 2002 Prentice Hall Chapter 6 Networking and Telecommunication

 2002 Prentice Hall 2 Topics Linking Up: Network Basics Electronic Mail, Teleconferences, and Instant Messages: Interpersonal Computing Converging Communication Technologies: From Messages to Money

 2002 Prentice Hall 3 Linking Up: Network Basics A computer network is any system of two or more computers that are linked together. How do networks impact systems?  People share computer hardware, thus reducing costs  People share data and software programs, thus increasing efficiency and production  People work together in ways that are otherwise difficult or impossible

 2002 Prentice Hall 4 Basic Network Anatomy The three basic components of a network:  Hardware  Software  People Direct Connection--one of many computers linked in an office Remote Access--computer linked to a network through a phone line, television cable system or satellite link

 2002 Prentice Hall 5 The Network Interface A network interface card (NIC) permits direct network connection It adds an additional serial port to the computer The network interface card controls the flow of data between the computer’s RAM and the network cable.

 2002 Prentice Hall 6 Communication á la Modem A modem is a hardware device that connects a computer’s serial port to a telephone line (for remote access). May be internal on the system board or external modem sitting in a box linked to a serial port. Modem transmission speed is measured in bits per second (bps) and generally transmit at 28,000 bps to 56.6K bps

 2002 Prentice Hall 7 Conversion of Signals Computers send digital signals. The modem (modulator/ demodulator) converts the digital signals to analog so that the message can be transmitted through telephone lines.

 2002 Prentice Hall 8 Conversion of Signals The modem (modulator/demodulator) converts the analog signals back to digital signals that are understood by the computer

 2002 Prentice Hall 9 Networks Near and Far Local-area network (LAN)  Computers are linked within a building or cluster of buildings.  Each computer and peripheral is an individual node on the network.  Nodes are connected by cables which may be either twisted pair (copper wires) or coaxial cable.

 2002 Prentice Hall 10 Networks Near and Far Wide-area network (WAN)  A network that extends over a long distance.  Each network site is a node on the network.  Data transmitted over common pathways called a backbone.

 2002 Prentice Hall 11 Wide-Area Networks Made up of LANs linked by phone lines, microwave towers, and communication satellites. Bridges, routers, and gateways are hardware devices that pass messages between networks.

 2002 Prentice Hall 12 Communication Software Protocol - set of rules for the exchange of data between a terminal and a computer or between two computers Communication software establishes a protocol that is followed by the computer’s hardware

 2002 Prentice Hall 13 Communication Software Many forms:  Network operating system (NOS) - handles communications between many workstations  Client/server model - one or more computers act as dedicated serves and all the remaining computers act as clients  Peer-to-peer model - every computer on the network is both client and server  Many networks are hybrids, using features of the client/server and peer-to-peer models

 2002 Prentice Hall 14 Client/Server Model Client software sends requests from the user to the server Server software responds to client requests by providing data

 2002 Prentice Hall 15 The Network Advantage Why do people use networks?  To share computer resources (hardware and software)  To support working together in new and different ways Lotus Notes is a groupware application that facilitates information sharing and workgroup collaboration.

 2002 Prentice Hall 16 Mail, Teleconferences, and IM: Interpersonal Computing Electronic mail, teleconferencing and instant messaging allow communications between two or more people. Meetings can be held in real-time (synchronous) or delayed (asynchronous) Chat rooms are examples of synchronous communications; bulletin boards are examples of asynchronous communications.

 2002 Prentice Hall 17 The Postal Alternative is fast. doesn’t depend on location. facilitates group communication. messages are digital data that can be edited and combined with other computer-generated documents.

 2002 Prentice Hall 18 Advantages of and Teleconferencing On-line communication is less intrusive. On-line communication allows time shifting. Teleconferences and e- mail promotes teleworking. Teleconferences and e- mail emphasize the message over the messenger.

 2002 Prentice Hall 19 On-line Issues for and Teleconferencing Vulnerable to machine failures, network glitches, human errors and security Threat to privacy forgery Information overload Missing “human” elements of communication

 2002 Prentice Hall 20 Rules of Thumb: On-line Survival Tips If you don’t have to be on line, go off line. Avoid peak hours Let your system do as much of the work as possible. Store names and addresses in an on-line address book Protect your privacy Cross-check on-line information sources Be aware and awake Avoid information overload.

 2002 Prentice Hall 21 Converging Communication Technologies: From Messages to Money On-line Information Services Fax Machines and Fax Modem Voice Mail and Computer Telephony Global Positioning System Video Teleconferencing E-Money

 2002 Prentice Hall 22 Physical Media for Networks Networks are built on physical media.  Twisted pair (Category 5)  Twisted pair (Traditional)  Coaxial Cable  Fiber optic  Wireless/infrared  Wireless/radio What affects network performance?  Bandwidth and maximum operating distance “Never in history has distance meant less.” Alvin Toffler

 2002 Prentice Hall 23 Bandwidth The amount of information that can be transmitted in a given amount of time Impacted by:  Physical media that make up the network  Amount of network traffic  Software protocols of the network  Type of network connection

 2002 Prentice Hall 24 Fiber Optic Cables Fiber optic cables are replacing aging cooper lines with high-capacity fiber optic cables. They use light waves to carry information at blinding speeds. A single fiber optic cable can transmit half a gigabit (500 million bits) per second, replacing 10,000 standard telephone cables. Data is transmitted more accurately and reliably.

 2002 Prentice Hall 25 Digital Communication Comes Home Digital communication lines will radically change services to our homes. Multi-person video phone conversations, universal , customized digital newspapers, automatic utility metering and unlimited entertainment options

 2002 Prentice Hall 26 ROUTERS Definition: Routers are physical devices that join multiple wired or wireless networks together. Technically, a wired or wireless router is a Layer 3 gateway, meaning that the wired/wireless router connects networks (as gateways do), and that the router operates at the network layer of the OSI model. Home networkers often use an Internet Protocol (IP) wired or wireless router, IP being the most common OSI network layer protocol.gateway

Home networkers often use an Internet Protocol (IP) wired or wireless router, IP being the most common OSI network layer protocol. An IP router such as a DSL or cable modem broadband router joins the home's local area network (LAN) to the wide-area network (WAN) of the Internet.broadband routerlocal area network (LAN)wide-area network (WAN)  2002 Prentice Hall 27

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