Post on 02-Dec-2014
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Chapter 1 1
Introduction to Computer Networks
Chapter 1
Chapter 1 2
Chapter Objectives
Explain the need of networks Explain history of computer networks (ARPANET) Explain the types of computer networks Explain Client/Server configuration Explain layers of OSI model Explain network selection criteria Network Application Explain Standards Organizations
Chapter 1 3
Computer Network
Interconnection of two or more computers and peripherals
Allows user to share and transfer information
Chapter 1 4
Need of Computer Networks
Sharing Resources Reduced Cost Reduced time Scalability Reliability Security
Chapter 1 5
History of Computer Networks (ARPANET) ARPA designed for Department of Defense
(DOD), US Small computers were connected to large
mainframe computers IMPs were connected to each other through
modem Supported different operating systems Telenet and ftp services was provided by
ARPANET
Chapter 1 6
Types of Computer Networks
Networks are classified depending on the geographical area covered by the network
ComputerNetworks
Local Area Network
(LAN)
CampusArea Network
(CAN)
MetropolitanArea Network
(MAN)
WideArea Network
(WAN)
Chapter 1 7
Local Area Network (LAN) - I
Covers a small area Connects computers and workstations covering a
local area like, office or home
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Local Area Network (LAN) - II Advantages of LAN:
Improves productivity due to faster work Provides easy maintenance New systems can be installed and configured
easily Disadvantages of LAN:
Limited number of systems can only be connected Cannot cover large area Network performance degrades as number of
users exceeds
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Campus Area Network (CAN)
Made up of multiple LANs within limited area Connects different LANs in a campus
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Metropolitan Area Network
Interconnects networks within a city Supports data and voice transmission
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Wide Area Network Covers a wide geographical area which includes
multiple computers or LANs e.g. Internet
Comparison of Networks
LAN CAN MAN WAN
Connects computers and workstations in office or home.
Connects two or more LANs within a campus.
Interconnects networks in a town or a city.
Connects geographically separated LANs.
Covers a local area of 1 Km.
Covers privately owned campus with an area of 5 to 10 Kms.
Covers larger area than LAN but smaller area than WAN with an area of 2 to 100 Kms.
Spans large geographical area more than 100 Kms.
Data Transmission Rate – 10/100 Mbps
Data Transmission Rate – Variable
Data Transmission Rate - Variable
Data Transmission Rate – 64 Kbps or 2 Mbps
Uses IEEE 802 standard.
____ Uses IEEE 802 standard.
Uses ITU standard.
Low cost High cost High cost (Repetitive)
High cost (Repetitive)
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Chapter 1 13
Case Study - I
MoneyMaker is a bank having its registered office at Delhi. It has branches at Mumbai, Chennai, Hyderabad and Bangalore. The operating departments in the bank are Finance, Insurance, Loan, IT, Marketing, Customer Service and HR. MoneyMaker bank uses LAN as their computer network for each department. All the branches of the bank from different cities are connected through WAN. The bank is expanding and decided to open its branches at different locations in the city.
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Problem
Determine which type of network to be used within a city
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Suggested Solution
Use LAN computer network for each department in the new branch. MAN can be used for connecting the different branches of the bank within the city
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Client/Server Configuration
Consists of two elements, Client and Server Server:
A centralized element which provides resources to client
Manages data, printers or network traffic Client:
Manages local resources used by users such as monitor, keyboard, CPU and peripherals
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OSI Model
Run it through CBT
Chapter 1 20
Network Selection Criteria
Helps to improve network functionality
NetworkCriteria
Performance Reliability Security
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Network Applications
Financial Institution (Banking Sector) Communication Services (Telecom Industry) Internet Service (WWW, ISP)
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Standards Organizations Also known as Standards Development Organization
(SDO) Develop, maintain, improve and revise standards Classified as:
ISO – Creates world wide industrial and commercial standards
ITU-T – Standardizes and regulates international radio and telecommunication
IEEE – Develops standards for power & energy, IT, telecommunication, biomedical and healthcare
ANSI – Creates standards for computer industry e.g. FDDI
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Summary - I
Computer network enables the user to share data and network resources
Network allows remote users to communicate with each other
Computer networks are divided into LAN, CAN, MAN and WAN depending on the coverage area
LAN is a small network and easy to create Client/Server configuration also called as two-tier
architecture, consist of two nodes, client and server
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Summary – II
OSI model consists of seven layers and provides standards for computer communication
Physical layer is responsible for actual transmission of bits over the medium
Data Link layer is responsible for node to node delivery of frames
Network layer is responsible for end to end delivery of packets, and routing
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Summary - III
Transport layer is responsible for end to end delivery of the entire message
Session layer is responsible for establishing, managing and terminating sessions
Presentation layer is responsible for translation, encryption and data compression
Application layer is responsible for providing access to the network
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Summary - IV
Performance, reliability and security are the network selection criterion which enables to choose efficient network
Standards organizations like ISO and ANSI develop technical and non- technical standards
International standards organizations are International Standard Organization (ISO), International Telecommunication Union (ITU), Institute of Electrical and Electronics Engineers (IEEE) and American National Standards Institute (ANSI)