《计算机网络》课程授课教案（双语，计算机科学与技术专业）

Teaching Plan Name Zhang Yu-fei Academic Year 2013-2013 Term 2 Date 2013.0306 Period 5-7 Textbook COMPUTER NETWORK波10计算机科学与技术本科 Content Chapter1计算机网络和因特网 3 Objectives 了解Iniemet的定义，熟悉Protoco的概念：掌握网络连接服务方式。 Key points Connectionless and Connection-Oriented Services Poinso Conor self sudy Some good hyperlinks.hp/wso Teaching equipment Multimedia Relaed knowedge Intemet Teaching methods 启发式、讨论式教学 Outlines requirements and time allocation Prefac 20分钟 What is unique about this textbook? Pedagogical features,Chapter dependencies (介绍本教材内容安排与特点，对学生的学习要求等。讲解法教学) Computer Networks and the Intemet(计算机网络和因特网) l.I What is the Intemet?(什么是因特网) 20分钟 I1 1 A Nuts and Bolts Description Basic hard ware and software components.Service todistributed applications 1.12 Connection-oriented service and connectionless service. Some good Hyperlinks http//www.ietforg http://www.w3.org http://www.data.com (讲解Internet的软硬件构成，因特网提供的服务类型：提供与因特网有关的知识网 站，供学生浏览自学：用讨论式教学方式教学。) 1.13 What is a Protocol(什么是协议) A Human Analogy 10分钟 “what's the time? “I have a question” introductions 10分钟 and actions taken on msg transmission,receipt

1 Teaching Plan Name Zhang Yu-fei Academic Year 2013-2013 Term 2 Date 2013.03.06 Period 5-7 Textbook COMPUTER NETWORK Specialty and Stratification 10 计算机科学与技术 本科 Content Chapter 1 计算机网络和因特网 Teaching hours 3 Objectives 了解 Internet 的定义，熟悉 Protocol 的概念；掌握网络连接服务方式。 Key points Connectionless and Connection-Oriented Services Points difficult to understand Connectionless and Connection-Oriented Services Content for self study Some good hyperlinks, http://www.ietf.org http://www.isoc.org Teaching equipment Multimedia Related knowledge Internet Teaching methods 启发式、讨论式教学 Outlines, requirements and time allocation Preface What is unique about this textbook? Pedagogical features, Chapter dependencies （介绍本教材内容安排与特点，对学生的学习要求等。讲解法教学） 1 Computer Networks and the Internet（计算机网络和因特网） 1.1 What is the Internet?（什么是因特网） 1.1.1 A Nuts and Bolts Description Basic hardware and software components. Service to distributed applications. 1.1.2 A Service Description Connection-oriented service and connectionless service. Some good Hyperlinks http://www.ietf.org http://www.w3.org http://www.data.com （讲解 Internet 的软硬件构成，因特网提供的服务类型；提供与因特网有关的知识网 站，供学生浏览自学；用讨论式教学方式教学。） 1.1.3 What is a Protocol（什么是协议） A Human Analogy “what’s the time?” “I have a question” introductions Network Protocols Protocols define format, order of msgs sent and received among network entities, and actions taken on msg transmission, receipt 20 分钟 20 分钟 10 分钟 10 分钟

Outlines requirements and time allocation (通过人类用语言交流信息的情况，重点讨论网络交换信息必须采用的各种协议，用 讨论式教学方式教学。) 12 The network Edge(网络边缘) 1.2.1 End System,Clients,and Servers 20分钟 Millions of connected computing devices:hosts,end-systems pe's workstations,servers PDA's phones,toasters running network apps 10分钟 Communication links fiber copper,ado,satellite routers:forward packets(chunks)of data thru network 1.2.2 Connectionless and Connection-Oriented Services 20分钟 Connection-oriented service Goal:data transfer between end sys. Handshaking:stup (prepare for)head ofme TCP-Transmission Control Protoco Internet's connection-oriented service 10分钟 Connectionless service Goal:data transfer between end systems UDP-User Datagram Protocol [RFC 768]:Intemet's connectionless service unreliable datatransfer no flow control no congestion control 20分钟 App's using TCP HTIP (WWW).FTP (file transfer),Telnet (remote login).SMTP (email) App's using UDP: treaming media,teleconferencing.Intemet telephony (重点讲解网络提供的两种连接服务，用讨论式教学方式教学。) 复习本次课的主要内容。 10分钟

2 Outlines, requirements and time allocation （通过人类用语言交流信息的情况，重点讨论网络交换信息必须采用的各种协议，用 讨论式教学方式教学。） 1.2 The network Edge（网络边缘） 1.2.1 End System, Clients, and Servers Millions of connected computing devices: hosts, end-systems pc’s workstations, servers PDA’s phones, toasters running network apps Communication links fiber, copper, radio, satellite routers: forward packets (chunks) of data thru network 1.2.2 Connectionless and Connection-Oriented Services Connection-oriented service Goal: data transfer between end sys. Handshaking: setup (prepare for) data transfer ahead of time TCP - Transmission Control Protocol Internet’s connection-oriented service Connectionless service Goal: data transfer between end systems UDP - User Datagram Protocol [RFC 768]: Internet’s connectionless service unreliable data transfer no flow control no congestion control App’s using TCP: HTTP (WWW), FTP (file transfer), Telnet (remote login), SMTP (email) App’s using UDP: streaming media, teleconferencing, Internet telephony （重点讲解网络提供的两种连接服务，用讨论式教学方式教学。） 复习本次课的主要内容。 20 分钟 10 分钟 20 分钟 10 分钟 20 分钟 10 分钟

Teaching Plan Name Zhang Yu-fei Academic Year 2013-2013 Term 2 Date 2013.03.08 Period 3-4 Textbook COMPUTER NETWORK 10计算机科学与技术本科 Content Chapter1计算机网络和因特网 Teaching Objectives 了解网络接入方式，网络传输介质：熟DydLs的概念：熟主干网概念 掌握网络数据交换方式。 Key points Packet switching.circuit switching Poin Delay and Loss in packet-switched networks Content for self study Some reference hyperlinks,http://www.cisco.com/ivered/ec/td/do/ Teaching equipment Multimedia Related knowledge Intemet Teaching methods 启发式、讨论式教学 Outlines.requirements and time allocation 复习上次课的重要内容 5分钟 I3 The Network Core(网络核心) 1.3.1 Circuit Switching.Packet Switching.and Message Switching 10分钟 The fundamental question:how is data transferred through net? r call:telephone ne “"chunks" 1.32 Routing in Data Network 10分钟 Goal:move packets among routers from source to destination datagram network: destination address deteines next hop roues may change analogy:driving.asking directions virtual circuit network: 10分钟 each packet camies tag (virtual circuit ID),tag determines next hop fixed path determined at call setup time.remains fixed thru call (重点详解数报 与线路交换方式对比讲解)》 I.4 Access Network and Physical Media(接入网和物理媒体》 1.4.1 Access Network residential access nets institutional access networks (school,company)10 mobile access networks

3 Teaching Plan Name Zhang Yu-fei Academic Year 2013-2013 Term 2 Date 2013.03.08 Period 3-4 Textbook COMPUTER NETWORK Specialty and Stratification 10 计算机科学与技术 本科 Content Chapter 1 计算机网络和因特网 Teaching hours 2 Objectives 了解网络接入方式，网络传输介质；熟悉 Delay and Loss 的概念；熟悉主干网概念； 掌握网络数据交换方式。 Key points Packet switching, circuit switching Points difficult to understand Delay and Loss in packet-switched networks Content for self study Some reference hyperlinks, http://www.cisco.com/univercd/cc/td/doc/ Teaching equipment Multimedia Related knowledge Internet Teaching methods 启发式、讨论式教学 Outlines, requirements and time allocation 复习上次课的重要内容 1.3 The Network Core（网络核心） 1.3.1 Circuit Switching, Packet Switching, and Message Switching The fundamental question: how is data transferred through net? Circuit switching: dedicated circuit per call: telephone net Packet-switching: data sent thru net in discrete “chunks” 1.3.2 Routing in Data Network Goal: move packets among routers from source to destination datagram network: destination address determines next hop routes may change during session analogy: driving, asking directions virtual circuit network: each packet carries tag (virtual circuit ID), tag determines next hop fixed path determined at call setup time, remains fixed thru call routers maintain per-call state （重点讲解数据报交换方式的特点，与线路交换方式对比讲解） 1.4 Access Network and Physical Media（接入网和物理媒体） 1.4.1 Access Network residential access nets institutional access networks (school, company) mobile access networks 5 分钟 10 分钟 10 分钟 10 分钟 10 分钟

Outlines requirements and time allocation 1.4.2 Physical Media Protocols 10分钟 Physical Media physical link:transmitted data bit propagates across link guided media:signals propagate in solid media:copper,fiber unguided media:signals propagate freelye.g.,radio Twisted Pair (TP).Coaxial cable,fiber.radio (通过当前家庭及单位接入因特网情况，讲解网络接入方式，网络传输介质，用讨论 式教学方式教学。) 1.5 Intemet Bachbones,NAPs,and ISPs(ISP和因特网主干) 10分钟 Roughly hierarchical National/intemational backbone providers (NBPs) Local ISP.company:connect into regional ISPs (了解网络主干网也是分层次结构的，用讨论式教学方式教学。) .6 Delay and Loss in Packet-.Switched Network(分组交换网络中的时延和分组丢失) 1.6.1 Types of Delay Delay in packet-switched networks 10分钟 Nodal Processing delay: check bit errors determine output link Transmission delay: R=link bandwidth(bps) 10分钟 L=packet length(bits) time to send bits into link =L/R s=propagation speed in medium(~2x108 m/sec) propagation delay=d/s Queuing delay: R=link bandwidth(bps) 10分钟 L=packet length (bits) a=average packet arrival rate traffic intensity=La/R La/R~0:average queuing delay small La/R->1:delays become large La/R>1:more"work"arriving than can be serviced,average delay 重点讲解Queuing delay,用启发、讨论式教学方式教学，) 复习本次课的主要内容。 5分钟

4 Outlines, requirements and time allocation 1.4.2 Physical Media Protocols Physical Media physical link: transmitted data bit propagates across link guided media: signals propagate in solid media: copper, fiber unguided media: signals propagate freelye.g., radio Twisted Pair (TP), Coaxial cable, fiber, radio （通过当前家庭及单位接入因特网情况，讲解网络接入方式，网络传输介质，用讨论 式教学方式教学。） 1.5 Internet Bachbones, NAPs, and ISPs（ISP 和因特网主干） Roughly hierarchical National/international backbone providers (NBPs) interconnect (peer) with each other privately, or at public Network Access Point (NAPs) Regional ISPs：connect into NBPs Local ISP, company：connect into regional ISPs （了解网络主干网也是分层次结构的，用讨论式教学方式教学。） 1.6 Delay and Loss in Packet-Switched Network（分组交换网络中的时延和分组丢失） 1.6.1 Types of Delay Delay in packet-switched networks Nodal Processing delay: check bit errors determine output link Transmission delay: R=link bandwidth (bps) L=packet length (bits) time to send bits into link = L/R Propagation delay: d = length of physical link s = propagation speed in medium (~2x108 m/sec) propagation delay = d/s Queuing delay: R=link bandwidth (bps) L=packet length (bits) a=average packet arrival rate traffic intensity = La/R La/R ~ 0: average queuing delay small La/R -> 1: delays become large La/R > 1: more “work” arriving than can be serviced, average delay infinite! （重点讲解 Queuing delay，用启发、讨论式教学方式教学。） 复习本次课的主要内容。 10 分钟 10 分钟 10 分钟 10 分钟 10 分钟 5 分钟

Teaching Plan Name Zhang Yu-fei Academic Year 2013-2013 Term 2 Date 2013.03.13 Period 5-7 Textbook COMPUTER NETWORK被10计算机科学与技术本科 Content Chapter1计算机网络和因特网 3 Objectives 掌握网络层次和服务模型。了解计算机网络、Interet的发展历史 Key points Protocol Layers and Their Service Models Poinso Layers and Their Service Models Confor sfstudy Some good hyperlinks http:wwis.com/niverd/ Teaching equipment Multimedia Related knowedge Intemet Teaching methods 启发式、讨论式教学 Outlines requirements and time allocation 5分钟 复习上次课的重要内容 L.7 Protocol Layers and Their Service Models(协议层次和它们的服务模型)》 10分钟 7.1 Layered Architecture Networks are complex! many“pieces” hosts 1.72 The Interet Protocol Stack 20分钟 application:supporting network applications host stdata ransfer network:routing of datagrams from source to destination link:data transfer between neighboring network elements physical:bits“on the wire

5 Teaching Plan Name Zhang Yu-fei Academic Year 2013-2013 Term 2 Date 2013.03.13 Period 5-7 Textbook COMPUTER NETWORK Specialty and Stratification 10 计算机科学与技术 本科 Content Chapter 1 计算机网络和因特网 Teaching hours 3 Objectives 掌握网络层次和服务模型。了解计算机网络、Internet 的发展历史 Key points Protocol Layers and Their Service Models Points difficult to understand Protocol Layers and Their Service Models Content for self study Some good hyperlinks, http://www.cisco.com/univercd/cc/td/doc/ Teaching equipment Multimedia Related knowledge Internet Teaching methods 启发式、讨论式教学 Outlines, requirements and time allocation 复习上次课的重要内容 1.7 Protocol Layers and Their Service Mod els（协议层次和它们的服务模型） 1.7.1 Layered Architecture Networks are complex! many “pieces”: hosts, routers, links of various media, applications, protocols, hardware, software 1.7.2 The Internet Protocol Stack application: supporting network applications transport: host-host data transfer network: routing of datagrams from source to destination link: data transfer between neighboring network elements physical: bits “on the wire” 5 分钟 10 分钟 20 分钟

Outlines requirements and time allocation 1.73 Network Entities and Layers 25分钟 End systems and packet switches (通过飞机旅行分层结果，重点讲解计算机网络分层方法与分层优点) 1.8 A Brief History of Computer Network and Intemet(计算机网络和因特网的历史) 1.8.11961-972 15分钟 1961:Kleinrock-queueing theory shows effectiveness of packet-switching 1964:Baran-packet-switching in military nets 1967:ARPAnet conceived by Advanced Reearch Projects Agency 15分钟 1969:first ARPAnet node operational 1972: ARPAnet demonstrated publicly NCP(Network Control Protocol)first host-host protocol first e-mail program ARPAnet has 15 nodes 1.8.21972-1990 15分钟 1970:ALOHAnet satellite network in Hawaii 1973:Metcalfe's PhDthesis proposes Ethemet 1974:Cerf and Kahn-architecture for interconnecting networks 15分钟 late70's:proprietary architectures:DECnet,SNA,XNA late 70's:switching fixed length packets(ATM precursor) 1979:ARPAnet has 200 nodes 1:deployment ofTCP/P 1983:DNS defined for name-to-IP-address translation 1985:ftp protocol defined 1988:TCP congestion control 1.8.31990s 15分钟 6

6 Outlines, requirements and time allocation 1.7.3 Network Entities and Layers End systems and packet switches （通过飞机旅行分层结果，重点讲解计算机网络分层方法与分层优点） 1.8 A Brief History of Computer Network and Internet（计算机网络和因特网的历史） 1.8.1 1961-1972 1961: Kleinrock - queueing theory shows effectiveness of packet-switching 1964: Baran - packet-switching in military nets 1967: ARPAnet conceived by Advanced Reearch Projects Agency 1969: first ARPAnet node operational 1972: ARPAnet demonstrated publicly NCP (Network Control Protocol) first host-host protocol first e-mail program ARPAnet has 15 nodes 1.8.2 1972-1990 1970: ALOHAnet satellite network in Hawaii 1973: Metcalfe’s PhD thesis proposes Ethernet 1974: Cerf and Kahn - architecture for interconnecting networks late70’s: proprietary architectures: DECnet, SNA, XNA late 70’s: switching fixed length packets (ATM precursor) 1979: ARPAnet has 200 nodes 1983: deployment of TCP/IP 1982: smtp e-mail protocol defined 1983: DNS defined for name-to-IP-address translation 1985: ftp protocol defined 1988: TCP congestion control 1.8.3 1990s 25 分钟 15 分钟 15 分钟 15 分钟 15 分钟 15 分钟

Early 1990's:ARPAnet decomissioned 1991:NSF lifts restrictions on commercial use ofNSFnet early 1990s:www hypertext,HTML,http:Bemers-Lee,1994:Mosaic,later Netscape late 1990's:commercialization of the WWW Late 1990's: est.50 million computers on Intemet est.100 million+users (讲解计算机网络发展历史。) 15分钟 复习本次课的主要内容。 复习本章主要内容，布置课后作业

7 Early 1990’s: ARPAnet decomissioned 1991: NSF lifts restrictions on commercial use of NSFnet early 1990s: WWW hypertext, HTML, http: Berners-Lee, 1994: Mosaic, later Netscape late 1990’s: commercialization of the WWW Late 1990’s: est. 50 million computers on Internet est. 100 million+ users （讲解计算机网络发展历史。） 复习本次课的主要内容。 复习本章主要内容，布置课后作业。 15 分钟

Teaching Plan Name Zhang Yu-fei Academic Year 2013-2013 Term 2 Date 2013.03.15 Period 3-4 Textbook COMPUTER NETWORK SPecialy and 10计算机科学与技术本科 Content Chapter2应用层 2 Objectives 了解网络应用层协议，掌握HTP协议的定义及格式等内容。 Key points HTTP Message Format Poinsi Non-persistent and persistent connections Content for f sudy htpw/e5.tx htp//wwrfeditr6.xt Teaching equipment Multimedia Related knowledge Intemet Teaching methds 启发式、讨论式教学 复习上章节的重要内容，从网络层次结构，引入本章 5分钟 2 Application Layer(应用层) 20分钟 .2 of Application Layer protoco(应用层协议原理） 2.1.1 Application-Layer Protocol Application:communicating.distrbuted processes running in network hosts in "user space",exchange messages to implement app egemail,file transfer,the Web Application-layer protocols one "piece"of an app.define messages exchanged by apps and actions taken user services provided by lower layer protocols 20分钟 2.12 What Services Does an Application Need? Data loss. ome apps( udio)can tolerate some loss tenet)require0%ele data transfe 6tprS是，化requremmmo n other apps ("elastic apps")make use of whatever bandwidth they get Timing:some apps (e.g,Intemet telephony,interactive games)require low delay 10分钟 2.1.3 Services Provided by the Intemet Transport Protocol TCP service:UDP service: 2.14 Network Applications Covered in this Book A Nuts and Bolts Description (讲解应用层需要下层运输层结构提供的服务；用启发讨论式教学方式。)

8 Teaching Plan Name Zhang Yu-fei Academic Year 2013-2013 Term 2 Date 2013.03.15 Period 3-4 Textbook COMPUTER NETWORK Specialty and Stratification 10 计算机科学与技术 本科 Content Chapter 2 应用层 Teaching hours 2 Objectives 了解网络应用层协议，掌握 HTTP 协议的定义及格式等内容。 Key points HTTP Message Format Points difficult to understand Non-persistent and persistent connections Content for self study http://www.rfc-editor.org/rfc/rfc1945.txt http://www.rfc-editor.org/rfc/rf c2616.txt Teaching equipment Multimedia Related knowledge Internet Teaching methods 启发式、讨论式教学 Outlines, requirements and time allocation 复习上章节的重要内容，从网络层次结构，引入本章 2 Application Layer（应用层） 2.1 Principles of Application Layer protocol（应用层协议原理） 2.1.1 Application-Layer Protocol Application: communicating, distributed processes running in network hosts in “user space”, exchange messages to implement app e.g., email, file transfer, the Web Application-layer protocols one “piece” of an app, define messages exchanged by apps and actions taken user services provided by lower layer protocols 2.1.2 What Services Does an Application Need? Data loss： some apps (e.g., audio) can tolerate some loss other apps (e.g., file transfer, telnet) require 100% reliable data transfer Bandwidth：some apps (e.g., multimedia) require minimum amount of bandwidth other apps (“elastic apps”) make use of whatever bandwidth they get Timing： some apps (e.g., Internet telephony, interactive games) require low delay 2.1.3 Services Provided by the Internet Transport Protocol TCP service；UDP service: 2.1.4 Network Applications Covered in this Book A Nuts and Bolts Description （讲解应用层需要下层运输层结构提供的服务；用启发讨论式教学方式。） 5 分钟 20 分钟 20 分钟 10 分钟

Outlines requirements and time allocation 2.2 What World Wide Web:HTTP(Web应用和HTTP协议) 2.2.1 A Nuts and Bolts Description 5分钟 http:hypertext transfer protocol Web's application layer protocol client/server model 222 Non-persistent and persistent connections 20分钟 server parses request,responds,and closes TCP connection 2 RTTs to fetch each object Each object transfer suffers from slow start Persistent default for HTTP/1.I on same TCP connection:server,parses request,responds,parses new request, Client sends requests for all referenced objects as soon as it receives base HTML Fewer RTTs and less slow start 2.2.3 HTTP Message Format HTTP/1.0 200 OK Date:Thu,06Aug 19981200:15 GMT Server:Apache/1.3.0 (Unix) Last-Modified:Mon,22 Jun 1998. Content-Length:6821 Content-Type text/html datadata data datadata 2.24 User-Service Interaction:Authentication and Cookies 15分钟 Authentication goal:control access to server documents stateless:client must present authorization in each request authorization:typically name,password 22.5 The Condition GET http request msg:If-modified-since:<date http response:HTTP/10,304 Not Modified 2.2.6 Web Caches user sets browser.Web accesses via web cache me:cache is ) smaller response time:cache "closer"to client decrease traffic to distant servers (重点讲解HTTP格式，引入Condition GET等内容，用启发、讨论式教学方式教学。) 复习本次课的主要内容。 5分钟

9 Outlines, requirements and time allocation 2.2 What World Wide Web: HTTP（Web 应用和 HTTP 协议） 2.2.1 A Nuts and Bolts Description http: hypertext transfer protocol Web’s application layer protocol client/server model 2.2.2 Non-persistent and persistent connections Non-persistent HTTP/1.0 server parses request, responds, and closes TCP connection 2 RTTs to fetch each object Each object transfer suffers from slow start Persistent default for HTTP/1.1 on same TCP connection: server, parses request, responds, parses new request,. Client sends requests for all referenced objects as soon as it receives base HTML. Fewer RTTs and less slow start 2.2.3 HTTP Message Format HTTP/1.0 200 OK Date: Thu, 06 Aug 1998 12:00:15 GMT Server: Apache/1.3.0 (Unix) Last-Modified: Mon, 22 Jun 1998 . Content-Length: 6821 Content-Type: text/html data data data data data . 2.2.4 User-Service Interaction: Authentication and Cookies Authentication goal: control access to server documents stateless: client must present authorization in each request authorization: typically name, password 2.2.5 The Condition GET http request msg: If-modified-since: http response: HTTP/1.0, 304 Not Modified 2.2.6 Web Caches user sets browser: Web accesses via web cache client sends all http requests to web cache Assume: cache is “close” to client (e.g., in same network) smaller response time: cache “closer” to client decrease traffic to distant servers （重点讲解 HTTP 格式，引入 Condition GET 等内容，用启发、讨论式教学方式教学。） 复习本次课的主要内容。 5 分钟 20 分钟 15 分钟 5 分钟

Teaching Plan Name Zhang Yu-fei Academic Year 2013-2013 Term 2 Date 2013.03.20 Period 5-7 Textbook COMPUTER NETWORK 10计算机科学与技术本科 Content Chapter2应用层 3 Objectives 了解Continous Media E-mail:掌握FTP和SMTP协议格式。 Key points SMTP Po可 Mail Access Protocol Conten for selfudy htp//www rfe-editoror5htp/wwrfe-editor.or/rfe/fe81xt Teaching equipment Multimedia Related knowledge FTPand Email Teaching methods 启发式、讨论式教学 Outlinesrquiremns and time all 复习上次课的HTTP格式等重要内容 5分钟 2.3 File Transfer:.FTP(文件传输协议：FTP) 20分钟 2 3 1 FTP Commands and Replies client/ver model fip client contacts fip server at port 21,specifying TCP as transport protoco two parallel TCP connections opened: control:exchange commands,responses between client,server data:file data to/from server fip server maintains"state"cumrent directory,earlier authentication 20分钟 Sample commands USER usemame,PASS password,LIST,RETR filename,STOR filename Sample retum codes:331 Usemame OK,password required 125 data connection already open;transfer starting (讲解FTP端口号，FTP命令格式、返回代码等；用讨论式教学方式教学。) 2.4 Electronic Mail in the Intemet(因特网中的电子邮件) 20分钟 24.1 SMTP Three major components: ui three phases of transfer:handshaking (greeting),transfer of messages,closure command/esponse interaction messages must be in 7-bit ASCII

10 Teaching Plan Name Zhang Yu-fei Academic Year 2013-2013 Term 2 Date 2013.03.20 Period 5-7 Textbook COMPUTER NETWORK Specialty and Stratification 10 计算机科学与技术 本科 Content Chapter 2 应用层 Teaching hours 3 Objectives 了解 Continuous Media E-mail；掌握 FTP 和 S MTP 协议格式。 Key points SMTP Points difficult to understand Mail Access Protocol Content for self study http://www.rfc-editor.org/rfc/rfc19 59.txt http://www.rfc-editor.org/rfc/rf c821.txt Teaching equipment Multimedia Related knowledge FTP and Email Teaching methods 启发式、讨论式教学 Outlines, requirements and time allocation 复习上次课的 HTTP 格式等重要内容 2.3 File Transfer: FTP（文件传输协议：FTP） 2.3.1 FTP Commands and Replies transfer file to/from remote host client/server model ftp client contacts ftp server at port 21, specifying TCP as transport protocol two parallel TCP connections opened: control: exchange commands, responses between client, server. data: file data to/from server ftp server maintains “state”: current directory, earlier authentication Sample commands: USER username, PASS password, LIST, RETR filename, STOR filename Sample return codes：331 Username OK, password required 125 data connection already open; transfer starting （讲解 FTP 端口号，FTP 命令格式、返回代码等；用讨论式教学方式教学。） 2.4 Electronic Mail in the Internet（因特网中的电子邮件） 2.4.1 SMTP Three major components: user agents, mail servers, simple mail transfer protocol: smtp uses tcp to reliably transfer email msg from client to server, port 25 direct transfer: sending server to receiving server three phases of transfer: handshaking (greeting), transfer of messages, closure command/response interaction messages must be in 7-bit ASCII 5 分钟 20 分钟 20 分钟 20 分钟