5. Conclusion Wavelength Division Multiple Access on a High-speed Optical Fibre

Actual MAC protocols show a lack of performances when dealing with high bit rate networks. On the other hand, WDM multichannel systems will allow for a better use of the huge bandwidth of fiber optic media. In this paper, we introduce a new CSMA/CD protocol for mul-tichannel optical LANs, based on the Ethernet standard. The key issues of this protocol are the network load and the wavelength swapping time. Simulation results show that the number of consecutive collisions before jumping to another wavelength, and the swapping time (laser tuning plus a certain delay), should depend on the network load values. This new CSMA/CD scheme will maximize throughput while keeping an acceptable delay. The proper values of the protocol parameters (the consecutive collisions before wavelength jumping and the swapping time) optimizes the network behaviour in terms of total capacity utilisation. 6. Acknowledgments The authors gratefully acknowledge funding by the Swiss government (Fond National Suisse de la Recherche Scientifique) under grant 21-42085.94 and thank Professor P.-G. Fon-tolliet for his useful comments. Special thanks are extended to C. Gallego and Y. Gachoud for their valuable support in programming and result processing. 7. References [1] IEEE-" ISO/IEC 8802-3 Std 802.3: Carrier Sense Multiple Access with Collision Detection (CSMA/CD) access method and physical layer specifications " , New York, 1992. [2] Shamsul Alam-" Retransmission probability selection of multichannel CSMA/CD protocols for LANs " , Computer Communications, vol 15 no 10 December 1992.