网络互连技术-第1章ip地址

IP寻址

IPAddress教学目标（Objectives

）1.IP地址概念（ConceptofIPAddress

）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.汇总和CIDR（Summarization

andCIDR）IP地址（IPAddress）IP地址唯一的标识网络上计算机，IP地址就是由0和1组成的32位字符串。EachcomputerinaTCP/IPnetworkmustbegivenauniqueidentifier,orIPaddress.AnIPaddressisa32-bitsequenceof1sand0s.IP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,theaddressisusuallywrittenasfourdecimalnumbersseparatedbyperiods192.168.123.2IP地址结构（StructureofIPAddress）IP地址的类别（ClassofIPAddress）A类地址（ClassA）地址范围：1~126(127保留)AddressRange:1-126(127Reserved)B类地址（ClassB）地址范围：128~191AddressRange:128-191C类地址（ClassC）地址范围：192~223AddressRange:192-223地址分配（AddressAllocating）分配A类IP：国际网络信息中心NIC分配B类IP：InterNIC、APNIC、ENIC分配C类IP：国家或地区的NIC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:IPAddressClassesAddressClassNetworkHost10.2.1.1128.63.2.100201.222.5.64192.6.141.2130.113.64.16256.241.201.10IPAddressClassesExerciseAnswersAddressClassNetworkHost10.2.1.1128.63.2.100201.222.5.64192.6.141.2130.113.64.16256.241.201.10ABCCBNonexistent10.0.0.0128.63.0.0201.222.5.0192.6.141.0130.113.0.00.2.1.10.0.2.1000.0.0.640.0.0.20.0.64.16网络掩码（NetworkMask）A类：255.0.0.0B类：255.255.0.0C类：255.255.255.0网络掩码的作用（FunctionofNetworkMask）10101100000100000000001010100000172.16.2.16011111111111111110000000000000000255.255.0.010101100000100000000000000000000172.16.0.0NetworkID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BroadcastContainment

3.为LAN提供低水平的安全

Low-levelsecurity

ontheLAN.

介绍子网划分（IntroductiontoSubnetting）划分子网要从主机位借位Hostbitsmustarereassigned(or“borrowed”)asnetworkbits.

3bitsborrowedallows23-2or6subnets5bitsborrowedallows25-2or30subnets12bitsborrowedallows212-2or4094subnets介绍子网划分（IntroductiontoSubnetting）网络号码主机号码网络号码主机号码网络号码主机号码子网号码不考虑子网网络掩码子网掩码扩充的网络号码考虑子网化Comparisonbetweendecimalandbinary实例1：C类地址2位子网化

（

E.g1TwoBits

SubnettingforClassC

）子网号（Subnet）地址范围（range）00000000000000001~001111111~62其中:0为网络地址，63为广播地址010000006401000001~0111111165~127其中:64为网络地址，127为广播地址1000000012810000001~10111111129~191其中:128为网络地址，191为广播地址11000000~11111111193~255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.g24Bits

SubnettingforClassC

）组合子网号地址范围00000000000000001~000011111~15其中：15为广播地址000100001600010001~0001111117~31其中：31为广播地址001000003200100001~0010111133~47其中：47为广播地址001100004800110001~0011111149~63其中：63为广播地址010000006401000001~0100111165~79其中：79为广播地址010100008001010001~0101111181~95其中：95为广播地址011000009601100001~0110111197~111其中：111为广播地址0111000011201110001~01111111113~127其中：127为广播地址1000000012810000001~10001111129~143其中：143为广播地址10010000~10011111145~159其中：159为广播地址10100000~10101111161~175其中：175为广播地址10110000~10111111177~191其中：191为广播地址11000000~11001111193~207其中：207为广播地址1101000020811010001~11011111209~223其中：223为广播地址1110000022411100001~11101111225~239其中：239为广播地址1111000024011110001~11111111241~255其中：255为广播地址可用的子网和主机数

（NumberofUsableSubnetsandHosts

）usablesubnets＝(2powerofborrowedbits)–2usablehosts=(2powerofremaininghostbits)–2C类地址划分子网情况汇总

（SummaryofClassCSubnetting）WrittenExercise:SubnetMasksAddressSubnetMaskClassSubnet172.16.2.1010.6.24.20172.30.36.12255.255.255.0255.255.0.0255.255.255.0202.30.36.82255.255.255.192SubnetMaskExerciseAnswersAddressSubnetMaskClassSubnet172.16.2.1010.6.24.2010.30.36.12255.255.255.0255.255.240.0255.255.255.0BAA172.16.2.010.6.16.010.30.36.0WrittenExercise:BroadcastAddressesAddressClassSubnetBroadcast201.222.10.60255.255.255.248SubnetMask15.16.193.6255.255.248.0128.16.32.13255.255.255.252153.50.6.27255.255.255.128BroadcastAddressesExerciseAnswers153.50.6.127AddressClassSubnetBroadcast201.222.10.60255.255.255.248C201.222.10.63201.222.10.56SubnetMask15.16.193.6255.255.248.0A15.16.199.25515.16.192.0128.16.32.13255.255.255.252B128.16.32.15128.16.32.12153.50.6.27255.255.255.128B153.50.6.0CaseStudy：SubnetProgrammingOthersubnets30hostspersubnetClassCaddress:201.222.5.0可变长度子网掩码（Variable-LengthSubnetMask）HQ172.16.0.0/16

可变长度子网掩码（Variable-LengthSubnetMask）HQ172.16.1.0/24172.16.2.0/24HQ172.16.0.0/16

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）CBA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)HQ172.16.1.0/24172.16.2.0/24HQ172.16.0.0/16

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)CBAHQ172.16.1.0/24172.16.2.0/24HQ172.16.0.0/16

172.16.14.136/30172.16.14.132/30172.16.14.140/30可变长度子网掩码（Variable-LengthSubnetMask）计算VLSM（CalculatingVLSMs）SubnettedAddress:172.16.32.0/20

InBinary10101100.00010000.00100000.00000000计算VLSM（CalculatingVLSMs）VLSMAddress:172.16.32.0/26

InBinary10101100.00010000.00100000.00000000SubnettedAddress:172.16.32.0/20

InBinary10101100.00010000.00100000.00000000计算VLSM（CalculatingVLSMs）NetworkSubnetVLSMsubnetHost10101100.00010000.00100000.00000000=172.16.32.0/261stsubnet:VLSMAddress:172.16.32.0/26

InBinary10101100.00010000.00100000.00000000SubnettedAddress:172.16.32.0/20

InBinary10101100.00010000.00100000.00000000SubnettedAddress:172.16.32.0/20

InBinary10101100.00010000.00100000.00000000VLSMAddress:172.16.32.0/26

InBinary10101100.00010000.00100000.00000000

1stsubnet:10101100.00010000.00100000.00000000=172.16.32.0/26172.16.00100000.01000000=172.16.32.64/26172.16.00100000.10000000=172.16.32.128/26172.16.00100000.1000000=172.16.32.192/26172.16.00100001.00000000=172.16.33.0/26NetworkSubnetVLSMSubnetHost12ndsubnet:3rdsubnet:4thsubnet:5thsubnet:计算VLSM（CalculatingVLSMs）练习：使用VLSM规划网路

（Exercise:DesignNetworkUsingVLSM）Derivedfromthe172.16.32.0/20Subnet(62Hosts)(62Hosts)(62Hosts)(62Hosts)练习答案（ExerciseAnswer）172.16.33.0/30172.16.33.4/30172.16.33.8/30172.16.33.12/30Derivedfromthe172.16.33.0/26Subnet30-BitMask(2Hosts)172.16.32.0/26172.16.32.64/26172.16.32.128/26172.16.32.192/2626-BitMask(62Hosts)Derivedfromthe172.16.32.0/20Subnet路由汇总（RouteSummarization）Routingtable172.16.25.0/24172.16.26.0/24172.16.27.0/24172.16.27.0/24172.16.26.0/24172.16.25.0/24A路由汇总（RouteSummarization）

路由协议能够将几条路由条目汇总成一条RoutingprotocolscansummarizeaddressesofseveralnetworksintooneaddressIcanroutetothe

172.16.0.0/16network.

RoutingTable172.16.0.0/16BRoutingTable172.16.25.0/24172.16.26.0/24172.16.27.0/24172.16.27.0/24172.16.26.0/24172.16.25.0/24A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（monBits=11）汇总：172.16.168.0/21（Summary:172.16.168.0/21）172.16.169.0/24=172 .16.10101001.0172.16.170.0/24