As appeared in Protocols for High-Speed Networks VI, ed. J. Touch, J. Sterbenz, Kluwer, 1999, pp. 43-60. HOW MANY WAVELENGTHS DO WE REALLY NEED IN AN INTERNET OPTICAL BACKBONE?

Coupling Internet protocol (IP) routers with wavelength-selective optical crossconnects makes it possible to support existing Internet infrastructur in a wavelength-division multiplexing optical network. Because optical wavelength routing is transparent to IP, very high throughput and low delay can be achieved when packets are made to bypass the IP forwarding process by being switched directly through the optical cross-connect. One version of this approach is called packets over wavelengths (POW). This paper presents the POW architecture in detail and discusses its salient features. Realistic simulations of the POW that use actual packet traces in a well-known Inte r-net backbone network reveal the level of performance that can be expected from POW under various options. Specifically, the fraction of packets that are switched through the crossconnect is evaluated as a function of the number wavelengths and the degree of flow aggregation that can be achieved. The resulting analysis, conducted in the context of the very-high bandwidt network service (vBNS) Internet backbone, suggests that as few as four wavelengths combined with a high degree of traffic aggregation can carry more than 98 % of IP packets in the streamlined switched mode. In cases where it is not possible to aggregate traffic, the deployment of wavelengthmerging technology would increase the fraction of IP packets carried in streamlined switched mode by up to 52%. 1