Telecommunications and Networks

Transcription

1 Chapter 6 Telecommunications and Networks McGraw-Hill/Irwin Copyright 2010 by the McGraw-Hill Companies, Inc. All rights reserved.

2 Learning Objectives Understand the concept of a network Apply Metcalfe s law in understanding the value of a network Identify major developments and trends in the industries, technologies, and business applications of telecommunications and Internet technologies Provide examples of the business value of Internet, intranet, and extranet applications 6-2

3 Learning Objectives Identify the basic components, functions, and types of telecommunications networks used in business Explain the functions of major components of telecommunications network hardware, software, media, and services Explain the concept of client/server networking Understand the two forms of peer-to-peer networking 6-3

4 Learning Objectives Explain the difference between digital and analog signals Identify the various transmission media and topologies used in telecommunications networks Understand the fundamentals of wireless network technologies Explain the concepts behind TCP/IP Understand the seven layers of the OSI network model 6-4

5 Case 1: Starbucks and Others Wi-Fi hot spots Emerged due to fast-growing popularity of laptops Wi-Fi coffee shops supplanted cybercafés, which relied on the expensive purchase and upkeep of PCs Public Wi-Fi access is at crossroad Recent moves toward free and advertising-based Wi-Fi service by Starbucks and others Web advertising can offset costs or make money Like television, Wi-Fi is increasingly given away in exchange for ads 6-5

6 Case Study Questions Some companies offer free Wi-Fi in exchange for viewing advertisements or answering questions for market research studies Would you be willing to do so in order to get free wireless access, say, at an airport? Would your answer change if you were using a corporate laptop versus your own, because of security concerns? 6-6

7 Network Concepts A network is an interconnected or interrelated chain, group, or system The number of possible connections on a network is N(N 1) or N 2 N N = number of nodes (points of connection) 10 computers on a network = 10(10 1) = 10x9 = 90 possible connections 6-7

8 Metcalfe s Law The usefulness (utility) of a network equals the square of the number of users The more users on a network, the more useful it becomes Until critical mass is reached, a change in technology only affects the technology Once critical mass is attained, social, political, and economic systems change Ex: The Internet is growing exponentially. We can expect more value, for less cost, virtually every time we log on 6-8

9 Telecommunication Trends 6-9

10 Telecommunications-Based Services 6-10

11 Internet Networking Technologies Internet networking technologies are being used as a technology platform Web browser suites HTML Web page editors Network management software Firewalls Being applied in Internet, intranet, and extranet applications Reinforces previous move toward client/server networks based on open-systems architecture 6-11

12 Open Systems Open systems use common standards for hardware, software, applications, and networks Internet networking technologies are a common standard for open systems Connectivity Open systems provide greater connectivity and network interoperability Middleware may be needed to help diverse systems work together 6-12

13 Middleware Middleware Programming that mediates between two separate programs Allows a particular database to access other databases without custom programming Routes data and information between back-end data sources and end user applications The Plumbing Essential component of any IT infrastructure 6-13

14 Digital Network Technologies Telecommunications are being revolutionized by the switch from analog to digital Analog: voice-oriented transmission Digital: discrete pulse transmission Benefits Higher transmission speeds Moves larger amounts of information Greater economy and much lower error rates Transmits multiple types of communications (data, voice, video) on the same circuits 6-14

15 Wireless Technologies Fiber-optic Uses pulses of laser-generated light Reduced size and installation effort Vastly greater communication capacity Faster transmission speeds Freedom from electrical interference Satellite Transmission Can move massive quantities of data, audio, and video over global networks Especially useful in isolated areas 6-15

16 Business Application Trends Telecommunications networks now play a vital and pervasive role in Web-enabled E-business processes Electronic commerce Enterprise collaboration Other applications that support operations, management, and strategic objectives 6-16

17 Internet2 The Next Generation High performance Different infrastructure Will not replace current Internet In limited use already Infinite bandwidth Users connect via Abilene at 120 Gbps May never become totally open 6-17

18 Value of Telecommunications Networks Overcome geographic barriers Overcome structural barriers Strategic Capabilities Overcome time barriers Overcome cost barriers 6-18

19 The Internet Revolution The Internet is a global information superhighway Millions of smaller, private networks 10 servers in 1991 to over 46 million today Growing by 1 million servers per month No central computer system No governing body Based on common standards 6-19

20 Internet Service Providers Companies that specialize in providing easy access to the Internet For a monthly fee, they provide software, user names, passwords, and Internet access ISPs themselves are connected to one another through network access points One ISP can easily connect to another to obtain addresses of websites or user nodes 6-20

21 Popular Uses of the Internet Surf Discuss Publish Buy & Sell Download Compute Connect Phone Calls And more 6-21

22 Business Use of the Internet 6-22

23 The Role of Intranets Many companies have sophisticated and widespread intranets Detailed data retrieval Collaboration Personalized customer profiles Links to the Internet Web browsers and servers Intranets use Internet technologies TCP/IP network protocols HTML publishing and databases 6-23

24 Intranets Encryption Passwords Intranets are protected by Firewalls Customers, suppliers, and other business partners can access an intranet via extranet links 6-24

25 Intranets as Information Portals 6-25

26 Extranets Network Links Virtual Private Networks Unsecured Extranet Uses Internet technologies to connect the intranet of a business to the intranets of another Direct private network links, or private secure Internet links between companies Link between a company and others via the Internet, relying on encryption of sensitive data and firewall security systems 6-26

27 Extranet Connectivity and Value 6-27

28 Telecommunications Network Alternatives Telecommunications is a highly technical, rapidly changing field Most business professionals don t need detailed technical knowledge However, understanding basic components and their characteristics is necessary Can help you make informed decisions about telecommunications alternatives 6-28

29 Case 2: Medicine Through Videoconferencing Every 45 seconds, someone in the U.S. suffers a stroke The first three hours are critical to survival and recovery Not all hospitals can handle stoke patients The Neuro Critical Care Center has on-call critical-care assistance Bidirectional videoconferencing and imaging capabilities Mobile Tandberg systems for bedside use 6-29

30 Case 2: Medicine Through Videoconferencing Arizona Telemedicine Program Uses technology to permit inter-disciplinary team training Statewide broadband health care communications network Links 55 healthcare organizations in 71 communities Telemedicine services provided in 60 subspecialties More than 600,000 patients have received services 6-30

31 Case Study Questions From the perspective of a patient, how would you feel about being diagnosed by a doctor who could be hundreds or thousands of miles away? What kind of expectations or concerns would you have about that kind of experience? 6-31

32 Case Study Questions What other professions, aside from health care and education, could benefit from application of some of the technologies discussed in this case? How would they derive business value from these projects? 6-32

33 Case Study Questions The deployment of IT in the health profession is still very much in its infancy What other uses of technology could potentially improve the quality of health care? 6-33

34 Telecommunications Network Model A telecommunications network is any arrangement where A sender transmits a message to a receiver Over a channel Consisting of some sort of medium 6-34

35 Types of Communications Networks Wide Area Communication Networks Local Area Peer-to-Peer Virtual Private Client/Server 6-35

36 Wide Area Network (WAN) Covers a large geographic area 6-36

37 Local Area Network (LAN) Connects computers within a limited physical area, such as an office, classroom, or building 6-37

38 Virtual Private Network 6-38

39 Client/Server Network 6-39

40 Network Computing Networks are the central computing resource of the organization Thin clients provide a browser-based user interface for processing applets Thin clients include Network computers Net PCs Other low-cost network devices or information appliances 6-40

41 Network Computing 6-41

42 Peer-to-Peer Networks Central Server Architecture P2P file-sharing software connects all PCs to a central server The server sends the requesting PC a list of links to all active peers who have the file Clicking a link connects the two PCs and automatically transfers the file to the requesting PC 6-42

43 Peer-to-Peer Networks Pure Peer-to-Peer Architecture No central directory or server File-sharing software connects one PC to another online user When you request a file, the software searches every online user, then sends you a list of active file names Clicking a link automatically transfers the file from that user s hard drive to yours 6-43

44 Central Server Peer-to-Peer Networks Advantages Disadvantages Can better protect the integrity and security of the content and users of the network Directory server can be slowed or overwhelmed by too many users or technical problems 6-44

45 Peer-to-Peer Network Diagrams 6-45

46 Digital and Analog Signals Analog Digital An electrical current is generated that is proportional to the quantity being observed If the temperature is 83 degrees, a measuring device would generate 8.3 volts The quantity being observed is expressed as a number A measurement of 83 degrees would display as the number

47 Telecommunications Media Twisted-Pair Wire Ordinary telephone wire Copper wire is twisted into pairs Coaxial Cable Sturdy copper or aluminum wire wrapped with spacers to insulate and protect it Fiber-Optic Cable One or more hair-thin filaments of glass fiber wrapped in a protective jacket 6-47

48 The Problem of The Last Mile Network providers use fiber optic cable as a communications backbone Houses connected to the backbone are wired with twisted pair Users don t benefit from the faster, better technology 6-48

49 Wireless Technologies Terrestrial Microwave Communications Satellites Telephone & Pager Systems Earthbound microwave systems transmit high-speed radio signals Follows line-ofsight path between relay systems spaced about 30 miles apart Serve as relay stations Use microwave radio signals Earth stations beam signals to the satellites Not suitable for interactive, realtime processing Geographic areas divided into cells Each cell has lowpower transmitter or radio relay antenna Computers & other communications processors coordinate/control transmissions to/from mobile users 6-49

50 Wireless Technologies Wireless LANS Bluetooth Other Wireless Systems Uses wireless radio-wave technology to connect PCs within an office or building Can be highfrequency (like digital cellular), or low frequency (spread spectrum) Short-range wireless Connects PCs to peripheral devices Fairly low cost to implement Cellular phones Mobile radio PDAs 6-50

51 Wireless Technologies Telecommunications networks now play vital and pervasive roles in Web-enabled e-business processes Electronic commerce Enterprise collaboration Other applications that support business operations, management, & strategic objectives 6-51

52 The Wireless Protocol (WAP) 6-52

53 Communications Processors 6-53

54 Comparing Technologies 6-54

55 Communications Processors Multiplexer allows a single communications channel to carry simultaneous data transmissions from many terminals In time division multiplexing (TDM), the multiplexer divides the time each terminal can use the high-speed into short time slots Multiplexers increase the number of transmissions possible Does not increase the number of physical data channels 6-55

56 Telecommunications Software May reside in PCs, servers, mainframes, and communications processors Vital part of all telecommunications networks Used to manage network performance WANs often use telecommunications monitors or teleprocessing monitors Other networks use operating system software Middleware helps diverse networks communicate with each other 6-56

57 Network Management Functions Traffic Management Security Network Monitoring Capacity Planning Manage network resources & traffic to avoid congestion, optimize service levels Provide authentication, encryption, firewall, auditing, & enforcement Troubleshoot & watch over the network, alerting administrators to problems Survey network resources, traffic patterns, and users needs Determine the best way to accommodate network needs as it grows and changes 6-57

58 Network Topologies 6-58

59 Network Architectures and Protocols Protocol A standard set of rules and procedures for control of communications in a network Handshaking The process of exchanging predetermined signals and characters Establishes a telecommunications session between terminals and computers Network Architecture Master plan of protocols, hardware, software, and interfaces between end users and computer systems Goal is to promote an open, simple, flexible, and efficient telecommunications environment 6-59

60 OSI and TCP/IP Models 6-60

61 Voice Over IP Internet Telephony Using an Internet connection to pass voice data using IP instead of a telephone network Often referred to as voice over IP or VoIP Works like a regular phone, but skips longdistance charges Runs over standard network infrastructure Requires a well-configured network to work smoothly Skype is a fast-growing example 6-61

62 Bandwidth Bandwidth The frequency range of a telecommunications channel that determines the maximum transmission rate Speed and capacity typically measured in bits per second (bps) Sometimes call baud rate Transmission Rates Narrow-band = low speed Broadband = high speed 6-62

63 Transmission Speeds 6-63

64 Switching Alternatives Circuit Switching Switch opens a circuit to establish a link between a sender and a receiver It remains open until the communication session is completed Packet Switching Breaks messages into groups called packets Transmits packets separately 6-64

65 Network Interoperability Ensures that anyone anywhere on one network can communicate with anyone anywhere on another network From a telecommunications perspective, no need to speak a common language Telecommunications would be possible without Complete accessibility Transparency Seamless interoperability across all networks 6-65

66 Case 3: Secure, Self-Managed Network Metric & Multistandard Components Corp. Telecommunications network managed by outside firm Frequent crashes disrupted communications and order taking Three-year contract limited options Requirements for new network Reliability Scalability Security Economy Responsibility 6-66

67 Case 3: Network Project Objectives Goals Higher reliability, security, and scalability Lower costs Strategy Design IP network with advanced technologies that can be managed by small IT group Technology Use virtual private network technologies Connect remote office and users securely Facilitate company expansion Support Use Hi-Link technical support whenever needed 6-67

68 Case 3: Secure, Self-Managed Network Benefits of new, internally managed network Network congestion eliminated Network bandwidth, reliability, security improved Improved network management Downtime reduced to nearly zero Significant cost savings 6-68