints on different types of metrics such as bandwidth (a concave metric), delay and bit-error-rate (additive metrics, and should be minimum for a best QoS path), and reliability (multiplicative metric, and should be maximum for a best path). The framework considers multiple QoS constrained routing which is an NP-Complete problem. We also propose a distributed routing algorithm for fault-tolerant connections, and describe how dedicated and shared protection can be provided in the case of single link failures. We have conducted simulation experiments with bit-error-rate and reliability as the metrics to evaluate the performance of the proposed multiple constrained QoS routing algorithm. We have also studied the performance of the fault-tolerant routing in terms of call acceptance ratio, cost of the path, hop length, and call setup time, and compared the results with that of an existing approach. Our experimental results suggest that our algorithms out perform the existing methods with respect to the average number of calls accepted.