Some principles for designing a wide-area optical network

Explores design principles for next generation optical wide-area networks, employing wavelength-division multiplexing (WDM), and targeted to nationwide coverage. This almost-all-optical network will exploit wavelength multiplexers and optical switches in routing nodes, so that arbitrary virtual topologies may be imbedded on a given physical network. The virtual topology, which is packet switched and which consists of a set of all-optical lightpaths, is set up to exploit the relative strengths of both optics and electronics viz. packets of information are carried by the virtual topology “as far as possible” in the optical domain, but packet forwarding from lightpath to lightpath is performed via electronic switching, whenever required. Algorithms are developed so that the WDM-based network architecture will (a) provide a high aggregate system capacity due to spatial reuse of wavelengths, and (b) support a large and scalable number of users, given a limited number of wavelengths. The authors illustrate their approaches by employing experimental traffic statistics collected from NSFNET