1. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 1 Managing Information Technology 6 th Edition CHAPTER 4 TELECOMMUNICATIONS AND NETWORKING

2. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 2 IT Building Blocks Building Blocks of Information Technology HardwareSoftwareNetworkData

3. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 3 Overview of Telecommunications and Networking The electronic linking of geographically dispersed devices required to accomplish telecommunications Networking Communication at a distance. Also synonymous with data communications, datacom, teleprocessing, telecom, and sometimes networking. Telecommunications

4. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 4 The Telecommunications Industry Three major segments – Carriers who sell the service of communication transmission – Equipment vendors who manufacture and sell telecommunications hardware and software – Service Providers who provide access to or services via the Internet

5. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 5 Telecommunications Industry AT&T – Largest corporation in industry – In 1984, AT&T split into several companies as a result of a US Department of Justice antitrust lawsuit – Breakup of AT&T has led to innovation through competition – Recent trend towards consolidation in the industry

6. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6 Reasons for Networking Five primary reasons for networking 1.Sharing of technology resources Prior to networking capabilities, computers could not even share printers!! 2.Sharing of data Enables virtual teams who can share data Allows efficient transactions between businesses, their suppliers, their and customers Some businesses share many terabytes of data per day 3.Distributed data processing and client/server systems 4.Enhanced communications 5.Marketing outreach

7. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 7 Reasons for Networking Five primary reasons for networking 1.Sharing of technology resources 2.Sharing of data 3.Distributed data processing and client/server systems Distributed data processing – Information processing that uses multiple computers at multiple sites that are tied together through telecommunication lines Client/Server Systems – A type of distributed systems in which the processing power is distributed between a central server and a number of client computers 4.Enhanced communications 5.Marketing outreach ClientServer Transfer of Data

8. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 8 Reasons for Networking Five primary reasons for networking 1.Sharing of technology resources 2.Sharing of data 3.Distributed data processing and client/server systems 4.Enhanced communications Telecommunication networks provide the ability to communication through Email, Bulletin Boards, Blogs, Instant Messaging, Wikis, and Videoconferencing Links between organizations can lead to strategic advantages in terms of business transactions – SABRE airline reservation system – EDI 5.Marketing outreach Businesses may share data with consumers to advertise or sell their products through a corporate web presence

9. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 9 Overview of Telecommunications and Networking A telecommunications network is more than a series of wires or radio waves Functions of a Telecommunications Network Table 4.1

10. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 10 Analog and Digital Signals A signal in which some physical property continuously varies across time Analog Signals A signal that is not a continuous function of time, but rather a series of discrete values that represent ones and zeros Digital Signals

11. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 11 Analog and Digital Signals Representation of digital and analog signals Figure 4.2

12. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 12 Analog and Digital Signals Digital computer data does not naturally mesh with analog transmission; it must be converted from ones and zeros to analog signals Solutions – Modem (Modulator/Demodulator) – Digital networks Advantages of lower error rates and higher speeds Figure 4.1

13. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 13 Transmission Speed Transmission speeds can be measured in several ways The difference between the highest and lowest frequencies that can be transmitted on a single medium; a measurement of capacity Bandwidth Cycles per second Hertz Signals per second Baud

14. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 14 Telecommunication Lines Types of Transmission Lines – Private (dedicated) Advantages – Ensures quality of transmission Disadvantages – Costly – Switched Advantages – Less costly Disadvantages – Message may take many different routes – Quality of transmission may degrade

15. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 15 Telecommunication Lines Types of Transmission Lines Data can only travel in one direction Simplex Data can travel in both directions, but not simultaneously Half-duplex Data can travel in both directions at once Full-duplex

16. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 16 Transmission Media Twisted Pair – Literally wires that are twisted to reduce interference – Can be shielded (STP) or unshielded (UTP), but the most commonly used is UTP – Commonly used in telephones and LANs

17. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 17 Transmission Media Coaxial (Coax) Cable – Baseband Inexpensive, designed for digital transmission – Broadband Originally for analog, now used for digital Commonly used in television cable Figure 4.3

18. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 18 Transmission Media – Wireless Not strictly a transmission media, but rather a technology in which radio signals are sent through the air There are many different wireless technologies such as cordless telephones and cellular telephones which are widely used in personal and business communications We will consider the following wireless technologies in more detail: Wireless LANs Microwave – Line of sight Satellite – Long distances – Line of sight – RFID – Bluetooth

19. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 19 Transmission Media Wireless – Wireless LANs Growing in popularity Useful when wiring is not possible Slower than some wired solutions Allow mobile devices to connect to network

20. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 20 Transmission Media Wireless – Microwave Widespread use for several decades Line of sight transmission Limited to 25-50 mile distances because of curvature of the earth Expensive, but less costly than fiber optic cables

21. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 21 Transmission Media Wireless – Satellite Geostationary Earth Orbit (GEO) – Remains stationary relative to earth – Inmarsat service of 11 GEO satellites Low Earth Orbit (LEO) – Iridium » First major LEO project with 66 satellites » Faced high operating costs and which resulted in a bankruptcy » Mostly military subscribers Figure 4.4

22. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 22 Transmission Media Wireless – RFID Acronym for Radio Frequency Identification An old technology that became popular in business when Wal-Mart required the use of RFID by some of its suppliers to improve inventory and supply chain management

23. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 23 Transmission Media Wireless – RFID Two Broad Types of RFID – Active – these tags have their own power supply and can transmit messages continuously, on request, or on a schedule » Cost over $1.00 – Passive – these tags only send a response the RFID reader sends a small radio signal which induces a current » Cost in the $0.08 - $0.20 range Many analysts believe that passive tags must cost only $0.05 for RFID to be widely adopted

24. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 24 Transmission Media Wireless – Bluetooth Named after Danish King who united Denmark – The technology is intended to unify telecom and computing Short-range wireless technology Designed to consume very little electrical power and be produced at a low cost Found in a growing number of devices such as cell phones, laptops, headsets, keyboards, mice, and home appliances – Over 318 million devices in 2005 used Bluetooth for communication between devices

25. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 25 Transmission Media Fiber Optics – Thin fiber of glass – Faster, lighter, and more secure than other media – Large diameter fiber is multimode (multiple light rays at the same time) while smaller diameter is single mode – Smaller diameter fiber has larger capacity due to less light bounces

26. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 26 Individual Network Access Internet Service Providers (ISPs) sell access to the Internet Early, the only way to access the Internet was through a dial-in modem connection Consumers now have more options including faster broadband connections – Digital Subscriber Line (DSL) is a connection through a telephone company – Cable modem is a connection through a cable television company – Satellite With one-way service, individuals must obtain uplink service from another provider – Wireless access may be through a municipal carrier or a private company There are several pricing methods for personal Internet access – Fixed price (usually monthly) Hotels and airports often offer Internet access for a shorter period (e.g., 24 hours) – Cost based on usage (data transferred) – Free to consumers, but supported by taxes or advertising

27. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 27 Network Topology Network topology refers to the configuration or arrangement of the devices Figure 4.5 Bus – All devices are attached to one cable – Single-point failure Ring Similar to bus, but ends are attached Not susceptible to single-point failure Star All nodes are attached to central device Susceptible to failure of central device, but easy to identify cable failure Tree Similar to the star, but with a hierarchical structure Mesh Devices are to multiple other devices A failure has little impact on the network Costly

28. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 28 Networking Devices Devices used to implement network topologies Simple devices that forwards all messages to every device attached to it Hub Central device that connects wireless LAN to other networks Wireless Access Point Connects two LAN segments and only forwards messages that need to go to other segment Bridge A multiport bridge; connects two or more LAN segments Switch Connects two ore more LANs and only forwards messages that go to the other LAN Router

29. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 29 Network Types There are several types of networks We will consider six types 1.Computer Telecommunications Networks 2.Local Area Networks (LANs) 3.Backbone Networks 4.Wide Area Networks (WANs) 5.The Internet 6.Internet2

30. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 30 Network Types 1.Computer Telecommunications Networks – This was the only type of network until the 1980s – Commonly used in mainframe architectures Figure 4.7

31. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 31 Network Types 2.Local Area Networks (LANs) – Standards developed by the Institute for Electrical and Electronic Engineering (IEEE) IEEE 802 is a family of standards for LANs and metropolitan area networks – Five types of LANs in common use today 1.Contention Bus (IEEE 802.3) 2.Token Bus (IEEE 802.4) 3.Token Ring (IEEE 802.5) 4.Wi-Fi (IEEE 802.11) 5.WiMAX (802.16e) – We will discuss each of the five types of LANs

32. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 32 Network Types 2.Local Area Networks (LANs) 1.Contention Bus (IEEE 802.3) Developed by Xerox Usually called Ethernet after the original Xerox version Half-duplex All devices must contend to use – CSMA/CD protocol for collisions 2.Token Bus (IEEE 802.4) 3.Token Ring (IEEE 802.5) 4.Wi-Fi (IEEE 802.11) 5.WiMAX (802.16e)

33. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 33 Network Types 2.Local Area Networks (LANs) 1.Contention Bus (IEEE 802.3) 2.Token Bus (IEEE 802.4) A token (special message) is passed among devices Only the device with the token can transmit a message Important for Manufacturing Automation Protocol (MAP) 3.Token Ring (IEEE 802.5) 4.Wi-Fi (IEEE 802.11) 5.WiMAX (802.16e) A token bus protocol that was developed by General Motors for factory automation Manufacturing Automation Protocol

34. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 34 Network Types 2.Local Area Networks (LANs) 1.Contention Bus (IEEE 802.3) 2.Token Bus (IEEE 802.4) 3.Token Ring (IEEE 802.5) Developed by IBM Combination of ring topology with use of tokens (used the same way as in token bus) 4.Wi-Fi (IEEE 802.11) 5.WiMAX (802.16e)

35. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 35 Network Types 2.Local Area Networks (LANs) 1.Contention Bus (IEEE 802.3) 2.Token Bus (IEEE 802.4) 3.Token Ring (IEEE 802.5) 4.Wi-Fi (IEEE 802.11) Short for Wireless Fidelity Most common wireless LAN type Uses a shared Ethernet design Use CSMA/CA Protocol – Similar to CSMA/CD, but with less collisions Commonly used in offices to supplement wired Ethernet networks or in areas where adding wiring is problematic Many cities are offering Wi-Fi networks 5.WiMAX (802.16e)

36. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 36 Network Types LANs 1.Contention Bus (IEEE 802.3) 2.Token Bus (IEEE 802.4) 3.Token Ring (IEEE 802.5) 4.Wi-Fi (IEEE 802.11) 5.WiMAX (802.16e) Newest of the network types Similar to Wi-Fi, but operates over longer distances and at higher speeds Can use both licensed and non-licensed frequencies Sprint Nextel are planning to offer their Xohm WiMAX service across the US in the 2.5GHz radio spectrum – In November 2007, Sprint Nextel abandoned talks of a joint venture with Clearwire, a WiMAX provider

37. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 37 Network Types Local Area Networks (LANs) – Problems with wireless networks (WiFi and WiMAX) More difficult to secure that other network types Organizations that offer wireless access to entice customers have problems with noncustomers or unprofitable customers overusing the network Unauthorized wireless use is also problematic in condos and apartments

38. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 38 Network Types Types of Networks 3.Backbone Networks Connect LANs Key to internetworking Figure 4.10

39. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 39 Network Types 4.Wide Area Networks (WANs) – Similar to LANs, but cover greater distances – We will consider the following three general types of WANs because they each have advantages and disadvantages 1.Switched Circuit 2.Dedicated Circuit 3.Packet-switched

40. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 40 Network Types 4.Wide Area Networks (WANs) 1.Switched Circuit (or circuit-switched) A single physical path is temporarily created between two nodes for their exclusive communication There are most widely available means of implementing a WAN using a switched circuit connection is to use the ordinary telephone network Advantages – Easy to set up Disadvantages – Low speed – High error rates There are two different pricing schemes available for this service – Direct Distance Dialing (DDD) - pay for usage – Wide Area Telephone Service (WATS) - fixed rate

41. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 41 Network Types 4.Wide Area Networks (WANs) 2.Dedicated Circuit These are permanent channels exclusive to the business Advantages – High capacity – Low error rates Disadvantages – Expensive There are two different types of dedicated circuits – Leased lines are cable, microwave, or fiber connections – Satellite circuits are popular for organizations with many global locations Table 4.3

42. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 42 Network Types 4.Wide Area Networks (WANs) 3.Packet-switched Multiple connections exist simultaneously over the same physical circuit Messages are broken up into packets Businesses use PADs (Packet assembly/disassembly devices) to connect their networks to a common carrier network Figure 4.11 Advantages Efficient use of network Can be high capacity Disadvantages Packets may arrive in different order or with delay

43. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 43 Network Types 5.The Internet – Network of networks that use the TCP/IP protocol – Similar to an enormous WAN – 433 million hosts as of January 2007 – Roots in ARPANET and NSFNET ARPANET (Advanced Research Projects Agency Network) was created by the US Department of Defense NSFNET (National Science Foundation Network) was created to link supercomputers for research Each of these were wide scale, packet-switching networks that lead to the creation of the Internet

44. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 44 Network Types 5.The Internet – Internet Applications

45. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 45 Network Types 6.Internet2 – Not-for-profit consortium made up of over 200 universities as well as industry and government partners that develops and deploys advanced network applications and technologies for research and commercial purposes – Goals Create a leading-edge network capability for the national research community Enable revolutionary Internet applications based on a much higher-performance Internet than we have today Ensure the rapid transfer of new network services and applications to the broader Internet community

46. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 46 Networking Protocols Network Protocols – An agreed-upon set of rules or conventions governing communication among elements of a network – Open Systems Interconnection (OSI) Reference Model Skeleton for standards Movement toward this model stopped with the growth of the Internet Figure 4.13

47. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 47 Networking Protocols OSI Model – Developed by the International Organization for Standardization (ISO)to outline a standard set of protocols for telecommunications Figure 4.14

48. Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 48 Networking Protocols Transmission Control Protocol/Internet Protocol (TCP/IP) – Created to link different types of networks (e.g., satellite and ground packet networks) together into a network of networks – Has become de facto standard protocol for networking TCP is responsible for the reliable and ordered transmission of messages IP is responsible for routing individual packets based on their individual addresses (IP addresses) – Roughly corresponds to network and transport layers of OSI model