网络工程师-2-tcpip协议

Chapter2TCP/IP协议1.5TCP／／IP协议基础础互联网协协议（IP）和传输控控制协议议（TCP））是互联网网协议族族中最为为有名的的两个协协议，其其应用非非常广泛泛，它能能够用于于任何相相互连接接的计算算机网络络系统之之间的通通信，对对局域网网（LAN））和广域网网（WAN））都有非常常好的效效果。1.5TCP／／IP协议基础础1.5..1TCP／／IP与OSI参考模型型●TCP//IP协议和OSI模型的对对应关系系TCP／IP协议OSI模型FTP,TELNET,SMTP,RPC,SNMP,DNS,TFTP,BOOTP,HTTP应用层TCP,UDP传输层IP(ICMP,IGMP),(ARP,RARP)网络层1.5TCP／／IP协议基础础●TCP//IP的主要协协议之间间的相关关性图中每个个封闭的的多边形形对应了了一个协协议，并并且位于于它所直直接使用用的协议议之上。。如SMTP依赖于TCP，，而TCP依赖于IP。1.5TCP／／IP协议基础础●TCP/IP的层次结结构l．应用层。。向用户提提供一组组常用的的应用程程序。2．传输层（（TCP和UDP））。提供应用用程序间间的通信信，提供供了可靠靠的传输输（UDP不能提供供可靠的的传输））等。3．网络络层（IP）。。负责数据据包的寻寻径功能能，以保保证数据据包可靠靠到达目目标主机机，若不不能到达达，则向向源主机机发送差差错控制制报文。。4．网络络接口层层。这是TCP／／IP软件的最最低层，，负责接接收IP数据包并并通过网网络发送送之，或或者从网网络上接接收物理理帧，抽抽出IP数据包，，并把它它交给IP层。1.5TCP／／IP协议基础础1.5..2网网络层（（IP层）将所有的的低层的的物理实实现隐藏藏起来，，作用是是将数据据包从源源主机发发送出去去，并且且使这些些数据包包独立地地到达目目的主机机。在数据包包传送过过程中，，即使是是连续的的数据包包，也可可能走过过不同的的路径，，到达目目的主机机的顺序序也会不不同于它它们被发发送时的的顺序。。

1.5TCP／／IP协议基础础●TCP//IP数据流程程1.5TCP／／IP协议基础础●IP数据包一个IP数据包由由包头和和数据体体两部分分组成。。包头由由20字字节的固固定部分分和变长长的可选选项成。。1.5TCP／／IP协议基础础●IP地址在Internet中，每一一台主机机都有一一个唯一一的地址址，网关关常常有有不止一一个的地地址。地地址由两两部分组组成：网网络号和和主机号号。这种种组合是是唯一的的，以使使每一个个IP地址表示示Internet中的唯——一台主主机。所所有IP地址都是是32位位长。IP地址分为为五类，，平常使使用的是是A，B，，C三类地址址地址类型地址形式AN.H.H.HBN.N.H.HCN.N.N.H1.5TCP／／IP协议基础础●IP层的其它它一些协协议ICMP（Internet控制信息息协议））用来传传送一些些关于网网络和主主机的控控制信息息。如目目标主机机是不可可到达的的、路由由的重定定向等。。ARP（（地址解析析协议））用来将将IP地址映射射成相应应的主机机MAC地址。RARP（反向地址址解析协协议）用用来将物物理地址址映射成成32位位的IP地址。1.5TCP／／IP协议基础础1.5..3传传输层（（TCP和UDP））●TCPTCP协议，即即传输控控制协议议，是一一个可靠靠的、面面向连接接的协议议。它允允许在Internet上两台主主机间信信息的无无差错传传输。●UDP无连接方方式，即即UDP方式，当当源主机机有数据据时，就就发送。。它不管管发送的的数据包包是否到到达目标标主机，，数据包包是否出出错，收收到数据据包的主主机也不不会告诉诉发送方方是否正正确收到到了数据据，因此此，这是是一种不不可靠的的数据传传输方式式。1.5TCP／／IP协议基础础EarlyprotocolsuiteUniversalIntroductiontoTCP/IPHostInternetTCP//IPHostTCP//IP协议栈7654325432ApplicationPresentationSessionTransportNetworkDataLinkPhysical1ApplicationTransportInternetDataLinkPhysical1应用层Overview*UsedbytherouterApplicationTransportInternetDataLinkPhysicalFileTransfer-TFTP**-FTP**-NFSE-Mail-SMTPRemoteLogin-Telnet**-rlogin**NetworkManagement-SNMP**NameManagement-DNS*传输层OverviewTransmissionControlProtocol((TCP)UserDatagramProtocol((UDP)ApplicationTransportInternetDataLinkPhysical面向连接接、可靠靠的无连接，，不可靠靠的TCP传输控制制协议面向连接接的先建立连连接，后后传数据据通过三次次握手建建立连接接可靠的发送数据据后，必必须等待待确认后后才继续续发送等不到确确认，会会重传数数据电话TCPSegmentFormatSourceport((16))Destinationport(16)Sequencenumber((32)Headerlength((4))Acknowledgementnumber(32)Reserved((6)Codebits((6))Window((16)Checksum((16))Urgent((16)Options(0or32ifany)Data(varies))20BytesBit0Bit15Bit16Bit31PortNumbersTCPPortNumbersFTPTransportLayerTELNETDNSSNMPTFTPSMTPUDPApplicationLayer2123255369161RIP520TCPPortNumbersSourcePortDest.Port…HostA102823…SPDPHostZTelnetZDest.port=23..SendpackettomyTelnetapplication.SendSYN(seq=100ctl==SYN)SYNreceivedHostAHostBTCP三次握手手1SendSYN(seq=100ctl==SYN)SYNreceivedSendSYN,ACK(seq=300ack==101ctl=syn,,ack)HostAHostBSYNreceived12TCPThreeWayHandshake/OpenConnectionSendSYN(seq=100ctl==SYN)SYNreceivedSendSYN,ACK(seq=300ack==101ctl=syn,,ack)Established(seq=101ack==301ctl=ack))HostAHostB123SYNreceivedTCPThreeWayHandshake/OpenConnectionTCPSimpleAcknowledgmentWindowsize==1SenderReceiverTCPSimpleAcknowledgmentWindowsize==1SenderReceiverSend1Receive1TCPSimpleAcknowledgmentWindowsize==1SenderReceiverSend1Receive1ReceiveACK2SendACK2TCPSimpleAcknowledgmentWindowsize==1SenderReceiverSend1Receive1ReceiveACK2SendACK2Send2Receive2TCPSimpleAcknowledgmentWindowsize==1SenderReceiverSend1Receive1ReceiveACK2SendACK2Send2Receive2ReceiveACK3SendACK3TCPSimpleAcknowledgmentWindowsize==1SenderReceiverSend1Receive1ReceiveACK2SendACK2Send2Receive2ReceiveACK3SendACK3Send3Receive3Windowsize==1SenderReceiverSend1Receive1ReceiveACK2SendACK2Send2Receive2ReceiveACK3SendACK3Send3Receive3ReceiveACK4SendACK4TCPSimpleAcknowledgmentTCPSequenceandAcknowledgmentNumbersSourcePortDest.Port…Sequence#Acknowledgement#SourceDest.Seq..Ack..102823101Ijustsent#10.TCPSequenceandAcknowledgmentNumbersIjustgot#10,nowIneed#11.SourcePortDest.Port…Sequence#Acknowledgement#102823SourceDest.10Seq..1Ack..102823SourceDest.11Seq..1Ack..Ijustsent#10.TCPSequenceandAcknowledgmentNumbersSourcePortDest.Port…Sequence#Acknowledgement#102823SourceDest.11Seq..2Ack..102823SourceDest.10Seq..1Ack..102823SourceDest.11Seq..1Ack..Ijustgot#10,nowIneed#11.Ijustsent#11.TCPSequenceandAcknowledgmentNumbersSourcePortDest.Port…Sequence#Acknowledgement#102823SourceDest.11Seq..2Ack..102823SourceDest.10Seq..1Ack..102823SourceDest.11Seq..1Ack..102823SourceDest.12Seq..2Ack..Ijustgot#11,nowIneed#12.Ijustsent#11.TCPWindowingSenderReceiverTCPWindowingWindowsize==3Send2SenderReceiverWindowsize==3Send1Windowsize==3Send3Windowsize==3Send2TCPWindowingSenderWindowsize==3Send1Windowsize==3Send3ACK3Windowsize==2Packet3isDroppedReceiverWindowsize==3Send2TCPWindowingSenderWindowsize==3Send1Windowsize==3Send3ACK3Windowsize==2Packet3isDroppedWindowsize==3Send4Windowsize==3Send3ReceiverWindowsize==3Send2TCPWindowingSenderWindowsize==3Send1Windowsize==3Send3ACK3Windowsize==2Packet3isDroppedWindowsize==3Send4Windowsize==3Send3ACK5Windowsize==2ReceiverUDP用户数据据报协议议面向无连连接发送数据据之前不不需要建建立连接接直接发送送不可靠没有发送送确认没有重传传机制（（由上层层协议控控制纠错错重传））Segment尺寸小，，发送速速度快传呼，短信NosequenceoracknowledgmentfieldsUDPSegmentFormatSourceport((16))Destinationport(16)Length((16)Data(ifany))1Bit0Bit15Bit16Bit31Checksum((16))8Bytes网络层（（IP）OverviewOSI网络层对对应TCP//IPinternet层InternetProtocol((IP))InternetControlMessageProtocol((ICMP)AddressResolutionProtocol((ARP)ReverseAddressResolutionProtocol(RARP)ApplicationTransportInternetDataLinkPhysicalIP层的主要要协议IP协议-------InternetProtocol控制数据据的路由由与转发发ICMP协议-----Internet控制消息息协议测试网络络连通性性的协议议，返回回目的不不可到达达、Echo、超时等消消息Ping，Trcert，PathpingARP协议-----地地址解析析协议RARP协议-----反反向地址址解析协协议IPDatagramVersion(4)DestinationIPAddress(32)Options(0or32ifany)Data(variesifany)1Bit0Bit15Bit16Bit31HeaderLength((4))Priority&&TypeofService(8)TotalLength((16)Identification((16))Flags(3)Fragmentoffset((13)Timetolive((8))Protocol((8)Headerchecksum((16)SourceIPAddress((32))20BytesDeterminesdestinationupper-layerprotocolProtocolFieldTransportLayerInternetLayerTCPUDPProtocolNumbersIP176InternetControlMessageProtocolApplicationTransportInternetDataLinkPhysicalDestinationUnreachableEcho(Ping)OtherICMP1AddressResolutionProtocol172..16..3.1172..16..3.2IP:172.16.3..2==????IneedtheEthernetaddressof176.16.3..2.AddressResolutionProtocol172..16..3.1172..16..3.2IP:172.16.3..2==????Iheardthatbroadcast.Themessageisforme.HereismyEthernetaddress.IneedtheEthernetaddressof.AddressResolutionProtocol172..16..3.1IP:172.16.3..2Ethernet:0800.0020.1111172..16..3.2IP:172.16.3..2==????Iheardthatbroadcast.Themessageisforme.HereismyEthernetaddress.IneedtheEthernetaddressof.AddressResolutionProtocolMapIPEthernetLocalARP172..16..3.1IP:172.16.3..2Ethernet:0800.0020.1111172..16..3.2IP:172.16.3..2==????Iheardthatbroadcast.Themessageisforme.HereismyEthernetaddress.IneedtheEthernetaddressof.ReverseARPEthernet:0800.0020.1111IP==????WhatismyIPaddress??ReverseARPEthernet:0800.0020.1111IP==????WhatismyIPaddress??Iheardthatbroadcast.YourIPaddressis172.16.3..25..ReverseARPEthernet:0800.0020.1111IP:172.16.3..25Ethernet:0800.0020.1111IP==????WhatismyIPaddress??Iheardthatbroadcast.YourIPaddressis172.16.3..25..ReverseARPMapEthernetIPEthernet:0800.0020.1111IP:172.16.3..25Ethernet:0800.0020.1111IP==????WhatismyIPaddress??Iheardthatbroadcast.YourIPaddressis172.16.3..25..网络中唯唯一路由选择择的依据据LocationisrepresentedbyanaddressIP地址172..18..0.2172..18..0.1172..17..0.2172..17..0.1172..16..0.2172..16..0.1SADAHDRDATA192..168.1..0192..168.1..1IPAddressing255255255255DottedDecimalMaximumNetworkHost32bitsIPAddressing255255255255DottedDecimalMaximumNetworkHost128643216842111111111111111111111111111111111Binary32bits1891617242532128643216842112864321684211286432168421IPAddressing255255255255DottedDecimalMaximumNetworkHost12864321684211111111111111111111111111111111110101100000100000111101011001100Binary32bits172

16122204ExampleDecimalExampleBinary1891617242532128643216842112864321684211286432168421ClassA:ClassB:ClassC:ClassD:MulticastClassE:ResearchIPAddressClassesNetworkHostHostHostNetworkNetworkHostHostNetworkNetworkNetworkHost8bits8bits8bits8bitsIPAddressClasses1ClassA:Bits:0NNNNNNNHostHostHost891617242532Range((1-126))1ClassB:Bits:10NNNNNNNetworkHostHost891617242532Range((128-191)1ClassC:Bits:110NNNNNNetworkNetworkHost891617242532Range((192-223)1ClassD:Bits:1110MMMMMulticastGroupMulticastGroupMulticastGroup891617242532Range((224-239)HostAddresses172..16..2.1172..16..3.10172..16..12..1210.1.1..110.250..8.1110.180..30..118E1172..161212NetworkHost..NetworkInterface172..16..0.010.0.0..0E0E1RoutingTable172..16..2.1E011111111DeterminingAvailableHostAddresses17216001010110000010000000000000000000016151413121110987654321NetworkHost000000000000000111111111111111111111111111111110......000000000000001111111101123655346553565536-...265534N2N-2=216-2==65534IPAddressClassesExerciseAddressClassNetworkHost10.2.1..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..16Network172..16..0.0AddressingwithoutSubnets172..16..0.1172..16..0.2172..16..0.3…....172..16..255.253172..16..255.254NetworkAddressingwithSubnets172..16..1.0172..16..2.0172..16..3.0172..16..4.0SubnetAddressing172..16..2.200172..16..2.2172..16..2.160172..16..2.1172..16..3.5172..16..3.100172..16..3.150E0172..16NetworkNetworkInterface172..16..0.0172..16..0.0E0E1NewRoutingTable2160Host..172..16..3.1E1SubnetAddressing172..16..2.200172..16..2.2172..16..2.160172..16..2.1172..16..3.5172..16..3.100172..16..3.150172..16..3.1E0E1172..162160NetworkHost..NetworkInterface172..16..2.0172..16..3.0E0E1NewRoutingTableSubnetSubnetMask1721600255255002552552550IPAddressDefaultSubnetMask8-bitSubnetMaskNetworkHostNetworkHostNetworkSubnetHostAlsowrittenas““/16”where16representsthenumberof1sinthemask.Alsowrittenas““/24”where24representsthenumberof1sinthemask.11111111111111110000000000000000DecimalEquivalentsofBitPatterns1 000 000 0==1281 100 000 0==1921 110 000 0==2241 111 000 0==2401 111 100 0==2481 111 110 0==2521 111 111 0==2541 111 111 1==2551286432168 42116NetworkHost17200101011001111111110101100000100001111111100010000000000000000000010100000000000000000000000000010SubnetMaskwithoutSubnets172..16..2.160255..255.0..0NetworkNumberSubnetsnotinuse——thedefaultNetworknumberextendedbyeightbitsSubnetMaskwithSubnets16NetworkHost172..16..2.160255..255.255.017220101011001111111110101100000100001111111100010000111111110000001010100000000000000000000000000010SubnetNetworkNumber128192224240248252254255SubnetMaskwithSubnets((cont..)NetworkHost172..16..2.160255..255.255.192101011001111111110101100000100001111111100010000111111110000001010100000110000001000000000000010SubnetNetworknumberextendedbytenbits161722128NetworkNumber128192224240248252254255128192224240248252254255SubnetMaskExerciseAddressSubnetMaskClassSubnet172..16..2.1002255..255.255.0255..255.240.0255..255.255.0SubnetMaskExerciseAnswersAddressSubnetMaskClassSubnet172..16..2.1002255..255.255.0255..255.240.0255..255.255.0BAA172..16..2.0BroadcastAddresses172..16..1.0172..16..2.0172..16..3.0172..16..4.0172..16..3.255(Directedbroadcast))255..255.255.255(Localnetworkbroadcast)X172..16..255.255(Allsubnetsbroadcast))AddressingSummaryExample16172216010101100000100001010000000000010HostMaskSubnetBroadcastLastFirst172..16..2.160255..255.255.19241AddressingSummaryExample1010110011111111000100001111111111111111101000001100000000000010HostMaskSubnetBroadcastLastFirst172..16..2.160255..255.255.19212161722160AddressingSummaryExample1010110011111111000100001111111111111111101000001100000000000010HostMaskSubnetBroadcastLastFirst172..16..2.160255..255.255.1921237161722160AddressingSummaryExample101011001111111100010000111111111111111110100000110000001000000000000010HostMaskSubnetBroadcastLastFirst172..16..2.160255..255.255.1921234161722160AddressingSummaryExample10101100111111110001000011111111111111111010000011000000100000000000001010111111HostMaskSubnetBroadcastLastFirst172..16..2.160255..255.255.192123456161722160AddressingSummaryExample1010110011111111000100001111111111111111101000001100000010000000000000101011111110000001HostMaskSubnetBroadcastLastFirst172..16..2.160255..255.255.192123456161722160AddressingSummaryExample101011001111111100010000111111111111111110100000110000001000000000000010101111111000000110111110HostMaskSubnetBroadcastLastFirst172..16..2.160255..255.255.1921234567161722160AddressingSummaryExample101011001111111110101100000100001111111100010000111111110000001010100000110000001000000000000010101011000001000000000010101111111010110000010000000000101000000110101100000100000000001010111110HostMaskSubnetBroadcastLastFirst172..16..2.160255..255.255.19212345678161722160AddressingSummaryExample101011001111111110101100000100001111111100010000111111110000001010100000110000001000000000000010101011000001000000000010101111111010110000010000000000101000000110101100000100000000001010111110HostMaskSubnetBroadcastLas