Grooming of Multicast Sessions in Sparse Splitting WDM Mesh Networks using Virtual Source Based Trees

Cost effective grooming of several sessions with fractional wavelength bandwidth onto a single wavelength has become prominent in WDM networks. We, in this paper, address the problem of routing and wavelength assignment of multicast sessions with subwavelength traffic demands in sparse splitting WDM networks. We assume a sparse splitting node architecture in which only a few nodes in the network are split-capable. A node with splitting capability can forward an incoming message to more than one outgoing link in the optical form. The multicast capability at the non-split nodes can be achieved by converting the optical signal into electronic form and transmitting in optical form onto all the required outgoing links. However, the traffic duplication at the electronic level is more expensive than the optical level in terms of the delay incurred due to the opticalelectronic- optical (O/E/O) conversion. We study the problem of assigning routes and wavelengths to the multicast sessions with the objective of minimizing the resources required for electronic copying. Since the multicast traffic grooming problem is computationally intractable, we adopt a heuristic approach called VSGroom. The performance of the proposed heuristic is studied and compared through extensive simulation experiments.