Multicast Routing in Light-Trail WDM Networks

Recently, light-trail is becoming an appealing architecture for WDM networks which have been considered as promising backbone of the next generation network. Light-trail can inherently support multicast given its bus nature. In this paper, we study how to use the minimum number of light- trails to form a multicast tree for supporting the given multicast session. The problem for general light-trail WDM networks is proved to be NP-hard. Two auxiliary graphs will be proposed to transform the problem into minimum steiner tree problem that many effective algorithms can be applied. We then show that the same problem in light-trail WDM ring networks can be solved in polynomial time. The simulations show the effectiveness of our work.