网络工程师：tcpip协议课件

Chapter2TCP/IP协议Chapter2TCP/IP协议1.5TCP／IP协议基础 互联网协议（IP）和传输控制协议（TCP）是互联网协议族中最为有名的两个协议，其应用非常广泛，它能够用于任何相互连接的计算机网络系统之间的通信，对局域网（LAN）和广域网（WAN）都有非常好的效果。1.5TCP／IP协议基础 互联网协议（IP）和传输控制1.5TCP／IP协议基础1.5.1TCP／IP与OSI参考模型

●

TCP/IP协议和OSI模型的对应关系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1.5.1TCP／IP与OSI1.5TCP／IP协议基础 ●

TCP/IP的主要协议之间的相关性 图中每个封闭的多边形对应了一个协议，并且位于它所直接使用的协议之上。如SMTP依赖于TCP，而TCP依赖于IP。1.5TCP／IP协议基础 ●TCP/IP的主要协议之1.5TCP／IP协议基础

●TCP/IP的层次结构

l．应用层。向用户提供一组常用的应用程序。

2．传输层（TCP和UDP）。 提供应用程序间的通信，提供了可靠的传输（UDP不能提供可靠的传输）等。

3．网络层（IP）。负责数据包的寻径功能，以保证数据包可靠到达目标主机，若不能到达，则向源主机发送差错控制报文。

4．网络接口层。这是TCP／IP软件的最低层，负责接收IP数据包并通过网络发送之，或者从网络上接收物理帧，抽出IP数据包，并把它交给IP层。1.5TCP／IP协议基础 ●TCP/IP的层次结构1.5TCP／IP协议基础1.5.2网络层（IP层） 将所有的低层的物理实现隐藏起来，作用是将数据包从源主机发送出去，并且使这些数据包独立地到达目的主机。 在数据包传送过程中，即使是连续的数据包，也可能走过不同的路径，到达目的主机的顺序也会不同于它们被发送时的顺序。

1.5TCP／IP协议基础1.5.2网络层（IP层）1.5TCP／IP协议基础

●TCP/IP数据流程1.5TCP／IP协议基础 ●TCP/IP数据流程1.5TCP／IP协议基础 ●IP数据包 一个IP数据包由包头和数据体两部分组成。包头由20字节的固定部分和变长的可选项成。1.5TCP／IP协议基础 ●IP数据包1.5TCP／IP协议基础 ●

IP地址 在Internet中，每一台主机都有一个唯一的地址，网关常常有不止一个的地址。地址由两部分组成：网络号和主机号。这种组合是唯一的，以使每一个IP地址表示Internet中的唯—一台主机。所有IP地址都是32位长。 IP地址分为五类，平常使用的是A，B，C三类地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 ●IP地址地址类型地址形式1.5TCP／IP协议基础 ●IP层的其它一些协议 ICMP（Internet控制信息协议）用来传送一些关于网络和主机的控制信息。如目标主机是不可到达的、路由的重定向等。 ARP（地址解析协议）用来将IP地址映射成相应的主机MAC地址。 RARP（反向地址解析协议）用来将物理地址映射成32位的IP地址。1.5TCP／IP协议基础 ●IP层的其它一些协议1.5TCP／IP协议基础1.5.3传输层（TCP和UDP） ●TCP

TCP协议，即传输控制协议，是一个可靠的、面向连接的协议。它允许在Internet上两台主机间信息的无差错传输。 ●UDP 无连接方式，即UDP方式，当源主机有数据时，就发送。它不管发送的数据包是否到达目标主机，数据包是否出错，收到数据包的主机也不会告诉发送方是否正确收到了数据，因此，这是一种不可靠的数据传输方式。1.5TCP／IP协议基础1.5.3传输层（TCP和UD1.5TCP／IP协议基础1.5.4应用层协议

Telnet，也就是虚终端服务。它允许一台主机上的用户登录进另一台远程主机，并在远程主机中工作，而用户当前所使用的主机好象仅仅是远程主机的一个终端。

FTP，即文件传输协议。提供了一个有效的途径，将数据从一台主机传送到另一台主机。文件传输有文本和二进制两种模式。文本模式用来传输文本文件，并实现一些格式转换。

SMTP，即电子邮件服务使用缺省的端口25，以电子数据的方式，使用户快速、方便地传送信息。即使相隔大洲、大洋，电子邮件也可以在短短的几分钟内到达接收方的电子信箱。

HTTP，即超文本传输协议，用来在.服务器上取得用超文本标记语言书写的页面。1.5TCP／IP协议基础1.5.4应用层协议EarlyprotocolsuiteUniversalIntroductiontoTCP/IPHostInternetTCP/IPHostEarlyprotocolsuiteIntroductiTCP/IP协议栈7654325432ApplicationPresentationSessionTransportNetworkDataLinkPhysical1ApplicationTransportInternetDataLinkPhysical1TCP/IP协议栈7654325432Applicatio应用层Overview*UsedbytherouterApplicationTransportInternetDataLinkPhysicalFileTransfer -TFTP* -FTP* -NFSE-Mail -SMTPRemoteLogin -Telnet* -rlogin*NetworkManagement -SNMP*NameManagement -DNS*应用层Overview*Usedbytheroute传输层OverviewTransmissionControlProtocol(TCP)UserDatagramProtocol(UDP)ApplicationTransportInternetDataLinkPhysical面向连接、可靠的

无连接，不可靠的传输层OverviewTransmissionContrTCP传输控制协议面向连接的先建立连接，后传数据通过三次握手建立连接可靠的发送数据后，必须等待确认后才继续发送等不到确认，会重传数据电话TCP传输控制协议面向连接的电话TCPSegmentFormatSourceport(16)Destinationport(16)Sequencenumber(32)Header

length(4)Acknowledgementnumber(32)Reserved(6)Codebits(6)Window(16)Checksum(16)Urgent(16)Options(0or32ifany)Data(varies)20

BytesBit0Bit15Bit16Bit31TCPSegmentFormatSourceportPortNumbersTCPPort

NumbersF

T

PTransport

LayerT

E

L

N

E

TD

N

SS

N

M

PT

F

T

PS

M

T

PUDPApplication

Layer2123255369161R

I

P520PortNumbersTCPPort

NumbersF

TCPPortNumbersSourcePortDest.Port…HostA102823…SPDPHostZTelnetZDest.port=23.

SendpackettomyTelnet

application.TCPPortNumbersSourceDest.…HoSendSYN(seq=100ctl=SYN)SYNreceivedHostAHostBTCP三次握手1SendSYNSYNreceivedHostAHosSendSYN(seq=100ctl=SYN)SYNreceivedSendSYN,ACK(seq=300ack=101ctl=syn,ack)HostAHostBSYNreceived12TCPThreeWayHandshake/OpenConnectionSendSYNSYNreceivedSendSYN,SendSYN(seq=100ctl=SYN)SYNreceivedSendSYN,ACK(seq=300ack=101ctl=syn,ack)Established(seq=101ack=301ctl=ack)HostAHostB123SYNreceivedTCPThreeWayHandshake/OpenConnectionSendSYNSYNreceivedSendSYN,TCPSimpleAcknowledgmentWindowsize=1

Sender

ReceiverTCPSimpleAcknowledgmentWindoTCPSimpleAcknowledgmentWindowsize=1

Sender

ReceiverSend1Receive1TCPSimpleAcknowledgmentWindoTCPSimpleAcknowledgmentWindowsize=1

Sender

ReceiverSend1Receive1ReceiveACK2SendACK2TCPSimpleAcknowledgmentWindoTCPSimpleAcknowledgmentWindowsize=1

Sender

ReceiverSend1Receive1ReceiveACK2SendACK2Send2Receive2TCPSimpleAcknowledgmentWindoTCPSimpleAcknowledgmentWindowsize=1

Sender

ReceiverSend1Receive1ReceiveACK2SendACK2Send2Receive2ReceiveACK3SendACK3TCPSimpleAcknowledgmentWindoTCPSimpleAcknowledgmentWindowsize=1

Sender

ReceiverSend1Receive1ReceiveACK2SendACK2Send2Receive2ReceiveACK3SendACK3Send3Receive3TCPSimpleAcknowledgmentWindoWindowsize=1

Sender

ReceiverSend1Receive1ReceiveACK2SendACK2Send2Receive2ReceiveACK3SendACK3Send3Receive3ReceiveACK4SendACK4TCPSimpleAcknowledgmentWindowsize=1SenderReceivTCPSequenceand

AcknowledgmentNumbersSourcePortDest.Port…Sequence#Acknowledgement#SourceDest.Seq.Ack.102823101Ijustsent#10.TCPSequenceand

AcknowledgmeTCPSequenceand

AcknowledgmentNumbersIjustgot#10,nowIneed#11.SourcePortDest.Port…Sequence#Acknowledgement#102823SourceDest.10Seq.1Ack.102823SourceDest.11Seq.1Ack.Ijustsent#10.TCPSequenceand

AcknowledgmeTCPSequenceand

AcknowledgmentNumbersSourcePortDest.Port…Sequence#Acknowledgement#102823SourceDest.11Seq.2Ack.102823SourceDest.10Seq.1Ack.102823SourceDest.11Seq.1Ack.Ijustgot#10,nowIneed#11.Ijustsent#11.TCPSequenceand

AcknowledgmeTCPSequenceand

AcknowledgmentNumbersSourcePortDest.Port…Sequence#Acknowledgement#102823SourceDest.11Seq.2Ack.102823SourceDest.10Seq.1Ack.102823SourceDest.11Seq.1Ack.102823SourceDest.12Seq.2Ack.Ijustgot#11,nowIneed#12.Ijustsent#11.TCPSequenceand

AcknowledgmeTCPWindowingSenderReceiverTCPWindowingSenderReceiverTCPWindowingWindowsize=3Send2SenderReceiverWindowsize=3Send1Windowsize=3Send3TCPWindowingWindowsize=3SeWindowsize=3Send2TCPWindowingSenderWindowsize=3Send1Windowsize=3Send3ACK3Windowsize=2Packet3is

DroppedReceiverWindowsize=3TCPWindowingSeWindowsize=3Send2TCPWindowingSenderWindowsize=3Send1Windowsize=3Send3ACK3Windowsize=2Packet3is

DroppedWindowsize=3Send4Windowsize=3Send3ReceiverWindowsize=3TCPWindowingSeWindowsize=3Send2TCPWindowingSenderWindowsize=3Send1Windowsize=3Send3ACK3Windowsize=2Packet3is

DroppedWindowsize=3Send4Windowsize=3Send3ACK5Windowsize=2ReceiverWindowsize=3TCPWindowingSeUDP用户数据报协议面向无连接发送数据之前不需要建立连接直接发送不可靠没有发送确认没有重传机制（由上层协议控制纠错重传）Segment尺寸小，发送速度快传呼，短信UDP用户数据报协议面向无连接传呼，短信NosequenceoracknowledgmentfieldsUDPSegmentFormatSourceport(16)Destinationport(16)Length(16)Data(ifany)1Bit0Bit15Bit16Bit31Checksum(16)8

BytesNosequenceoracknowledgment网络层（IP）OverviewOSI网络层对应TCP/IPinternet层InternetProtocol(IP)InternetControlMessageProtocol(ICMP)AddressResolutionProtocol(ARP)ReverseAddressResolutionProtocol(RARP)ApplicationTransportInternetDataLinkPhysical网络层（IP）OverviewOSI网络层对应TCP/IP层的主要协议IP协议-----InternetProtocol控制数据的路由与转发ICMP协议----Internet控制消息协议测试网络连通性的协议，返回目的不可到达、Echo、超时等消息Ping，Trcert，PathpingARP协议----地址解析协议RARP协议----反向地址解析协议IP层的主要协议IP协议-----InternetProtIPDatagramVersion

(4)DestinationIPAddress(32)Options(0or32ifany)Data(variesifany)1Bit0Bit15Bit16Bit31Header

Length(4)Priority&Type

ofService(8)TotalLength(16)Identification(16)Flags

(3)Fragmentoffset(13)Timetolive(8)Protocol(8)Headerchecksum(16)SourceIPAddress(32)20

BytesIPDatagramVersion

(4)DestinatDeterminesdestinationupper-layerprotocolProtocolFieldTransport

LayerInternet

LayerTCPUDPProtocol

NumbersIP176Determinesdestinationupper-lInternetControlMessage

ProtocolApplicationTransportInternetDataLinkPhysicalDestination

UnreachableEcho(Ping)OtherICMP1InternetControlMessage

ProtAddressResolutionProtocolIP:=???IneedtheEthernetaddressof.AddressResolutionProtocol172AddressResolutionProtocolIP:=???Iheardthatbroadcast.Themessageisforme.HereismyEthernetaddress.IneedtheEthernetaddressof.AddressResolutionProtocol172AddressResolutionProtocolIP:Ethernet:0800.0020.1111IP:=???Iheardthatbroadcast.Themessageisforme.HereismyEthernetaddress.IneedtheEthernetaddressof.AddressResolutionProtocol172AddressResolutionProtocolMapIP EthernetLocalARPIP:Ethernet:0800.0020.1111IP:=???Iheardthatbroadcast.Themessageisforme.HereismyEthernetaddress.IneedtheEthernetaddressof.AddressResolutionProtocolMapReverseARPEthernet:0800.0020.1111IP=???WhatismyIPaddress?ReverseARPEthernet:0800.0020ReverseARPEthernet:0800.0020.1111IP=???WhatismyIPaddress?Iheardthatbroadcast.YourIPaddressis5.ReverseARPEthernet:0800.0020ReverseARPEthernet:0800.0020.1111IP:5Ethernet:0800.0020.1111IP=???WhatismyIPaddress?Iheardthatbroadcast.YourIPaddressis5.ReverseARPEthernet:0800.0020ReverseARPMapEthernet IPEthernet:0800.0020.1111IP:5Ethernet:0800.0020.1111IP=???WhatismyIPaddress?Iheardthatbroadcast.YourIPaddressis5.ReverseARPMapEthernet网络中唯一路由选择的依据LocationisrepresentedbyanaddressIP地址SADAHDRDATA网络中唯一IP地址IPAddressing

255255

255

255Dotted

DecimalMaximumNetworkHost32bitsIPAddressing255255255255DoIPAddressing

255255

255

255Dotted

DecimalMaximumNetworkHost128

64

32

16

8

4

2

1

11111111

11111111

11111111

11111111Binary32bits1891617242532128

64

32

16

8

4

2

1

128

64

32

16

8

4

2

1

128

64

32

16

8

4

2

1

IPAddressing255255255255DoIPAddressing

255255

255

255Dotted

DecimalMaximumNetworkHost128

64

32

16

8

4

2

1

11111111

11111111

11111111

11111111

10101100

00010000

01111010

11001100Binary32bits

172

16

122

204Example

DecimalExample

Binary1891617242532128

64

32

16

8

4

2

1

128

64

32

16

8

4

2

1

128

64

32

16

8

4

2

1

IPAddressing255255255255DoClassA:ClassB:ClassC:ClassD: MulticastClassE:ResearchIPAddressClassesNetworkHostHostHostNetworkNetworkHostHostNetworkNetworkNetworkHost8bits8bits8bits8bitsClassA:IPAddressClassesNeIPAddressClasses1ClassA:Bits:0NNNNNNNHostHostHost891617242532Range(1-126)1ClassB:Bits:10NNNNNNNetworkHostHost891617242532Range(128-191)1ClassC:Bits:110NNNNNNetworkNetworkHost891617242532Range(192-223)1ClassD:Bits:1110MMMMMulticastGroupMulticastGroupMulticastGroup891617242532Range(224-239)IPAddressClasses1ClassA:BitHostAddresses02118E1172.161212NetworkHost..NetworkInterfaceE0E1RoutingTableE0HostAddresses172.16

11111111DeterminingAvailableHostAddresses172

1600

10101100

00010000

00000000

0000000016

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

NetworkHost

00000000

00000001

11111111

11111111

11111111

11111110......

00000000

00000011

11111101123655346553565536-...265534N2N-2=216-2=6553411111111DeterminingAvailableIPAddressClassesExerciseAddressClassNetworkHost004620IPAddressClassesExerciseAddIPAddressClassesExerciseAnswersAddressClassNetworkHost004620ABCCBNonexistent0046IPAddressClassesExerciseAnNetworkAddressingwithoutSubnets…...5354NetworkAdNetworkAddressingwithSubnetsNetworkAddressingwSubnetAddressing00600050E0172.16NetworkNetworkInterfaceE0E1NewRoutingTable2160Host..E1SubnetAddressing001SubnetAddressing00600050E0E1172.162160NetworkHost..NetworkInterfaceE0E1NewRoutingTableSubnetSubnetAddressing001SubnetMask1721600255255002552552550IP

AddressDefault

Subnet

Mask8-bit

Subnet

MaskNetworkHostNetworkHostNetworkSubnetHostAlsowrittenas“/16”where16representsthenumberof1sinthemask.Alsowrittenas“/24”where24representsthenumberof1sinthemask.11111111111111110000000000000000SubnetMask1721600255255002552DecimalEquivalentsofBitPatterns1 0 0 0 0 0 0 0 = 1281 1 0 0 0 0 0 0 = 1921 1 1 0 0 0 0 0 = 2241 1 1 1 0 0 0 0 = 2401 1 1 1 1 0 0 0 = 2481 1 1 1 1 1 0 0 = 2521 1 1 1 1 1 1 0 = 2541 1 1 1 1 1 1 1 = 255128 64 32 16 8 4 2 1DecimalEquivalentsofBitPat16NetworkHost17200101011001111111110101100000100001111111100010000000000000000000010100000000000000000000000000010SubnetMaskwithoutSubnets60

Network

Number16NetworkHost17200101011001111Subnetsnotinuse—thedefaultSubnetsnotinuse—thedefaultNetworknumberextendedbyeightbitsSubnetMaskwithSubnets16NetworkHost6017220101011001111111110101100000100001111111100010000111111110000001010100000000000000000000000000010SubnetNetwork

Number128192224240248252254255NetworknumberextendedbyeigSubnetMaskwithSubnets(cont.)NetworkHost6092101011001111111110101100000100001111111100010000111111110000001010100000110000001000000000000010SubnetNetworknumberextendedbytenbits161722128Network

Number128192224240248252254255128192224240248252254255SubnetMaskwithSubnets(contSubnetMaskExerciseAddressSubnetMaskClassSubnet002SubnetMaskExerciseAddressSubSubnetMaskExerciseAnswersAddressSubnetMaskClassSubnet002BAASubnetMaskExerciseAnswersAdBroadcastAddresses55(Directedbroadcast)55(Localnetworkbroadcast)X55(Allsubnetsbroadcast)BroadcastAddresses1AddressingSummaryExample16172216010101100000100001010000000000010HostMaskSubnetBroadcastLastFirst609241AddressingSummaryExample1617AddressingSummaryExample1010110011111111000100001111111111111111101000001100000000000010HostMaskSubnetBroadcastLastFirst609212161722160AddressingSummaryExample1010AddressingSummaryExample1010110011111111000100001111111111111111101000001100000000000010HostMaskSubnetBroadcastLastFirst60921237161722160AddressingSummaryExample1010AddressingSummaryExample101011001111111100010000111111111111111110100000110000001000000000000010HostMaskSubnetBroadcastLastFirst60921234161722160AddressingSummaryExample1010AddressingSummaryExample10101100111111110001000011111111111111111010000011000000100000000000001010111111HostMaskSubnetBroadcastLastFirst6092123456161722160AddressingSummaryExample1010AddressingSummaryExample1010110011111111000100001111111111111111101000001100000010000000000000101011111110000001HostMaskSubnetBroadcastLastFirst6092123456161722160AddressingSummaryExample1010AddressingSummaryExample101011001111111100010000111111111111111110100000110000001000000000000010101111111000000110111110HostMaskSubnetBroadcastLastFirst60921234567161722160AddressingSummaryExample1010AddressingSummaryExample101011001111111110101100000100001111111100010000111111110000001010100000110000001000000000000010101011000001000000000010101111111010110000010000000000101000000110101100000100000000001010111110HostMaskSubnetBroadcastLastFirst609212345678161722160AddressingSummaryExample1010AddressingSummaryExample101011001111111110101100000100001111111100010000111111110000001010100000110000001000000000000010101011000001000000000010101111111010110000010000000000101000000110101100000100000000001010111110HostMaskSubnetBroadcastLastFirst609228912990123456789161722160AddressingSummaryExample1010IPHostAddress: 21SubnetMask:SubnetAddress=HostAddresses=–54BroadcastAddress=55EightbitsofsubnettingNetworkSubnetHost1010110000010000000000101111111121::1010110011111111Subnet:10101100000100000001000011111111000000100000001011111111011110010000000000000000ClassBSubnetExampleBroadcast:NetworkIPHostAddress: 21SSubnetPlanningOthersubnets62820subnets5hostspersubnetClassCaddress:

SubnetPlanningOther192.168.511111000IPHostAddress: 21SubnetMask:48NetworkSubnetHost21:1100000011111111Subnet:11000000101010001010100011111111000001010000010111111111011110010111100048:ClassCSubnetPlanningExampleSubnetAddress=20HostAddresses=21–26BroadcastAddress=27FiveBitsofSubnettingBroadcast:NetworkNetwork1100000010101000000001010111111111111000IPHostAddress: 192.1BroadcastAddressesExerciseAddressClassSubnetBroadcast048SubnetMask

352728BroadcastAddressesExerciseAdBroadcastAddressesExerciseAnswers27AddressClassSubnetBroadcast048C36SubnetMask

A55352B52728BBroadcastAddressesExerciseA网络工程师：tcpip协议课件Chapter2TCP/IP协议Chapter2TCP/IP协议1.5TCP／IP协议基础 互联网协议（IP）和传输控制协议（TCP）是互联网协议族中最为有名的两个协议，其应用非常广泛，它能够用于任何相互连接的计算机网络系统之间的通信，对局域网（LAN）和广域网（WAN）都有非常好的效果。1.5TCP／IP协议基础 互联网协议（IP）和传输控制1.5TCP／IP协议基础1.5.1TCP／IP与OSI参考模型

●

TCP/IP协议和OSI模型的对应关系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1.5.1TCP／IP与OSI1.5TCP／IP协议基础 ●

TCP/IP的主要协议之间的相关性 图中每个封闭的多边形对应了一个协议，并且位于它所直接使用的协议之上。如SMTP依赖于TCP，而TCP依赖于IP。1.5TCP／IP协议基础 ●TCP/IP的主要协议之1.5TCP／IP协议基础

●TCP/IP的层次结构

l．应用层。向用户提供一组常用的应用程序。

2．传输层（TCP和UDP）。 提供应用程序间的通信，提供了可靠的传输（UDP不能提供可靠的传输）等。

3．网络层（IP）。负责数据包的寻径功能，以保证数据包可靠到达目标主机，若不能到达，则向源主机发送差错控制报文。

4．网络接口层。这是TCP／IP软件的最低层，负责接收IP数据包并通过网络发送之，或者从网络上接收物理帧，抽出IP数据包，并把它交给IP层。1.5TCP／IP协议基础 ●TCP/IP的层次结构1.5TCP／IP协议基础1.5.2网络层（IP层） 将所有的低层的物理实现隐藏起来，作用是将数据包从源主机发送出去，并且使这些数据包独立地到达目的主机。 在数据包传送过程中，即使是连续的数据包，也可能走过不同的路径，到达目的主机的顺序也会不同于它们被发送时的顺序。

1.5TCP／IP协议基础1.5.2网络层（IP层）1.5TCP／IP协议基础

●TCP/IP数据流程1.5TCP／IP协议基础 ●TCP/IP数据流程1.5TCP／IP协议基础 ●IP数据包 一个IP数据包由包头和数据体两部分组成。包头由20字节的固定部分和变长的可选项成。1.5TCP／IP协议基础 ●IP数据包1.5TCP／IP协议基础 ●

IP地址 在Internet中，每一台主机都有一个唯一的地址，网关常常有不止一个的地址。地址由两部分组成：网络号和主机号。这种组合是唯一的，以使每一个IP地址表示Internet中的唯—一台主机。所有IP地址都是32位长。 IP地址分为五类，平常使用的是A，B，C三类地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 ●IP地址地址类型地址形式1.5TCP／IP协议基础 ●IP层的其它一些协议 ICMP（Internet控制信息协议）用来传送一些关于网络和主机的控制信息。如目标主机是不可到达的、路由的重定向等。 ARP（地址解析协议）用来将IP地址映射成相应的主机MAC地址。 RARP（反向地址解析协议）用来将物理地址映射成32位的IP地址。1.5TCP／IP协议基础 ●IP层的其它一些协议1.5TCP／IP协议基础1.5.3传输层（TCP和UDP） ●TCP

TCP协议，即传输控制协议，是一个可靠的、面向连接的协议。它允许在Internet上两台主机间信息的无差错传输。 ●UDP 无连接方式，即UDP方式，当源主机有数据时，就发送。它不管发送的数据包是否到达目标主机，数据包是否出错，收到数据包的主机也不会告诉发送方是否正确收到了数据，因此，这是一种不可靠的数据传输方式。1.5TCP／IP协议基础1.5.3传输层（TCP和UD1.5TCP／IP协议基础1.5.4应用层协议

Telnet，也就是虚终端服务。它允许一台主机上的用户登录进另一台远程主机，并在远程主机中工作，而用户当前所使用的主机好象仅仅是远程主机的一个终端。

FTP，即文件传输协议。提供了一个有效的途径，将数据从一台主机传送到另一台主机。文件传输有文本和二进制两种模式。文本模式用来传输文本文件，并实现一些格式转换。

SMTP，即电子邮件服务使用缺省的端口25，以电子数据的方式，使用户快速、方便地传送信息。即使相隔大洲、大洋，电子邮件也可以在短短的几分钟内到达接收方的电子信箱。

HTTP，即超文本传输协议，用来在.服务器上取得用超文本标记语言书写的页面。1.5TCP／IP协议基础1.5.4应用层协议EarlyprotocolsuiteUniversalIntroductiontoTCP/IPHostInternetTCP/IPHostEarlyprotocolsuiteIntroductiTCP/IP协议栈7654325432ApplicationPresentationSessionTransportNetworkDataLinkPhysical1ApplicationTransportInternetDataLinkPhysical1TCP/IP协议栈7654325432Applicatio应用层Overview*UsedbytherouterApplicationTransportInternetDataLinkPhysicalFileTransfer -TFTP* -FTP* -NFSE-Mail -SMTPRemoteLogin -Telnet* -rlogin*NetworkManagement -SNMP*NameManagement -DNS*应用层Overview*Usedbytheroute传输层OverviewTransmissionControlProtocol(TCP)UserDatagramProtocol(UDP)ApplicationTransportInternetDataLinkPhysical面向连接、可靠的

无连接，不可靠的传输层OverviewTransmissionContrTCP传输控制协议面向连接的先建立连接，后传数据通过三次握手建立连接可靠的发送数据后，必须等待确认后才继续发送等不到确认，会重传数据电话TCP传输控制协议面向连接的电话TCPSegmentFormatSourceport(16)Destinationport(16)Sequencenumber(32)Header

length(4)Acknowledgementnumber(32)Reserved(6)Codebits(6)Window(16)Checksum(16)Urgent(16)Options(0or32ifany)Data(varies)20

BytesBit0Bit15Bit16Bit31TCPSegmentFormatSourceportPortNumbersTCPPort

NumbersF

T

PTransport

LayerT

E

L

N

E

TD

N

SS

N

M

PT

F

T

PS

M

T

PUDPApplication

Layer2123255369161R

I

P520PortNumbersTCPPort

NumbersF

TCPPortNumbersSourcePortDest.Port…HostA102823…SPDPHostZTelnetZDest.port=23.

SendpackettomyTelnet

application.TCPPortNumbersSourceDest.…HoSendSYN(seq=100ctl=SYN)SYNreceivedHostAHostBTCP三次握手1SendSYNSYNreceivedHostAHosSendSYN(seq=100ctl=SYN)SYNreceivedSendSYN,ACK(seq=300ack=101ctl=syn,ack)HostAHostBSYNreceived12TCPThreeWayHandshake/OpenConnectionSendSYNSYNreceivedSendSYN,SendSYN(seq=100ctl=SYN)SYNreceivedSendSYN,ACK(seq=300ack=101ctl=syn,ack)Established(seq=101ack=301ctl=ack)HostAHostB123SYNreceivedTCPThreeWayHandshake/OpenConnectionSendSYNSYNreceivedSendSYN,TCPSimpleAcknowledgmentWindowsize=1

Sender

ReceiverTCPSimpleAcknowledgmentWindoTCPSimpleAcknowledgmentWindowsize=1

Sender

ReceiverSend1Receive1TCPSimpleAcknowledgmentWindoTCPSimpleAcknowledgmentWindowsize=1

Sender

ReceiverSend1Receive1ReceiveACK2SendACK2TCPSimpleAcknowledgmentWindoTCPSimpleAcknowledgmentWindowsize=1

Sender

ReceiverSend1Receive1ReceiveACK2SendACK2Send2Receive2TCPSimpleAcknowledgmentWindoTCPSimpleAcknowledgmentWindowsize=1

Sender

ReceiverSend1Receive1ReceiveACK2SendACK2Send2Receive2ReceiveACK3SendACK3TCPSimpleAcknowledgmentWindoTCPSimpleAcknowledgmentWindowsize=1

Sender

ReceiverSend1Receive1ReceiveACK2SendACK2Send2Receive2ReceiveACK3SendACK3Send3Receive3TCPSimpleAcknowledgmentWindoWindowsize=1

Sender

ReceiverSend1Receive1ReceiveACK2SendACK2Send2Receive2ReceiveACK3SendACK3Send3Receive3ReceiveACK4SendACK4TCPSimpleAcknowledgmentWindowsize=1SenderReceivTCPSequenceand

AcknowledgmentNumbersSourcePortDest.Port…Sequence#Acknowledgement#SourceDest.Seq.Ack.102823101Ijustsent#10.TCPSequenceand

AcknowledgmeTCPSequenceand

AcknowledgmentNumbersIjustgot#10,nowIneed#11.SourcePortDest.Port…Sequence#Acknowledgement#102823SourceDest.10Seq.1Ack.102823SourceDest.11Seq.1Ack.Ijustsent#10.TCPSequenceand

AcknowledgmeTCPSequenceand

AcknowledgmentNumbersSourcePortDest.Port…Sequence#Acknowledgement#102823SourceDest.11Seq.2Ack.102823SourceDest.10Seq.1Ack.102823SourceDest.11Seq.1Ack.Ijustgot#10,nowIneed#11.Ijustsent#11.TCPSequenceand

AcknowledgmeTCPSequenceand

AcknowledgmentNumbersSourcePortDest.Port…Sequence#Acknowledgement#102823SourceDest.11Seq.2Ack.102823SourceDest.10Seq.1Ack.102823SourceDest.11Seq.1Ack.102823SourceDest.12Seq.2Ack.Ijustgot#11,nowIneed#12.Ijustsent#11.TCPSequenceand

AcknowledgmeTCPWindowingSenderReceiverTCPWindowingSenderReceiverTCPWindowingWindowsize=3Send2SenderReceiverWindowsize=3Send1Windowsize=3Send3TCPWindowingWindowsize=3SeWindowsize=3Send2TCPWindowingSenderWindowsize=3Send1Windowsize=3Send3ACK3Windowsize=2Packet3is

DroppedReceiverWindowsize=3TCPWindowingSeWindowsize=3Send2TCPWindowingSenderWindowsize=3Send1Windowsize=3Send3ACK3Windowsize=2Packet3is

DroppedWindowsize=3Send4Windowsize=3Send3ReceiverWindowsize=3TCPWindowingSeWindowsize=3Send2TCPWindowingSenderWindowsize=3Send1Windowsize=3Send3ACK3Windowsize=2Packet3is

DroppedWindowsize=3Send4Windowsize=3Send3ACK5Windowsize=2ReceiverWindowsize=3TCPWindowingSeUDP用户数据报协议面向无连接发送数据之前不需要建立连接直接发送不可靠没有发送确认没有重传机制（由上层协议控制纠错重传）Segment尺寸小，发送速度快传呼，短信UDP用户数据报协议面向无连接传呼，短信NosequenceoracknowledgmentfieldsUDPSegmentFormatSourceport(16)Destinationport(16)Length(16)Data(ifany)1Bit0Bit15Bit16Bit31Checksum(16)8

BytesNosequenceoracknowledgment网络层（IP）OverviewOSI网络层对应TCP/IPinternet层InternetProtocol(IP)InternetControlMessageProtocol(ICMP)AddressResolutionProtocol(ARP)ReverseAddressResolutionProtocol(RARP)ApplicationTransportInternetDataLinkPhysical网络层（IP）OverviewOSI网络层对应TCP/IP层的主要协议IP协议-----InternetProtocol控制数据的路由与转发ICMP协议----Internet控制消息协议测试网络连通性的协议，返回目的不可到达、Echo、超时等消息Ping，Trcert，PathpingARP协议----地址解析协议RARP协议----反向地址解析协议IP层的主要协议IP协议-----InternetProtIPDatagramVersion

(4)DestinationIPAddress(32)Options(0or32ifany)Data(variesifany)1Bit0Bit15Bit16Bit31Header

Length(4)Priority&Type

ofService(8)TotalLength(16)Identification(16)Flags

(3)Fragmentoffset(13)Timetolive(8)Protocol(8)Headerchecksum(16)SourceIPAddress(32)20

BytesIPDatagramVersion

(4)DestinatDeterminesdestinationupper-layerprotocolProtocolFieldTransport

LayerInternet

LayerTCPUDPProtocol

NumbersIP176Determinesdestinationupper-lInternetControlMessage

ProtocolApplicationTransportInternetDataLinkPhysicalDestination

UnreachableEcho(Ping)OtherICMP1InternetControlMessage

ProtAddressResolutionProtocolIP:=???IneedtheEthernetaddressof.AddressResolutionProtocol172AddressResolutionProtocolIP:=???Iheardthatbroadcast.Themessageisforme.HereismyEthernetaddress.IneedtheEthernetaddressof.AddressResolutionProtocol172AddressResolutionProtocolIP:Ethernet:0800.0020.1111IP:=???Iheardthatbroadcast.Themessageisforme.HereismyEthernetaddress.IneedtheEthernetaddressof.AddressResolutionProtocol172AddressR