Wavelength requirements for multicasting in all-optical networks

Multicasting in a network is needed for a number of applications where a session requires connectivity between more than two participants. In this paper, we consider a wavelength-division multiplexing (WDM)-based all-optical network. We derive asymptotic upper bounds on the number of wavelengths needed to support multicasting capability in an all-optical network. The number of wavelengths in a WDM network continues to be a major constraint. The results derived here should be seen as the limit on scalability of all-optical networks that support multicasting. The derivation of the upper bound uses some properties of expander graphs.