Post on 21-Dec-2015
CS 325 Computer Networks
Sami Rollins
srollins@mtholyoke.edu
Fall 2003
9/4/2003
Introduction
• Main Course Page– http://www.mtholyoke.edu/courses/srollins/cs325/
9/4/2003
Assignments
• Homework 0– Send me an email and introduce yourself
• Homework 1– Chapter 1 review
• Read all of chapter 1 for next week– Read section 1.8, though we will only cover it
briefly in class
9/4/2003
Chapter 1Computer Networks
and the Internet
Computer Networking: A Top Down
Approach Featuring the Internet, 2nd edition.
Jim Kurose, Keith Ross
Addison-Wesley, July 2002.
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 1996-2002J.F Kurose and K.W. Ross, All Rights Reserved
9/4/2003
Chapter 1: Introduction
• What applications do you use that use a computer network?– We want to understand what is under the
hood
• Top-down approach– Understand how apps use the network, then
understand how the network works
• Use the Internet as an example
9/4/2003
What’s the Internet: “nuts and bolts” view
local ISP
companynetwork
regional ISP
router workstation
servermobile
9/4/2003
What’s the Internet: “nuts and bolts” view
• connect hosts or end systems running network applications
• other examples of hosts?
local ISP
companynetwork
regional ISP
router workstation
servermobile
9/4/2003
“Cool” internet appliances
World’s smallest web serverhttp://www-ccs.cs.umass.edu/~shri/iPic.html
IP picture framehttp://www.ceiva.com/
Web-enabled toaster+weather forecaster
9/4/2003
What’s the Internet: “nuts and bolts” view
• connected via communication links
• physical media– fiber optics– coaxial cable– others?
• bandwidth how fast bits are transmitted– examples?
local ISP
companynetwork
regional ISP
router workstation
servermobile
9/4/2003
What’s the Internet: “nuts and bolts” view
• routers connect links• forward packets along
a path or route– what’s in a packet?
• packet switching
local ISP
companynetwork
regional ISP
router workstation
servermobile
9/4/2003
What’s the Internet: “nuts and bolts” view
• ISPs connect hosts to the Internet– example ISPs?
local ISP
companynetwork
regional ISP
router workstation
servermobile
9/4/2003
What’s the Internet: “nuts and bolts” view
• Internet: “network of networks”– loosely hierarchical– public Internet versus private intranet
• Internet standards– IETF: Internet Engineering Task Force– RFC: Request for comments
• protocols define message format, processing, etc– TCP/IP – others?
9/4/2003
What’s the Internet: a service view
• communication infrastructure enables distributed applications:– games – what else?
• communication services provided to apps:– connection-oriented, reliable
• example apps?
– connectionless, unreliable• example apps?
9/4/2003
What’s a protocol?
• human protocols– define communication between two people
• network protocols– protocols define format, order of msgs sent
and received among network entities, and actions taken on msg transmission, receipt
• Why are protocols so important?
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What’s a protocol?a human protocol and a computer network protocol:
Hi
Hi
Got thetime?
2:00
TCP connection req
TCP connectionresponseGet http://www.awl.com/kurose-ross
<file>time