《计算机网络 Computer Networking》课程PPT教学课件（A Top Down Approach，8th edition）Chapter 1 Computer Networks and the Internet

Chapter 1 James F.Kurose Keith W.Ross Introduction A note on the use of these PowerPoint slides: We're making these slides freely available to all(faculty,students, readers).They're in PowerPoint form so you see the animations;and 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. COMPUTER In return for use,we only ask the following: NETWORKING If you use these slides(e.g.,in a class)that you mention their A TOP-DOWN APPROACH source(after all,we'd like people to use our book!) If you post any slides 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. Computer Networking:A For a revision history,see the slide note for this page. Top-Down Approach Thanks and enjoy!JFK/KWR 8th edition All material copyright 1996-2020 Jim Kurose,Keith Ross J.F Kurose and K.W.Ross,All Rights Reserved Pearson,2020 Introduction:1-1

Introduction: 1-1 Chapter 1 Introduction A note on the use of these PowerPoint slides: We’re making these slides freely available to all (faculty, students, readers). They’re in PowerPoint form so you see the animations; and 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) that you mention their source (after all, we’d like people to use our book!) ▪ If you post any slides 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. For a revision history, see the slide note for this page. Thanks and enjoy! JFK/KWR All material copyright 1996-2020 J.F Kurose and K.W. Ross, All Rights Reserved Computer Networking: A Top-Down Approach 8 th edition Jim Kurose, Keith Ross Pearson, 2020

Chapter 1:introduction Chapter goal: Overview/roadmap: Get"feel,"“big picture,” What is the Internet? introduction to terminology What is a protocol? more depth,detail later in Network edge:hosts,access network, course physical media Approach: Network core:packet/circuit switching, internet structure use Internet as example Performance:loss,delay,throughput ■Security Protocol layers,service models ■History Introduction:1-2

Chapter 1: introduction Chapter goal: ▪ Get “feel,” “big picture,” introduction to terminology • more depth, detail later in course ▪ Approach: • use Internet as example Introduction: 1-2 Overview/roadmap: ▪ What is the Internet? ▪ What is a protocol? ▪ Network edge: hosts, access network, physical media ▪ Network core: packet/circuit switching, internet structure ▪ Performance: loss, delay, throughput ▪ Security ▪ Protocol layers, service models ▪ History

The Internet:a "nuts and bolts"view Billions of connected mobile network computing devices: OL TO national or global ISP ■hosts=end systems running network apps at Internet's"edge” Packet switches:forward packets(chunks of data) local or ■routers,switches home network content Communication links provider network datacenter fiber,copper,radio,satellite network transmission rate:bandwidth Networks enterprise collection of devices,routers, network links:managed by an organization Introduction:1-3

Internet The Internet: a “nuts and bolts” view Introduction: 1-3 mobile network home network enterprise network national or global ISP local or regional ISP datacenter network content provider network Packet switches: forward packets (chunks of data) ▪ routers, switches Communication links ▪ fiber, copper, radio, satellite ▪ transmission rate: bandwidth Billions of connected computing devices: ▪ hosts = end systems ▪ running network apps at Internet’s “edge” Networks ▪ collection of devices, routers, links: managed by an organization

"Fun"Internet-connected devices Pacemaker Monitor Tweet-a-watt: monitor energy use Amazon Echo IP picture frame Web-enabled toaster+ weather forecaster Internet refrigerator Slingbox:remote control cable TV Security Camera AR devices sensorized. bed Internet phones mattress Others? Fitbit Introduction:1-4

“Fun” Internet-connected devices Introduction: 1-4 IP picture frame Web-enabled toaster + weather forecaster Internet phones Internet refrigerator Slingbox: remote control cable TV Tweet-a-watt: monitor energy use sensorized, bed mattress Security Camera Amazon Echo Pacemaker & Monitor Others? Fitbit AR devices

The Internet:a "nuts and bolts"view mobile network 4G -Internet:"network of networks" national or global ISP ·Interconnected ISPs protocols are everywhere Streaming Skype video control sending,receiving of messages local or e.g.,HTTP(Web),streaming video, Skype,TCP,IP,WiFi,4G,Ethernet home network content provider Internet standards HTTP network atacenter network RFC:Request for Comments Ethernet IETF:Internet Engineering Task TCP Force enterprise network WiFi Introduction:1-5

▪ Internet: “network of networks” • Interconnected ISPs The Internet: a “nuts and bolts” view Introduction: 1-5 mobile network home network enterprise network national or global ISP local or regional ISP datacenter network content provider network ▪ protocols are everywhere • control sending, receiving of messages • e.g., HTTP (Web), streaming video, Skype, TCP, IP, WiFi, 4G, Ethernet ▪ Internet standards • RFC: Request for Comments • IETF: Internet Engineering Task Force Ethernet HTTP Skype IP WiFi 4G TCP Streaming video

The Internet:a "service"view Infrastructure that provides mobile network services to applications: national or global ISP Web,streaming video,multimedia teleconferencing,email,games,e- Streaming commerce,social media,inter- Skype video connected appliances,.. local or provides programming interface regionaMSP to distributed applications: home network content provider "hooks"allowing sending/receiving HTTP network datacenter apps to“connect'”to,use Internet network transport service provides service options,analogous enterprise to postal service network Introduction:1-6

▪ Infrastructure that provides services to applications: • Web, streaming video, multimedia teleconferencing, email, games, e￾commerce, social media, inter￾connected appliances, … The Internet: a “service” view Introduction: 1-6 mobile network home network enterprise network national or global ISP local or regional ISP datacenter network content provider HTTP network Skype Streaming video ▪ provides programming interface to distributed applications: • “hooks” allowing sending/receiving apps to “connect” to, use Internet transport service • provides service options, analogous to postal service

What's a protocol? Human protocols: Network protocols: ·“what's the time?” computers(devices)rather than humans .“I have a question” all communication activity in Internet ·introductions governed by protocols ..specific messages sent Protocols define the format,order of ..specific actions taken when message received, messages sent and received among or other events network entities,and actions taken on msg transmission,receipt Introduction:1-7

What’s a protocol? Introduction: 1-7 Human protocols: ▪ “what’s the time?” ▪ “I have a question” ▪ introductions … specific messages sent … specific actions taken when message received, or other events Network protocols: ▪ computers (devices) rather than humans ▪ all communication activity in Internet governed by protocols Protocols define the format, order of messages 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: TCP connection request Hi TCP connection response Got the time? GET http://gaia.cs.umass.edu/kurose_ross 4一2：00 time Q:other human protocols? Introduction:1-8

What’s a protocol? Introduction: 1-8 A human protocol and a computer network protocol: Q: other human protocols? Hi Hi Got the time? 2:00 time TCP connection response TCP connection request GET http://gaia.cs.umass.edu/kurose_ross

Chapter 1:roadmap -What is the Internet? ■What is a protocol? Network edge:hosts,access network, physical media Network core:packet/circuit switching,internet structure Performance:loss,delay,throughput Security Protocol layers,service models ■History Introduction:1-9

Chapter 1: roadmap Introduction: 1-9 ▪ What is the Internet? ▪ What is a protocol? ▪ Network edge: hosts, access network, physical media ▪ Network core: packet/circuit switching, internet structure ▪ Performance: loss, delay, throughput ▪ Security ▪ Protocol layers, service models ▪ History

A closer look at Internet structure mobile network Network edge: national or global ISP hosts:clients and servers servers often in data centers local or regionalsp home network content provider network datacenter network enterprise network Introduction:1-10

A closer look at Internet structure Introduction: 1-10 mobile network home network enterprise network national or global ISP local or regional ISP datacenter network content provider network Network edge: ▪ hosts: clients and servers ▪ servers often in data centers