CC451 Computer Networks

Computer and Communication Engineering Department SSP

Fall 2014

Bassem Mokhtar, Ph.D. Assistant Professor

Department of Electrical Engineering

Alexandria University

Introduction 1-1

Course details

Credit hour: 3

Allocated time per week: Lecture weekly

Tutorial weekly

Lab weekly

Course Website: http://eng.alexu.edu.eg/~bmokhtar/courses/computer_networks_ssp/computer_networks_ssp.htm

Introduction 1-2

Course outline Fundamental concepts in the design and implementation of

computer networks Protocols, standards and applications

Introduction to network programming

The topics to be covered include: Introduction to network architecture, OSI and the TCP/IP reference

models

Network technologies, especially LAN technologies (Ethernet, wireless networks and Bluetooth)

Issues related to routing and internetworking, Internet addressing and routing

Internet transport protocols (UDP and TCP)

Network-programming interface

Application layer protocols and applications such as DNS, E-mail, and WWW

Introduction 1-3

Course Objectives

Having successfully completed this course, the student will be able to describe :

(a) the principles of computer networking

(b) the relationships and features of each layer in the ISO Open Systems Interconnect reference model

(c) the features and evaluate the performance of automatic retransmission request schemes for error recovery in point-to-point links

(d) the features and evaluate the relative performance of common medium access control protocols

(e) the features and evaluate the performance of standard switched data networks and wireless networks

Introduction 1-4

References “Computer Networking: A Top Down Approach

“,6th edition, James Kurose and Keith Ross, Addison-Wesley, 2013

“Computer Networks”, 5th edition, Tanenbaum and Wetherall, Pearson, 2011

“Data and Computer Communications”, 8th edition, William Stallings, Pearson, 2007

Other Course Materials: Supplemental journal and conference papers, and other

supplemental readings will be used to introduce the latest developments and to provide more detailed documentation for projects.

Introduction 1-5

Assessment

Assignments: 20% Class assignments 10% (around 4 assignments)

Lab assignments 10% (around 4 assignments)

Midterm exam: 20%

Term Project: 20% Submitting project paper related to a computer network topic (Due

date of submission and project presentation and discussion: TBD)

• Grading will relay on project material understanding, quality of submitted paper, presentation and oral discussion

+2% bonus for project simulations (ns-3, MATLAB, others) and code

+2% bonus for related project survey papers (current situation)

Final exam: 40%

Introduction 1-6

Project The final project will run in parallel with the course. Each team (up to three

students per team) will choose freely a computer network-related topic (not covered in the course)

The topic will be chosen by the team on a first-come first-serve (FCFS) basis (no more than one team per topic)

The team will need to do more extensive searching for the latest research work concerning the selected topic (survey paper bonus is here)

Each team will prepare and submit a project paper (using WORD, LATEX) which provides qualitative study for the their topic via including: Motivation for selecting the topic

Discussion of the current research contributions related to the selected topic

Discussion of the major challenges related to the selected topic

Table of performance measure metrics for the related topic

Table of comparison which compare existing solutions/work concerning the selected topic

Showing evaluation scenarios which describe case studies related to the topic

Citation of all referenced work, figures, etc

(You can add other issues based on your selected topic) example: doing modifications for getting new evaluation results

Each team must work on a different topic

Teams will present their project and they will be discussed Introduction 1-7

Examples of Project Topics Routing Metric Selection and Design for Multi-purpose WSN

Routing Protocols in Limited Resource Constrained Networks

Intelligent Sensor Networks for Smart Grids

Context-aware Self-Organizing Networks

Clean Slate Networking Architectures (e.g., cross-layering)

Detection and Defense Technologies of Cyber Attacks in Wireless Networks

Network Monitoring Techniques

Security in Wireless Computer Networks

Highly dynamic Networks (Opportunistic Networks)

Information Centric Networking

SDN in Wireless Environments

Introduction 1-8

DEADLINE for Project Team Formation and Project Topic

Selection: 25th October.

Office Hours

Wednesdays (10:00 am to 11:00 am) or appointment Email me at bmokhtar@alexu.edu.eg

Introduction 1-9

Attendance

Attendance in class is considered essential

Course TAs Eng. Mohamed Shady (tutorials and labs)

Eng. Nour Nabil (labs)

Book Chapters

Chapter 1: Introduction Computer Networks and Internet (2 lectures)

Chapter 2: Application Layer (2 lectures)

Chapter 3: Transport Layer (2 lectures)

Chapter 4: Network Layer (2 lectures)

Chapter 5: Link Layer (2 lectures)

Chapter 6: Wireless and Mobile Networks (2 lectures)

Chapter 7: Multimedia Networking (one lecture)

Chapter 8: Security in Computer Networks (one lecture)

Chapter 9: Network Management (one lecture) Introduction 1-10

Not covered in the course

Not a “communications” course

Does not cover Modulation schemes

Transmitter/Receiver design

Signal processing and antenna design

Etc.

This is course on Understanding, analyzing, and (perhaps) designing of

protocols and algorithms in wired/wireless networking systems

Introduction 1-11

Finally

I cannot / will not / should not be speaking alone in class Questions

Comments

Disagreements

Debates … are highly encouraged

Introduction 1-12

Introduction 1-13

Chapter 1 Introduction

Computer Networking: A Top Down Approach , 4th edition. Jim Kurose, Keith Ross Addison-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 1996-2007

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

Introduction 1-14

Chapter 1: Introduction

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; hosts, access net, physical media

network core: packet/circuit switching, Internet structure

performance: loss, delay, throughput

security

protocol layers, service models

history

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 models

1.6 Networks under attack: security

1.7 History

Introduction 1-16

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

wireless laptop

cellular handheld

wired links

access points

communication links

fiber, copper, radio, satellite

transmission rate = bandwidth

routers: forward packets (chunks of data)

Introduction 1-17

Examples of internet appliances

World’s smallest web server

http://www-ccs.cs.umass.edu/~shri/iPic.html

IP picture frame

http://www.ceiva.com/

Web-enabled toaster +

weather forecaster

Internet phones

Introduction 1-18

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 1-19

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 1-20

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 1-21

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

<file>

time

Introduction 1-22

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 models

1.6 Networks under attack: security

1.7 History

Introduction 1-23

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 1-24

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

Introduction 1-25

Access networks and physical media

Q: How to connect end systems to edge router?

residential access nets

institutional access networks (school, company)

mobile access networks

Keep in mind:

bandwidth (bits per second) of access network?

shared or dedicated?

Introduction 1-26

Residential access: point to point access

Dialup via modem

up to 56Kbps direct access to router (often less)

Can’t surf and phone at same time: can’t be “always on”

DSL: digital subscriber line

deployment: telephone company (typically)

up to 1 Mbps upstream (today typically < 256 kbps)

up to 8 Mbps downstream (today typically < 1 Mbps)

dedicated physical line to telephone central office

Introduction 1-27

Residential access: cable modems

HFC: hybrid fiber coax

asymmetric: up to 30Mbps downstream, 2 Mbps upstream

network of cable and fiber attaches homes to ISP router

homes share access to router

deployment: available via cable TV companies

Introduction 1-28

Residential access: cable modems

Diagram: http://www.cabledatacomnews.com/cmic/diagram.html

Introduction 1-29

Cable Network Architecture: Overview

home

cable headend

cable distribution

network (simplified)

Typically 500 to 5,000 homes

Introduction 1-30

Cable Network Architecture: Overview

home

cable headend

cable distribution

network

server(s)

Introduction 1-31

Cable Network Architecture: Overview

home

cable headend

cable distribution

network (simplified)

Introduction 1-32

Cable Network Architecture: Overview

home

cable headend

cable distribution

network

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1 2 3 4 5 6 7 8 9

FDM (more shortly):

Introduction 1-33

Company access: local area networks

company/univ local area network (LAN) connects end system to edge router

Ethernet:

10 Mbs, 100Mbps, 1Gbps, 10Gbps Ethernet

modern configuration: end systems connect into Ethernet switch

LANs: chapter 5

Introduction 1-34

Wireless access networks

shared wireless access network connects end system to router via base station also known as

“access point”

wireless LANs: 802.11b/g (WiFi): 11 or 54 Mbps

wider-area wireless access provided by telco operator

~1Mbps over cellular system (EVDO, HSDPA)

next up (?): WiMAX (10’s Mbps) over wide area

base station

mobile hosts

router

Introduction 1-35

Home networks

Typical home network components:

DSL or cable modem

router/firewall/NAT

Ethernet

wireless access

point

wireless access point

wireless laptops

router/ firewall

cable modem

to/from cable

headend

Ethernet

Introduction 1-36

Physical Media

Bit: propagates between transmitter/rcvr pairs

physical link: what lies between transmitter & receiver

guided media: signals propagate in solid

media: copper, fiber, coax

unguided media: signals propagate freely,

e.g., radio

Twisted Pair (TP)

two insulated copper wires Category 3: traditional

phone wires, 10 Mbps Ethernet

Category 5: 100Mbps Ethernet

Introduction 1-37

Physical Media: coax, fiber

Coaxial cable: two concentric copper

conductors bidirectional baseband:

single channel on cable legacy Ethernet

broadband: multiple channels on

cable HFC

Fiber optic cable: glass fiber carrying light

pulses, each pulse a bit

high-speed operation: high-speed point-to-point

transmission (e.g., 10’s-100’s Gps)

low error rate: repeaters spaced far apart ; immune to electromagnetic noise

Introduction 1-38

Physical media: radio

signal carried in electromagnetic spectrum

no physical “wire”

bidirectional

propagation environment effects: reflection

obstruction by objects

interference

Radio link types: terrestrial microwave

e.g. up to 45 Mbps channels

LAN (e.g., Wifi) 11Mbps, 54 Mbps

wide-area (e.g., cellular) 3G cellular: ~ 1 Mbps

4G LTE : ~ 5Mbps upload, 12 Mbps download

satellite Kbps to 45Mbps channel (or

multiple smaller channels)

270 msec end-end delay

geosynchronous versus low altitude

Introduction 1-39

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 models

1.6 Networks under attack: security

1.7 History

Introduction 1-40

The Network Core

mesh of interconnected routers

the fundamental question: how is data transferred through net?

circuit switching: dedicated circuit per call: telephone net

packet-switching: data sent thru net in discrete “chunks”

Introduction 1-41

Network Core: Circuit Switching

End-end resources reserved for “call”

link bandwidth, switch capacity

dedicated resources: no sharing

circuit-like (guaranteed) performance

call setup required

Introduction 1-42

Network Core: Circuit Switching

network resources (e.g., bandwidth) divided into “pieces”

pieces allocated to calls

resource piece idle if not used by owning call (no sharing)

dividing link bandwidth into “pieces”

frequency division

time division

Introduction 1-43

Circuit Switching: FDM and TDM

FDM

frequency

time

TDM

frequency

time

4 users

Example:

Introduction 1-44

Numerical example

How long does it take to send a file of 640,000 bits from host A to host B over a circuit-switched network? All links are 1.536 Mbps

Each link uses TDM with 24 slots/sec

500 msec to establish end-to-end circuit

Let’s work it out!

Introduction 1-45

Introduction: Summary

Covered a “ton” of material! Internet overview what’s a protocol? network edge, core, access

network Circuit switching

You now have: context, overview,

“feel” of networking more depth, detail to

follow!