Working Paper on Comparison of Performance over IPv6 versus

Working Paper on

Comparison of Performance over IPv6 versus IPv4

By

Arthur Berger

Akamai Technologies

AbstractAsIPv4addressspacegetstighter,thereisincreasingpressuretodeployIPv6.TheInternetAssignedNumberAuthority(IANA)allocatedthelastoftheavailable/8’softhev4addressspacetotheRegionalInternetRegistries(RIR’s)onFebruary3,2011.Currently,theRIR’sarerestrictingallocationstocoveronlyabout3monthsofgrowth.Amarketforlegacyv4addresshasbegun:InMarch,2011,aspartofNortel'sbankruptcy,Microsoftbought667,000legacyv4addressesfor$11/address.SincethetransitiontoIPv6willbeslow,therewillbealongperiodwheremanyend‐pointswillbedualstack.Thus,theabilitytopickthebetterperformingpathoverv4versusv6willbeavaluablefeature.Wehavedoneaperformancecomparisonofv4versusv6latencyandloss,withresultsbycontinent,andbytunneledversusnativev6addresses.Althoughoverallperformanceisbetteroverv4,itisnotalwaysso;forexample10%ofthetimethelatencybetweentheU.S.andEuropeisshorteroverv6byatleast10ms,andtoAsiaisshorterbyatleast38ms.Latencyandlossoverv6isingeneralhighertotunneledv6destinations,ascomparedwithnative.Somewhatsurprisingly,thelatencyandlossover_v4_isalsohighertonameserverswhosev6interfaceistunneled,ascomparedwithnameserverswhosev6interfaceisnative.Weconjecturethatnameserverswithatunneledv6interfacearemorelikelytobeinsmallernetworks,lowerdowninthehierarchy.Thus,thecommonobservationthatv6latencyishigherovertunnelsisnotdueexclusivelytothepoorerv6architectureoftunnels,butalsoispartiallyduetootherfactors,suchasthetopologicallocation.

ArthurBerger Page2of30 March29,2011

TableofContents1 Dataset ....................................................................................................................................................3

2 SummaryStatsbyGeoRegion......................................................................................................33 ComparisonofV6andV4Latency:Distributions ...............................................................6

4 ComparisonAcrossTime................................................................................................................9

4.1 ApriltoDecember,2010.........................................................................................................94.2 July12through14,2010..................................................................................................... 15

5 RelatedWork..................................................................................................................................... 21

6 References .......................................................................................................................................... 227 AppendixA.DistributionofPacketLoss ............................................................................... 23

8 AppendixB.AdditionalLatencyDistributions .................................................................. 27


PerformanceComparisonofv6versusv4

1 DatasetPingsweresentto6,864globallydistributeddual‐stacknameserversfromthreelocationsintheU.S.:Dallas,TX;SanJose,CA;andReston,VA.ThepresentreportconsidersmeasurementsfortheperiodfromApril12,2010throughDecember19,2010.Forthisperiod,wehave44millionmeasurementson9,223distincttimeepochs.

Therearetimeperiodswherenomeasurementswerecollected,mostnotablyApril24to25,June25toJuly1,August11to24,andOctober27toNovember8.

For2,085ofthe6,864nameservers,theIPv6interfaceisa6to4tunnel(address2002::/16)and33areaTeredotunnel(address2001:0::/32),wherethesearethetwomostpopulartunnelingmethodologiescurrentlyinuse.Wehavepartitionedsomeoftheresultsbelowinto"tunneled"and"native"basedontheIPv6addressofthenameservers.Caution:itispossiblethatapathtoa"native"nameserverdoescontainatunnel.

2 SummaryStatsbyGeoRegionIntermsofthesummarystatistics,Table1showsthesummarystatisticsofmedian,mean,andninety‐fifthpercentileoflatencyoverv4andoverv6,conditionedonthegeographicregionofthenameserverandwhetherthev6interfaceofthenameserverisnative,tunneled,oreither.Afirstobservationisthatintermsofthesesummarystatistics,thelatencyislessoverv4thanv6.Forexample,fordestinationsintheNorthAmerica,themeanlatencyis55msoverv4butsubstantiallyhigher,101ms,overv6.

Asecondobservationisthat,exceptforSouthAmerica,thelatencyishighertodestinationswherethev6interfaceistunneled,asopposedtonative,andthispertainsforboththev6andv4path.Forexample,fordestinationsinAsiawherethev6interfaceisnative,themeanlatencyoverv6was212ms.Forv6interfacesthataretunneled,themeanlatencyoverv6wassignificantlyhigherat317ms.Andalsooverv4,themeanlatencyisagainhighertodestinationswherethev6interfaceistunneled,205msversus245ms.Thatthelatencyoverv6ishighertotunneleddestinationsisconsistentwithcommonexpectations;however,itissomewhatasurprisethatthelatencyoverv4isalsohigher.Howcouldthev6interfaceaffectthelatencyoverthev4path?Admittedlythesetofnameserversaredistinct;thatis,wearecomparingv4latencytoonesetofdestinations,thosewhosev6interfaceistunneled,withthev4latencytoanotherset,albeitinthesamegeographicregion.However,thisalonedoesnotimplyanyintrinsicbiasandthusdoesnotexplainwhythelatency(intermsofthe


summarystatistics)isconsistentlyhighertooneofthetwosets.Also,thenumberofdestinationsineachsetisreasonablylarge,2,085and4,779,andthecauseisnotduetoafewoutliers,astheaffectalsopertainsforthemedianand95percentile.AlthoughIdonothavethedefinitiveexplanation,aplausibleexplanationisthatthenameserverswithatunneledv6interfacearemorelikelytobeinsmallernetworks,lesswell‐connectednetworks,lowerdowninthehierarchy.Supportingthisexplanationwehaveestimatesofv4loadfromthenameservers,asseenbyAkamai,andtheloadfromthenameserverswithtunneledv6interfacesoverallisindeedlower.

Latency[ms]Median Mean 95thpercentile

Geo‐Region

SetofNameserversbasedonv6interface v4 v6 v4 v6 v4 v6

native 47 86 52 95 101 172all 49 92 55 101 108 192

NorthAmerica

tunneled 53 101 61 114 119 216

native 151 162 154 163 218 231all 154 166 158 168 224 240

Europe

tunneled 167 182 172 188 252 273

native 184 198 205 212 359 331all 196 215 216 240 367 388

Asia

tunneled 229 313 245 317 378 469

native 183 198 188 208 272 345all 176 217 186 235 306 392

SouthAmerica

tunneled 172 233 186 246 330 404

native 344 357 337 350 438 454all 348 368 356 379 481 529

Africa

tunneled 355 393 377 415 557 697

native 208 216 211 232 293 317all 210 227 216 244 298 384

Australia

tunneled 225 275 235 288 329 401Table1

Regardlessofthecorrectexplanation,Table1showsthatthecommonobservationthatv6latencyishigherovertunnels,ascomparedwithnative,isnotdueexclusivelytothepoorerv6architectureoftunnels,butalsoispartiallyduetootherfactors,inparticularassuggestedabove,thetopologicallocation.


Insubsequentresultswherewesplitoutthev6measurementsbasedontunneledornative,wedolikewiseforv4,whichyieldsaperspectiveon"thehigherv6latencyovertunnels"thatisduetothetunnels.Athirdobservationisthattheextentv4isbetterthanv6(inthesenseoflowerlatency)ismoresubstantialfordestinationswithv6tunnels.Forexample,fordestinationsinAsia,thereductioninthemedianlatencyis84ms(229minus313)giventunneleddestinations,andisonly14ms(184minus198)givennativedestinations.ThisaffectismorenoticeableforAsia,SouthAmerica,Africa,andAustralia,thanforNorthAmericaandEurope,thoughitisstillpresent.ThefollowingTable2providesthesummarystatisticsonpacketloss.Themedianvaluesareomittedfromthetableastheywereall0,exceptforv6pathstotunneledinterfacesinAfrica,wherethemedianwas0.3%.Observations:

PercentPacketLoss[0,100]Mean 95thpercentile

Geo‐Region

SetofNameserversbasedonv6interface v4 v6 v4 v6native 0.4 2.1 0.5 6.6all 0.6 3.2 1.2 23.2

NorthAmerica

tunneled 1.0 5.2 3.2 32.4

native 0.5 0.7 1.3 2.0all 0.7 1.8 2.2 10.3

Europe

tunneled 1.4 6.0 6.5 31.8

native 3.0 1.2 20.8 6.3all 2.8 2.7 19.0 18.6

Asia

tunneled 2.2 6.9 11.4 34.8

native 0.8 1.0 4.8 4.7all 1.7 4.4 8.6 27.9

SouthAmerica

tunneled 2.1 5.7 9.8 31.6

native 2.0 4.8 9.5 32.8all 2.8 6.7 12.4 40.0

Africa

tunneld 3.9 9.0 19.1 43.4

native 0.4 1.0 1.6 5.0all 0.6 2.0 2.9 11.5

Australia

tunneled 1.4 5.6 7.8 31.3Table2

Thepacketlossoverv4islessthanoverv6,exceptfordestinationsinAsia,whereinterestinglythelossishigheroverv4tothosenameserverswithanativev6interface.


The95thpercentileofpacketlossisquitehighatthev6tunneledinterfaces.Thepacketlosstothev4interfaceislowertothesetofnameserverswhosev6interfaceisnative,asopposedtothesetofnameserverswhosev6interfaceistunneled,exceptagainforAsia.Thisisconsistentwiththeheuristicexplanationabovethatnameserverswithtunneledinterfacestendtobeinnetworksthataresmaller,furtherdowninthehierarchy.AppendixAcontainsplotsofthecomplementarydistributionfunctionsofpacketloss.Theseplotsemphasizethepointsabove.

3 ComparisonofV6andV4Latency:DistributionsThefollowingtwoplotsshowthedistributionofthedifference:IPv6latencyminusIPv4latency,partitionedbygeoregion.Positivevaluesonthex‐axiscorrespondtov6latencybeinggreaterthanv4.Therangeonthex‐axiswaschosensoastohighlightmostoftheaction,althoughitcuts‐offeachendofthedistributions.Ifthefullrangewereshown,thedistributionswouldgofrom0to1.Forexample,considerthefirstplotandthedistributiongivendestinationsinEurope.Atthezeropointonthex‐axis,thedistributionis0.29.Thus,for29%ofthemeasurementsthelatencyoverv6waslessthanorequaltothatoverv4.Likewisefor71%ofthemeasurements,thelatencyoverv6wasgreater.Lookingatthe‐10msonthex‐axis,wefindthatfor11%ofthemeasurements,thelatencyofv6wassmaller(better)byatleast10ms.Consideringtheticksat‐10msand10ms,for48%(59%minus11%)ofthemeasurements,thelatencyoverv6waswithin10msofthatoverv4.Ifonedidn'tcareaboutlatencydifferenceswithin10ms,thenforabouthalfofthetime,onewouldbeindifferent(consideringonlythisfactor)betweenthetwoprotocols.Asfirst‐ordersummary,theplotsshowthatmoreoftenthelatencyisgreateroverv6.However,therewillbegivenclientsforwhichthisisnotthecase.Inthecontextofoptimizingperformance,onewouldideallyliketobeabletodistinguishwhichwouldbebetter.

Figure1.Distributionofdifferenceinv6versusv4latencies



Thefollowingtwoplotsprovideanotherviewpointonthesamedatabyconsideringtheratioofv6latencydividedbyv4latencyandwherethex‐axisisonalogscale.

Figure2.Distributionofratiooflatencies


AppendixBcontainsanalogousplots,exceptpartitionedbytunneledversusnative.

4 ComparisonAcrossTimeThissectioncomparesv4versusv6latencyandloss,viewedacrosstime.

4.1 ApriltoDecember,2010InthefollowingFigure3,eachplottedpointisthemeanovera24‐hourperiod.(Recallthattherearegapsinthemeasurementdataasisevidentintheplots.)Therearesixplotsoflatency,oneforeachgeographicarea,followedbysixplotsofpacketloss.Notethattherangeonthey‐axisvariesfromplottoplot.Themostobviousfeatureofthelatencyplotsistheclearvariationacrosstime.Aseachpointistheaverageover24hours,thevariationinlatencyisonlongertimescalesthandailyvariation(whichisconsideredinthenextsection).Sometimeshigherlatencycanpersistformonths,asforexampleoverv6totunneleddestinations(thegreenline)inNorthAmerica,AsiaandSouthAmerica.Also,allofthegeographicregionshavespikesinlatency.Notethatsometimesthevariationisstronglycorrelatedacrossthefourcases,asforEurope,andsometimesnot,asforNorthAmerica.Theseobservationssuggestthatamoredetailedstudycouldmake


inferencesastowherecongestionwasoccurring.ThiscouldbepossiblefutureworkfortheIPv6project.Considernowthedifferenceinlatencyacrossthefourcaseswithineachgeographicregion.Ineachgeographicregion,thehighestlatencyisonthev6pathtotunneleddestinations,whichisconsistentwiththesummarystatisticsinSection2.Likewise,thelowestlatencyisonthev4pathtodestinationswhosev6interfaceisnative,exceptforSouthAmerica.Considerthedifferencebetweenthegreenandbluelines,i.e.thelatencyoverv6totunneledversusnativedestinations.Someofthedifferenceisduetothewell‐knownpoorerarchitectureofv6tunnelsand,some,assuggestedinSection2,islikelyduethetunneleddestinationsbeinginnetworksthataresmaller,furtherdowninthehierarchy(callthissecondfactor“inferiortopology”).Asaroughestimateofthissecondfactor,wecanusethedifferencebetweenthev4latencytodestinationswhosev6interfacesaretunneledversusnative,i.e.thedifferencebetweentheyellowandredlinesintheplots.Forexample,inNorthAmerica,thespacebetweentheyellowandredlinesisfairlysmallandsoisthespacebetweentheblueandyellowlinesuntilroughlyOct.1.Thesubsequentjumpinthegreenlineisprobablyduetosomethingregardingthetunnels,asopposedtotheinferiortopology,astheyellowlineremainsrelativelyflat.Itisworthemphasizingthatthedifferencebetweentheyellowandredlinesisjustaroughestimateofthe“inferiortopology”factor:forexample,intheNorth‐Americaplottherearepointswherethedifferencebetweentheyellowandredlinesisgreaterthanthatbetweenthegreenandblue,andthusmakesnosensetobeviewedasapieceofthelatter.IntheEuropeplot,thespacebetweentheyellowandredlinesisaboutequaltothatbetweenthegreenandbluethussuggestingthepoorerperformancewithv6tunnels,versusnative,isduetotheinferiortopology.Noticealsothatthefourlinesarequiteinsyncwitheachother,whichsuggeststhatthevariationinlatencyisduetocongestiononfacilitiesthataresharedbyallfourcases,suchastrans‐oceanicopticalcables.Theremaininggeographicregionscanbeviewedwiththeabovecommentsinmind.Inaddition,notethatintheAsiaplot,theredlineissignificantlymorevariablethantheyellow(thoughisstilllower).Ihaven’tthoughtofalikelyexplanationthoughafurtherexaminationofthedatamightbeilluminating.NoticealsothatinAsiathebluelineissometimesbelowthered‐thelatencyoverv6,tonativedestinations,issometimesfasterthanoverv4.ThisisexaminedmorethoroughlyinAppendixB.InSouthAmerica,theredandyellowlinesroughlyoverlap,and,asreportedinTable1ofSection2,thev4latencytodestinationswhosev6interfaceisnativeisactuallyabithigherthantodestinationswhosev6interfaceistunneled.Thus,thisdatadoesnotsupportthesuppositionof“inferiortopology”fortunneledinterfacesforSouthAmerica.


Figure3.TimeHistoryofLatency,April–Dec.,2010



Thefollowingaretheanalogoussixplotsforpacketloss.Notethattherangeonthey‐axisvaries.Themoststrikingfeatureisthatthereareperiodsofhighloss.FromSeptemberthroughDecember,thereishighv6losstotunneleddestinationsinallgeographicregions.Allthreeoriginregionshadhighloss.Thusthecausewasbroadenoughtoaffectmultipleorigins.Apossibleexplanationisthatforallthreeorigins,theroutetotheanycast6to4address,2002::/16,ledtorelaysthatwereoverloaded,andthatthisconditionpersisted.AnycastroutingisbasedonBGP,whichdoesnotadapttocongestion.Assuch,anetworkoperatorwouldneedtointerveneandchangepolicy.AlsonotethatduringJuneandJuly,therewashighv6losstonativedestinationsinoneofthegeographicregions:NorthAmerica.Inthiscase,justoneofthreeoriginregionshadthehighloss,thusthecausewaslocalized.Notethatthelosstooverv4andoverv6todestinationswithv6tunneledinterfaces(yellowandgreenlines)ishigherthantodestinationswithv6nativeinterfaces,exceptforAsiawherethereversepertainsforperiodsforv4.(ThisisconsistentwithTable1inSection2.)Idon’thaveanexplanationforthisexceptioninAsia.

Figure4.TimeHistoryofPacketLoss,April–Dec.,2010



4.2 July12through14,2010Togetasenseofanhour‐of‐daypattern,ifany,weplotathree‐dayperiodinJuly.Eachplottedpointisthemeanoveraone‐hourperiod.Againtherearesixplotsoflatency,followedbysixplotsofpacketloss.Therangeonthey‐axisvariesfromplottoplot.Dailyvariationinlatencyandlossistypicallyduehigherloadsandthusincreasedcongestionduringthebusyperiodoftheday.Relativelyconstantlatencyandlossoverthecourseofthedaytypicallyisindicativeofeitherconstant(lightorheavy)load,orvariableloadthathoweverremainslight.ThelatencyplotforSouthAmericashowsstrongdailyvariationforallfourcases,indicatingcongestiononthepathsbetweenthereandtheUS.Fordestinationsin


Europe,thedailyvariationinlatencyisalsoevident,thoughlessextreme.ForNorthAmericathedailyvariationisaslight,ifany.ForAustralia,noneisapparent.ThelatencyplotforAsiaismorecurious:thereisstrongdailyvariationforthreeofthefourcases,butthelatencyisratherconstantfortrafficoverv6tonativedestinations.Possiblytheroutesfromthethreeoriginstothenativev6addressesinAsiaareonanuncongestedtrans‐oceanicchannelthoughIwouldbesurprisedifafiberchannelwerereservedforv6traffic,butmaybeitis.(Theroutestothetunneledv6addressesmostlikelygoviaanycast6to4relaysintheU.S.,inwhichcasethetrans‐oceanichopinalllikelihoodisoverv4.)ThelatencyplotforAfricainonesenseisthereverseofAsia’s–threeofthecaseshavelittletonodailyvariation,andonedoes:v6totunneleddestinations.Apossibilityisthatatthefar‐endofthetunnel,thev6networksareresourceconstrained.(Althoughlatencyoverv4todestinationswithnativev6interfacesisalsovariable,theredline,thevariabilityisnotsomuchinadailypattern.)Ifthereisinterest,futureworkcouldinvestigatetheaboveconjecturesandingeneralinvestigatethecausesforvariousbehaviordisplayedintheseplots.Asafinalnote:whenIexaminedotherthree‐dayintervals,Iwouldsometimesseethesamepatternsashereandsometimesseedifferentones.Whatpertainedforonethree‐dayintervalneednotpertainmonthslater.

Figure5.TimeHistoryofLatency,July1214,2010



Thefollowingarethecorrespondingplotsforpacketloss.Notethattherangeonthey‐axisvariesfromplottoplotAswithlatency,SouthAmericahasveryevidentdailyvariationinloss.Againaswithlatency,adailyvariationinlossisalsoevidentforEurope,thoughmoremodest.NorthAmericahasnoevidentdailyvariation;also,asdiscussedaboveinSection4.1,therelativelyhighv6losstonativedestinationsinNorthAmericaisduetojustoneofthethreeorigins.Asiahasdailyvariationinlossforallfourcases,including,thoughmoremodest,v6probestonativev6,whoselatencyhadbeenflat.Africaisnotableforhighspikesinloss.


Australia,whichhadnodailyvariationinlatency,hasnoticeablevariationinloss,thatsomewhatfollowsadailypattern.Asaroughsummary,thepresenceorabsenceofdailyvariationinlossmirrorsthatoflatency.

Figure6.TimeHistoryofPacketLoss,July1214,2010



5 RelatedWorkHereisasampling,inreversechronologicalorder,ofstudiesthatcomparev4andv6performance.Narayanetal.[1]onatestbed,comparev4andv6onWindowsVistaandUbuntu.Theyfindthatv4hadslightlyhigherthroughput.v6hadsignificantlyhigherlatencyonUbuntu,ascomparedwithVista.Lawetal.[2]probefromalocationinHongKongto2,000dual‐stack,globalhosts.v6hadlowerhop‐countsandhigherRTTandhigherthroughput.RTTwas40%higherontunneledv6versusnativev6.Zhuoetal.[3]used26testboxesofRIPE,globallydistributed,thoughconcentratedinEurope,and600end‐to‐endpaths.TheyreportthatIPv6hashigherlossandlatency,mainlyduetotunneling.Siauetal.[4]inalarge‐scalenetworkenvironmentfindaminordegradationinthroughputofTCP,aslightlyhigherthroughputofUDP,alowerpacketlossrateandaslightlylongerroundtriptimeoverv6ascomparedwithv4.Zhouetal.[5]reportthatv6pathshadlargerdelayvariation,andlongerdelay.Fromabout1,000dual‐stackwebserversin44countries,Wangetal.[6]foundthatv6connectionstendtohavesmallerRTTs,butsufferhigherpacketloss.Theauthorsalsofindthattunneledpathsdonotshowanotabledegradedperformancecomparedwithnative.Choetal.[7]introducetechniquesforidentifyingIPv6networkproblemsatdual‐stacknodes.TheyfindthatIPv6networkqualitycanbeimprovedbyfixingalimitedamountoferroneoussettings.ARINandRIPEhavelinkstovariousmeasurementstudies,[8,9].


6 References[1] S.Narayan,P.Shang&N.Fan,"PerformanceEvaluationofIPv4andIPv6on

WindowsVistaandLinuxUbuntu,"Inter.ConferenceonNetworksSecurity,WirelessCommunicationsandTrustedComputing,2009

[2] Y.N.Law,M.C.Lai,W.Tan&W.Lau,"EmpiricalperformanceofIPv6vs.IPv4underadual‐stackenvironment,"IEEEInter.ConferenceonCommunications,2008.

[3] X.Zhou,M.Jacobsson,H.Uijterwaal&P.Mieghem,"IPv6delayandlossperformanceevaluation,"Inter.J.ofCommunicationSystems,Vol.21,2008.

[4] W.L.Siau,Y.F.Li,H.C.Chao&P.Y.Hsu,"EvaluatingIPv6onalarge‐scalenetwork,"ComputerCommunications,Vol.29,No.16,2006.

[5] X.Zhou&P.Mieghem,"HopcountandE2EDelay:IPv6versusIPv4,"PassiveandActiveNetworkMeasurements,2005.

[6] Y.Wang,S.Ye&X.Li,"UnderstandingCurrentIPv6Performance:Ameasurementstudy,"IEEESymposiumonComputersandCommunications,2005.

[7] K.Cho,M.Luckie&B.Huffaker,"IdentifyingIPv6NetworkProblemsintheDual‐StackWorld,"ACMSIGCOMMWorkshoponNetworkTroubleshooting,2004.

[8] labs.ripe.net/Members/mirjam/content‐ipv6‐measurement‐compilation.

[9] www.getipv6.info/index.php/IPv6_Penetration_Survey_Results


7 AppendixA.DistributionofPacketLossThefollowingplotsshowthecomplementarydistributionfunctionofpacketloss(a.k.a.thecomplementarycumulativedistributionfunction,i.e.1minusthecumulativedistributionfunction,i.e.theprobabilitytherandomvariableisgreaterthanagivenvalue).Thecomplementarydistributionfunctionisoftenusedwhentheinterestisinthetailbehavior.Thereisoneplotforeachofthesixgeographicareas.Notethatrangeonthey‐axisvaries.Tointerprettheseplots,considerthefirstone,forNorthAmerica,andtheredlinerepresentingv6packetlosstotunneledv6interfaces.Thepoint(5,0.2)ontheplotmeansthat20%ofthemeasurementshadpacketlossof5%ormore.TheseplotsemphasizetheobservationsmadeinSection2.Thehigherv6packetlosstotunneledinterfacesisclearlyevident.

Figure7.ComplementaryDistributionFunctionsofPacketLoss





8 AppendixB.AdditionalLatencyDistributionsThefollowingplotsareanalogoustothoseinSection3exceptinadditiontodisplayingthecaseofallthedestinationsinagivengeo‐region,alsoshownisthepartitionofdestinationsintonativeandtunneled.Therangeontheaxesisheldconstantacrosstheplots,andischosentohighlighttheportionwherethereisthemostaction.(Thedistributionsdoincreaseto1,ifthefullrangeonthex‐axiswereshown.)Notethatthedistributiongivennative(blueline)liesabovethatgiventunneled(redline).Thisimpliesthattheamountthattransportisbetteroverv4(inthesenseoflowerlatency)isgreaterfordestinationswithv6tunneledinterfacesthanfornative.Forexample,considerthe0.5valueonthey‐axis,themedian.ForNorthAmerica,50%ofthetimethev4latencyisatleast14msbetterthanv6fornativedestinations(blueline),andissignificantlymore,atleast40msbetterfortunneleddestinations(redline).ForSouthAmerica,thesetimesare7msand43ms.Foranotherviewpointonthesameconcept,considerSouthAmerica(andlookingat20msonthex‐axis,andtakingthecomplementofthey‐value),fordestinationswherev6istunneled(redline),thev4latencyisbetterbyatleast20ms68%ofthetime,whereasfordestinationswherev6isnative,thev4latencyisbetterbyatleast20msonly31%ofthetime.Lookingat‐20msonthex‐axis,v6isbetterbyatleast20ms14%ofthetimefornativeinterfacesandisbetterbyatleast20msnotasfrequently,5%ofthetime,fortunneledinterfaces.

Figure8.Distributionofdifferenceinlatencies,partitionedbyv6interface




Documents

Working Paper on Comparison of Performance over IPv6 versus