Ender204426777乾颐堂CCNAv3.0课程Part1(ICND1)v3.0EstablishingInternetConnectivityUnderstandingtheTCP/IPInternetLayer理解互联网层乾颐堂CCNAv3.0Ender204426777InternetProtocolIPcharacteristics:•OperatesattheinternetlayeroftheTCP/IPstack•Connectionlessprotocol无连接协议•Packetstreatedindependently独立处理报文•Hierarchicaladdressing结构化的编址•Best-effortdelivery尽力而为的转发•Nodata-recoveryfeatures•Media-independent与媒介无关•Twovariants:IPv4andIPv6EnderICND1—2-3乾颐堂CCNAv3.0Ender204426777IPv4AddressRepresentation•Everyhost(computer,networkingdevice,peripheral)musthaveauniqueaddress.•AnIPaddressconsistsoftwoparts:–NetworkID:•Identifiesthenetworkofwhichthehostisapart-主机所处的网段•Usedbyrouterstomaintaininformationaboutroutes-路由器维护的路由表–HostID:•Identifiestheindividualhost-唯一的表示主机•Assignedbyorganizationstoindividualdevices-被组织分配给设备EnderICND1—2-4乾颐堂CCNAv3.0Ender204426777IPv4HeaderAddressFieldsVer.IHLServiceTypeTotalLengthIdentificationFlagFragmentOffsetTimetoLiveProtocolHeaderChecksumSourceAddressDestinationAddressOptionsPaddingEnderICND1—2-5乾颐堂CCNAv3.0Ender204426777DecimalandBinarySystems十进制和二进制•Decimalnumbersarerepresentedbythenumbers0through9.•Binarynumbersarerepresentedbyaseriesof1sand0s.EnderICND1—2-6乾颐堂CCNAv3.0Ender204426777Decimal-to-BinaryConversionBaseExponent2726252423222120PlaceValue1286432168421Example:Convertdecimal35tobinary0010001135=(27*0)+(26*0)+(25*1)+(24*0)+(23*0)+(22*0)+(21*1)+(20*1)35=(32*1)+(2*1)+(1*1)35=0+0+1+0+0+0+1+135=00100011EnderICND1—2-7302/2=151余0151/2=75余175/2=37余137/2=18余118/2=9余09/2=4余14/2=2余02/2=1余0故302的二进制为10010111035/2=17余117/2=8---18/2=4----04/2=2----02/2=1----01/2=0----1所以35的二进制为00100011乾颐堂CCNAv3.0Ender204426777IPAddressClassesEnderICND1—2-8还有D类的组播地址1110XXXX224-239E类的实验用的地址乾颐堂CCNAv3.0Ender204426777IPAddressClasses(Cont.)IPAddressRangesIPAddressClassFirstOctetDecimalValueFirstOctetBinaryValuePossibleNumberofHostsClassA1–1260...
