Dynamic reconfiguration and routing algorithms for IP-over-WDM networks with stochastic traffic

We develop algorithms for joint IP layer routing and WDM logical topology reconfiguration in IP-over-WDM networks experiencing stochastic traffic. At the WDM layer, we associate a non-negligible tuning latency with WDM reconfiguration, during which time tuned transceivers cannot service backlogged data. The IP layer is modeled as a queueing system. We demonstrate that our algorithms achieve asymptotic throughput optimality by using frame-based maximum weight scheduling decisions. We study both deterministic and random frame durations. In addition to dynamically triggering WDM reconfiguration, our algorithms specify precisely how to route packets over the IP layer during the phases in which the WDM layer remains fixed. Our algorithms remain valid under a variety of optical layer constraints. We provide an analysis of the specific case of WDM networks with multiple ports per node. In order to gauge the delay properties of our algorithms, we conduct a simulation study and demonstrate an important tradeoff between WDM reconfiguration and IP layer routing. We find that multi-hop routing is extremely beneficial at low throughput levels, while single-hop routing achieves improved delay at high throughput levels. For a simple access network, we demonstrate through simulation the benefit of employing multi-hop IP layer routes.