Traffic grooming for survivable WDM networks - shared protection

This paper investigates the survivable trafficgrooming problem for optical mesh networks employing wavelength-division multiplexing (WDM). In the dynamic-provisioning context, a typical connection request may require bandwidth less than that of a wavelength channel, and it may also require protection from network failures, typically fiber cuts. Based on a generic grooming-node architecture, we propose three approaches—protection-at-lightpath (PAL) level, mixed protection-at-connection (MPAC) level, and separate protection-at-connection (SPAC) level—for grooming a connection request with shared protection. In shared-mesh protection, backup paths can share resources as long as their corresponding working paths are unlikely to fail simultaneously. These three schemes explore different ways of backup sharing, and they tradeoff between wavelengths and grooming ports. Since the existence version of the problem for provisioning one connection request with shared protection is -complete, we propose effective heuristics. Our findings are as follows. Under today’s typical connection-bandwidth distribution where lower bandwidth connections outnumber higher bandwidth connections: 1) it is beneficial to groom working paths and backup paths separately, as in PAL and SPAC; 2) separately protecting each individual connection, i.e., SPAC, yields the best performance when the number of grooming ports is sufficient; and 3) protecting each specific lightpath, i.e., PAL, achieves the best performance when the number of grooming ports is moderate or small.