During the past few years, we have observed the emergence of new applicationsthat use multicast transmission. For a multicast routing algorithm to beapplicable in optical networks, it must route data only to group members,optimize and maintain loop-free routes, and concentrate the routes on a subsetof network links. For an all-optical switch to play the role of a branchingrouter, it must be equipped with a light splitter. Light splitters areexpensive equipments and therefore it will be very expensive to implementsplitters on all optical switches. Optical light splitters are only implementedon some optical switches. That limited availability of light splitters raises anew problem when we want to implement multicast protocols in optical network(because usual multicast protocols make the assumption that all nodes havebranching capabilities). Another issue is the knowledge of the locations oflight splitters in the optical network. Nodes in the network should be able toidentify the locations of light splitters scattered in the optical network soit can construct multicast trees. These problems must be resolved byimplementing a multicast routing protocol that must take into considerationthat not all nodes can be branching node. As a result, a new signaling processmust be implemented so that light paths can be created, spanning from source tothe group members.
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