Fair uni- and multicasting in a ring metro WDM network

Packet-switched wavelength-division multiplexing (WDM) ring networks have been extensively studied as solutions to the increasing amount of traffic in metropolitan area networks, which is widely expected to be a mix of unicast and multicast traffic. We study the fairness between unicasting and multicasting in slotted packet-switched WDM ring networks that employ a tunable transmitter and fixed tuned receiver at each node and a posteriori buffer selection. We find that single-step longest-queue (LQ) buffer selection generally results in unfairness between unicasting and multicasting or a fixed relative priority for multicast versus unicast traffic. We propose and evaluate dual-step buffer selection policies that achieve fairness and allow for a range of relative priorities of multicast versus unicast traffic.