R. Leela and S. Selvakumar




Novel routing paradigms, based on policies and quality of service (QoS) requirements, have been proposed for the Internet over the last decade. Constraint-based path selection algorithm is of utmost importance in the field of QoS routing. An Internet service provider wants to find paths for QoS flows that optimize the network resources and satisfy the user requirements. But, unfortunately the problem of finding a path with multiple constraints such as delay, jitter, bandwidth, and packet loss is a Nondeterministic polynomial (NP)-complete problem. Hence, various heuristics have been proposed to find a path that satisfies more than one constraint. All these heuristics find feasible path using link-state information, which are considered to be static throughout. These heuristics do not consider the dynamic parameter such as the queuing situation at a given node. Hence, in this paper, a heuristic called dynamic multi constraint multi path routing algorithm (DMCMPRA), which incorporates a better cost model using dynamic variables (viz., buffer occupancy at a node to estimate the link cost) to compute the best path for the QoS flow and to balance the load among alternate feasible paths to the destination, is proposed. DMCMPRA uses the self-adaptive multi-constrained routing algorithm (SAMCRA) to find the k QoS aware paths. Then the link-disjoint multiple constraints routing algorithm (DIMCRA) is used to find all the n link disjoint paths among these k paths. The proposed new cost model is used to select the best path from the n link disjoint paths. On congestion notification, load balancing is achieved by selecting an alternate feasible path from the n − 1 link disjoint path using the same cost model. Computer simulations show that the performance of DMCMPRA is better than SAMCRA in terms of the metrics such as percentage of successfully received packets, average delay, etc.

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