Differentiated reliability in optical networks: theoretical and practical results

• Published in: Journal of lightwave technology Vol. 21; no. 11; pp. 2576 - 2586
• Main Authors: Tacca, M., Fumagalli, A., Paradisi, A., Unghvary, F., Gadhiraju, K., Lakshmanan, S., Rossi, S.M., de Campos Sachs, A., Shah, D.S.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.11.2003; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Circuit testing; Circuit topology; Circuits; Computer networks; Network topology; Networks; Optical fiber networks; Optical fiber testing; Protection; Reliability theory; Restoration; Routing; Studies; Switching; Switching theory; Wavelength division multiplexing; WDM networks
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2003.819554

This paper presents both theoretical and experimental studies carried on wavelength-division multiplexing (WDM) networks with arbitrary (mesh) topology that provide optical circuits with differentiated reliability (DiR). Reliability is obtained by means of a modified shared path protection (SPP) switching scheme-here referred to as SPP-DiR. As explained in the paper, SPP-DiR networks provide multiple degrees of circuit reliability that satisfy client-specific reliability requirements in a cost-effective way. The theoretical study first defines the problem of optimally designing SPP-DiR WDM networks. It then presents a time-efficient suboptimal algorithm that determines the routing and the reliability degree of each demand in the given traffic matrix by applying both the conventional SPP and the SPP-DiR scheme. When compared to dedicated path protection switching, results obtained for the pan-European network using the proposed algorithm indicate cost reductions of about 16% when SPP is applied, and up to 34% when SPP-DiR is applied. The experimental study describes the /spl Omega/ testbed-a WDM optical circuit-switched mesh network with an IP control plane-which is believed to be the first testbed ever built that makes use of the SPP-DiR scheme. Experimental results performed on the /spl Omega/ testbed report restoration times of the optical circuits-disrupted by a fiber fault-that are few tens of milliseconds.