McGraw-Hill/Irwin ©2005 The McGraw-Hill Companies, All rights reserved Extended Learning Module E NETWORK BASICS (on your CD)

E-2 INTRODUCTION Computer network – two or more computers connected so that they can communicate with each other and share information, software, peripheral devices, and/or processing power

E-3 INTRODUCTION

E-4 Basic Principles of Networks 1.Each computer must have a network interface to provide a doorway for information 2.The network needs at least one connecting device 3.The network must have communications media as pathways for information

E-5 Basic Principles of Networks 4.Each computer must have a network operating system These four principles apply to all networks, large and small

E-6 PEER-TO-PEER HOME NETWORK Peer-to-peer network – a network in which a small number of computers share hardware, software and/or information A small peer-to-peer network can be wired with Ethernet cable or it can be wireless

E-7 Home Network Components To set up a small home network you’ll need –An Ethernet network card in each computer –A home router as a connecting device –Cables as the communications media –Windows as the network operating system

E-8 Network Cards Network interface card (NIC) – an expansion card or PC Card that connects your computer to a network –Ethernet card – the most common type of (NIC)

E-9 Connecting Devices: Hubs, Switches Network hub – a device that connects multiple computers into a network –Only one communications line is available at a time and all computers see every message Switch – a device that connects multiple computers into a network in which multiple communications links can be in operation simultaneously

E-10 Connecting Devices: Routers Router – a device that connects computers into a network and separates it from any other network it’s connected to –Allows multiple simultaneous communications links; also acts as a firewall, which is hardware and/or software that protects a computer or network from intruders

E-11 Wired Transmission Media Cat 5 (Category 5) cable – better constructed version of phone twisted-pair cable –Each end has an RJ-45 connector (looks like a phone connector, but is bigger)

E-12 Wireless Transmission Media Wireless network access point (wireless access point) – device that allows computers to access a network using radio waves

E-13 Wireless Standards Wifi (wireless fidelity or IEEE a, b or g) – a standard for transmitting information in the form of radio waves over distances up to about 300 feet –Used for wireless connection to a network Bluetooth – a standard for transmitting information over distances of up to 30 feet –Used for devices (synch PDAs and cell phones)

E-14 Typical Home Network

E-15 INTERNET ACCESS Five ways: 1.Phone line and dial-up modem 2.Phone line and DSL modem 3.Cable TV line and cable modem 4.Satellite dish and satellite modem 5.Wireless Internet provider with WiFi card

E-16 INTERNET ACCESS Broadband – high-capacity telecommunications pipeline capable of providing high-speed Internet service All Internet access methods on the previous slide are broadband except the dial-up modem type

E-17 Telephone or Dial-Up Connection Telephone modem (modem) – connects your computer to your phone line so that you can access another computer or network

E-18 Pros and Cons of Dial-Up Advantages –Cheaper than broadband –Less vulnerable to intruders since it’s not always on Disadvantages –Slow –Can’t use phone line to talk while you’re online

E-19 Digital Subscriber Line Digital Subscriber Line (DSL) – high-speed Internet connection using phone lines, which allows you to use your phone for voice communications at the same time

E-20 Pros and Cons of DSL Advantages –High speed access –DSL guarantees a certain access speed Disadvantages –you have to live close to a CO (Central Office) –DSL is an always-on connection

E-21 Cable Modem Cable modem – device that uses your TV cable to deliver an Internet connection

E-22 Pros and Cons of Cable Modem Advantages –High speed access –Available wherever cable TV can be had Disadvantages –Speed degrades as number of people using it increases –Always-on connection

E-23 Internet over Satellite Satellite modem – modem that allows you to get Internet access from your satellite dish

E-24 Pros and Cons of Satellite Modem Advantages –High speed –Allows Internet access in remote areas Disadvantages –Need special dish –Download about 10 times faster than upload

E-25 Wireless Internet Wireless Internet service provider (wireless ISP) – does the same job as a standard Internet services except that you don’t need wires

E-26 Personal Digital Assistant (PDA) Personal digital assistant (PDA) – small hand-held computer that allows you surf the Web and perform certain personal organization tasks Two types –Palms and Handsprings run on Palm Operating System –Pocket PCs run on Pocket PC OS

E-27 BUSINESS NETWORKS Client/server network - a network in which one or more computers are servers and provide services to the other computers, called clients

E-28 Client/Server: A Business View Client/server networks differ according to –Where the processing for the presentation of information occurs –Where the processing of logic or business rules occurs –Where the data management component (DBMS) and information (database) are located

E-29 Client/Server Implementation: Model 5

E-30 The Five Models of Client/Server 1.Distributed Presentation: –The server handles almost all functions, including a major portion of the presentation 2.Remote Presentation –The client handles all presentation functions

E-31 The Five Models of Client/Server 3.Distributed Logic –The server handles all data management and the client handles all presentation formatting, and the logic processing is shared

E-32 The Five Models of Client/Server 4.Remote Data Management –The server handles data management only, and the client processes business rules and formats the presentation of results 5.Distributed Data Management –The client handles all presentation formatting and business rule processing, and both the server and client share data management duties

E-33 The Five Models of Client/Server

E-34 Client/Server: A Physical View Communications protocol (protocol) – a set of rules that every computer follows to transfer information

E-35 LANs, MANs, WANs, WLANs, AND COMMUNICATIONS MEDIA Networks can be classified by size –Local area network (LAN) - covers a limited geographic distance, such as an office, building, or a group of buildings in close proximity to each other –Municipal (or metropolitan) area network (MAN) - covers a metropolitan area

E-36 Networks by Size –Wide area network (WAN) – covers a large geographic distance, such as a state, a country, or even the entire world –Wireless local area network (WLAN or LAWN) – a local area network that uses radio waves rather than wires to transmit information

E-37 Telecommunications Media: The Paths That Carry Information Communications media - the paths, or physical channels, in a network over which information travels Wired communications media - transmit information over a closed, connected path Wireless communications media - transmit information through the air

E-38 Bandwidth Bandwidth – capacity of the communications medium, refers to the amount of information that it can transfer in a given amount of time

E-39 Wired Communications Media Twisted-pair cable –Comes in several varieties; Cat 5 is usual for networks Coaxial cable (coax) – a central wire surrounded by insulation, a metallic shield, and a final covering of insulating material

E-40 Wired Communications Media Optical fiber – uses a very thin glass or plastic fiber through which pulses of light travel

E-41 Wireless Communications Media Infrared, IR or IrDA (infrared data association) – uses red light to send and receive information Microwave – a type of radio transmission Repeater – a device that receives a radio signal, strengthens it, and sends it on

E-42 Wireless Communications Media

E-43 Wireless Communications Media Communications satellite – microwave repeater in space

E-44 COMMUNICATIONS SERVICE PROVIDERS Network ownership determines –Rights to the network –Cost –Availability –Services provided –Speed –security

E-45 Types of Network Ownership Communications service provider – third party that furnishes the conduit for information Public network – a network on which your organization competes for time with others

E-46 Types of Network Ownership Private network – consists of the communications media that your organizations owns or exclusively leases to connect networks or network components

E-47 Types of Network Ownership Virtual private network (VPN) – uses software to establish a secure channel on the Internet for transmitting information International virtual private network (international VPN) – to transmit information over a network that extends beyond national borders

E-48 Key Considerations for Communications Media Capacity Reliability Cost Distance Mobility