Chapter 9 Objectives. Chapter 9 Communications and Networks. Communications. Communications

Transcription

1 Chapter 9 Objectives Define the components required for successful communications Understand the various communications technologies Identify various sending and receiving devices Identify uses of intranets and extranets Chapter 9 and Explain communications applications List advantages of using a Differentiate between a local area and a wide area Explain the purpose of communications software Understand the telephone Describe commonly used communications devices Identify various physical and wireless transmission media p.9.2 What are communications? Process in which one transfers data, instructions, p.9.2 Fig. 9-1 and information to another (s) system contains many types of devices (a) s (b) notebook s b (c) Web-enabled cellular c telephones (d) Web-enabled handheld s (e) WebTV a (f) GPS receivers e f a a c d a p.9.2 What is needed for successful communications? sending device communications device communications channel communications device receiving device What is the primary function of a communications device? To convert digital signals to analog signals or analog signals to digital signals Sending and Receiving Devices What is a sending and receiving device? Initiates or accepts transmission of data, instructions, and information analog signal Continuous electrical wave notebook s mid-range servers digital signal Distinct pulses that represent bits grouped together into bytes desktop s mainframe s Internet appliances and Web-enabled devices p.9.3 Fig. 9-2 p.9.3

2 What are some uses of communications technology? Uses of voice mail instant messaging newsgroups telephony videoconferencing fax chat rooms Uses of What is instant messaging (IM)? 1: Login to the IM server 2: Server checks if any established friends, family, or co-workers, called buddies, are online 3: Send instant messages to online buddy 4: Instant message travels through messaging server and then to online buddy Step 1 Step 2 IM server messaging server Step 3 p.9.4 collaboration groupware global positioning system (GPS) p.9.6 Fig. 9-4 Step 4 Uses of What is a chat room? Permits users to converse in real time via the Internet Types of chat rooms Voice chats Video chats Radio chats What is a newsgroup? Area on the Web where users conduct written discussions about a particular subject Also called threaded discussion Uses of p.9.6 Fig. 9-5 p.9.7 p.9.8 Uses of What is Internet telephony? Enables you to talk to other people over the Internet Uses of What is collaboration? Working with other users connected to a server You can conduct online meetings Allows you to everyone share in in online online documents meeting with others in can can see see and and edit edit real time document Microsoft s NetMeeting allows collaboration p.9.9 Fig. 9-7 NetMeeting window chat chat room room

3 Uses of What is groupware? Software application that helps groups of people work together on projects and share information over a Lotus Notes Microsoft Exchange Uses of What is a global positioning system (GPS)? 1: GPS satellites orbit the earth. Every thousandth of a second, each satellite sends a signal that indicates its current position to the GPS receiver. Step 1 p.9.10 manage projects schedule meetings communicate make group decisions 2: GPS receiver (such as in a car) determines its location on Earth by analyzing signals from the satellites. p.9.10 Fig. 9-8 Where am I? Step 2 p.9.10 What is a Digital Angel? Necklace, bracelet, or receiver woven into fabric that communicates with another party using GPS satellite system Measures and sends biological information to satellite Uses of necklace lets doctor s office keep tabs on you in real time p.9.11 What is a site license? Legal agreement that allows multiple users to run a software package simultaneously License fee usually based on number of users or number of s attached to What is a local area (LAN)? Network in limited geographical area such as home, school laboratory, or office building What is a peer-to-peer LAN? Small that shares hardware, data, or information located on any other in Each stores files on its own storage devices operating system system and and application software installed on on each each p.9.12 Fig. 9-9 nodes in p.9.13 Fig printer printer may may be be used used by by all all s on on

4 What is a client/server LAN? Network in which one or more s act as a server and other s on the can request services from server client client client What is a wide area (WAN)? Network that covers large geographic area Internet is world s largest WAN communications satellite p.9.14 Fig laser printer server p.9.15 Fig What is an Internet use of peer-to-peer (P2P)? Enables users with same ing software to connect to each other s hard disks and exchange files directly What is a metropolitan area (MAN)? Backbone that connects local area s in a metropolitan area such as a city or town p.9.16 Fig p.9.16 p.9.16 What is a topology? Configuration, or physical arrangement, of devices in a communications usually use combinations of three topologies bus ring star What is a bus? Consists of a single central cable, to which all s and other devices connect Bus is physical cable or backbone Inexpensive and easy to install p.9.17 Fig. 9-15

5 What is a ring? Cable forms closed ring, or loop, with all s and devices arranged along ring Data travels from device to device around entire ring, in one direction What is a star? All devices connect to a central, called the hub All data transferred from one to another passes through hub host p.9.16 Fig p.9.18 Fig printer file server What are communications technologies? Specific combinations of hardware and software that allow different devices on several types of s to communicate Ethernet token ring What is Ethernet? LAN technology that allows s to contend for access to Based on bus technology TCP/IP WAP p.9.18 p.9.19 p.9.19 What is token ring? LAN technology that controls access to by requiring devices to share or pass a special signal, called a token Device with token can transmit data over Only one token exists per Based on ring topology, although it can use star topology p.9.19 What is TCP/IP? Short for transmission control protocol/internet protocol Transmits data by breaking it up into packets Commonly used for Internet transmissions packets Data divided into small pieces called packets routers Devices that direct packets along fastest available path packet switching Technique of breaking a message into packets, sending packets, and then reassembling data

6 p.9.20 What is the Wireless Applications Protocol (WAP)? Allows wireless mobile devices to access Internet and its services Wireless device contains client software, which connects to Internet service provider's server What is an intranet? Internal that uses Internet technologies Lets company make information accessible to employees and facilitate working in groups Typically includes a connection to Internet p.9.20 has a Web server accessible via a Web browser users can post and update information on intranet by creating and posting a Web page What is an extranet? Allows customers or suppliers to access part of company s intranet What is a firewall? Hardware and/or software that restricts access to data and information on printer customer checking package on Fed Ex s intranet via the Internet corporate Internet p.9.20 Fig p.9.21 Fig firewall What is a home? Ways to connect Ethernet connect each via cable HomePLC (powerline cable) use electrical lines in house Phoneline use telephone lines HomeRF (radio frequency) wireless p.9.22 Fig Multiple s connected together in home p.9.23 What is an intelligent home? Extends basic home to include features such as lighting control, thermostat adjustment, and security system

7 p.9.23 Software What is communications software? Programs that help establish connection to another or Software What is file transfer protocol (FTP)? p.9.24 Fig Internet standard that allows you to upload and download files to and from a Web server, called the FTP server files files on on the the FTP FTP server server files files on on your your The Telephone Network What is the public switched telephone (PSTN)? Worldwide telephone system that handles voice-oriented telephone calls The Telephone Network What is a dial-up line and a dedicated line? Dial-up line is temporary connection using telephone line for communications Dedicated line is line always connected between two communications devices p.9.25 Fig analog signal satellite most of the PSTN use digital technology final link from local telephone company to home or office analog signal p.9.25 Advantages of dial-up line 1. Costs no more than making regular call 2. Computers at any two locations can establish a connection using modems and telephone Advantages of dedicated line 1. Quality and consistency of connection are better 2. Computer locations are fixed 3. Can be digital or analog The Telephone Network What is transfer rate? Speed at which a line carries data and information Faster the transfer rate, the faster you can send and receive data and information Usually expressed as a measure of bits per second The Telephone Network What are popular types of digital dedicated lines? bits per second (bps) p.9.26 kilobits per second (Kbps) megabits per second (Mbps) gigabits per second (Gbps) p.9.26 Fig. 9-25

8 Devices What is a communications device? Any type of hardware capable of transmitting data, instructions, and information between sending device and receiving device Devices What is a dial-up modem? device that converts 's digital signals to analog signals and analog signals to digital signals ISDN and DSL use digital modem with a digital telephone line p.9.27 dial-up modems ISDN and DSL modems cable modems interface cards p.9.28 modulate To convert a digital signal into an analog signal mo + dem demodulate To convert an analog signal into a digital signal Devices What is a cable modem? Modem that sends and receives data over cable television Much faster than modem or ISDN Usually attaches to card Devices What is a interface card (NIC)? Card inserted into expansion slot of or other device, enabling it to connect to a NIC for desktop p.9.29 Fig cable modem p.9.29 Fig NIC for notebook What is a hub? Device that provides a central point for cables in a hub Devices Channel What is a channel? path between two devices bandwidth Width of communications channel transmission media Materials or techniques capable of carrying one or more signals p.9.30 Fig p.9.31

9 Channel Sending a request over the Internet 1: Sending device requests information 2: When request leaves the ISP, it travels over a variety of lines until it reaches Internet backbone 3: Request travels over T3 lines along Internet backbone 4: Request travels over T1 lines until it reaches destination p.9.31 Fig server modem sending device communications satellite earth-based stations T1 lines T1 lines microwave station ISP T1 lines T1 lines destination T3 lines T3 lines mainframe server Internet backbone T3 lines T1 lines mainframe Physical Transmission What is physical transmission media? Wire, cable, and other tangible (touchable) materials used to send communications signals p.9.32 Fig Physical Transmission What is twisted-pair cable? Transmission media used by telephone system and cabling Physical Transmission What is coaxial cable? Single copper wire surrounded by at least three layers Often used for cable television wiring twisted-pair cable twisted pair cable twisted-pair wire coaxial cable woven or braided metal copper wire p.9.33 Fig p.9.33 Fig plastic outer coating insulating material Physical Transmission What is fiber-optic cable? Contains core of dozens or hundreds of thin strands of glass or plastic Uses light to transmit signals optical fiber core What is wireless transmission media? Send communications signals through air or space Used when inconvenient, impractical, or impossible to install cables p.9.34 Fig cable contains many optical fibers glass cladding outer protective covering fiber-optic coating cable jacket between floors of a building p.9.34 Fig. 9-36

10 What is an example of a wireless local area? switch What is cellular radio? Form of broadcast radio used widely for mobile communications mobile telephone switching office (MTSO) calling party in auto cell p.9.36 Fig access point p.9.36 Fig cell cell cell base station (microwave station) called party public switched telephone What is a microwave station? Earth-based reflective dish that contains antenna, transceivers, and other equipment necessary for microwave communications Uses line-of-sight transmission Must transmit in straight line with no obstructions between microwave antennas p.9.38 Fig What is a communications satellite? Space station that receives microwave signals from an earthbased station, amplifies the signals, and then broadcasts the signals back over a wide area to any number of earthbased stations p.9.38 Fig What is infrared (IR)? Wireless transmission media that sends signals using infrared light waves Requires line-of-sight transmission Many s and devices have an IrDA port that enables transfer of data using infrared light rays p.9.39 Fig Sending and receiving devices Uses of communications technologies software Telephone devices channel Physical transmission media Wireless transmission media Summary of and Chapter 9 Complete