efficient因特网是什么

Internetpeering:WhatdoesitmeanfordevelopingcountriesTimKelly--ITUTheinternationaltelecommunicationsregimehastraditionallybeencharacterisedbybilateral,correspondentrelationsbetweencountries,operatingunderwhatisknownastheaccountingratesystem.
Thissystem,rootedintheprincipleofnationalsovereignty,hasoperatedinoneformoranotherformorethanonehundredyearsandisbasedaninternationaltreaty,theInternationalTelecommunicationRegulations(ITR),lastrevisedin1988.
Thissystemisbasedonrevenue-sharingratherthancost-orientationandisoftenblamedforkeepingthepriceofinternationaltelephonecallsattoohighalevel.
Whiletheaccountingratesystemisremarkableforitslongevity,itisnowwidelyperceivedtobeindangerofcollapse,underpressurefromcompetitivemarketentry,technologicalchangeandby-pass.
TheInternethasevolvedaverydifferentsystemofrelationsbetweennetworkswhichmightbroadlybedescribedaspeeringarrangements.
Trafficisexchangedbetweennetworksinamannerwhichisindependentofitsultimateoriginanddestination.
Whilepeeringbeganasaconvenientandnon-for-profitarrangementbetweenacademicnetworks,ithassubsequentlybecomemorecommercialwiththeprogressiveprivatisationoftheInternetbackbone.
Peeringarrangementsarenotcurrentlyregulatedandarenotsubjecttoanyinternationaltreaty.
ItiswidelybelievedthatnetworksrunningIPtrafficbecomethemajorbearerforbothvoiceanddatatrafficinthefuture.
Ifso,doesthismeanthatpeeringarrangementswillsteadilyreplacetheaccountingratesystemonthepublicnetworkInparticular,whataretheimplicationsofsuchashiftfordevelopingcountries,whoareamongthemajorbeneficiariesofpaymentsmadeundertheexistingregimeWillthetransitionfromahalf-circuittoawhole-circuitregimemeanthatdevelopingcountriesenduppaying,ratherthanreceivingmoney,toterminatetrafficWhatpotentialrolecouldinternationalorganisations,suchastheITU,playWhyistheInternetsocheapProbablythesinglemostimportantfactorinexplainingthephenomenalsuccessoftheInternetisthatitischeap,oratleastispopularlyperceivedtobecheap.
Ofcourse,whenoneremembersthatpossessionofaPersonalComputer,appropriatesoftware,amodemandatelephonelineareallfairlyessentialprerequisitesforInternetaccess,thenmaybeitisnotsocheap,especiallyfordevelopingcountrycitizens.
Andwhenoneaddstothattheconstantpressurefromthecomputerindustrytoupgradetothelatestmodels,touseahigherbandwidthconnection,ortostartpayingforinformationthatwaspreviouslyavailableforfree,thenInternetbeginstolookdistinctlylikealuxuryitem.
TheperceptionthatInternetischeapreallyrelatestotheusagecostsratherthanthefixedcosts.
Formanyusers,theirinitialcontactwiththeInternetwouldbeatschooloruniversity,orperhapsatwork,wherethefixedcostsofinstallationandmaintenancearelargelyhiddentothem.
Thustheyareawareprimarilyofthe"saving"theyaremaking,say,byplacingatelephonecallovertheInternetratherthanoverafixedlinenetwork,ratherthanthetotalpictureofwhatthatcallcosts.
Certainly,therateswhichareavailableforanInternettelephonycallareconsiderablycheaperthanforanequivalenttelephonycall,especiallywhenthecallcrossesinternationalborders.
WhyshouldperminuteusagecostsforinternationaltelephonecallsontheInternetbesomuchlowerthanonthepublicswitchedtelephonenetwork(PSTN)Afterall,theybothusethesamecablesandthesamecopper:ThestraightforwardansweristhattheInternetusestheavailablecapacityinamoretechnicallyefficientmanner.
AtypicalcallplacedoverthePSTNwouldoccupyaduplex(two-way)circuitfortheentiredurationofthecall,includingthepausesbetweenwordsorbetweenreplies.
AcallplacedovertheInternethowevercouldtheoreticallyberoutedoverseveraldifferentcircuits,eachofwhichwouldbeoccupiedforafewthousandthsofasecondatatime,aspacketsareroutedacrossthenetworktobereassembledatthedistantend.
ThePSTNisoptimisedforvoicetransmission,sampledin8bitbytes,8'000timesasecond,foranaggregaterateof64kbit/s.
TheInternet,bycontrast,isdesignedtobeplatformindependent,collectingandterminatingtrafficuptothemaximumspeedthattheweakestlinkonthenetworkwillbear.
ThequalityoftheInternetconnectionmaybelower,butit'sefficiencywillinvariablybehigher.
AfurtherelementisthegreatercapacityutilisationachievedforInternetuse.
TheInternetisengineeredtomeetaverageloads,andthetypicalutilisationoveranextendedtimeperiodisaround60-70percent.
Bycontrast,thePublicSwitchedTelephoneNetworkisengineeredtomeetthebusinesspeakhourandthusutilisationistypicallybelow20percent.
Athirdfactoriseconomiesofscale.
IfyoucoulddrawthePSTN,itwouldlooklikeadensemeshofconnectionsinthatmostofthenodesinthenetworkareconnectedtoeveryothernodeor,iftheylackadirectconnection,couldbeconnectedbyjustoneintermediary.
Bycontrast,apictureoftheInternetwouldlookmuchmorelikeanairlineroutemapinwhichasmallnumberofhubsareconnectedtoeachotherandareeachsurroundedbyastar-shapednetworkoflocalpeeringarrangements.
Atypicalinternationalvoicetelephonycallwouldpassbetweenthehandsortwoorperhapsthreecarriers;atypicalInternettelephonycallwouldpassthroughanaverageof15hopsandmultipledifferentcarriers.
Thelogicoftheroutingisunrelatedtogeographyandinsteadrelatedtothevolumeoftrafficflows.
Trafficgravitatestothickroutes,thatisthosecableswhichhavethehighest(available)capacity.
TheseareinvariablytheoneswithintheUnitedStates,orwhichlinktheUnitedStatestoothercountries.
Whattheseexamplesillustrateisthatthe"cheapness"oftheInternetdependsonone'sviewpoint.
Internetappearcheapifoneconsidersusagecostsonlyratherthanthecompletepictureofusageandfixedcharges.
Similarly,Internetappearscheapwhencomparedtocomparableinternationalcallsbutlesssowhencomparedtolocalcalls.
TheInternetisalsocheapertheclosertheuseristoahighbandwidthpipe.
ThatmeansthatittendstobemoreexpensiveforusersoutsidetheUnitedStates.
WhyareinternationaltelephonecallssoexpensiveThecorollarytothequestion"WhyistheInternetsocheap"is"Whyisthetelephonenetworksoexpensive",particularlyforinternationalcalls.
Typically,auserin,say,sub-SaharanAfrica,wouldpaymanytimesmoreforathreeminuteinternationaltelephonecalltotheUnitedStatesthantheywouldtobeloggedonforanhourorsotoawebsitelocatedintheUnitedStates.
Andyet,thefacilitiesusedinthetwocallswouldbesimilar.
Indeed,thetwomessageswouldprobablypassundertheAtlanticonthesamecable,albeitondifferentfibrestrands,withthetelephonemessagebringingperhapsahundredtimesmorerevenuetothecarriersinvolvedthanthewebbrowsingsession.
Thesimple,thoughnotentirelyconvincinganswertothequestionisthatinternationaltelephonecallsareexpensivebecausetheyhavealwaysbeenexpensive.
Originally,internationaltelephonecallswerepricedasaluxurycommoditybecausethebandwidththatconveyedthem—initiallyHFradio,latersatellitesandunderseacables—wasinshortsupply.
Themostsignificantpricereductionsininternationalservicewereachievedinthe1960sand1970s.
Sincetheearly1980sthepricehasbeenrelativelystable(albeitdecreasingrelativetoinflation).
Ontheotherhand,thecostsofterminatingthecall,asshownbythesettlementrate,havefallensubstantiallyonalmostallroutes.
Since1995,theaveragerateofreductioninsettlementratesgloballyhasbeenoftheorderof12percentperyear,andin1998thereductionislikelytoexceed20percent.
Thishasbeenmuchfasterthantherateofreductioninprices,hencecreatingscopeforserviceswhicharbitragethedifferencebetweenthepriceoforiginatingacallandterminatingit,suchascall-back.
Furthermore,theunderlyinginfrastructurecostsfortransmissionofinternationalcallshavebeenfallingevenfaster.
Onthetrans-Atlanticroute,forinstance,thecostoftheAC-1cable,completedin1998,isjustoverUS$300per64kbit/scircuitperyear,whereastheTAT-8cable,completedadecadeearlier,costmorethanUS$10'000percircuitperyear.
Tothispriceerosioncanbeaddedthefactthatthepossibilitiesfordatacompressionhavealsoincreasedsignificantlyduringthatperiod.
Theoverallconclusionthereforemustbethatthecostreductionsbeingachievedthroughtechnologicalchangeandsettlementratereformarenotbeingpassedoninfulltotelephonyconsumers.
Itisthusnotsurprisingthatthereisconsiderablyinterest,indevelopingcountriesaswellasdevelopedones,inthepotentialforInternetTelephony,tobringlowerpricesforconsumers.
Settlementsandpeering:What'sthedifferenceFordevelopingcountries,theimplicationsofashiftawayfromsettlementstowardsapeeringregimearemixed.
Ontheonehand,itcouldmeanareductioninpriceforoutgoinginternationalcallsifthepromiseofInternetTelephonyisembraced.
Ontheotherhand,itcouldmeanthatinpaymentsreceivedforterminatinginternationalcallsaresubstantiallyreduced.
DevelopingcountriesareestimatedtogainsomeUS$7-10billionperyearinnetsettlements,muchofwhichcomesfromtheUnitedStates.
Asthesepaymentsaremadeintheformofregularmonthlycheques,cashedinhardcurrency,theyformaninvaluablesupportforadevelopingcountry'sbalanceofpayments,aswellastheirtelecommunicationinfrastructureinvestmentprogramme.
Anincominginternationaltelephoneorfaxcallwouldbringwithitasettlementpaymentofuptoacoupleofdollarsperminute.
Bycontrast,anincomingInternetcallwhichispatchedtothePSTNmightbringonlysufficientrevenuetocoverthecostofalocalcall,whichwouldamount,atmost,toafewUScentsperminute.
Indeed,inthecasewherethedevelopingcountryInternetServiceProvider(ISP)paysforthewholecircuitwhichconnectsittotheInternetbackbonenetwork,sayintheUnitedStates,thenitmayfindthatitactuallylosesmoneyonthetransactionaswellasthelostsettlementpayment.
ThedifferencebetweenthetreatmentofanincomingPSTNcallandanInternetTelephonycallisillustratedinFigure1.
Intheleftchart,thedevelopedcountrypublictelecommunicationoperator(PTOA)whichdeliversaPSTNcalltothedevelopingcountry(PTOB),alsomakesasettlementpayment,inlinewithitscorrespondentrelationshipwithPTOB.
Thiswouldnormallybehalfoftheaccountingratenegotiatedbetweenthetwo.
Intherightchart,anInternetServiceProviderinadevelopedcountry(ISPA)picksupacallwhichitpassesontoitslocalInternetExchangePoint(IXPX).
ThisisthendeliveredtoanIXPwithpeeringarrangementswiththedestinationcountry(IXPY).
ItisthendeliveredoveraleasedlinetoISPBinthedevelopingcountry(presumingISPBhasnodirectpeeringarrangementswithIXPX)whereitispatchedontothePSTNanddeliveredtotheuser.
ThereisnofinancialpaymentwhatsoeverbetweenISPAandISPB,exceptinsofarasISPBisabletorecoverthecostofalocaltelephonecall(thoughtheprocessofbillingthiscallfromISPAmayprovetobemoreexpensivethanthecallitself!
).
FurthermoreISPBmayactuallybecross-subsidisingthecallinthatitispayingforthewholecircuitleasedlinetoIXPYinaforeigncountry.
ItisrequiredtopayforthecostsbecauseISPB'suserswishtobrowsecontentonwebsitesintheforeigncountry(invariablytheUnitedStates).
ThustheincomingInternetTelephonycalliseffectivelyfreeridingthenetwork.
Figure1:EquityandinequityContrastbetweenaccountingandsettlementarrangementsfromdevelopedcountryAtodevelopingcountryB,viathePublicTelephoneNetworkandtheInternetSource:ITU"ChallengestotheNetwork:Internetfordevelopment",1998.
StrategiesfordevelopingcountriesDevelopingcountriesuptonowhavebeenmuchmorefocusedontheimplicationsofaccountingratereformthanonanypossibleimplicationsofInternetpeeringarrangements.
Forinstance,whentheFCC,theUSregulator,launcheditsNoticeofProposedRulemakinglatein1997ontheso-called"benchmarking"ofsettlementrates,itdrewcomplaintsfromsome90countries,manyofthemdeveloping.
Ontheotherhand,littleattentionhasbeenpaidtoInternetPeering.
FewdevelopingcountrieshavedevelopedpoliciesforInternettelephonyandfewerstillhavequestionedexistingpeeringarrangements.
Itmaywellbethatdevelopingcountrieshavebeenfightingyesterday'sbattlesratherthantomorrow'swars.
Settlementratesareundoubtedlytrendingtowardscosts,albeitmoreslowlythanmostconsumerswouldlike.
Developingcountriesmayconceivablybeabletoslowthisprocessdown,butonlyatthecostofseeinglargetrafficstreamsleavingtheaccountingratesystemaltogether.
Ontheotherhand,pricesforinternationalleasedlinesremainstubbornlyhigh,bothforhalfcircuitsfromtheUnitedStatesandforhalfcircuitsfromdevelopingcountries.
DevelopingcountrieswantingtoconnecttotheInternethavetopayforboth.
Whatthismeansisthat,asmoretrafficshiftsoffpublicswitchednetworksandontotheInternetwhichoperatesoverleasedlines,thenitwillbethepriceoftheleasedlineswhichwillbecomethemajordeterminantofservicecosts.
Furthermore,thetraditionalsystemofcostandrevenue-sharingforinternationalservicesislikelytobeeclipsedbyanewparadigmofdevelopingcountrieshavingtopaythefullcostsofbothhalfcircuits,aswellaspayingforpeering,iftheywanttoconnecttotheInternetbackbone.
Thereisaveryrealdangerthandevelopingcountriesmayhavetopayalotmorethandevelopedcountriesiftheywanttoavoidbeingbypassedbytheglobalinformationsuperhighway.
TheITUistryingtobringtheattentionofpolicy-makersindevelopingcountriestothisissue.
AccountingratereformdiscussionsarecurrentlybeingdebatedonafasttrackbasisthroughaFocusGroup,setupinMarch1998andduetoreporton6thNovember1998.
Also,aRapporteur'sGrouphasbeenestablishedtoexaminetheinternationalcostcomponentsoftheInternet.
BothGroupsareduetoreporttoITU-TStudyGroup3atitsDecember1998meeting.
Thusthe300orsoexpertsfromaroundtheworldwhoattendthemeetingwillhavethechancetodebatethelinkagebetweenaccountingratereformandInternetpeeringarrangementsinthesameforum.
Inalllikelihood,itistheaccountingratereformissuethatwilldominatethemeetingandgraballtheheadlines.
ButitislikelytobeInternet-stylepeeringarrangementswhichwilldominatethepublicnetworkinthecomingdecade.
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