[信息与通信]第02章 OSI和TCPIP——new 2.ppt
Chapter 2 OSI Model & TCP/IP Protocol Suite,The OSI/RM Layers in the OSI/RM TCP/IP protocol suite Addressing in TCP/IP TCP/IP versions,2.1 The OSI/RM,An ISO standard Open System Interconnection/ Reference Model 开放系统互连/参考模型 Released in 1984 Ensured greater compatibility and interoperability 7 layers, each of which 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？,Advantages Reduces complexity Standardizes interfaces Facilitates modular engineering Ensures interoperable technology Accelerates evolution Simplifies teaching and learning Disadvantages Strict layered architecture makes its software not so efficient.,N+1,N,N-1,The Features of Layering,Each layer concerns on its own details Each layer provides a service to the layer above Each 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 layer Peer entity：存在通信关系的对等层实体 Multiple protocols in one layer Protocol：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 Data,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 transmission,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 Internet Wanted 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,Network Access,Socket,TCP/IP协议,FTP,HTTP,SMTP,DNS,TCP,UDP,IP,LANs,MANs,WANs,DNS,TFTP,SNMP,ICMP,IGMP,ARP,RARP,Multiplexing of TCP/IP Protocols,Telnet,FTP,SMTP,SNMP,TFTP,TCP,UDP,ICMP,IP,ARP,Ethernet software,Ethernet hardware,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 address IP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 0x0005.5D06.1418,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, 80 8080, 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,Physical address,IP address,Port address,Example 1,Example 2,2.5 TCP/IP Versions,Version 4（current） Insufficient address space: 32-bit Inefficient mechanism: poor QoS and security Version 5 A proposal on the OSI model Never went beyond the proposal stage Version 6（future） Only change network layer protocols: IPv6, ICMPv6 Large address space：128-bit Improve 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. ISO Physical address vs. MAC address Network address vs. IP address,
