Since IP-over-WDM has become a natural choice for the next generation backbone networks. It is more eminent to implement efficient multicast in WDM networks. A light-tree has been defined to support multicast sessions in WDM layer, it construct a point-to-multipoint light-paths from a source to multiple destinations and can be implemented by power-splitters. With the mature of power-splitters, there is a need to develop framework at higher layers to efficiently
use the multicast available at WDM layer. In this paper, we concentrate on OBS-based multicast, new node models supporting WDM multicast are proposed. Then base on the models, we put forward novel implementation architecture of GMPLS-based OBS network to support multicast services, which maps an IP multicast-tree onto a multicast LSP that are connected to form a WDM light-tree. Two salient features of the architecture are: multicast LSP is constructed by data-driven; and the inter-operation between GMPLS framework and OBS. Finally, we discuss the performance of the proposed architecture.