Comprehensive performance modeling and analysis of multicasting in optical networks

Multicasting is becoming increasingly important in today's networks. In optical networks, optical splitters facilitate the multicasting of optical signals. By eliminating the transmission of redundant traffic over certain links, multicasting can improve network performance. However, in a wavelength-division multiplexed (WDM) optical network, the lack of wavelength conversion necessitates the establishment of a single multicast circuit (light-tree) on a single wavelength. On the other hand, establishing several unicast connections (lightpaths) to satisfy a multicast request, while requiring more capacity, is less constrained in terms of wavelength assignment. The objective of the paper is to evaluate the tradeoff between capacity and wavelength continuity in the context of optical multicasting. To this end, we develop accurate analytical models with moderate complexity for computing the blocking probability of multicast requests realized using light-trees, lightpaths, and combinations of light-trees and lightpaths. Numerical results indicate that a suitable combination of light-trees and lightpaths performs best when no wavelength conversion is present.