Managing Information Technology 6 th Edition

1. Managing Information Technology6th Edition CHAPTER 4TELECOMMUNICATIONS AND NETWORKING

2. IT Building Blocks

3. Overview of Telecommunications and Networking

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. 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. Reasons for Networking • Five primary reasons for networking • Sharing of technology resources • Prior to networking capabilities, computers could not even share printers!! • 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 • Distributed data processing and client/server systems • Enhanced communications • Marketing outreach

7. Reasons for Networking • Five primary reasons for networking • Sharing of technology resources • Sharing of data • 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 • Enhanced communications • Marketing outreach Client Server Transfer of Data

8. Reasons for Networking • Five primary reasons for networking • Sharing of technology resources • Sharing of data • Distributed data processing and client/server systems • 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 • Marketing outreach • Businesses may share data with consumers to advertise or sell their products through a corporate web presence

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. Analog and Digital Signals

11. Analog and Digital Signals • Representation of digital and analog signals Figure 4.2

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. Transmission Speed • Transmission speeds can be measured in several ways

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. Telecommunication Lines • Types of Transmission Lines

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. 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. 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. 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. 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. Transmission Media Figure 4.4 • 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

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. 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. 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. 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. 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. 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. Networking Devices • Devices used to implement network topologies

29. Network Types • There are several types of networks • We will consider six types • Computer Telecommunications Networks • Local Area Networks (LANs) • Backbone Networks • Wide Area Networks (WANs) • The Internet • Internet2

30. Network Types • Computer Telecommunications Networks • This was the only type of network until the 1980s • Commonly used in mainframe architectures Figure 4.7

31. Network Types • 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 • Contention Bus (IEEE 802.3) • Token Bus (IEEE 802.4) • Token Ring (IEEE 802.5) • Wi-Fi (IEEE 802.11) • WiMAX (802.16e) • We will discuss each of the five types of LANs

32. Network Types • Local Area Networks (LANs) • 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 • Token Bus (IEEE 802.4) • Token Ring (IEEE 802.5) • Wi-Fi (IEEE 802.11) • WiMAX (802.16e)

33. Network Types • Local Area Networks (LANs) • Contention Bus (IEEE 802.3) • 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) • Token Ring (IEEE 802.5) • Wi-Fi (IEEE 802.11) • WiMAX (802.16e)

34. Network Types • Local Area Networks (LANs) • Contention Bus (IEEE 802.3) • Token Bus (IEEE 802.4) • Token Ring (IEEE 802.5) • Developed by IBM • Combination of ring topology with use of tokens (used the same way as in token bus) • Wi-Fi (IEEE 802.11) • WiMAX (802.16e)

35. Network Types • Local Area Networks (LANs) • Contention Bus (IEEE 802.3) • Token Bus (IEEE 802.4) • Token Ring (IEEE 802.5) • 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 • WiMAX (802.16e)

36. Network Types • LANs • Contention Bus (IEEE 802.3) • Token Bus (IEEE 802.4) • Token Ring (IEEE 802.5) • Wi-Fi (IEEE 802.11) • 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 XohmWiMAX 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. 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. Network Types Figure 4.10 • Types of Networks • Backbone Networks • Connect LANs • Key to internetworking

39. Network Types • 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 • Switched Circuit • Dedicated Circuit • Packet-switched

40. Network Types • Wide Area Networks (WANs) • 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. Network Types Table 4.3 • Wide Area Networks (WANs) • 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

42. Network Types • Wide Area Networks (WANs) • 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 • Advantages • Efficient use of network • Can be high capacity • Disadvantages • Packets may arrive in different order or with delay Figure 4.11

43. Network Types • 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. Network Types • The Internet • Internet Applications

45. Network Types • 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. Networking Protocols Figure 4.13 • 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

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. 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