Using application layer knowledge in Routing and Wavelength Assignment algorithms

Preemptive Routing and Wavelength Assignment (RWA) algorithms preempt established lightpaths in case not enough resources are available to set up a new lightpath in a Wavelength Division Multiplexing (WDM) network. The selection of lightpaths to be preempted relies on internal decisions of the RWA algorithm. Thus, if dedicated properties of the network topology are required by the applications running on the network, these requirements have to be known to the RWA algorithm. We present a family of preemptive RWA algorithms for WDM networks. These algorithms have two distinguishing features: a) they can handle dynamic traffic by on-the-fly reconfiguration, and b) users can give feedback for reconfiguration decisions and thus influence the preemption decision of the RWA algorithm, leading to networks which adapt directly to application needs. This is different from traffic engineering where the network is (slowly) adapted to observed traffic patterns. Our algorithms handle various WDM network configurations including networks consisting of heterogeneous WDM hardware. To this end, we are using the layered graph approach together with a newly developed graph model that is used to determine conflicting lightpaths.