Distributed queue packet scheduling algorithms for WDM-based networks

Two protocols for scheduling variable-length packet transmissions in an optical passive star network using wavelength division multiplexing (WDM) are specified and analyzed. These protocols require: a separate channel for transmission of control packets, a fixed transmitter and receiver and a tunable transmitter and receiver. The distinction between these protocols and other WDM protocols is that message transmissions are initiated by the receipt of a control message; other schemes schedule packet transmission for some fixed point in the future. This flexibility allows these protocols to avoid “head-of-line” blocking which is a problem encountered in some other protocols. The protocols presented place no constraints on the size of a message, the size of a packet or on the number of available data channels; maintain a distributed queue for each of the output nodes; and guarantee that there are no receiver or data channel collisions. The delay characteristics of these protocols are analyzed and compared to those of the TTAS algorithm