Introduction 1-1

Networking Admin

1 to 4 lectures a week for 11 weeks for a total of 23 lectures

Interleaves with Functional Programming

First prac this week (THU 17): then every second teaching week (5 pracs in total)

Practicals with a difference

Two weeks to ‘execute them’Self assessment They will be as last year, so you will be

able to have the solutions ahead of handing in, if you like responsibility

Well, PERSONAL RESPONSIBILITY should be the keyword of your relation with this course

It worked reasonably well last year and the year before

Introduction 1-2

The course is entirely based on a book (a very good one!) First 5 chapters (about 500 pages) Of course, some material will be left

out: altogether about 260 pages Still, 10 to 20 pages to read per lecture

(depending on difficulty) Book must be read BEFORE practicals,

though might be understood for real just after ending prac

Introduction 1-3

The book again…

Important: references in the book. Get used to that and use them (within reason)

Another important resource, of course: the internet (for example wikipedia and from there to ‘core’ documents, up to RFCs; www.networksorcery.com is a very useful resource for protocols)

Introduction 1-4

So why having lectures?

Actually not too sure: tradition? Lack of inventiveness? Because life has to be hard, as parents / teachers kept telling you? ;-)

Lectures to get your interest going, or to clarify general / difficult concepts

To ease the difficulty of self learning (which remains the best way to learn, however)

As interactive as possible, please (like, don’t fall asleep…)

Introduction 1-5

Introduction 1-6

The book (and a lot of material!)

Computer Networking: A Top Down Approach ,4th edition. Jim Kurose, Keith RossAddison-Wesley, July 2007.

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 1996-2007J.F Kurose and K.W. Ross, All Rights Reserved

Introduction 1-7

Chapter 1: IntroductionOur 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; hosts, access

net, physical media network core: packet/circuit

switching, Internet structure performance: loss, delay,

throughput security protocol layers, service

models history

Introduction 1-8

Chapter 1: roadmap

1.1 What is the Internet?1.2 Network edge

end systems, access networks, links

1.3 Network core circuit switching, packet switching, network structure

1.4 Delay, loss and throughput in packet-switched networks

1.5 Protocol layers, service models1.6 Networks under attack: security1.7 History

Introduction 1-9

What’s the Internet: “nuts and bolts” view

millions of connected computing devices: hosts = end systems running network

apps Home network

Institutional network

Mobile network

Global ISP

Regional ISP

router

PC

server

wirelesslaptop

cellular handheld

wiredlinks

access points

communication links fiber, copper,

radio, satellite transmission

rate = bandwidth

routers: forward packets (chunks of data)

Introduction 1-10

“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

Internet phones

Introduction 1-11

What’s the Internet: “nuts and bolts” view protocols control sending,

receiving of msgs e.g., TCP, IP, HTTP, Skype,

Ethernet

Internet: “network of networks” loosely hierarchical public Internet versus

private intranet

Internet standards RFC: Request for comments IETF: Internet Engineering

Task Force

Home network

Institutional network

Mobile network

Global ISP

Regional ISP

Introduction 1-12

What’s the Internet: a service view communication

infrastructure enables distributed applications: Web, VoIP, email, games,

e-commerce, file sharing communication services

provided to apps: reliable data delivery

from source to destination

“best effort” (unreliable) data delivery

Introduction 1-13

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

Introduction 1-14

What’s a protocol?a human protocol and a computer network protocol:

Q: Other human protocols?

Hi

Hi

Got thetime?

2:00

TCP connection request

TCP connectionresponseGet http://www.awl.com/kurose-ross

<file>time

Introduction 1-15

Chapter 1: roadmap

1.1 What is the Internet?1.2 Network edge

end systems, access networks, links

1.3 Network core circuit switching, packet switching, network structure

1.4 Delay, loss and throughput in packet-switched networks

1.5 Protocol layers, service models1.6 Networks under attack: security1.7 History

Introduction 1-16

A closer look at network structure:

network edge: applications and hosts

access networks, physical media: wired, wireless communication links network core: interconnected

routers network of

networks

Introduction 1-17

The network edge: end systems (hosts):

run application programs e.g. Web, email at “edge of network”

client/server

peer-peer

client/server model client host requests,

receives service from always-on server

e.g. Web browser/server; email client/server peer-peer model:

minimal (or no) use of dedicated servers

e.g. Skype, BitTorrent