Date Added: Aug 2009
WDM multicast networks are evolving towards all optical multicast routing, which is made up of several promising techniques designed to take advantage of light-trees (optical trees that avoid OEO conversions along the switching path). Although all-optical elements are not yet a mature technology, different research efforts held in this area during the last decade, are contributing to achieve this objective. In the present work authors analyze and summarize the most relevant problems regarding this topic, then explain some significant contributions made by several authors and by the own in previous papers. Finally, authors present the key challenges that must be assumed in future works for light-tree routing.