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CSE 422
Computer Networks
Dr. Abdol-Hossein Esfahanian
Computer Science and Engineering
Department
3115 Engineering Building
Catalog Description
CSE 422: Computer Networks
Prerequisite: (STT 351 or ECE 280) and (CSE
320 or ECE 331) and (CSE 410 or concurrently)
Description: Computer network architectures and
models. Physical media and signaling. Data link
protocols. Medium access control. Routing and IP.
Transport services including TCP/UDP. Network
applications. Local-area and wide-area networks.
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Course Objectives
Learn the fundamentals of computer networking.
Understand how these fundamentals are applied in
real networks, in particular, the Internet.
Understand the relationship between theory and
practical design issues in network hardware and
software.
Gain an in-depth understanding of how network
applications software is supported by underlying
protocols.
Learn that computer networks evolve.
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Course Outline
Introduction
 Overview of computer networks
 Network architecture models
 Network programming interfaces
Physical Layer
 Services provided to the data link layer
 Theoretical basis for data communication
 Bandwidth limitations
 Analog and digital transmission
 Transmission media
 Signaling methods
 Multiplexing and switching
 Wireless/Mobile communication
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Course Outline …
Data Link Layer
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Services provided to the network layer
Error detection and correction
Stop-and-wait protocols
Sliding window protocols
Medium Access Sublayer
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Channel allocation problems
Contention-based protocols
Ethernet architecture
802.x protocols
Network Layer
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Services provided to the Transport layer
Routing algorithms
Internetworking
Internet Protocol
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Course Outline…
Transport Layer
 Services provided to the upper layers
 Connection management
 UDP, TCP, sockets
 Performance issues
Application-level Protocol Standards
 Domain name services
 Application standards: SNMP, FTP, TELNET, SMTP,
NNTP, HTTP
Network Security
 Introduction to Cryptography
 Public-key algorithms
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Class Procedures and Policies
Class attendance and
participation (5%)
Homework & Labs (15%)
Two exams (25% each) and a
final (30%)
Course Grade is based on
straight scale; percentages are
on total scores possible:
93 – 100%
85 – 92 %
80 – 84 %
75 – 79 %
70 – 74 %
65 – 69 %
60 – 64 %
4.0
3.5
3.0
2.5
2.0
1.5
1.0
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Class Procedures ……..
Class notes and other course materials and
resources will be available on the course website:
http://www.cse.msu.edu/~cse422/
It is password protected (cse422, tan4me).
Visit this site on regular basis. It is your
responsibility!
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Class Procedures
When attending the class, we ask you to observe a
few simple rules which are meant to create a better
learning environment.
 Come to class on time since we will start lectures right away.
 Once class begins, we expect students to pay attention and not read
the newspaper or talk, etc. TURN YOUR CELL PHONE OFF.
 If you have a question, do not hesitate to ask.
 Others are likely to have the same question.
 Do not be afraid to ask questions and slow down the pace of the
class. If we feel there are too many questions and that we must
move on, we will say so, but that should not be taken to mean
that the question was ``dumb'' or inappropriate.
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Class Procedures …
Textbook: Computer Networks, by Andrew
Tanenbaum, Fourth Edition.
Students are required to get a copy of this
textbook. You will have regular reading
assignments from this textbook.
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Class Procedures …
Instructor: Dr. Abdol-Hossein Esfahanian
Email: [email protected]
Url: http://www.cse.msu.edu/~esfahani/
Office: 2134EB
Tel: 353-4389
Office Hours: Wed 1:00pm – 2:00pm, or by
appointment, or whenever you can find me.
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Class Procedures …
Course TA: Bo Wang [[email protected]]
Office hours will be on Thursdays 10-12 noon.
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Class Procedure …
All students will have computer accounts on CSE
machines. If your home account is under another domain,
then it is your responsibility to have your mail forwarded.
Students are encouraged to work together on homework
assignments. However, each student must do his/her writeup.
Unless otherwise specified, exams will be closed-book and
will cover material assigned from the texts, notes, handouts,
and lectures. For exams only, you are allowed to use an 8½
x 11 note sheet. You should utilize this to write down
important formulae, proof techniques etc.
Being caught cheating on ANY aspect of the course is
grounds for receiving a grade of 0.0 for the course.
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Academic Integrity
Academic Integrity is very important in this class
and in this university. It is important that students
do their work on their own without help from
anyone except the instructor or the teaching
assistant. Students are permitted to discuss the
homework problems with each other. However, the
work they turn in must be completely their own.
Obviously, no cooperation is permitted during
examinations. Students violating this will be dealt
with according to the university policy.
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Important dates
Exam #1
 Thursday Feb 22, 2007
Exam #2
 Thursday April 5, 2007
Final:
 Thursday May 3, 2007, 10:00-12:00 noon
Make note of these dates. Normally there will NOT be any
make-up exams.
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Technologies over the centuries
18th Century: Mechanical Systems Accompanying
The Industrial Revolution
19th Century: Age of The Steam Engine
20th Century: Information Gathering, Processing,
and Distribution. Examples:
 Worldwide Telephone Network
 Invention of Radio and TV
 Computer Industry
 Launching of Communication Satellites
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A brief history of Networking
1961-1972: Early packet-switching principles
1961: Kleinrock - queuing
theory shows effectiveness of
packet-switching
1964: Baran - packet-switching
in military nets
1967: ARPAnet conceived by
Advanced Research Projects
Agency
1969: First ARPAnet node
operational
1972:
 ARPAnet demonstrated
publicly
 NCP (Network Control
Protocol) first host-host
protocol
 First e-mail program
 ARPAnet has 15 nodes
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Networking History (Cont.)
1972-1980: Internetworking, new and proprietary nets
1970: ALOHAnet satellite network
in Hawaii
1973: Metcalfe’s PhD thesis
proposes Ethernet
1974: Cerf and Kahn - architecture
for interconnecting networks
late70’s: Proprietary Architectures:
DECnet, SNA, XNA
late 70’s: switching fixed length
packets (ATM precursor)
1979: ARPAnet has 200 nodes
Cerf and Kahn’s internetworking
principles:
 minimalism, autonomy - no
internal changes required to
interconnect networks
 best effort service model
 stateless routers
 decentralized control define
today’s Internet architecture
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Networking History (Cont.)
1980-1990: new protocols, a proliferation of
networks
1983: deployment of TCP/IP
1983: smtp e-mail protocol
defined
1983: DNS defined for name-toIP-address translation
1985: ftp protocol defined
1988: TCP congestion control
new national networks: Csnet,
BITnet, NSFnet, Minitel
100,000 hosts connected to
confederation of networks
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Networking History (Cont.)
1990’s: commercialization, the WWW
Early 1990’s: ARPAnet
decommissioned
1991: NSF lifts restrictions on
commercial use of NSFnet
(decommissioned, 1995)
early 1990s: WWW
 hypertext [Bush 1945, Nelson
1960’s]
 HTML, http: Berners-Lee
 1994: Mosaic, later Netscape
 late 1990’s: commercialization
Late 1990’s:
est. 50 million computers on
Internet
est. 100 million+ users
backbone links running at 1
Gbps
of the WWW
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The ARPANET
Growth of the ARPANET (a) December 1969. (b) July 1970.
(c) March 1971. (d) April 1972. (e) September 1972.
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Hosts on the Web
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Over the past year, the UK added a net increase of 6.1 subscribers per 100 inhabitants. The US
added 4.7 subscribers, while Japan added 2.6. The UK's superior growth rate propelled it past
the US and Japan to become second only to Canada among G7 countries surveyed in broadband
penetration.
Source: http://www.websiteoptimization.com/bw/0611/
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Total Broadband Subscribers
Over the past year, the US has maintained its lead
with 31% of total broadband subscribers
worldwide.
Source: http://www.websiteoptimization.com/bw/0611/
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Broadband Penetration by Country and Population Density - June 2006
Source: http://www.websiteoptimization.com/bw/0611/
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Lecture 01
Tuesday January 09, 2007
Notable
Read Chapter 1
Read the article Nothing but Net
Forthcoming Topics
 What is a computer network
 Classification of networks
 The layering concept
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What is a Computer Network?
A computer network is an interconnected collection
of autonomous computers.
 Two computer are interconnected if they are able to
exchange information
 Two computer are autonomous if they are capable of
operating independently, that is, neither is capable of
forcibly starting, stopping, or controlling the other.
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What is not a Computer Network?
Master/slave systems, in which one computer
controls several others
single-host networks, consisting of a single
computer with an attached collection of terminals.
Multicomputers, such as the old hypercube, which
normally operate as a back-end to a host system.
In terms of (operating) systems, there is some
confusion between network systems and
distributed systems
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Network Systems
An interconnection of computers through a
communication subnet
The user is aware of the networking of different
computers
Network services
 remote login
 remote file transfer
 remote job execution
 mail service
 Etc,
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Distributed Systems
A distributed system is a special case of computer network,
in which the network of computers appears as a single
system to the user, all operations being performed
transparently.
Combination of an interconnection of computers and
distributed control programs.
Most operations are transparent to the user.
User sees an integrated service environment; distributed
system is hidden from the user.
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Distributed Systems …
Provides location-independent services.
The difference lies with the software rather than
hardware.
Allows concurrent processing and greater sharing
of resources
Permits development of distributed application
programs
Ongoing problems in distributed systems
 load balancing
 fault-tolerance
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Applications of Networks
Access to Remote Programs
 Simulation
 Computer Aided Ed.,
 Medical Diagnosis
Access to Remote Data Bases
 Reservations For Hotels, Airplanes
 Home Banking
 Automated Newspaper
 Automated Library
 Access to Information System: (e.g. World Wide Web)
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Applications of Networks…
Communication Medium
 Electronic Funds Transfer System
 Electronic Mail
 Teleconferencing
 Worldwide Newsgroups
 International Contacts by Humans
Entertainment Industry
 Video On Demand
 Multiperson real-time simulation games
 Selecting any movie/TV program ever made
 Live TV may become interactive with audience
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Social Issues
Views on politics, religion, …., become distributed
 Newsgroups debate sensitive issues
 Network operators risk being sued for contents
 Rights to free speech may be violated
 Anonymous messages can be desirable, but ...
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Network Classification based on physical size
Typical
Distance
Area covered
System Type
10m – 1Km
Room, Building Campus
Local Area Networks
10 – 100Km
City, County, Continent
Metropolitan Area, Wide
Area Network
Over 100Km
Planet
Internet
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Network Structure
Communication Subnet (Subnet)
 Switching Elements (Routers)
 Transmission Lines (Circuits)
Boundary of the
Communication subnet
Routers
Hosts
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Types of Design For Subnets
Point-to-Point Circuits (Channels)
(a)
(b)
(c)
(d)
(e)
(f)
Some possible topologies for a point-to-point subnet
(a) Star (b) Loop (c) Tree (d) Complete (e) Intersecting loops (f) Irregular
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Types of Design For Subnets…
Broadcast Channels
(a)
(b)
(c)
Communication subnet using broadcasting
(a) Bus (b) Satellite or Radio (c) Ring
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Types of Design For Subnets…
Broadcast Subnets May Allocate Channel By:
 Static Method
 TDMA
 Dynamic Methods
 Centralized
 Decentralized
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Classification based on switching techniques
Circuit-switched networks
 A physical circuit must be established between the two
communicating stations before any exchange of
information.
Packet-switched networks
 No physical circuit is established in advance.
 The message is stored and then forwarded at each
intermediate node.
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