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The authors consider the dynamic routing problem in a network comprised of internet protocol (IP) routers interconnected via optical wavelength division multiplexing links and optical cross-connects. Traditionally, routing in this context is carried out as two separate processes: path selection at the IP (logical) layer and routing and wavelength assignment at the optical (physical) layer to establish lightpaths that constitute the logical links in the IP layer. This separate handling of the routing processes in the two layers usually leads to inefficient exploitation of the network resources. The proposed augmented integrated routing algorithm (AIRA) scheme addresses this apparent in efficiency by implementing a dual-layer routing scheme that utilises information from both the IP and optical layers. The scheme also provides preferential treatment to high-priority connections. The path selection is done using a variant of the hop-constrained adaptive shortest-path scheme in the two layers. The performance evaluation study shows that AIRA outperforms existing state-of-the-art methods in terms of reduced blocking probability, better handling of non-uniform traffic, and shorter path length at both the IP and optical layers. The scheme also exhibits good robustness in handling dynamic changes and non-uniform traffic loading in the IP layer.
Date of Publication: July 1 2011