CHAPTER 4 TELECOMMUNICATIONS AND NETWORKING

1. CHAPTER 4 TELECOMMUNICATIONS AND NETWORKING

2. THE NEED FOR NETWORKING • Sharing of technology resources • Sharing of data • Distributed data processing and client/server systems • Enhanced communications • Marketing outreach Page 96-97

3. AN OVERVIEW OF TELECOMMUNICATIONS AND NETWORKING Networking – the electronic linking of geographically dispersed devices Telecommunications – communications (voice and data) at a distance Page 97-98

4. Table 4.1 Functions of a Telecommunications Network Page 98

5. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • Analog network uses continuous voltage varying as a function of time • Example: voice over telephone lines • Digital network directly transmits two discrete states • Note: 0 for pulse off and 1 for pulse on Analog and Digital Signals Page 98-100

6. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • Modem • Device needed when transmitting data over analog lines • Converts data from digital to analog to be sent over analog telephone lines • Also reconverts data back to digital after data transmission • Abbreviation for modulator/demodulator Analog and Digital Signals Page 99

7. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING Analog and Digital Signals Figure 4.1 Use of Modem in Analog Network Page 99

8. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING Speed of Transmission • Bandwidth – • difference between highest and lowest frequencies • (cycles per second) that can be transmitted on a single medium • common measure of a medium’s capacity Page 100

9. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • Hertz – cycles per second • Baud – number of signals sent per second • Bits per second (bps) – number of bits sent per second When each cycle sends one signal that transmits exactly one bit of data (often the case), then the three terms are identical Speed of Transmission Note: Page 100

10. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • Switched line system • Example: public telephone system • Uses switching centers to route signals along best possible path to destination • Private (dedicated) lines • Leased from companies such as MCI, Sprint, AT&T • Use direct physical lines between source and destination Types of Transmission Lines Page 101

11. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • Simplex – data travels in one direction only • Half-duplex – data can travel in both directions, but only one direction at a time • Full-duplex – data travels in both directions at the same time Types of Transmission Lines Page 101

12. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING Transmission Media Page 101

13. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING Transmission Media Typical Speeds Table 4.2 Telecommunications Transmission Speeds Page 101

14. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING Transmission Media Page 102 Figure 4.3 Construction of a Coaxial Cable

15. Cordless telephone Cellular phone Wireless LAN Microwave Satellite KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING Transmission Media • Wireless – • broadcast technology in which radio signals are sent out into the air Page 102

16. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING Transmission Media Page 102 Figure 4.4 Satellite Communications

17. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • Fiber-optic cabling • Newest transmission medium • Transmits data by pulses of light through thin fiber of glass • Much faster than other media • Thinner … requires less space • More secure … harder to tap Types of Transmission Lines Page 105-106

18. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING Topology of Networks • Topology– • term used to describe the configuration or arrangement of network devices and media Page 106

19. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING Topology of Networks Page 106 Figure 4.5 Network Topologies

20. More Complex Networks Page 107 Figure 4.6 vBNS+ Network Map

21. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • Computer Telecommunications Networks • Private branch exchange (PBX) Networks • Local Area Networks (LANs) • Backbone Networks • Wide Area Networks (WANs) • Internet • Internet2 Types of Networks Page 108

22. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • Computer Telecommunications Networks • Emanates from a single medium or large computer • Usually arranged as a tree • Uses coaxial and twisted pair cabling • Controlled by central computer • Often has a front-end processor to handle all aspects of telecommunications Types of Networks Page 108

23. Figure 4.7 Computer Telecommunications Network Page 108

24. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • Private Branch Exchanges (PBX) • Originally analog, today usually digital • Can serve as the central device in a star or ring network • Can function as front-end processor for mainframe Types of Networks Page 109

25. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • Private Branch Exchanges (PBX) • Advantages: • Can connect ALL telecommunications devices in a building or campus • Can use existing telephone wiring • Can carry voice and data over same network • Has a high-potential throughput Types of Networks Page 109

26. Figure 4.8 Schematic Representation of a PBX Page 109

27. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • Local Area Networks • Owned by a single organization • Operate within area 2-3 miles in diameter • Contain a number of intelligent devices, usually microcomputers, that can process data … based on peer-to-peer relationship • No part of telephone system, have their own wiring Types of Networks Page 109

28. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • LAN Topologies and Standards • Contention bus design … IEEE 802.3 • Token bus design … IEEE 802.4 • Token ring design … IEEE 802.5 • Wireless design … IEEE 802.11 Local Area Networks Page 109

29. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • Contention Bus Design (Ethernet) • Bus topology • Implemented with coax or twisted pair • Usually half-duplex • All devices contend for use of cable • Design now called Shared Ethernet … uses a contention bus as its logical topology and implemented with a physical star arrangement … Local Area Networks Page 110

30. Figure 4.9 Shared Ethernet Topology: Logical Bus, Physical Star Page 109

31. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • Switched Ethernet • Newer variation, better performance, higher price • Uses switch instead of hub • Operates both logical and physical star • Each device has own dedicated circuit Local Area Networks Page 110

32. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • Token Bus • Employs bus topology, no contention • Uses single token passed around to all devices in order • Device can only transmit when has token • Central to Manufacturing Automation Protocol (MAP) – connects robots and other machines on assembly line by a LAN Local Area Networks Page 110

33. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • Token Ring • Device attached to ring must seize token before can send a message • Collisions cannot occur • Usual implementation is physical star, logical ring Local Area Networks Page 111

34. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • Wireless LAN • Known as Wi-Fi (wireless fidelity) • Growing in demand for corporate and home use • Use IEEE 802.11 standards with shared Ethernet design • Requires use of wireless network interface card (NIC) • Wireless Access Point (WAP) – radio transceiver that acts as a hub Local Area Networks Page 111

35. Figure 4.10 Wireless Local Area Network Topology Page 112

36. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • Backbone Network In-between network that interconnects LANs in a single organization with each other and with organization’s WAN and the Internet Types of Networks Page 113

37. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • Backbone network terminology: • Bridge – connects two LANs using same protocol • Router (gateway) – connects two or more LANs that may use different protocols • Switch – connects more than two LANs using the same protocols Types of Networks Page 113

38. Page 112 Figure 4.11 Sample Backbone Network

39. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • Wide Area Networks (WANs) • Communicate voice and data across greater distances • Usually owned by several organizations (including user organization and common carrier) • Employ point-to-point transmission • Often rely on public telephone network Types of Networks Page 114

40. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • Switched-circuit • Direct distance dialing (DDD) • Wide Area Telephone Service (WATS) • Integrated Service Digital Network (ISDN) • Dedicated-circuit • Leased lines • Satellite Types of WANs Page 115

41. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • Packet-switched • Shared private lines using store-and-forward data transmission • Permits multiple connections to exist simultaneously over the same physical circuit Types of WANs Page 116

42. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • ATM – fast packet switching with short, fixed-length packets • Virtual Private Networks (VPNs) – provide same as private packet-switched network using the public Internet Types of WANs Page 117

43. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • The Internet • Network of networks that use the TCP/IP protocol • Contain gateways to computers that do not use TCP/IP • Provides four basic functions: • Electronic mail • Remote login • Discussion groups • Sharing of data resources Types of Networks Page 117-118

44. Page 118 Table 4.4 Internet Applications

45. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • Internet access services: • Digital subscriber line (DSL) – service offered by telephone companies using copper wire already installed in homes … moving data over wires without disturbing voice traffic • Cable modem – connection obtained from cable TV company using existing home coaxial cable • Satellite – most expensive, but may be only option for customers in rural areas DSL, Cable Modem, and Satellite Page 120

46. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING Intranets • Intranet– • a network operating within an organization that uses the TCP/IP protocol Page 122

47. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • Internet2– • not-for-profit consortium of over 200 universities, working with over 60 technology companies and the U.S. government, to develop and deploy advanced network applications and technologies Page 122

48. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • Primary goals of Internet2: • Create a leading-edge network capability for the national research community • Enable revolutionary Internet applications based on a much higher-performance Internet that we have today • Ensure the rapid transfer of new network services and applications to the broader Internet community Page 123

49. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING Network Protocols • Protocol– • agreed-upon set of rules governing communication among layers or levels of a network Page 124

50. KEY ELEMENTS OFTELECOMMUNICATIONS ANDNETWORKING • LAN protocols: • Contention bus • Token bus • Token ring • Wireless • IBM’s own protocol – Systems Network Architecture (SNA) Network Protocols Page 124