HARP: a hybrid random access and reservation protocol for WDM passive star networks

A hybrid random access and reservation protocol (HARP) for WDM passive star networks is introduced. According to the HARP protocol, all the ready stations transmit their packets in a slotted ALOHA-like fashion. An array of acoustooptic tunable filters which is placed at the network hub, allows at most one packet per wavelength to pass to the star coupler. In this way, collisions are eliminated. All the blocked packet transmissions are used as reservations for future transmissions. Thus, HARP is a hybrid protocol which stands between random access and reservation protocols and combines the advantages of both families of protocols. Analytical and simulation results are presented which indicate that a WDM passive star network operating under the HARP protocol achieves a high performance under any load conditions.