1. Impact of OXC Failures on Network Reliability Zsolt Pándi a, Andrea Fumagalli a, Marco Tacca a, Lena Wosinska b a OpNeAR Lab., Erik Jonsson Shool of EECS, University of Texas at Dallas b Department of Teleinformatics, Royal Institute of Technology, Kista, Sweden Purpose Characterize influence of OXC equipment reliability on end-to-end connection provisioning Combine detailed component-based node reliability models with network level Differentiated Reliability Study of different networking scenarios with realistic data Node Equipment Node architectures: –Wavelength-selective optical cross-connect with electronic protection path (1) –Wavelength selective optical cross-connect w/o protection (2) –Clos architecture with one path for shared protection (3) –Clos architecture w/o protection (4) Switching technologies –InGaAsP/InP (laser-amplifier gate-switch arrays) (a) –MEMS (MicroElectroMechanical Systems) (b) Node Reliability Model Network Reliability Model Differentiated Reliability Basic idea: provide just the necessary level of protection and thus improve resource sharing Introduction of node failures makes it impossible to survive every single failure Validation of single-failure approach is necessary (reason for missing curves: requirements cannot be guaranteed by considering only single failures) Networking scenarios Link reliability is a function of the length of cable span Three examined scenarios based on scaled versions of the same network: –European (continental size), –National (1:5 size), –Metropolitan (1:50 size) 4 wavelengths per fiber is assumed Each type of node equipment is tested in all the scenarios Methodology Simulation of WDM networks –No wavelength conversion –Dynamic traffic, different call arrival intensities (lambda) –Arriving demands specify reliability requirements –Resource allocation using the extension of DSPP- DiR –Only single failure scenarios are considered for optimization with simulated annealing –Centralized call admission control with a single-slot buffer to ensure that endpoints of served calls are distributed evenly –Statistical analysis of results –Measure of goodness: call blocking probability Continental scale Maximum failure probability: 0.05 National scale Metropolitan scale Summary Provided reliability is higher than the guarantees (not all possible multiple failures disrupt each connection) Single failure approach seems to work well for metropolitan scale networks and may be applied on the national scale, as well In the continental scale link failures determine network reliability, while in the metropolitan scale node failures do OXC equipment selection does make a difference under certain circumstances Network components (links and atomic nodes) also have two states Independent component failures Asymptotic unavailability is assigned to each component SPP protection scheme Maximum failure probability: 0.005 Maximum failure probability: 0.0005  OM … SS 15/16 1 2 16 4  MT 2  OM 2  WDM Reliability block diagram –Built from two-state components (operating, failed) each having their independent reliability characteristics –One component failure puts whole equipment into failed state