mạng máy tính phạm trần vũ bài giảng 1 2 introduction

Computer Networks 1
(Mạng Máy Tính 1)
Lectured by: Dr. Phạm Trần Vũ

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Course details
 Number of credits: 4

 Study time allocation per week:
 3 lecture hours for theory
 2 lecture hours for exercises and lab work
 8 hours for self-study
 Website:
 />
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Course outline (1)
 Fundamental concepts in the design and

implementation of computer networks
Protocols, standards and applications
 Introduction to network programming.


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Course outline (2)
 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.

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References


“Computer Networking: A Top Down Approach “,
5th edition, Jim Kurose, Keith Ross

Addison-Wesley, April 2009.

 “Computer

Networks”, Andrew S. Tanenbaum,

4th Edition, Prentice Hall, 2003.
 “TCP/IP Protocol Suite”, B. A. Forouzan, Mc
Graw-Hill, 1st ed., 2000.

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Assessment
 Assignment 20%


Two assignments, 10% each

 Midterm exam: 20%
 Final exam: 60%

 Laboratory work is compulsory
 No lab work = No assignment mark

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Chapter 1
Introduction
Computer Networking: A Top Down Approach ,
5th edition.
Jim Kurose, Keith Ross
Addison-Wesley, April 2009.

All material copyright 1996-2009
J.F Kurose and K.W. Ross, All Rights Reserved
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Introduction

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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






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net, physical media
network core: packet/circuit
switching, Internet structure
performance: loss, delay,
throughput
security
protocol layers, service models
history
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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

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What’s the Internet: “nuts and bolts” view
 millions of connected

PC
server

computing devices:

hosts = end systems

 running network
apps
 communication links

wireless
laptop
cellular
handheld

fiber, copper,
radio, satellite
 transmission
rate = bandwidth
 routers: forward
packets (chunks of
data)

access
points
wired
links

router

Mobile network

Global ISP

Home network
Regional ISP



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Institutional network

Introduction

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“Cool” internet appliances
Web-enabled toaster +
weather forecaster
IP picture frame
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World’s smallest web server
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Internet phones
Introduction

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



protocols control sending,
receiving of msgs




Mobile network

e.g., TCP, IP, HTTP, Skype,
Ethernet

Internet: “network of
networks”



loosely hierarchical
public Internet versus
private intranet

Global ISP

Home network
Regional ISP

Institutional network

 Internet standards

 RFC: Request for comments
 IETF: Internet Engineering
Task Force
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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
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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

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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

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

TCP connection
request

Hi

TCP connection
response

Got the
time?

Get />
2:00

<file>
time

Q: Other human protocols?
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Introduction

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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

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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


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The network edge:
 end systems (hosts):





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

peer-peer

 client/server model




client host requests, receives
service from always-on server
client/server
e.g. Web browser/server;
email client/server

 peer-peer model:



minimal (or no) use of
dedicated servers
e.g. Skype, BitTorrent
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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?
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Dial-up Modem
central
office

home
PC

home
dial-up
modem

telephone
network

Internet

ISP
modem
(e.g., AOL)

Uses existing telephony infrastructure
 Home is connected to central office
 up to 56Kbps direct access to router (often less)
 Can’t surf and phone at same time: not “always on”


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Digital Subscriber Line (DSL)
Existing phone line:
0-4KHz phone; 4-50KHz
upstream data; 50KHz-1MHz

downstream data

home
phone

Internet

DSLAM

telephone
network

splitter
DSL
modem
home
PC

central
office

Also uses existing telephone infrastruture
 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


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Residential access: cable modems
 Does not use telephone infrastructure
 Instead uses cable TV infrastructure
 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
 unlike DSL, which has dedicated access


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Residential access: cable modems

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Cable Network Architecture: Overview

Typically 500 to 5,000 homes

cable headend

cable distribution
network (simplified)
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Cable Network Architecture: Overview
server(s)

cable headend

cable distribution
network
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