WASPNET-a wavelength switched photonic network for telecommunication transport

WASPNET is an EPSRC-funded collaboration between Strathclyde, Essex, and Bristol Universities, with the aim of designing a flexible packet-based transport network. It supports both conventional optical paths for the transport of SDH and also switches optical packets, thus providing a smooth upgrade path from SDH over WDM while still supporting legacy SDH equipment. A key feature of this network is the use of multiple wavelengths to help resolve packet contention and hence reduce the size of optical buffers that are required. This is advantageous since large optical buffers will be expensive and difficult to build. This paper describes some of the developments in WASPNET. Two possible control architectures have been studied, namely scattered wavelength path (SCWP) and shared wavelength path (SHWP). SCWP is the most suitable as it can distribute the load more efficiently and it requires a lower buffer size. Two possible node designs are then addressed; one based on feedback delays and one on feed forward delays, followed by a description of the sub-system components and their advantages and limitations. Finally the decoding of subcarrier modulated headers is covered.