1-8-IP地址_VLSM

©2007CiscoSystems,Inc.Allrightsreserved.ICND2v1.0—3-1UnderstandingVLSM西邮普创思科网络技术实验室©2007CiscoSystems,Inc.Allrightsreserved.ICND2v1.0—3-2Decimalnumbersarerepresentedbythenumbers0through9.Binarynumbersarerepresentedbyaseriesof1sand0s.Decimalvs.BinaryNumbers©2007CiscoSystems,Inc.Allrightsreserved.ICND2v1.0—3-3DecimalandBinaryNumbersChartMSBLSBBaseexponent107106105104103102101100ColumnValue63204829DecimalWeight100000001000000100000100001000100101ColumnWeight60000000300000020000004000800209Base-10DecimalConversion—63204829MSBLSBBaseexponent2726252423222120ColumnValue11101001DecimalWeight1286432168421ColumnValue128643208001Base-2BinaryConversion—1110100(233)60000000+3000000+200000+0+4000+800+20+9=63204829128+64+32+0+8+0+0+1=233©2007CiscoSystems,Inc.Allrightsreserved.ICND2v1.0—3-4Powersof2©2007CiscoSystems,Inc.Allrightsreserved.ICND2v1.0—3-5Decimal-to-BinaryConversion35=25+21+2035=(32*1)+(2*1)+(1*1)35=0+0+1+0+0+0+1+135=00100011©2007CiscoSystems,Inc.Allrightsreserved.ICND2v1.0—3-6Binary-to-DecimalConversion10111001=(128*1)+(64*0)+(32*1)+(16*1)+(8*1)+(4*0)+(2*0)+(1*1)10111001=128+0+32+16+8+0+0+110111001=185©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-7InternetProtocolCharacteristicsOperatesatnetworklayerofOSIConnectionlessprotocolPacketstreatedindependentlyHierarchicaladdressingBest-effortdeliveryNodata-recoveryfeatures©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-8WhyIPAddresses?TheyuniquelyidentifyeachdeviceonanIPnetwork.Everyhost(computer,networkingdevice,peripheral)musthaveauniqueaddress.HostID:–Identifiestheindividualhost–Isassignedbyorganizationstoindividualdevices©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-9IPPDUHeader©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-10IPAddressFormat:DottedDecimalNotationThebinary-to-decimalanddecimal-to-binaryconversionwillbedetailedlaterinthiscourse.©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-11IPAddressClasses:TheFirstOctet©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-12IPAddressRanges*127(01111111)isaClassAaddressreservedforloopbacktestingandcannotbeassignedtoanetwork.©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-13ReservedAddress•DirectedBroadcastAddress(ex.172.16.0.0/16172.16.255.255)•LocalBroadcastAddress(ex.255.255.255.255)©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-14PrivateIPAddressesClassPrivateAddressRangeA10.0.0.0to10.255.255.255B172.16.0.0to172.31.255.255C192.168.0.0to192.168.255©2007CiscoSystems,Inc.Allrightsreserved.ICND2v1.0—3-15WhataSubnetMaskDoesTellstherouterthenumberofbitstolookatwhenroutingDefinesthenumberofbitsthataresignificantUsedasameasuringtool,nottohideanything©2007CiscoSystems,Inc.Allrightsreserved.ICND2v1.0—3-16OctetValuesofaSubnetMaskSubnetmasks,likeIPaddresses,arerepresentedinthedotteddecimalformatlike255.255.255.0©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-17FlatTopologyProblemsAlldevicessharethesamebandwidth.Alldevicessharethesamebroadcastdomain.Itisdifficulttoapplyasecuritypolicy.©2007CiscoSystems,Inc.Allrightsreserved.ICND1v1.0—1-18SubnetworksSmallernetworksareeasiertomanage.Overalltrafficisreduced.Youcanmoreeasilyapplynetworksecuritypolicies.©2007CiscoSystems,Inc.Allrightsreserved.ICND2v1.0—3-19SubnettingReviewToidentifysubnets,youwill“borrow”bitsfromthehostIDportionoftheIPaddress:Thenumberofsubnetsavailabledependsonthenumberofbitsborrowed.–Theavailablenumberofsubnets=2s,Iwhichsisthenumberofbitsborrowed.ThenumberofhostspersubnetavailabledependsuponthenumberofhostIDbitsnotborrowed.–Theavailablenumberofhostspersubnet=2h-2,inwhichhisthenumberofhostbitsnotborrowed.–Oneaddressisreservedasthenetworkaddress.–Oneaddressisreservedasthebroadcastaddress.©2007CiscoSystems,Inc.Allrightsreserved.ICND2v1.0—3-20PossibleSubnetsandHostsforaClassCNetwork©2007CiscoSystems,Inc.Allrightsreserved.ICND2v1.0—3-21PossibleSubnetsandHostsforaClassBNetwork©2007CiscoSystems,Inc.Allrightsreserved.ICND2v1.0—3-22PossibleSubnetsandHostsforaClassANetwork©2007CiscoSystems,Inc.Allrightsreserved.ICND2v1.0—3-23SubnettingReviewExerciseSubnetanetworkwithaprivatenetworkaddressof172.16.0.0./16sothatitprovides100subnetsandmaximizesthenumberofhostaddressesforeachsubnet.Howmanybitswillneedtobeborrowed?Whatisthenewsubnetmask?Whatarethefirstfoursubnets?Whataretherangeofhostaddressesforthefoursubnets?©2007CiscoSystems,Inc.Allrightsreserved.ICND2v1.0—3-24ProcedureforImplementingSubnets1.DeterminetheIPaddressassignedbytheregistryauthority.2.Basedontheorganizationalandadministrativestructure,determinethenumberofsubnetsrequired.3.Basedontheaddressclassandrequirednumberofsubnets,determinethenumberofbitsyouneedtoborrowfromthehostID.4.Determinethebinaryanddecimalvalueofthesubnetmask.5.ApplythesubnetmasktothenetworkIPaddresstodeterminethesubnetandhostaddresses.6.Assignsubnetaddressestospecificinterfaces.©2007CiscoSystems,Inc.Allrightsreserved.ICND2v1.0—3-25EightEasyStepsforDeterminingSubnetAddresses©2007CiscoSystems,Inc.Allrightsreserved.ICND2v1.0—3-26EightEasyStepsforDeterminingSubnetAddresses(Cont.)©2007Cisco