资源描述：
《最新What is the Internet Yale University什么是互联网耶鲁大学教学讲义PPT.ppt》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。
1、WhatistheInternetYaleUniversity什么是互联网耶鲁大学IntroductionBGPisrelativelyeasytogetconfiguredandbasicallyannouncingandusingroutes.Itisdifficulttoscaletothetens-to-hundredsofroutersscalewithfulliBGPmesh,AS-Pathfilters,andAS-Pathpaddingastheonlytools.WepresentCommunities,Confederat
2、ions,andlocal-prefuse,andsomeotherfeatures,andshowthemusedincontext.Topics(1)ReviewbasicBGPconceptsSimpleBGPScalingconceptsInsertingBGPRoutesStableRoutingandScalingw/LoopbacksSaveCPUandTypingw/Peer-GroupsMeaningfulMEDsBGPIntroBGP4istheprotocolusedontheInternettoexchangerout
3、inginformationbetweenproviders,andtopropagateexternalroutinginformationthroughnetworks.EachautonomousnetworkiscalledanAutonomousSystem.ASswhichinjectroutinginformationontheirownbehalfhaveASNs.BGPPeeringBGP-speakingrouterspeerwitheachotheroverTCPsessions,andexchangeroutesthr
4、oughthepeeringsessions.Providerstypicallytrytopeeratmultipleplaces.EitherbypeeringwiththesameASmultipletimes,orbecausesomeASsaremulti-homed,atypicalnetworkwillhavemanycandidatepathstoagivenprefix.TheBGPRouteTheBGProuteis,conceptually,a“promise”tocarrydatatoasectionofIPspace
5、.Therouteisa“bag”ofattributes.ThesectionofIPspaceiscalledthe“prefix”attributeoftheroute.AsaBGProutetravelsfromAStoAS,theASNofeachASisstampedonitwhenitleavesthatAS.CalledtheAS_PATHattribute,or“as-path”inCisco-speak.BGPRouteAttributesInadditiontotheprefix,theas-path,andthenex
6、t-hop,theBGProutehasotherattributes,affectionatelyknownas“knobsandtwiddles”-weight,rarelyused-“sledgehammer”local-pref,sometimesused-“hammer”origincode,rarelyusedMED(“metric”)-agentlenudgeSequenceofAS(s)aroutehastraversed.Providesamechanismforloopdetection.Policiesmaybeappl
7、iedbasedonASpath.LocalASaddedonlywhensendtoexternalpeer.ShortestASpathpreferredASPathAS3847207.240.0.0/16AS1673140.222.0.0/16AS701 192.67.95.0/24AS3561204.70.0.0/15192.67.95.0/243847701i140.222.0.038471673i204.70.0.0/1538473561i207.240.0.0/163847iAS6201ECFGDBANext-hopIPaddr
8、esstoreachanetwork.RouterAwilladvertise198.3.97.0/24torouterBwithanext-hopof207.24
