As Internet traffic continues to grow unabated at an exponential rate, it is unclear whether the existing packet routing network architecture based on electronic routers will continue to scale at the necessary pace. On the other hand, optical fiber and switching elements have demonstrated an abundance of capacity that appears to be unmatched by electronic routers. Although a number of optical backbone architectures have been proposed (e.g., optical burst switching), they generally rely on frequent dynamic circuit reconfigurations and new signaling protocols for network-wide coordination. Recently, we proposed an alternative optical backbone architecture called COPLAR based on a paradigm of coarse optical circuit switching by default and adaptive re-routing over circuits when necessary [4]. This approach is based on the provisioning of long-duration quasi-static optical circuits between IE (Ingress-Egress) router pairs at the boundary of the network to carry the traffic by default. When a provisioned circuit is inadequate, we adaptively load-balance the excess traffic across circuits with spare capacity so that all traffic can be routed to their final destinations without the need to create new circuits on-the-fly. Our initial work was focused on the system architecture design and the provisioning of quasi-static circuits. In this paper, we focus on the problem of adaptive re-routing over circuits. Our evaluation using real traffic data on two real backbone networks (Abilene and GEANT) shows that our adaptive re-routing over circuits approach can effectively accommodate excess traffic even under heavy traffic loads.
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