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We describe the WDM request/allocation protocol (WRAP), a media-access control protocol for wavelength-routed passive optical networks (WR-PONs) in which each node has a single fixed optical receiver and a single tunable optical transmitter. The protocol does not require a carrier sensing capability, a separate control channel, or any centralized control or scheduling. Access to transmission channels is regulated by allocations made at destination nodes in response to requests made by source nodes. Computer simulation is used to investigate three different allocation algorithms, one of which-the preferential/random algorithm-is shown to provide significantly better performance than the alternatives. Simulations are presented comparing the performance of WRAP to two previously proposed applicable protocols-the interleaved time division multiple access (I-TDMA) protocol, and the FatMAC protocol. WRAP is shown to provide fair and flexible access to the transmission capacity, enabling high network utilization to be achieved under a wide range of traffic conditions, while providing a guaranteed minimum bandwidth between each source-destination pair. We conclude that of the three protocols considered here, WRAP is the best-suited to general-purpose data communications applications such as local, campus, and metropolitan area networks.