TCP-IP协议栈

nullnull© 2004, Cisco Systems, Inc. All rights reserved.nullTCP/IP本章目标本章目标了解TCP/IP通信 协议 离婚协议模板下载合伙人协议 下载渠道分销协议免费下载敬业协议下载授课协议下载 掌握TCP、UDP及IP报文 格式 pdf格式笔记格式下载页码格式下载公文格式下载简报格式下载 理解并掌握TCP、UDP、IP通信原理 熟悉PING、TRACEROUTE、ARP、RARP等几种三层协议介绍 TCP/IP介绍 TCP/IP早期的协议栈 普遍性的主机InternetTCP/IP主机TCP/IP 协议栈TCP/IP 协议栈764325432应用层表示层会话层传输层网络层数据链路层物理层1应用层传输层互联网层数据链路层物理层1应用层概述应用层概述*Used by the router应用层传输层互联网层数据链路层物理层File Transfer - TFTP * - FTP * - NFS E-Mail - SMTP Remote Login - Telnet * - rlogin * Network Management - SNMP * Name Management - DNS*传输层概述传输层概述Transmission Control Protocol (TCP) User Datagram Protocol (UDP)应用层传输层互联网层数据链路层物理层面向连接的 非面向连接的 TCP 报文格式TCP 报文格式Source port (16)Destination port (16)Sequence number (32)Header length (4)Acknowledgement number (32)Reserved (6)Code bits (6)Window (16)Checksum (16)Urgent (16)Options (0 or 32 if any)Data (varies)20 BytesBit 0Bit 15Bit 16Bit 31端口号端口号TCP端口号F T P传输层T E L N E TD N SS N M PT F T PS M T PUDP应用层2123255369161R I P520TCP 端口号TCP 端口号Source PortDest. Port…Host A102823…SPDPHost ZTelnet ZDest. port = 23. Send packet to my Telnet application.TCP 三次握手建立连接TCP 三次握手建立连接Send SYN (seq=100 ctl=SYN)SYN receivedHost AHost BTCP 三次握手建立连接TCP 三次握手建立连接Send SYN (seq=100 ctl=SYN)SYN receivedSend SYN, ACK (seq=300 ack=101 ctl=syn,ack)Host AHost BSYN receivedTCP 三次握手建立连接TCP 三次握手建立连接Send SYN (seq=100 ctl=SYN)SYN receivedSend SYN, ACK (seq=300 ack=101 ctl=syn,ack)Established (seq=101 ack=301 ctl=ack)Host AHost BSYN receivedTCP简单确认TCP简单确认Window size = 1 Sender ReceiverTCP简单确认TCP简单确认Window size = 1 Sender ReceiverSend 1Receive 1TCP简单确认TCP简单确认Window size = 1 Sender ReceiverSend 1Receive 1Receive ACK 2 Send ACK 2TCP简单确认TCP简单确认Window size = 1 Sender ReceiverSend 1Receive 1Receive ACK 2 Send ACK 2Send 2Receive 2TCP简单确认TCP简单确认Window size = 1 Sender ReceiverSend 1Receive 1Receive ACK 2 Send ACK 2Send 2Receive 2Receive ACK 3Send ACK 3TCP简单确认TCP简单确认Window size = 1 Sender ReceiverSend 1Receive 1Receive ACK 2 Send ACK 2Send 2Receive 2Receive ACK 3Send ACK 3Send 3Receive 3TCP简单确认TCP简单确认Window size = 1 Sender ReceiverSend 1Receive 1Receive ACK 2 Send ACK 2Send 2Receive 2Receive ACK 3Send ACK 3Send 3Receive 3Receive ACK 4Send ACK 4TCP 序列号和确认号TCP 序列号和确认号Source PortDest. Port…Sequence #Acknowledgement #SourceDest.Seq.Ack.102823101I just sent #10.TCP 序列号和确认号TCP 序列号和确认号I just got #10, now I need #11.Source PortDest. Port…Sequence #Acknowledgement #102823SourceDest.10Seq.1Ack.102823SourceDest.11Seq.1Ack.I just sent #10.TCP序列号和确认号TCP序列号和确认号Source PortDest. Port…Sequence #Acknowledgement #102823SourceDest.11Seq.2Ack.102823SourceDest.10Seq.1Ack.102823SourceDest.11Seq.1Ack.I just got #10, now I need #11.I just sent #11.TCP序列号和确认号TCP序列号和确认号Source PortDest. Port…Sequence #Acknowledgement #102823SourceDest.11Seq.2Ack.102823SourceDest.10Seq.1Ack.102823SourceDest.11Seq.1Ack.102823SourceDest.12Seq.2Ack.I just got #11, now I need #12.I just sent #11.TCP窗口TCP窗口SenderReceiverTCP窗口TCP窗口Window size = 3 Send 2SenderReceiverWindow size = 3 Send 1Window size = 3 Send 3TCP窗口TCP窗口Window size = 3 Send 2SenderWindow size = 3 Send 1Window size = 3 Send 3ACK 3 Window size = 2Packet 3 is DroppedReceiverTCP窗口TCP窗口Window size = 3 Send 2SenderWindow size = 3 Send 1Window size = 3 Send 3ACK 3 Window size = 2Packet 3 is DroppedWindow size = 2 Send 4Window size = 2 Send 3ReceiverTCP窗口TCP窗口Window size = 3 Send 2SenderWindow size = 3 Send 1Window size = 3 Send 3ACK 3 Window size = 2Packet 3 is DroppedWindow size = 2 Send 4Window size = 2 Send 3ACK 5 Window size = 2ReceiverUDP 报文格式UDP 报文格式没有序列号或 确认号字段Source port (16)Destination port (16)Length (16)Data (if any)1Bit 0Bit 15Bit 16Bit 31Checksum (16)8 Bytes互联网层概述互联网层概述OSI 网络层在TCP/IP里被描述成互联网层Internet Protocol (IP) Internet Control Message Protocol (ICMP) Address Resolution Protocol (ARP) Reverse Address Resolution Protocol (RARP)应用层传输层互联网层数据链路层物理层IP 数据包IP 数据包Version (4)Destination IP Address (32)Options (0 or 32 if any)Data (varies if any)1Bit 0Bit 15Bit 16Bit 31Header Length (4)Priority & Type of Service (8)Total Length (16)Identification (16)Flags (3)Fragment offset (13)Time to live (8)Protocol (8)Header checksum (16)Source IP Address (32)20 Bytes协议字段协议字段决定目的高层协议 传输层互连网层TCPUDP协议号IP176因特网控制报文协议因特网控制报文协议ApplicationTransportInternetData LinkPhysicalDestination Unreachable Echo (Ping) OtherICMP1Internet Control Message ProtocolInternet Control Message Protocol1、目的不可达ICMP报文（目的网络、目的主机、目的协议、目的端口不可达） 2、超时ICMP报文（TTL每经过一次路由器就减1，减到0时，数据包被丢弃。Trace充分利用了ICMP超时报文） 3、重定向ICMP报文（向源主机通知更好的路由） 4、ICMP回应请求与回应应答（ping发送和接收icmp echo/icmp echo reply报文）Ping命令的结论Ping命令的结论Ping的主要功能是确定一个给定的IP地址是否可以到达。如果ping执行成功，则暗示： 1）从源到目的节点存在一条可以工作的路径； 2）目标IP地址对应的机器在正常工作； 3）从目标节点到源节点存在一条可以工作的路径。 但是，从源到目标的路径与从目标回源节点的路径可能不一致。即不对称路由。Ping命令的输出结果Ping命令的输出结果! Ping操作成功，收到了icmp echo reply报文 . 未收到任何报文 U icmp不可到达目的主机 N icmp不可到达目的网络 P icmp不可到达目的端口 Q icmp源地址失踪 M icmp禁止数据包分段 ? 收到无法识别的数据包Traceroute命令的原理Traceroute命令的原理Traceroute命令描述了从源到目的地址的详细路径，即整个路径上的所有路由器。其原理如下： 1）最开始，源向目的地址发送3个TTL＝1的数据包，第1个路由器收到该包后将其TTL改为0，并向源发送一个ICMP超时消息，源在接到这个消息后便知道了到达目的地址要经过的第1个路由器的地址。 2）接下来，源向目的地址发送3个TTL＝2的数据包，于是，第一个路由器收到该包后改其TTL＝1并转发给第2个路由器，第2个路由器改其TTL＝0，并向源发一个ICMP超时消息，源就知道了应经过的第2个路由器的地址。 3）最后，向目的地址发送3个TTL＝n且目的节点不认识的包，目的节点就向源发回一个目的地址不可达的ICMP消息，于是，源就知道自己已到达了最终目标。 4）依据上述原理，源就知道了到达目的地址应经过的各个路由器的地址。地址解析协议地址解析协议172.16.3.1172.16.3.2IP: 172.16.3.2 = ???I need the Ethernet address of 176.16.3.2.地址解析协议地址解析协议172.16.3.1172.16.3.2IP: 172.16.3.2 = ???地址解析协议地址解析协议172.16.3.1IP: 172.16.3.2 Ethernet: 0800.0020.1111 172.16.3.2IP: 172.16.3.2 = ???地址解析协议地址解析协议Map IP Ethernet Local ARP172.16.3.1IP: 172.16.3.2 Ethernet: 0800.0020.1111 172.16.3.2IP: 172.16.3.2 = ???反向 ARP反向 ARPEthernet: 0800.0020.1111 IP = ???What is my IP address?反向 ARP反向 ARPEthernet: 0800.0020.1111 IP = ???What is my IP address?I heard that broadcast. Your IP address is 172.16.3.25.反向 ARP反向 ARPEthernet: 0800.0020.1111 IP: 172.16.3.25Ethernet: 0800.0020.1111 IP = ???What is my IP address?I heard that broadcast. Your IP address is 172.16.3.25.反向ARP反向ARPMap Ethernet IP Ethernet: 0800.0020.1111 IP: 172.16.3.25Ethernet: 0800.0020.1111 IP = ???What is my IP address?I heard that broadcast. Your IP address is 172.16.3.25.总结总结通过完成本章学习, 你可以完成以下任务: 识别 TCP/IP 协议栈并描述每层的功能 将IP地址分成几个部分描述: 网络号, 子网号, 和主机地址部分 在Cisco的路由器和交换机上配置IP地址问题回顾问题回顾1. 在传输层里,TCP协议和UDP协议有什么不同? 2. 给定一个主机地址, 192.168.20.1 255.255.255.240,在这个子网内还有其他多少个主机地址可用? null