Segment-based approaches to survivable translucent network design under various ultra-long-haul system reach capabilities (Invited)

One of the most practical architectural options for optical networking is a so-called translucent network based on a predominance of optically transparent switch nodes and a smaller number of strategically placed opaque (electronic core) switch nodes. In such a network it is technically easier to assume failure detection at the opaque nodes only and thus natural to consider viewing the transparent path segments between opaque nodes as the entities to be protected for network survivability, as opposed to single spans or entire end-to-end paths. We develop and test capacity-design models to compare this type of segmentbased restoration scheme with conventional schemes. More important, however, a fast, nearly optimal, algorithm is proposed that can determine the placement of opaque nodes so that the fewest possible number is needed that ensures complete translucent reachability and single-failure survivability on the basis of the corresponding transparent path segments. Our data and methods also reveal the trade-off between the transparent reach obtainable by an ultra-long-haul (ULH) system and the corresponding number of opaque nodes required in the network (including survivability considerations), and thus we attain important insights to guide the relative allocation of research and development efforts on ULH systems as opposed to optical‐electronic‐optical cross-connect cost reduction. © 2003 Optical Society of America