Part I Using and Building Internet Applications

2023/9/171Computer Networks and Internetswith Internet Applications2023/9/172Ch1 IntroductionnGrowth of computer networking:recent 25 yearsnComplexity in network systems Different technologiesVarious theories and conceptionsMultiple terminologies2023/9/173Organizationn1.Introduction:Ch13n2.Underlying hardware:Ch4Ch6n3.Packet switching:Ch7Ch16n4.Internet protocols:Ch17Ch27n5.Network applications:Ch28Ch41Study Calendar2023/9/174Ch2 Motivation And Tools Words and PhasesARPA:Advanced Research Projects Agency,高级高级研究计划署研究计划署Packet Switching:分组交换分组交换CCP:Communication Control Processor，通通信信控控制器制器Probe:探测探测Linear:线性的线性的Exponential:指数的指数的2023/9/175Ch2 Motivation And Tools 2.1 MotivationnEarly digital computers were extremely expensive and scarce.Motivation:resource sharingnARPA began its network project in 1960s.nPacket switching became the basis for all the future data networks.2023/9/176Example:ARPANET architectureFeature:The communication sub-network is the center,using the Communication Control Processor(CCP)to process communication tasks.2023/9/177nInternet grew very slowly at beginning.nIt started to grow from 1990.nRapid growth started from 1998.2.2 Growth of the Internet2023/9/1782.2 Growth of the Internet2011:2.1 billion users in the world,485 million users in China.2023/9/1792.3 ToolsProbing the Internet:1.pingping 2.traceroutetraceroute 2023/9/17102.3.1 Interpreting a ping response2023/9/1711Interpreting a ping response2023/9/17122.3.2 Tracing a route2023/9/1713Ch3 Network Programming And Applications3.1 How do computers communicate?1.Network itself does not understand any data it sends.2.Applications do all the processing in pairs.3.The computer who is standing there and waiting for requests from other computers is Server.4.The computer who is having a requirement and sending a connection request is Client.2023/9/1714Ch3 Network Programming And Applications3.2 What is Client-Server paradigm?1.The server application starts first,and waits for contact from a client.2.The client specifies the servers location and request a connection be established.3.Once connection is in place,the client and server use the connection to exchange data.4.When sending finishes,they terminate the connection.2023/9/1715Ch3 Network Programming And Applications3.3 How to set up a connection?1.Client sends request to network by command:echoclient 200002.Server receives the command.3.Server sends command to its application 20000 by:echoserver 200004.If each echo is ok,the connection sets up.2023/9/1716Ch3 Network Programming And Applications3.4 Example1.Server code:page 26-27 2.Client code:page 28-30