Traffic Grooming for Survivable WDM Networks – Dedicated Protection

This paper investigates the survivable traffic-grooming problem for optical mesh networks employing wavelength-division multiplexing (WDM) and dedicated protection. We consider the dynamic-provisioning environment where 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. Based on a generic grooming-node architecture, we propose two approaches—protectionat-lightpath (PAL) level and protection-at-connection (PAC) level—for grooming a connection request. In this paper, we investigate dedicated protection. In a companion paper (Ou et al. 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/grooming-port efficiency. Our findings are as follows. Under today’s typical connectionbandwidth distribution where lower bandwidth connections outnumber higher bandwidth connections, PAC outperforms PAL (in terms of bandwidth-blocking ratio, lightpath utilization, and wavelength utilization) if the number of grooming ports is large; however, PAL outperforms PAC (in terms of bandwidth-blocking ratio and grooming-port utilization) when the number of grooming ports is moderate or small. c © 2003 Optical Society of America