Computer Network Lecture 1 2005 2006

(c) Dr. Rahul Banerjee, BITS-Pilani, India 1

Introduction to Computer Networks Introduction to Computer Networks

Dr. Rahul BanerjeeDr. Rahul BanerjeeAssociate Professor: CS & IS GroupAssociate Professor: CS & IS GroupBirla Institute of Technology & Science, Pilani Birla Institute of Technology & Science, Pilani (India)(India)Email: Email: rahul@[email protected]: Home: http://discovery.bitshttp://discovery.bits--pilani.ac.in/rahul/pilani.ac.in/rahul/

Lecture-1 of 42Second Semester: 2005-2006

(c) Dr. Rahul Banerjee, BITS-Pilani, India 2

Interaction Points

A brief introduction to:

the Course Objectives and Scope

the Plan of Interaction & Content Delivery

the Plan of Course Administration

Why do we need Computer Networks and Internetworks?

Examples of networks and internetworks

Types of networks and internetworks

Internetworks and Security

Discussions

Recommendations for further reading

(c) Dr. Rahul Banerjee, BITS-Pilani, India 3

Course Objectives & Scope Introducing the CS majors to the fundamental

design aspects of a modern computer network / internetwork is the primary objective of this course. This shall, in turn, involve: Study of elements of computer

communication, algorithms and networking protocols

Study of system/application design issues in building good networks / internetworks

Understanding of Design Trade-offs required for building robust, economical and efficient Networks

Focus shall be on system design aspects in the specific context of networks / internetworks.

Where time so permits, analysis of these designs shall be carried out vis--vis current best practices and evolving trends.

(c) Dr. Rahul Banerjee, BITS-Pilani, India 4

Plan of Interaction & Content Delivery

Course-specific interaction & content delivery Course does have instructor-led and self-study

components We will have 42 lecture sessions . We will cover concepts, issues, design and deployment

aspects in the class. We shall NOT attempt to discuss the entire handout /

text book. You are expected to read the text book and other referred material in addition to the lecture notes.

We shall have unstructured interaction sessions outside the scheduled classes, where necessary.

Course-specific contents shall be uploaded at: Courses Web page: http://discovery.bits-

pilani.ac.in/rahul/CompNet/ shall be updated at least once a week with Lecture Slides in PDF form. This page already has the detailed Course Handout in HTML and PDF formats.

In addition, Courses internal portal at http://intraBITS.bits-pilani.ac.in shall be enabled on January 21, 2006. This site shall have additional reading material, laboratory manuals, assignment descriptions, and notices for Tests , extra classes, answer script distribution and grading etc.

In addition, students shall be expected to upload electronic copy of their assignment reports.

(c) Dr. Rahul Banerjee, BITS-Pilani, India 5

Plan of Course Administration You will have 10-minute quizzes based on previous

weeks classroom discussions conducted during the first lecture of each week. Thus, these are scheduled quizzed for which you know schedule right now.

Not all quizzes shall be evaluated. Out of each months quizzes any one quiz shall be evaluated.

There shall be one study-based / design-based / implementation-based assignment that shall involve not more than two students working on it. Marks shall be based on viva-voce and / or demonstration as the case may require.

Use of any unfair means in Assignment Submission etc. shall invariably lead to award of zero marks and may attract appropriate disciplinary action.

There shall be a Mid-Semester Test

Comprehensive Examination shall be completely an Open Book examination.

P.S. First week shall have no lecture during Jan. 11-13, 2006 due to my being out of station on official business. This shall be compensated through an extra lecture on the following Saturday in the Room No. 3160 at 3:00 PM.

(c) Dr. Rahul Banerjee, BITS-Pilani, India 6

What is a Computer Network? Defining a Computer Network

A Computer Network is an interconnected group of autonomous computing nodeswhich:

Use a well-defined, mutually-agreed set of rules and conventions known as Protocols,

Interact with one-another, if duly authenticated and authorized, meaningfully;

Allow resource-sharing preferably in a predictable and controllable manner.

Autonomous computing node A computer / node that has its own

processing capabilities and that does not act under the control of any other computer / is known as an Autonomous Computer or an Autonomous Computing Node.

It should NOT be confused with the traditional Dumb Terminals in Unix, Linux, SunOS and several other computing environments.

(c) Dr. Rahul Banerjee, BITS-Pilani, India 7

An Example of a Computer Network

Shared BUS / Switch

Workstation

Workstation

Workstation

Workstation

Workstation

Workstation

Workstation

(c) Dr. Rahul Banerjee, BITS-Pilani, India 8

Why do we need Computer Networks?

Resource sharing and communication are two principal reasons of building and using computer networks.

Some of the most popular applications include: Electronic Mail Web-browsing Digital Libraries Video-on-Demand File Transfer Video / Audio Conferencing E-commerce

(c) Dr. Rahul Banerjee, BITS-Pilani, India 9

Networks versus Distributed Systems

Terms Computer Network and Distributed System must NOT be used interchangeably since: In the former, locations and elements

of network remain visible to the user; whereas

in the latter, the underlying network remains transparent to the user who sees the system as a uni-processor.

Similar differences can be cited in case of Network Operating Systems and Distributed Operating Systems.

(c) Dr. Rahul Banerjee, BITS-Pilani, India 10

Types of Computer Networks 1 of 2

Class One: Function-based classification

Data Networks Voice Networks Multimedia Networks

Class Two: Location-and-Distance-based classification

Personal Area Networks (PANs) Local Area Networks (LANs) Metropolitan Area Networks (MANs) Wide Area Networks (WANs)

(c) Dr. Rahul Banerjee, BITS-Pilani, India 11

Types of Computer Networks 2 of 2 Class Three: Forwarding-based

classification Switched Networks

Circuit-Switched Networks Packet-Switched Networks

Shared Networks Hybrid Networks

Class Four: Ownership-based classification

Public Networks Private Networks Virtual Private Networks Leased Networks

(c) Dr. Rahul Banerjee, BITS-Pilani, India 12

Defining a LAN

The term LAN stands for Local Area Network.

The term local area in the world of networking usually refers to a geographically contiguous area in which the inter-computer distance is lesser than or equal to one kilometer.

(c) Dr. Rahul Banerjee, BITS-Pilani, India 13

Local Area Networks ...

It is wholly owned by a single organization / entity, is locally installed (i.e. in a single contiguous geographic location like an office, a laboratory, a building or a campus) is called a Local Area Network (LAN).

Although, normally, in a LAN, the inter-node distance does not exceed a kilometer; in most of the real-life situations, it is far less than this ceiling.

(c) Dr. Rahul Banerjee, BITS-Pilani, India 14

Local Area Network: An Example

Core Switch

Distribution Switch Distribution Switch Distribution Switch

Access Switch Access Switch Access Switch

PC / Laptop /Tablet / Network Printer

(c) Dr. Rahul Banerjee, BITS-Pilani, India 15

Defining a MAN

The term MAN stands for Metropolitan Area Network.

A computer network that is not usually owned by a single organization / entity and that is spread over a metropolitan city area is called a Metropolitan Area Network.

Normally, in a MAN, the inter-node distance does not exceed ten kilometers. This, however, is not a hard-and-fast rule.

(c) Dr. Rahul Banerjee, BITS-Pilani, India 16

Defining a WAN

The term WAN stands for Wide Area Network.

A computer network that is not usually owned by a single organization / entity and that is spread over an area larger than that of any city of operation is called a Wide Area Network .

A WAN may be spread over several cities / towns, a state, a country or even a continent.

In many a cases, when people say WAN, they actually mean Wide Area Internetwork (WAI), however!

(c) Dr. Rahul Banerjee, BITS-Pilani, India 17

Defining a PAN

The term PAN stands for Personal Area Network.

Typically these networks are small in size, belong to a single person and are limited to his / her environment within a small area like his room, body or garden etc.

PANS mostly use short-range wireless technologies for interconnecting various nodes that comprise them.

(c) Dr. Rahul Banerjee, BITS-Pilani, India 18

Defining Internetworks

An Internetwork may be defined as a network of computer networksany authorized node of which could directly or indirectly communicate with any other member node.

It may consist of several PANs, LANs, MANs or WANs interconnected via LAN / MAN / WAN oriented communication technology.

(c) Dr. Rahul Banerjee, BITS-Pilani, India 19

Of the Internet, Intranet and Extranet The Global Public Internetwork: The

Internet The Wholly Owned / Private

Internetwork: Intranet The Hybrid Internetwork-- private

networks / internetworks connected through the Internet: ExtranetIn the early stages of development, technologies used for the internetworks of all type were essentially the same, except probably at the lowest level. This situation is rapidly changing.

(c) Dr. Rahul Banerjee, BITS-Pilani, India 20

BITS Campus Internetwork

Wireless Bridge Cisco Aironet Access Point

Firewall

Rana

Ashok

Vishkarma

Bhagi

Krishna

Gandhi

Shankar

Vyas

Ram

Budh

Malvya

M W

3M

W 6

M W

8

M W 10

Library

M B LRE

Existing Network

Guest House

Server Farm

(c) Dr. Rahul Banerjee, BITS-Pilani, India 21

Internetworks & Security

Participating networks in an Internetwork may be interconnected for restricted or unrestricted resource sharing

Security Security is often viewed as the need to

protect one or more aspects of networks operation and permitted use(access, behaviour, performance, privacy and confidentiality included),

Security requirements may be Local or Global in their scope, depending upon the networks or internetworks purpose of design and deployment.

(c) Dr. Rahul Banerjee, BITS-Pilani, India 22

Summary Autonomous Computer controls its

own function, does NOT work as a slave / dumb terminal.

Computer Network is formed by a set of autonomous computers that follow a certain set of rules and conventions to interact meaningfully.

Networks can be switched or shared, public or private, short-distance or long-distance, data-optimized or synchronous-media-optimized etc.

In distributed systems, networks presence is invisible to the user.

(c) Dr. Rahul Banerjee, BITS-Pilani, India 23

Recommendations for Further Reading

Books Larry L. Peterson & Bruce S. Davie: Computer

Networks: A Systems Approach, Third Edition, Morgan Kaufmann / Elsevier, New Delhi, 2003.

A. S. Tanenbaum: Computer Networks, Fourth Edition, Pearson Education, New Delhi, 2003.

S. Keshav: Computer Networking: An Engineering Approach, Pearson Education, New Delhi, 1997.

Thomas G. Robertazzi: Computer Networks and Systems: Queuing Theory and Performance Evaluation, Third Edition, Springer-Verlag, New York, 2000.

William A. Shay: Understanding Data Communications and Networks, 3rd Edition, Thomson Learning, Singapore, 2004.

Michael A. Gallo & William M.Hancock: Computer Communications and Networking Technologies, Thomson Learning, Singapore, 2002.

Mohaamed G. Gouda: Elements of Network Protocol Design, Wiley Student Edition, John Wiley & Sons (Pte.) Ltd., Singapore, 2004.

(c) Dr. Rahul Banerjee, BITS-Pilani, India 24

Recommendations for Further Reading Journals & Magazines

IEEE / ACM Transactions on Networking

IEEE Transactions on Wireless Communications

IEEE Transactions on Computers IEEE Security & Privacy IEE Proceedings on Information

Security IEEE Network IEEE Computer IEEE Pervasive Computing IEEE Personal Communications Elseviers Pervasive Computing

(c) Dr. Rahul Banerjee, BITS-Pilani, India 25

Recommendations for Further Reading On-line Resources

IETF Postings at ietf.org Periodic updates at nist.gov Select FIPS documents at fips.org Digital Libraries / Archives / Technical

Reports at major research universities active in this area as shall be mentioned from time to time during lectures

Rahul Banerjee: Lecture Notes on Computer Networks, Electronic Read-only edition to be available just before Mid-Sem Test at the URL: http://discovery.bits-pilani.ac.in/rahul/CompNet/

(c) Dr. Rahul Banerjee, BITS-Pilani, India 26

Thats all for today!

Any questions?

Thank you!