Performability Estimation ofToken Ring Network

Abstract

Theworkreportedinthispaperpresentsanewmethodfortheperformabilityevaluationofthetoken ring network. Performabilityisatermusedtodescribeperformanceandreliability.Performanceis definedasqualityofserviceprovidedthesystemiscorrect.Reliabilityisthepropertyofasystemwhichallowsreliancetobejustifiablyplacedontheserviceitdelivers.However,theproblemthatarisesfromevaluatingtheseitemsseparatelyisthatperformancedependsonreliability.Thus,itisobviousthatcombiningperformanceandreliabilitywasneededforacompleteevaluation;theissuewashowtocombine them. Themethodusedforperformabilityevaluationoftokenringnetworkisbasedonanalysisdescribingtheactionofthetokenringnetwork. ItwasassumedthattheMeanTimeFrameTransfer (MTFT) to be the main measure of the performabilitywhichiscomposedoftheMeanWaitingTime(MWT)forafreetokenandtheMeanRealTransferTime(MRTT)ofadataframe(togetherwiththeacknowledgementreceipt),takinginconsiderationallpossiblemalfunctions. Inaddition,theinfluenceoftheefectiveparameters[numberofnodes(N),lengthofthelink(L),channelbandwidth(b),exponentialdistributionratiooftheuseraccessprobability()andratioofmalfunctions(km)]onMTFTand its components were investigated. Asageneralconclusionthepresentinvestigationprovidesanewmethodforevaluationofperformabilityofthetokenringnetwork.ItwasfoundthattheMeanTimeFrameTransferanditstwomaincomponentsvarylinearlywithnumberofnodes,lengthofthelink,exponentialdistributionratiooftheuseraccessprobabilityandtheratioofmalfunctionandvaryinverselywithchannelbandwidth.