1. Prof. M. Ulema Manhattan College Computer Information Systems
Business Data Communications and Networking 8th Edition Jerry Fitzgerald and Alan Dennis John Wiley & Sons, Inc
Prof. M. Ulema
Manhattan College
Computer Information Systems
Copyright 2005 John Wiley & Sons, Inc

2. Introduction to Data Communications
Chapter 1
Introduction to Data Communications
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3. Copyright 2005 John Wiley & Sons, Inc
Outline
Brief history
Communications, Information Systems and the Internet
Data Communications Networks
Network components, network types
Network Models
OSI model, Internet model, Layers
Network Standards
Standards making, common standards
Future Trends
Pervasive networking, integration of voice, video, and data, new information services
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Information Age
First Industrial Revolution
Introduction of machinery
New organizational methods
Changed the way people worked
Second Industrial Revolution – Information Age
Introduction of computers
Introduction of networking and data communication
Changed the way people worked again
Faster communication  Collapsing Information lag
Brought people together  Globalization
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5. Collapsing Information Lag
sped up the rate of transmission of information,
Electronic communications
telegraph
1900
1950
2004
1850
Information took days or weeks to be transmitted
Information transmitted in minutes or hours
huge quantities of information transmitted in a fraction of a second.
growth of telecommunications and especially computer networks
globalization phenomenon (WWW)
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6. Three Faces of Networking
Fundamental concepts of networking
How data moves from one computer to another over a network
Theories of how network operate
Technologies in use today
How theories are implemented, specific products
How do they work, their use, applications
Management of networking technologies
Security
Network Design
Managing the network
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7. Advances in Phone Technology
1962
Telstar (Telecommunications via satellite), Fax services, digital transmission (T-carriers)
first trans-continental and transatlantic phone connections
1915
1976
Packet-switched data communications
1876
Phone invented
1948
Microwave trunk lines (Canada)
1919
Strowger (stepper) switch,
rotary dial phones
(enabling automatic connections)
1969
Picturefone
(failed commercially)
1984
Cellular telephone
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8. Invention to Regulation
1934
FCC established
1996
US Telecom Act
1968
Carterfone court decision allowing non-Bell CPE
A time for technological change
Regulation began in the USA (ICC)
Phone invented (rapid acceptance)
1876
1900
millions of phones in use in the US
1885
AT&T
Bell System:
de facto monopoly
1910
1970
MCI wins court case; begins providing some long distance services
1984
Consent decree by US federal court
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1984 Consent Decree
Divestiture:
AT&T broken up into a long distance company (AT&T) & 7 Regional Bell Operating Companies (RBOCs)
Deregulation:
Competitive long distance (IXC) market; MCI & Sprint enter LD market (among others)
Local Exchange Carrier (LEC) service markets remained under RBOC monopoly
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US Telecom Act of 1996
Replaced all current laws, FCC regulations, 1984 consent decree, and overrules state laws
Main goal: open local markets to competition
To date, though, local competition slow to take hold…
Large IXCs expected to move into the local markets, happening only recently
Likewise, RBOCs expected to move into long distance markets, happening only recently
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11. Worldwide Competitive Markets
Internet market
Extremely competitive with more than 5000 Internet Service Providers (ISPs) in the US alone.
Heavy competition in this area may lead to a shake out in the near future.
World Trade Organization (WTO) agreement (1997)
commitments by 68 countries to open, deregulate or lessen regulation in their telecom markets
Multi-national telecom companies
US companies offering services in Europe, South America
European companies offering services in USA
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12. History of Information Systems
Online real-time, transaction oriented systems (replaced batch processing. DBMSs become common)
PC LANs become common
Batch processing mainframes
1950
1960
1990
2000
1970
1980
Data communications over phone lines (became common and mainframes became multi-user systems)
PC revolution
Networking everywhere
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13. NSFNet created as US Internet backbone
Internet Milestones
NSFNet created as US Internet backbone
1986
1990
commercial access to the Internet begins
Originally called ARPANET, the Internet began as a military-academic network
1969
Over 240 million servers and 400 million users
2001
ARPANET splits:
Milnet - for military
Internet - academic, education and research purposes only
1983
Government funding of the backbone ends
1994
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14. Broadband Communications Copyright 2005 John Wiley & Sons, Inc
Datacom Basics
Telecommunications
transmission of voice, video, data,
imply longer distances
- broader term
Data Communications
movement of computer information by means of electrical or optical transmission systems
convergence
Broadband Communications
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15. Components of a Local Area Network
To other networks
(e.g., Internet)
Router
Servers
File Server
HUB
Client Computers
Web Server
Circuits
Print Server
Printer
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16. Network Types (based on Scale)
Local Area Networks (LANs) - room, building
a group of PCs that share a circuit.
Backbone Networks - less than few kms
a high speed backbone linking the LANs at various locations.
Metropolitan Area Networks (MAN) - (< few 10 kms)
connects LANs and BNs at different locations
leased lines or other services used to transmit data.
Wide Area Networks (WANs) - (> few 10 kms)
Same as MAN except wider scale
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LAN vs. BN vs. MAN vs. WAN
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Intranet vs. Extranet
Intranet
A LAN that uses the Internet technologies
Open only those inside the organization
Example: insurance related information provided to employees over an intranet
Extranet
Open only those invited users outside the organization
Accessible through the Internet
Example: Suppliers and customers accessing inventory information in a company over an extranet
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19. Implementation of Communications Functions
Single layer implemen-tation
Applications OS
Communication
Applications OS
Multi layer implementation
Breaking down into smaller components
Easier to implement
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20. Multi-layer Network Models
The two most important such network models: OSI and Internet
Open Systems Interconnection Model
Created by International Standards Organization (ISO) as a framework for computer network standards in 1984
Based on 7 layers
Internet Model
Created by DARPA originally in early 70’s
Developed to solve to the problem of internetworking
Based on 5 layers
Based on Transmission Control Protocol/ Internet Protocol (TCP/IP) suite
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7-Layer Model of OSI
Physical DataLink Network Transport Session Presentation Application
Application Layer
set of utilities used by application programs
Presentation Layer
formats data for presentation to the user
provides data interfaces, data compression and translation between different data formats
Session Layer
initiates, maintains and terminates each logical session between sender and receiver
Please Do Not Touch Steve’s Pet Alligator
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7-Layer Model of OSI
Transport Layer
deals with end-to-end issues such as segmenting the message for network transport, and maintaining the logical connections between sender and receiver
Network Layer
responsible for making routing decisions
Data Link Layer
deals with message delineation, error control and network medium access control
Physical Layer
defines how individual bits are formatted to be transmitted through the network
Copyright 2005 John Wiley & Sons, Inc

23. Internet’s 5-Layer Model
Application Layer
used by application program
Transport Layer
responsible for establishing end-to-end connections, translates domain names into numeric addresses and segments messages
Network Layer - same as in OSI model
Data Link Layer - same as in OSI model
Physical Layer - same as in OSI model
Physical DataLink Network Transport Application
Please Do Not Touch Alligator *
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24. Comparison of Network Models
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25. Message Transmission Using Layers
sender
receiver
Applications
Applications
A receiving layer wraps incoming message with an envelope
Adds layer related addressing information
A receiving layer removes the layer related envelope and forwards the message up
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Protocols
Used by Network model layers
Sets of rules to define how to communicate at each layer and how to interface with adjacent layers
Layer N+1
Layer N+1
Layer N
Layer N
Layer N-1
Layer N-1
sender
receiver
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27. Message Transmission Example
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28. Important Points to Observe
Many different software packages (protocols) and many different packets (at different layers)
Easy to develop new software
Simple to change the software at any level
Matching layers communicate at different computers
Accomplished by standards
e.g., Physical layer at the sending computer must be the same in the receiving computer
Somewhat inefficient
Involves many software and packets
Packet overhead (slower transmission, processing time)
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Standards
Importance
Provide a “fixed” way for hardware and/or software systems (different companies) to communicate
Help promote competition and decrease the price
Types of Standards
Formal standards
Developed by an industry or government standards-making body
De-facto standards
Emerge in the marketplace and widely used
Lack official backing by a standards-making body
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30. Standardization Processes
Specification
Developing the nomenclature and identifying the problems to be addressed
Identification of choices
Identifying solutions to the problems and choose the “optimum” solution
Acceptance
Defining the solution, getting it recognized by industry so that a uniform solution is accepted
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31. Major Standards Bodies
ISO (International Organization for Standardization)
Technical recommendations for data communication interfaces
Composed of each country’s national standards orgs.
Based in Geneva, Switzerland (
ITU-T (International Telecommunications Union –Telecom Group
Technical recommendations about telephone, telegraph and data communications interfaces
Composed of representatives from each country in UN
Based in Geneva, Switzerland (
Copyright 2005 John Wiley & Sons, Inc

32. Major Standards Bodies (Cont.)
ANSI (American National Standards Institute)
Coordinating organization for US (not a standards- making body)
IEEE (Institute of Electrical and Electronic Engineers)
Professional society; also develops mostly LAN standards
standards.ieee.org
IETF (Internet Engineering Task Force)
Develops Internet standards
No official membership (anyone welcomes)
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33. Some Data Comm. Standards
Layer
Common Standards
5. Application layer
HTTP, HTML (Web)
MPEG, H.323 (audio/video)
IMAP, POP ( )
4. Transport layer
TCP (Internet)
SPX (Novell LANs)
3. Network layer
IP (Internet)
IPX (Novell LANs)
2. Data link layer
Ethernet (LAN)
Frame Relay (WAN)
PPP (dial-up via modem for MAN)
1. Physical layer
RS-232c cable (LAN)
Category 5 twisted pair (LAN)
V.92 (56 kbps modem)
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34. Emerging Trends in Networking
Pervasive Networking
Integration of Voice, Video and Data
New Information Services
Copyright 2005 John Wiley & Sons, Inc

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Pervasive Networking
Means “Network access everywhere”
Exponential growth of Network use
Many new types of devices will have network capability
Exponential growth of data rates for all kinds of networking
Broadband communications
Use circuits with 1 Mbps or higher (e.g., DSL)
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36. Relative Capacities of Telephone, LAN, BN, WAN, and Internet Circuits.
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37. Integration of Voice, Video & Data
Also called “Convergence”
Networks that were previously transmitted using separate networks will merge into a single, high speed, multimedia network in the near future
First step (already underway)
Integration of voice and data
Next Step
Video merging with voice and data
Will take longer partly due to the high data rates required for video
Copyright 2005 John Wiley & Sons, Inc

38. New Information Services
World Wide Web based
Many new types of information services becoming available
Services that help ensure quality of information received over www
Application Service Providers (ASPs)
Develop specific systems for companies
Providing and operating a payroll system for a company that does not have one of its own
Information Utilities (Future of ASPs)
Providing a wide range of info services ( , web, payroll, etc.) (similar to electric or water utilities)
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39. Implications for Management
Embrace change and actively seek to apply networks to improve what you do
Information moved quickly and easily anywhere and anytime
Information accessed by customers and competitors globally
Use a set of industry standard technologies
Can easily mix and match equipment from different vendors
Easier to migrate from older technologies to newer technologies
Smaller cost by using a few well known standards
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