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

Introduction to Data Communications Chapter 1 Introduction to Data Communications Copyright 2005 John Wiley & Sons, Inc

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 Copyright 2005 John Wiley & Sons, Inc

Copyright 2005 John Wiley & Sons, Inc 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 Copyright 2005 John Wiley & Sons, Inc

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) Copyright 2005 John Wiley & Sons, Inc

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 Copyright 2005 John Wiley & Sons, Inc

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 Copyright 2005 John Wiley & Sons, Inc

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 Copyright 2005 John Wiley & Sons, Inc

Copyright 2005 John Wiley & Sons, Inc 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 Copyright 2005 John Wiley & Sons, Inc

Copyright 2005 John Wiley & Sons, Inc 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 Copyright 2005 John Wiley & Sons, Inc

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 Copyright 2005 John Wiley & Sons, Inc

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 Copyright 2005 John Wiley & Sons, Inc

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 Copyright 2005 John Wiley & Sons, Inc

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 Copyright 2005 John Wiley & Sons, Inc

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 Copyright 2005 John Wiley & Sons, Inc

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 Copyright 2005 John Wiley & Sons, Inc

Copyright 2005 John Wiley & Sons, Inc LAN vs. BN vs. MAN vs. WAN Copyright 2005 John Wiley & Sons, Inc

Copyright 2005 John Wiley & Sons, Inc 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 Copyright 2005 John Wiley & Sons, Inc

Implementation of Communications Functions Single layer implemen-tation Applications OS Communication Applications OS Multi layer implementation Breaking down into smaller components Easier to implement Copyright 2005 John Wiley & Sons, Inc

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 Copyright 2005 John Wiley & Sons, Inc

Copyright 2005 John Wiley & Sons, Inc 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 Copyright 2005 John Wiley & Sons, Inc

Copyright 2005 John Wiley & Sons, Inc 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

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 * Copyright 2005 John Wiley & Sons, Inc

Comparison of Network Models Copyright 2005 John Wiley & Sons, Inc

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 Copyright 2005 John Wiley & Sons, Inc

Copyright 2005 John Wiley & Sons, Inc 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 Copyright 2005 John Wiley & Sons, Inc

Message Transmission Example Copyright 2005 John Wiley & Sons, Inc

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) Copyright 2005 John Wiley & Sons, Inc

Copyright 2005 John Wiley & Sons, Inc 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 Copyright 2005 John Wiley & Sons, Inc

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 Copyright 2005 John Wiley & Sons, Inc

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 (www.iso.ch) 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 (www.itu.int) Copyright 2005 John Wiley & Sons, Inc

Major Standards Bodies (Cont.) ANSI (American National Standards Institute) Coordinating organization for US (not a standards- making body) www.ansi.org 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) www.ietf.org Copyright 2005 John Wiley & Sons, Inc

Some Data Comm. Standards Layer Common Standards 5. Application layer HTTP, HTML (Web) MPEG, H.323 (audio/video) IMAP, POP (e-mail) 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) Copyright 2005 John Wiley & Sons, Inc

Emerging Trends in Networking Pervasive Networking Integration of Voice, Video and Data New Information Services Copyright 2005 John Wiley & Sons, Inc

Copyright 2005 John Wiley & Sons, Inc 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) Copyright 2005 John Wiley & Sons, Inc

Relative Capacities of Telephone, LAN, BN, WAN, and Internet Circuits. Copyright 2005 John Wiley & Sons, Inc

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

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 (email, web, payroll, etc.) (similar to electric or water utilities) Copyright 2005 John Wiley & Sons, Inc

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 Copyright 2005 John Wiley & Sons, Inc

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