Optical network design and modeling is an essential issue for planning and operating networks for the next century. The main issues in optical networking are being widely investigated, not only for WDM networks but also for optical TDM and optical packet switching. This book contributes to further progress in optical network architectures, design, operation and management and covers the following topics in detail: Optical switching and Teabit networking; Future OTDM and packet switched networks; WDM ring networks; Optical interworking and `packets over wavelength'; Hybrid and switchless networks; Medium access protocols for optical LANs and MANs. This book contains the selected proceedings of the Fourth International Working