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Towards Quantification of IP Network Reliability. Hao Wang, Alex Gerber, Albert Greenberg, Jia Wang, Yang R. Yang AT&T Labs Research Microsoft Research Yale University. Internet: A Critical Infrastructure. Model & Methodology. The Messages. VoIP Video Conferencing Online Trading
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Towards Quantification of IP Network Reliability Hao Wang, Alex Gerber, Albert Greenberg, Jia Wang, Yang R. Yang AT&T Labs Research Microsoft Research Yale University Internet: A Critical Infrastructure Model & Methodology The Messages • VoIP • Video Conferencing • Online Trading • Online gaming • E-Commerce • Evaluation of the effects of various factors on IP network reliability • Abilene has decent yet insufficient reliability • >70% higher than two 9’s • <60% higher than five 9’s • IP layer reliability techniques help • IGP re-convergence vs. the others • No single reliability techniques prevails • As failures last longer (high failure -> low failure) • IGP histogram improves • All others histograms degrades IP Network Reliability • Quantification of Reliability: # of Nine’s Future Work • IP network topology • Abilene router-level as of October, 2006 • Traffic demands • Abilene Oct. 4 2006 – Oct. 31, 2006 • Failure models • Generate synthetic failures • Parametric model • Mean time-to-failure (MTTF) • Mean time-to-repair (MTTR) • Failure ratio (severity) level (FRL) • Evaluations on more (typical) IP networks • Incorporating more practical factors • Edge router reliability • Interdomain (BGP) route oscillation • Questions around IP Network Reliability • Estimations vary from ~99% to ~99.999% • Methodology of estimations unclear • Effects of traffic engineering (TE) techniques on reliability • TE optimizes for network specific metrics • MLU, network costs, etc • Reliability perceived by end-users • Connectivity, loss rate, delay, etc • What is the effect of TE on reliability? • Availability vs. Reliability • Mere connectivity is not enough - performance matters • Low failure example: maintenance • High failure example: aging equipment Major Results Objective: Quantification of Reliability • In terms of aggregated statistics of O-D pair reliability level • Question #1: What is the reliability level of IP networks? • Defined using Service Level Agreement (SLA) • Connectivity • Delay • Loss rate • Reliability Level = Time SLA satisfied / Total time • How many nines can they achieve? • Question #2: How effective are the IP layer techniques in improving the reliability of IP networks? • IGP (CSPF) re-convergence • IGP (CSPF) fast rerouting • TE with fast rerouting • TE with CSPF fast rerouting • Do they make a difference?