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1、Chapter 2 OSI Model&TCP/IP Protocol Suite,The OSI/RMLayers in the OSI/RMTCP/IP protocol suiteAddressing in TCP/IPTCP/IP versions,2.1 The OSI/RM,An ISO standardOpen System Interconnection/Reference Model开放系统互连/参考模型Released in 1984Ensured greater compatibility and interoperability7 layers,each of whic
2、h illustrates a particular network function,ISO is the organization,OSI is the model,OSI is not a protocol,but a conceptual model,OSI Model,Application,Presentation,Session,Transport,Network,Data Link,Physical,7,6,5,4,3,2,1,应用层,表示层,会话层,传输层,网络层,数据链路层,物理层,网络支持层（软/硬件）,应用支持层（软件）,Why Layered？,AdvantagesR
3、educes complexityStandardizes interfacesFacilitates modular engineeringEnsures interoperable technologyAccelerates evolutionSimplifies teaching and learningDisadvantagesStrict layered architecture makes its software not so efficient.,N+1,N,N-1,The Features of Layering,Each layer concerns on its own
4、detailsEach layer provides a service to the layer aboveEach layer communicates with its peer layer in another node through the use of a corresponding protocol,Peer-to-Peer Communication,Interface接口,Service服务,Peer Layer vs.Peer Entity,Multiple entities in one layerPeer entity：存在通信关系的对等层实体Multiple pro
5、tocols in one layerProtocol：对等实体间的通信规则,CutFTP,FTP Server,Outlook,Mail Server,IE,WWW Server,Layer 7,Layer 7,Outlook,IE,CutFTP,FTP Server,Mail Server,WWW Server,FTP,HTTP,SMTP,Data Exchange:Encapsulation,Source,Destination,A,P,S,T,N,DL,Ph,PDU：Protocol Data Unit 协议数据单元,帧 Frame,分组 Packet,数据段 Segment,数据 D
6、ata,Postal Delivery,同层间需要约定规则协议,2.2 Layers in the OSI/RM,Application,Presentation,Session,Transport,Network,Data Link,Physical,7,6,5,4,3,2,1,Network processes to applications,Data representation,Inter-host communication,End-to-end connections,Addressing and best path,Access to media,Binary transmiss
7、ion,Physical Layer,Date Link Layer,Point-to-Point Delivery,Network Layer,Host-to-Host Delivery,Transport Layer,Reliable End-to-End Delivery of a Message,Session Layer,Presentation Layer,Application Layer,2.3 TCP/IP Protocol Suite,OSI/RM,TCP/IP,The historical and technical open standard of the Intern
8、etWanted a network that could survive any conditions,even a nuclear war,Application,Presentation,Session,Transport,Network,Data Link,Physical,1,2,3,4,5,6,7,Application,Transport,Internet,NetworkAccess,Socket,TCP/IP协议,FTP,HTTP,SMTP,DNS,TCP,UDP,IP,LANs,MANs,WANs,DNS,TFTP,SNMP,ICMP,IGMP,ARP,RARP,Multip
9、lexing of TCP/IP Protocols,Telnet,FTP,SMTP,SNMP,TFTP,TCP,UDP,ICMP,IP,ARP,Ethernetsoftware,Ethernethardware,Port,Protocol ID,Type,MAC,23,21,25,161,69,6,17,1,0800H,0806H,2.4 Addressing in TCP/IP,Address,Physical address物理地址,IP addressIP地址,Port address端口地址,标识通信节点节点所属LAN或WAN指定LAN或WAN内唯一链路地址/硬件地址0 x0005.
10、5D06.1418,标识通信节点的网络连接Internet指定Internet内唯一网络地址202.115.12.34,标识通信进程所使用的端口操作系统指定一台计算机内唯一21,23,25,808080,10000,Relation-ship of Layers and Addresses in TCP/IP,Process,TCP,UDP,IP and other protocols,Underlying physical networks,Application layer,Transport layer,Network layer,Network Access layer,Physica
11、l address,IP address,Port address,Example 1,Example 2,2.5 TCP/IP Versions,Version 4（current）Insufficient address space:32-bitInefficient mechanism:poor QoS and securityVersion 5A proposal on the OSI modelNever went beyond the proposal stageVersion 6（future）Only change network layer protocols:IPv6,IC
12、MPv6Large address space：128-bitImprove the weakness of version 4,2.6 Summary,对分层网络协议体系的理解不同节点：层次组成不同，作用不同横向理解：虚通信，对等实体，协议，PDU纵向理解：封装与解封，服务，接口OSI/RM作用各层的名称和功能（概要描述）TCP/IP层次：与OSI模型的对应关系协议：主要协议及其所在层次,Summary（cont.）,Addressing物理、IP、端口地址：作用，所在层次区别OSI vs.ISOPhysical address vs.MAC addressNetwork address vs.IP address,
