Optimization of multicast light-trees in real-time avionics WDM network

Demands for avionics Wavelength Division Multiplexing (WDM) network have been increasing dramatically in multicasting applications such as the in-flight multimedia in recent years. The topic of multicasting routing problem has been investigated with enthusiasm, because a proper design of routing can not only make full use of the resource, but also improve the performance of networks. However, different from other WDM networks like the backbone WDM network or the WDM LAN, the requirements of reliability and predictability of avionics WDM network are far stricter. In this article, we study light-trees optimization that aim to minimize the cost of the network after giving the general problem definition. In order to expand our work, we first propose the integer linear programming (ILP) algorithms for a simple situation without traffic grooming. Then we consider a more practical situation on the basis of this algorithm. By analyzing three schemes for supporting multicast connections, we select Stop-and-Go (S/G) Light-tree because it can save resource and meanwhile decrease the delay of messages. We also propose an integer linear programming algorithm for this scenario. This algorithm focuses on: 1) the delay constraint, which means sessions need to arrive at destination in limited time; 2) the load constraint to meet the requirement of reliability; 3) sparse splitting constraint, i.e., some switches are incapable of splitting light because of economical reason. The simulation results of WDM network show the algorithm can minimize the cost while ensure the timing requirement.