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Modelling Differentiated Availability Services in IP-Over-WDM ...

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shows that EF traffic connections have better service availability than BE connections and thoseserved without any protection. This result along with that shown <strong>in</strong> Figure 4 substantiate our claim thattraffic connections can enjoy better service availability and less service disruption rate by us<strong>in</strong>g adedicated protection scheme, though backup resources should be effectively allocated for trafficconnections based on their QoS requirements.10.99981:5 <strong>Differentiated</strong> Shared Protection SchemeEqual connection protection schemeBE Connection protection schemeEF connection protection scheme120100<strong>Differentiated</strong> Disruption servicesEqual connection protectionEF connection protectionBE connection protectionA v e ra g e C o n n e c tio n A v a ila b ility0.99960.99940.99920.999A v e ra g e d i s ru p t io n ra t e p e r y e a r8060400.9988200.9986600 800 1000 1200 1400 1600 1800 2000Path Length (km)00 500 1000 1500 2000 2500 3000 3500 4000 4500 5000Path Length (km)Figure 3. Average availabilityFigure 4. Average disruption rate.6. ConclusionBy allocat<strong>in</strong>g enough backup network resources, traffic connections can be recovered and hencecustomers can enjoy guaranteed service availability. In this paper, we analyzed a mathematical modelwhich can differentiate availability and disruption services <strong>in</strong> <strong>IP</strong>/<strong>WDM</strong> networks. This model canprovide different configuration sett<strong>in</strong>gs for service providers, which can be used to control the amountof allocated network resources for protect<strong>in</strong>g traffic connections based on their QoS requirements.<strong>Availability</strong> services as well as disruption services rate can be improved by <strong>in</strong>creas<strong>in</strong>g the repair rate;however, this may <strong>in</strong>crease the total network cost operation. As a next step, we will <strong>in</strong>troducedifferentiated resilience mechanisms for efficiently protect<strong>in</strong>g dynamic traffic.References[1] N. Golmie, T. Ndousse and D. Sue. A differentiated optical services model for <strong>WDM</strong> networks.IEEE Communication Magaz<strong>in</strong>e, vol. 38, no. 2, pp. 68–73, Feb. 2000.[2] M.Tacca, A.Fumagalli, A. Paradisi, F. Unghvary et al. <strong>Differentiated</strong> reliability <strong>in</strong> opticalnetworks: theoretical and practical results. Journal of Lightwave Technology, vol. 21, no. 11, pp.2576–2586, Nov. 2003.[13] J.H. Sarker, H. T. Mouftah. Service Reliability with Enhanced Failure Recovery Rate forMultiple Failures <strong>in</strong> Survivable Optical Networks Communications. 24th Biennial Symposium on,Page (s):89 - 92, 24-26 June 2008.[24] J.E.Angus. On comput<strong>in</strong>g mtbf for a k-out-of-n: g repairable system. In IEEE Transactions onReliability, volume Vol37 (3), pages 312-313, August 1988.London Communications Symposium 2009

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