第2章－IP子网划分和VLSM.ppt

IP子网划分和VLSMIPSubnettingandVLSM,熊金波jbxiong福建师范大学软件学院,教学目标（Objectives）,1.IP地址表示（RepresentationofIPAddress）2.IP地址分类（ClassofIPAddress）3.保留和私有地址（ReservedandPrivateIPAddress）4.网络掩码和子网划分（NetworkMaskandSubnetting）5.可变长度子网掩码（VLSM）6.使用VLSM设计自己的网络（DesignOurNetworkUsingVLSM）7.路由汇总（Summarization）8.IP寻址故障诊断（IPAddressingTroublesDiagnosis）,1IP地址表示（RepresentationofIPAddress）,为了容易使用，采用点分十进制格式来表示IP地址TomaketheIPaddresseasiertouse,theaddressisusuallywrittenasfourdecimalnumbersseparatedbyperiods,192.168.123.2,2IP地址的类别（ClassofIPAddress）,3保留地址（ReservedAddress）,保留地址指某些地址不能分配网络上的设备使用Certainhostaddressesarereservedandcannotbeassignedtodevicesonanetwork.1.主机部分全0表示网络地址AnIPaddressthathasbinary0sinallhostbitpositionsisreservedforthenetworkaddress.2.主机部分全1表示广播地址AnIPaddressthathasbinary1sinallhostbitpositionsisreservedforthebroadcastaddress.3.全0的IP地址，即0.0.0.0。设置缺省路由时使用。AnIPaddressthathasbinary0sinallbitpositionsisreservedfordefaultroute4.全1地址255.255.255.255，表示泛洪广播AnIPaddressthathasbinary0sinallbitpositionsisreservedforfloodbroadcast,私有地址（PrivateIPAddress）,1.私有地址可以节省IP地址PrivateIPaddressesareanothersolutiontotheproblemoftheimpendingexhaustionofpublicIPaddresses.2.私有地址不能在Internet上被路由PrivateIPaddressesarenotroutedontheInternetbackbone.,Exercise:IPAddressClasses,Address,Class,Network,Host,10.2.1.1,128.63.2.100,201.222.5.64,192.6.141.2,130.113.64.16,256.241.201.10,IPAddressClassesExerciseAnswers,网络掩码的作用（FunctionofNetworkMask）,10101100000100000000001010100000172.16.2.16011111111111111110000000000000000255.255.0.010101100000100000000000000000000172.16.0.0,NetworkID,4网络掩码（NetworkMask）,A类：255.0.0.0,B类：255.255.0.0,C类：255.255.255.0,子网划分（Subnetting）,为了克服有限的IP地址，所有类别网络可以被划分为更小的子网。ToefficientlymanagealimitedsupplyofIPaddresses,allclassescanbesubdividedintosmallersubnetworks.,划分子网原因（ReasonsforSubnetting）,1.提供灵活的编址ProvidesaddressingflexibilityProvides2.提供广播抑制BroadcastContainment3.为LAN提供低水平的安全Low-levelsecurityontheLAN.,简单实例（SimpleCase）,介绍子网划分（IntroductiontoSubnetting）,介绍子网划分（IntroductiontoSubnetting）,划分子网要从主机位借位Hostbitsmustarereassigned(or“borrowed”)asnetworkbits.,3bitsborrowedallows23-2or6subnets,5bitsborrowedallows25-2or30subnets,12bitsborrowedallows212-2or4094subnets,Comparisonbetweendecimalandbinary,ClasslessInter-DomainRouting(CIDR),CIDR值:1.掩码255.0.0.0:/8(A类地址默认掩码)2.掩码255.128.0.0:/93.掩码255.192.0.0:/104.掩码255.224.0.0:/115.掩码255.240.0.0:/126.掩码255.248.0.0:/137.掩码255.252.0.0:/148.掩码255.254.0.0:/159.掩码255.255.0.0:/16(B类地址默认掩码)10.掩码255.255.128.0:/1711.掩码255.255.192.0:/1812.掩码255.255.224.0:/19,13.掩码255.255.240.0:/2014.掩码255.255.248.0:/2115.掩码255.255.252.0:/2216.掩码255.255.254.0:/2317.掩码255.255.255.0:/24(C类地址默认掩码)18.掩码255.255.255.128:/2519.掩码255.255.255.192:/2620.掩码255.255.255.224:/2721.掩码255.255.255.240:/2822.掩码255.255.255.248:/2923.掩码255.255.255.252:/30,ClasslessInter-DomainRouting(CIDR),划分子网的几个捷径(ShortcutsofSubnetting),1、你所选择的子网掩码将会产生多少个子网?-2的x次方-2(x代表掩码位，即2进制为1的部分)2、每个子网能有多少主机?-2的y次方-2(y代表主机位，即2进制为0的部分)3、合法子网是多少?-块大小=256-10进制的子网掩码(结果叫做blocksize或basenumber)，从0开始以块大小递增，即可得到合法子网。4、每个子网的广播地址是?-广播地址=下个子网号-15、每个子网的有效主机范围分别是?-忽略子网内全为0和全为1的地址剩下的就是有效主机地址。最后有效1个主机地址=下个子网号-2(即广播地址-1),实例1：C类地址2位子网化（E.g1TwoBitsSubnettingforClassC）,子网号（Subnet）地址范围（range）0000000000000000100111111162其中:0为网络地址，63为广播地址0100000064010000010111111165127其中:64为网络地址，127为广播地址100000001281000000110111111129191其中:128为网络地址，191为广播地址110000001921100000111111111193255其中:192为网络地址，255为广播地址,实例2：C类地址4位子网化（E.g24BitsSubnettingforClassC）,组合子网号地址范围0000000000000000100001111115其中：15为广播地址000100001600010001000111111731其中：31为广播地址001000003200100001001011113347其中：47为广播地址001100004800110001001111114963其中：63为广播地址010000006401000001010011116579其中：79为广播地址010100008001010001010111118195其中：95为广播地址0110000096011000010110111197111其中：111为广播地址011100001120111000101111111113127其中：127为广播地址100000001281000000110001111129143其中：143为广播地址100100001441001000110011111145159其中：159为广播地址101000001601010000110101111161175其中：175为广播地址101100001761011000110111111177191其中：191为广播地址110000001921100000111001111193207其中：207为广播地址110100002081101000111011111209223其中：223为广播地址111000002241110000111101111225239其中：239为广播地址111100002401111000111111111241255其中：255为广播地址,可用的子网和主机数（NumberofUsableSubnetsandHosts）,usablesubnets(2powerofborrowedbits)2usablehosts=(2powerofremaininghostbits)2,C类地址划分子网情况汇总（SummaryofClassCSubnetting）,WrittenExercise:SubnetMasks,Address,SubnetMask,Class,Subnet,172.16.2.10,10.6.24.20,201.222.10.60,255.255.255.0,255.255.240.0,255.255.255.248,SubnetMaskExerciseAnswers,5可变长度子网掩码（Variable-LengthSubnetMask）,HQ,172.16.0.0/16,可变长度子网掩码（Variable-LengthSubnetMask）,HQ,172.16.1.0/24,172.16.2.0/24,HQ,172.16.0.0/16,172.16.14.32/27,172.16.14.64/27,172.16.14.96/27,可变长度子网掩码（Variable-LengthSubnetMask）,C,B,A,将子网172.16.14.0/24划分为更小的子网，首先掩码长度为27Subnet172.16.14.0/24isdividedintosmallersubnets:Subnetwithonemaskatfirst(/27),HQ,172.16.1.0/24,172.16.2.0/24,HQ,172.16.0.0/16,172.16.14.32/27,172.16.14.64/27,172.16.14.96/27,将没有使用的掩码长度为27的子网进一步划分为掩码长度为30Subnetwithonemaskatfirst(/27)Furthersubnetoneofthesesubnetsnotusedelsewhere(/30),C,B,A,HQ,172.16.1.0/24,172.16.2.0/24,HQ,172.16.0.0/16,172.16.14.136/30,172.16.14.132/30,172.16.14.140/30,可变长度子网掩码（Variable-LengthSubnetMask）,主机30台以内,计算VLSM（CalculatingVLSMs）,SubnettedAddress:172.16.32.0/20InBinary10101100.00010000.00100000.00000000,计算VLSM（CalculatingVLSMs）,VLSMAddress:172.16.32.0/26InBinary10101100.00010000.00100000.00000000,SubnettedAddress:172.16.32.0/20InBinary10101100.00010000.00100000.00000000,计算VLSM（CalculatingVLSMs）,Network,Subnet,VLSMsubnet,Host,1,0,1,0,1,1,0,0,.,0,0,0,1,0,0,0,0,.,0,0,1,0,0,0,0,0,.,0,0,0,0,0,0,0,0,=,172.16.32.0/26,1stsubnet:,VLSMAddress:172.16.32.0/26InBinary10101100.00010000.00100000.00000000,SubnettedAddress:172.16.32.0/20InBinary10101100.00010000.00100000.00000000,SubnettedAddress:172.16.32.0/20InBinary10101100.00010000.00100000.00000000,VLSMAddress:172.16.32.0/26InBinary10101100.00010000.00100000.00000000,1stsubnet:,1,0,1,0,1,1,0,0,.,0,0,0,1,0,0,0,0,.,0,0,1,0,0,0,0,0,.,0,0,0,0,0,0,0,0,=,172.16.32.0/26,1,7,2,.,16,.,0,0,1,0,0,0,0,0,.,0,1,0,0,0,0,0,0,=,172.16.32.64/26,1,7,2,.,16,.,0,0,1,0,0,0,0,0,.,1,0,0,0,0,0,0,0,=,172.16.32.128/26,1,7,2,.,16,.,0,0,1,0,0,0,0,0,.,1,0,0,0,0,0,0,=,172.16.32.192/26,1,7,2,.,16,.,0,0,1,0,0,0,0,1,.,0,0,0,0,0,0,0,0,=,172.16.33.0/26,Network,Subnet,VLSMSubnet,Host,1,2ndsubnet:,3rdsubnet:,4thsubnet:,5thsubnet:,计算VLSM（CalculatingVLSMs）,6练习：使用VLSM规划自己的网路（Exercise:DesignOurNetworkUsingVLSM）,(62Hosts),(62Hosts),(62Hosts),(62Hosts),练习答案（ExerciseAnswer）,172.16.33.0/30,172.16.33.4/30,172.16.33.8/30,172.16.33.12/30,30-BitMask(2Hosts),172.16.32.0/26,172.16.32.64/26,172.16.32.128/26,172.16.32.192/26,26-BitMask(62Hosts),7路由汇总（RouteSummarization）,Routingtable172.16.25.0/24172.16.26.0/24172.16.27.0/24,172.16.27.0/24,172.16.26.0/24,172.16.25.0/24,A,路由汇总（RouteSummarization）,路由协议能够将几条路由条目汇总成一条Routingprotocolscansummarizeaddressesofseveralnetworksintooneaddress,Icanroutetothe172.16.0.0/16network.,RoutingTable172.16.0.0/16,B,RoutingTable172.16.25.0/24172.16.26.0/24172.16.27.0/24,172.16.27.0/24,172.16.26.0/24,172.16.25.0/24,A,RoutingTable172.16.16.0/20,在一个位组内汇总（SummarizingwithinanOctet）,172.16.168.0/24=10101100.00010000.10101000.00000000,相同的位数为21（NumberofCommonBits=21）不同位数11位（NoncommonBits=11）汇总：172.16.168.0/21（Summary:172.16.168.0/21）,172.16.169.0/24=172.16.10101001.0,172.16.170