Routing multicast sessions with differentiated reliability requirement in WDM mesh networks

The concept of differentiated reliability (DiR) has been introduced in the literature to provide multiple levels of reliability in optical networks employing wavelength-division multiplexing (WDM) technology. In this paper, we study the problem of routing multicast sessions with DiR requirements in WDM mesh networks under dynamic network environment, where it is assumed that multicast sessions arrive dynamically one at a time and a decision as to accept or reject a multicast session has to be made without a prior knowledge of future arrivals. Given the current network state, the objective is to minimize the cost for routing each dynamic arrival. We propose three efficient heuristics, namely segment-based bottom-up protection algorithm (SBP), segment-based top-down protection algorithm (STP), and sub-path protection algorithm (SPP). The basic idea of the three algorithms is to first derive a primary light-tree and then to protect a part or the whole light-tree, according to the DiR requirement. For the purpose of comparison, we also present an integer-linear-programming (ILP) formulation, with which one can obtain optimal solutions. Numerical results from extensive simulations show that the heuristics achieve comparable solutions to the ILP approach and that the SPP algorithm outperforms the other two heuristics.