Shared-Risk Logical Span Groups in Span-Restorable Optical Networks: Analysis and Capacity Planning Model
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In an optical transport network distinct logical groups of lightwave channels between neighboring OXC nodes (called spans) may sometimes be realized over a common physical resource such as a duct or conduit, and hence share a common cause of failure. This is closely related to the concept of shared risk on individual channels or links, called SRLGs, which is relevant to pre-planned path protection schemes with shared capacity on backup paths. But when considering span-restorable networks, shared risk over logical spans (not individual channels) is the corresponding issue of concern. This work considers several aspect of how such shared-risk span groups (SRSG) affect the protection capacity design and other aspects of span-restorable mesh networks. We provide a model for capacity planning any span-restorable network in the presence of a known set of such shared-risk spans and study the relationship between capacity requirements and the number and placement of such situations. This provides guidelines as to how many SRSGs can be sustained before the capacity penalty becomes severe and methods to diagnose which of them are the most limiting to overall protection efficiency. One finding of interest is that if a given percentage of all possible dual-failure combinations incident to a common node are allowed for in the design, then nearly the same percentage of other dual-span failure combinations (any two spans in the network) will also be restorable. We also show that designing a network to withstand even a small number of multi-span co-incident spared-risk span groups will yield a significant improvement in overall dual-failure restorability and hence also in network availability.
KeywordsSRLG optical network design transport networks capacity planning restoration and protection restorability availability optimization WDM
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- A. J. Vernon, J. D. Portier, Protection of optical channels in all-optical networks, Proceedings of the 18th Annual National Fiber Optic Engineers Conference (NFOEC 2002), (Dallas, TX, Sept. 2002), pp. 1695–1706.Google Scholar
- OPNET, (September 2002) [Online] Flow analysis, Available: http://www.opnet.com/products/modules/flow_analysis.html, (17 April 2003).
- P. Sebos, J. Yates, G. Hjalmtysson, A. Greenberg, Auto-discovery of shared risk link groups, Proceedings of the Optical Fiber Communication Conference and Exhibit (OFC 2001), (Anaheim, CA, March 2001), pp. WWD3-1–WWD3-3.Google Scholar
- S. Kini, M. Kodialam, T. V. Laksham, S. Sengupta, C. Villamizar, Shared backup label switched path restoration, IETF Internet Draft, draft-kini-restoration-shared-backup-01.txt, work in progress, May 2001.Google Scholar
- S. Sengupta, R. Ramamurthy, Capacity efficient distributed routing of mesh-restored lightpaths in optical networks, Proceedings of the IEEE Global Telecommunications Conference (GlobeCom 2001), (San Antonio, TX, Nov. 2001), pp. 2129–2133.Google Scholar
- R. Bhandari, Survivable Networks: Algorithms for Diverse Routing, (Kluwer Academic Publishers, 1998).Google Scholar
- Iraschko, R.R., MacGregor, M.H., Grover, W.D. 1998Optimal capacity placement for path restoration in stm or atm mesh-survivable networksIEEE/ACM Transactions on Networking6325326Google Scholar
- J. Doucette, W. D. Grover, Comparison of mesh protection and restoration schemes and the dependency on graph connectivity, Proceedings of the 3rd International Workshop on Design of Reliable Communication Networks (DRCN 2001), (Budapest, Hungary, October 2001), pp. 121–128.Google Scholar
- Grover, W.D., Doucette, J. 2002Design of a meta-mesh of chain sub-networks: enhancing the attractiveness of mesh-restorable wdm networking on low connectivity graphsIEEE Journal on Selected Areas in Communications (JSAC)204761Google Scholar
- Clouqueur, M., Grover, W. D. 2002Availability analysis of span-restorable mesh networksIEEE Journal on Selected Areas in Communications (JSAC)20810821MayGoogle Scholar
- M. Clouqueur, W. D. Grover, Computational and design studies on the unavailability of mesh-restorable networks, Proc. Workshop on the Design of Reliable Communication Networks (DRCN 2000), (Munich, Germany, April 2000), pp. 181–186Google Scholar
- Grover, W. D. 1997Self-organizing broad-band transport networksProceedings of the IEEE8515821611Oct.Google Scholar
- Médard, M., Barry, R.A., Médard, M., Finn, S.G., He, W., Lumetta, S.S. 2002Generalized Loop-Back Recovery in Optical Mesh NetworksIEEE/ACM Transactions on Networking10153164Feb.Google Scholar
- Grover, W. D., Li, D. Y. 1999The forcer concept and its applications to express route planning in mesh survivable networksJournal of Networks and Systems Management7199223JuneGoogle Scholar
- Herzberg, M., Bye, S.J., Utano, A. 1999The hop-limit approach for spare-capacity assignment in survivable networksIEEE/ACM Transactions on Networking3775784Dec.Google Scholar
- Y. Wang, Modelling and solving single and multiple facility restoration problems, Ph.D. dissertation, Sloan School of Management, MIT, (June 1998), pp. 32–33.Google Scholar
- Doucette, J., Grover, W. 2000Influence of modularity and economy-of-scale effects on design of mesh-restorable dwdm networksIEEE Journal on Selected Areas in Communications (JSAC), Special Issue on Protocols and Architectures for Next Generation Optical WDM Networks1819121923Oct.Google Scholar
- W. D. Grover, The protected working capacity envelope concept: An alternative paradigm for automated service provisioning, IEEE Communications Magazine, vol. 42, no. 1, (January 2004), pp.62–69. Google Scholar