Introduction Main Course Page CS 336 ❍ http://www.cs.usfca.edu/~srollins/courses/cs336 Computer Networks Sami Rollins [email protected] Spring 2007 Introduction 1-1 Introduction 1-2 Chapter 1 Chapter 1: Introduction Introduction What applications do you use that use a computer network? A note on the use of these ppt slides: Computer Networking: We’re making these slides freely available to all (faculty, students, readers). They’re in PowerPoint form so you can add, modify, and delete A Top Down Approach 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 Featuring the the following: Internet, 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!) 3rd edition. 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, Jim Kurose, Keith Ross and note our copyright of this material. Addison-Wesley, July Thanks and enjoy! JFK/KWR 2004. All material copyright 1996-2004 J.F Kurose and K.W. Ross, All Rights Reserved Introduction 1-3 Introduction 1-4 Chapter 1: Introduction What’s the Internet: “nuts and bolts” view millions of connected router workstation What applications do you use that use a computing devices: hosts server computer network? = end systems mobile local ISP ❍ We want to understand what is under the hood ❍ examples of hosts? Top-down approach running network apps regional ISP ❍ Understand how applications use the network, ❍ examples of applications? then understand how the network supports those applications Use the Internet as an example company network Introduction 1-5 Introduction 1-6 1 What’s the Internet: “nuts and bolts” view What’s the Internet: “nuts and bolts” view communication links router workstation protocols control sending, router workstation ❍ fiber, copper, radio, server receiving of msgs server satellite mobile mobile ❍ e.g., TCP, IP, HTTP, FTP, PPP ❍ transmission rate = local ISP local ISP bandwidth Internet: “network of • typical bandwidth for networks” modem? wireless? regional ISP ❍ loosely hierarchical regional ISP ❍ public Internet versus private intranet routers: forward packets (chunks of data) Internet standards ❍ RFC: Request for comments ❍ what’s in a packet? company company network ❍ IETF: Internet Engineering network Task Force Introduction 1-7 Introduction 1-8 What’s the Internet: a service view What’s a protocol? communication human protocols: network protocols: infrastructure enables “what’s the time?” machines rather than distributed applications: “I have a question” humans ❍ Web, email, other examples? introductions all communication communication services activity in Internet provided to apps: governed by protocols ❍ connection-oriented reliable protocols define format, order of msgs • example apps? sent and received among network ❍ Connectionless unreliable entities, and actions taken on msg • example apps? transmission, receipt Introduction 1-9 Introduction 1-10 What’s a protocol? A closer look at network structure: a human protocol and a computer network protocol: network edge: applications and Hi TCP connection hosts req Hi TCP connection network core: Got the response ❍ routers time? Get http://www.awl.com/kurose-ross 2:00 ❍ network of <file> networks time access networks, physical media: Q: Why are protocols so important? Introduction 1-11 communication links Introduction 1-12 2.