Efficient routing of sub-wavelength multicast sessions in WDM mesh networks

As the popularity of the new multicast based services like video conferencing and distance learning is gaining significant attention, the network operator's concern to provide such services in an off-line and on-line manner with optimum network resource utilization is increasing rapidly. In recent past, traffic grooming also gained significant importance to handle sub-wavelength level demands in the WDM mesh networks to optimize the network resources. The majority of traffic grooming work addresses issues related to the unicast traffic scenario. We, in this paper, address the problem of routing and wavelength assignment of multicast sessions (MC-RWA) with sub-wavelength traffic demands in the scenario of WDM mesh networks. We deal with two scenarios where the traffic demands are either static or dynamic. Individual nodes need to have the capability of duplicating traffic in order to support multicast traffic grooming. So, we propose a node architecture, which performs the task of traffic duplication in the optical as well as in the electronic domain. This architecture is cost effective as it allows the duplication in optical domain also. The traffic duplication at the electronic level is much more expensive than at the optical level. In static scenario, we study the problem of assigning routes and wavelengths to the multicast sessions so as to minimize the total electronic copying cost at the nodes. We present a non-linear programming (NLP) formulation as an analytical model for the problem. As solving the model for large network is intractable, we propose three heuristic algorithms namely k-SPT, GRS, and GCOT. In dynamic scenario, we study the problem with the objective of reducing the blocking of dynamically arriving requests using the proposed technique called maximizing the minimum freeload (MMFL). We have conducted extensive simulation experiments to demonstrate the effectiveness of the proposed schemes. © 2006 - IOS Press and the authors. All rights reserved.