2018/8/23,Computer Networks -1-Part 1,1/59,COMPUTER NETWORKS Chapter 01 Introduction (1),2018/8/23,Computer Networks -1-Part 1,2/59,About the course (1),1. The purpose of the class To make students to learn and get familiar with the basic concepts and aspects of computer networks; thoroughly understand network architectures, primary ideas of network engineering, as well as applications; build up ground work for further study and R&D in computer networks field.,2018/8/23,Computer Networks -1-Part 1,3/59,About the course (2),2. The contents of the classsystematically teach computer networks principles, ISO/OSI reference model (the seven layers), especially the hybrid module of five layers, and TCP/IP module.以层次为线索介绍网络体系结构、协议、网络实例等。ISO/OSI-rm Hybrid Application application Presentation transport Session network Transport data link Network physical Data link Physical,2018/8/23,Computer Networks -1-Part 1,4/59,About the course (3),3. Textbook Andrew Tanenbaum, Computer Networks, 4th ed, Prentice Hall, 2003 4. References(1). Larry Peterson, Computer Networks: A Systems Approach, 2nd ed, Morgan Kaufmann, 2000(2). A lots of other network books both in Chinese or English,2018/8/23,Computer Networks -1-Part 1,5/59,About the course (4),5. Credits56 teaching hours plus 16 project hours with 4 credits 6. AssignmentsHomework is given un-periodically 7. Final TestsAfter class 8. Grading policy20% for assignments, 80% for final.,2018/8/23,Computer Networks -1-Part 1,6/59,Contact information,InstructorYazhe Tang，唐亚哲yztanggmail.com西一楼 431房间Tel：82668642-8021 答疑： 课后 (也可以预约办公室答疑) qq 56479860 （随时留言） email 2009huibiangmail.com 可以下载讲义，文献等,2018/8/23,Computer Networks -1-Part 1,7/59,Chapter 01 Introduction,Contents of This Book 01 Introduction 02 The Physical Layer 物理层 03 The Data Link Layer 数据链路层 04 The MAC Sublayer 介质访问控制子层 05 The Network Layer 网络层 06 The Transport Layer 传输层 07 The Application Layer 应用层,2018/8/23,Computer Networks -1-Part 1,8/59,Course Goal,Be familiar with the concept, basic ideas that we have to know to proudly say I have leant that course and to be able to get further study on this area in the future Understand how internet works, how and why I can get my email through foxmail, how to deal with network problems we meet in our daily life This is something I did not make it when I was in your age,2018/8/23,Computer Networks -1-Part 1,9/59,Historic Review,ENIAC: 1946, the very first computer ARPANET: 1969, the very first computer network for advanced research project agent of defense department, USA. Internet: 1986 National Information Infrastructure: 1993 Commercialized Internet: 1995 NGI: 1995, next generation internet I2: 1996, Internet2 CNGI: Cernet2 + ,2018/8/23,Computer Networks -1-Part 1,10/59,Why Networking?,The integration of computers and communication techniques:(1) communication network is the infrastructure for computer network;(2) computer progress facilitates telecommunicationComputer Network = computer + communication Why networking?The needs for efficiently collecting, storing, processing, distributing and managing informationThe needs for changing manner of using computersThe needs for changing manner of using networks,2018/8/23,Computer Networks -1-Part 1,11/59,What is a computer network?,Tanenbaums definitionComputer network - Interconnected collection of autonomous computers Our definition:A system that interconnecting multiple autonomous computers in different locations with communication equipments, trunks, and communication software(OS, protocols, etc.), for resource sharing,2018/8/23,Computer Networks -1-Part 1,12/59,Differences between computer networks and distributed system,Key distinction is that in a distributed system, the existence of multiple autonomous computers is transparent to users. It looks like a virtual machine with uniprocessor. With a network, users must explicitly log on to one machine, explicitly submit jobs remotely, explicitly move files around and handle network personally.,2018/8/23,Computer Networks -1-Part 1,13/59,Important conclusion,In effect, a distributed system is a software system built on top of networks. The software gives it a high degree of cohesiveness and transparency. Thus the distinction between a network and a distributed system lies in the software (especially the operating system) rather than the hardware.,2018/8/23,Computer Networks -1-Part 1,14/59,1.1 Use of Computer Networks,1.1.1 Business applications Resource sharing, information sharing High reliability Saving money client-server modelScalability,2018/8/23,Computer Networks -1-Part 1,15/59,Business Applications of Networks,Fig. 1-1 A network with two clients and one server.,Fig. 1-2 The client-server model involves requests and replies,2018/8/23,Computer Networks -1-Part 1,16/59,1.1.2 Home Network Applications,Access to remote information Person-to-person communication Interactive entertainment Electronic commerce,2018/8/23,Computer Networks -1-Part 1,17/59,Home Network Applications (2),