QoS-VNS-CS: QoS constraints core selection algorithm based on variable neighborhood search algorithm

Within the development of network multimedia technology, more and more real-time multimedia applications arrive with the need to transmit information using multicast communication. Multicast IP routing is an important topic, covering both theoretical and practical interest in different networks layers. In network layer, there are several multicast routing protocols using multicast routing trees different in the literature. However PIM-SM and CBT protocols remain the most used multicast routing protocols; they propose to use a shared Core-based Tree CBT. This kind of tree provides efficient management of multicast path in changing group memberships, scalability and performance. The main problem concerning the construction of a shared tree is to determine the best position of the core. QoS-CS's problem (QoS constraints core Selection) consists in choosing an optimal multicast router in the network as core of the Shared multicast Tree (CBT), within specified associated QoS constraints. The choice of this specific router, called RP in PIM-SM protocol and core in CBT protocol, affects the structure of multicast routing tree, and therefore influences performances of both multicast session and routing scheme. QoS-CS is an NP complete problem which needs to be solved through a heuristic algorithm: in this paper, we propose a new core Selection algorithm based on Variable Neighborhood Search algorithm and a new CMP fitness function. Simulation results show that good performance is achieved in multicast cost, end-to-end delay, tree construction delay and others metrics.