Lightnets: topologies for high-speed optical networks

An inherent problem of conventional point to point WAN architectures is that they cannot translate optical transmis- sion bandwidth into comparable user available throughput due to the limiting electronic processing speed of the switching nodes. This paper presents a solution to WDM based WAN networks that addresses this limitation. The proposed Lightnet architecture trades the ample bandwidth obtained by using multiple wave- length for a reduction in the number of processing stages and a simplification of each switching stage, leading to substantially increased throughputs. The principle of the Lightnet architecture is the construction and use of a virtual topology network in the wavelength domain, embedded in the original network. This paper studies the em- bedding of virtual networks whose topologies are regular, using algorithms which provide bounds on the number of wavelengths, switch sizes, and average number of switching stages per packet transmission. Algorithms for the embedding of alternative regu- lar topologies are presented and their performance is evaluated. It is shown that compared to conventional network architectures, the Lightnets offer substantial performance gains in terms of increased throughput and smaller buffering requirements.