Optimizing light-trail assignment to WDM networks for dynamic IP centric traffic

The rapid growth of IP centric communication in worldwide networks and the parallel mass deployment of fiber based WDM networks have propelled IP over WDM being considered as an eventual solution for bandwidth on demand to customers. Contemporary optical networks are, however, based on lightpath communication and a lightpath represents end-to-end optical circuits from source to destination. Light-trails are a generalization of lightpaths, such that multiple nodes along a trail can participate in time differentiated communication over the same established trail. Managing and setting up of light-trails in order to cater to IP centric traffic is a key to the success of IP centric communication at the optical layer. A light-trail represents an open optical path that allows multiple users to communicate without the need for switch reconfiguration at any user node, the light-trail itself being static. IP communication on the other hand represents a bursty traffic flow often characterized by spurts or bursts of data. The goal of this paper is to show how to create an efficient light-trails based virtual topology for a given network traffic flow. We first describe a tree-shaped variant of light-trail, called the clustered light-trail (CLT) and then present optimization techniques for satisfying the given IP centric communication requirements, using the light-trails framework that is very flexible, despite being basically a static mechanism.