Traffic grooming for survivable WDM networks: dedicated protection [Invited

Abstract

We investigate the survivable traffic-grooming problem for optical mesh networks employing wavelength-division multiplexing (WDM) and dedicated protection. We consider the dynamic-provisioning environment in which a connection arrives at random, holds for a random amount of time, and then departs. A typical connection request may require bandwidth less than that of a wavelength, and it may also require protection from network failures, typically fiber cuts. On the basis of generic grooming-node architecture, we propose two approaches--protection-at-lightpath (PAL) level and protection-at-connection (PAC) level--for grooming a connection request. Here we investigate dedicated protection. In a companion paper [IEEE J. Sel. Areas Commun. 21, 1367 (2003)], we investigate shared protection, which leads to a substantially different treatment. For dedicated protection, we prove that the problem of provisioning a connection under PAC is NP-complete, propose effective heuristics for both schemes, and define comprehensive performance metrics to compare PAL with PAC with respect to wavelength or grooming-port efficiency. Our findings are as follows. Under today's typical connection-bandwidth distribution in which lower-bandwidth connections outnumber higher-bandwidth connections, PAC outperforms PAL (in terms of bandwidth-blocking ratio, lightpath use, and wavelength use) if the number of grooming ports is large; however, PAL outperforms PAC (in terms of bandwidth-blocking ratio and grooming-port use) when the number of grooming ports is moderate or small.