《计算机网络》课程PPT教学课件（自顶向下方法，英文第三版）第一章 Computer Networks and the Internet

Chapter 1 Computer Networks and the Internet computer networking rhind flitho James F.Kurose Keith W Ross A note on the use of these ppt slides: We're making these slides freely available to all (faculty,students,readers). They're in PowerPoint form so you can add,modify,and delete slides Computer Networking: (including this one)and slide content to suit your needs.They obviously A Top Down Approach represent a lot of work on our part.In return for use,we only ask the following: Featuring the Internet, If you use these slides (e.g.,in a class)in substantially unaltered form, 3rd edition that you mention their source(after all,we'd like people to use our book!) f you post any slides in substantially unaltered form on a ww site,that Jim Kurose,Keith Ross you note that they are adapted from(or perhaps identical to)our slides,and note our copyright of this material. Addison-Wesley,July 2004. Thanks and enjoy!JFK/KWR All material copyright 1996-2006 J.F Kurose and K.W.Ross,All Rights Reserved Introduction 1-1

Introduction 1-1 Chapter 1 Computer Networks and the Internet Computer Networking: A Top Down Approach Featuring the Internet, 3rd edition. Jim Kurose, Keith Ross Addison-Wesley, July 2004. A note on the use of these ppt slides: We’re making these slides freely available to all (faculty, students, readers). They’re in PowerPoint form so you can add, modify, and delete slides (including this one) and slide content to suit your needs. They obviously represent a lot of work on our part. In return for use, we only ask the following: ❑ If you use these slides (e.g., in a class) in substantially unaltered form, that you mention their source (after all, we’d like people to use our book!) ❑ If you post any slides in substantially unaltered form on a www site, that you note that they are adapted from (or perhaps identical to) our slides, and note our copyright of this material. Thanks and enjoy! JFK/KWR All material copyright 1996-2006 J.F Kurose and K.W. Ross, All Rights Reserved

Chapter 1:Computer Networks and the Internet Our goal: Overview: 口get"feel"and ▣what's the Internet terminology 口what's a protocol3? 口more depth,detail ▣network edge later in course ▣network core 口approach: access net,physical media *use Internet as Internet/ISP structure example performance:loss,delay protocol layers,service models 口network modeling Introduction 1-2

Introduction 1-2 Chapter 1: Computer Networks and the Internet Our goal: ❑ get “feel” and terminology ❑ more depth, detail later in course ❑ approach: ❖ use Internet as example Overview: ❑ what’s the Internet ❑ what’s a protocol? ❑ network edge ❑ network core ❑ access net, physical media ❑ Internet/ISP structure ❑ performance: loss, delay ❑ protocol layers, service models ❑ network modeling

Chapter1:roadmap(路标) 1.1 What is the Internet? 1.2 Network edge 1.3 Network core 1.4 Network access and physical media 1.5 Internet structure and ISPs 1.6 Delay loss in packet-switched networks 1.7 Protocol layers,service models 1.8 History Introduction 1-3

Introduction 1-3 Chapter 1: roadmap(路标) 1.1 What is the Internet? 1.2 Network edge 1.3 Network core 1.4 Network access and physical media 1.5 Internet structure and ISPs 1.6 Delay & loss in packet-switched networks 1.7 Protocol layers, service models 1.8 History

What's the Internet:"nuts and bolts'"view俱体细 millions of connected X router 必 computing devices:hosts workstation end systems 目server mobile □running network apps cal ISP ▣communication links fiber,copper,radio, satellite transmission rate bandwidth routers:forward packets (chunks(大块)of data) compary边 network Introduction 1-4

Introduction 1-4 What’s the Internet: “nuts and bolts” view (具体细节) ❑ millions of connected computing devices: hosts = end systems ❑ running network apps ❑ communication links ❖ fiber, copper, radio, satellite ❖ transmission rate = bandwidth ❑ routers: forward packets (chunks（大块） of data) local ISP company network regional ISP router workstation server mobile

"Cool"internet appliances Web-enabled toaster weather forecaster IP picture frame(框架) http://www.ceiva.com/ World's smallest web server http://www-ccs.cs.umass.edu/-shri/iPic.html Internet phones Introduction 1-5

Introduction 1-5 “Cool” internet appliances World’s smallest web server http://www-ccs.cs.umass.edu/~shri/iPic.html IP picture frame（框架） http://www.ceiva.com/ Web-enabled toaster + weather forecaster Internet phones

What's the Internet:"nuts and bolts"view X protocols control sending, router 珍 workstation receiving of msgs 目server 区 e.g.,TCP,IP,HTTP,FTP,PPP mobile Internet:"network of eal ISP networks" Loosely(宽松的)hierarchical public Internet versus private intranet(内联网) ▣Internet standards RFC:Request for comments IETF:Internet Engineering Task Force(因特网工程任务组) company network Introduction 1-6

Introduction 1-6 What’s the Internet: “nuts and bolts” view ❑ protocols control sending, receiving of msgs ❖ e.g., TCP, IP, HTTP, FTP, PPP ❑ Internet: “network of networks” ❖ Loosely（宽松的） hierarchical ❖ public Internet versus private intranet（内联网） ❑ Internet standards ❖ RFC: Request for comments ❖ IETF: Internet Engineering Task Force（因特网工程任务组） local ISP company network regional ISP router workstation server mobile

What's the Internet:a service view ▣communication infrastructure(下部胸造) enables distributed(分布式的) applications: Web,email,games,e- commerce,file sharing communication services provided to apps: Connectionless unreliable connection-oriented reliable Introduction 1-7

Introduction 1-7 What’s the Internet: a service view ❑ communication infrastructure （下部构造） enables distributed（分布式的） applications: ❖ Web, email, games, e￾commerce, file sharing ❑ communication services provided to apps: ❖ Connectionless unreliable ❖ connection-oriented reliable

What's a protocol? human protocols: network protocols: ▣"what's the time?" ▣machines rather than 口"I have a question" humans ▣introductions ▣all communication activity in Internet .specific msgs sent governed by protocols specific actions taken protocols define format, when msgs received, order of msgs sent and or other events received among network entities,and actions taken on msg transmission,receipt Introduction 1-8

Introduction 1-8 What’s a protocol? human protocols: ❑ “what’s the time?” ❑ “I have a question” ❑ introductions . specific msgs sent . specific actions taken when msgs received, or other events network protocols: ❑ machines rather than humans ❑ all communication activity in Internet governed by protocols protocols define format, order of msgs sent and received among network entities, and actions taken on msg transmission, receipt

What's a protocol? a human protocol and a computer network protocol: Hi ICP connection Hi request TCP connection Got the response time? Get http://www.awl.com/kurose-ross ★-2：00 kfile> time Q:Other human protocols? Introduction 1-9

Introduction 1-9 What’s a protocol? a human protocol and a computer network protocol: Q: Other human protocols? Hi Hi Got the time? 2:00 TCP connection request TCP connection response Get http://www.awl.com/kurose-ross time

Chapter 1:roadmap 1.1 What is the Internet? 1.2 Network edge 1.3 Network core 1.4 Network access and physical media 1.5 Internet structure and ISPs 1.6 Delay loss in packet-switched networks 1.7 Protocol layers,service models 1.8 History Introduction 1-10

Introduction 1-10 Chapter 1: roadmap 1.1 What is the Internet? 1.2 Network edge 1.3 Network core 1.4 Network access and physical media 1.5 Internet structure and ISPs 1.6 Delay & loss in packet-switched networks 1.7 Protocol layers, service models 1.8 History