On fundamental issues in IP over WDM multicast

As WDM technology matures, IP over WDM multicast becomes a new challenging topic. Supporting multicast at the WDM layer provides additional advantages, but also raises many new issues that do not exist in IP multicast. For example, the limitation on the light splitting capability of switches is one major difficulty in WDM multicast, and in addition, the limitations on both the wavelength conversion capability and optical buffer space may affect multicast routing as well. In this paper, we focus on the IP over WDM multicast routing problem, i.e. how to construct multicast trees at the WDM layer based on IP multicast routing protocols. More specifically, we study how label switched paths for optical label switching can be set up for multicast traffic. We propose two approaches, one without modification of existing IP multicast routing protocols, and the other with modification of existing IP multicast routing protocols.