computers © 2005 prentice-hall, inc.slide 1. computers chapter 6 networks ( 網路 ) and networking...
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ComputersChapter 6 – Networks and Networking
Objectives ( 目標 ) Apply the concept ( 觀念 ) of connectivity ( 連接性 ) to your life Understand data communications hardware ( 硬體 ) Identify ( 認識 ) data transmissions services ( 服務 )Understand the various ( 各樣 ) network topologiesRecognize ( 認識 ) the potential ( 潛力 ) of home networking
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ComputersNetworks and Networking
Our Wired ( 連線 )World Connectivity – the degree ( 程度 ) to which software ( 軟體 ), hardware, and databases ( 資料庫 ) are functionally ( 功能 ) linked
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Our Wired World Cooperative ( 合作式 ) processing
Intracompany ( 公司內 ) networking – cooperation ( 合作 ) within the company Intercompany ( 公司 間 ) networking – cooperation with other companies and customers ( 客戶 )
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Our Wired World Intranet ( 內網路 ) –internal network based on Internet technology Extranet ( 萬網路 ) – an extension ( 擴充 ) of an intranet, partially ( 部分 ) available ( 可用 ) to customers and suppliers ( 供應商 )
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Our Wired World Virtual ( 虛擬 ) Private ( 私人 ) Network (VPN) – network transmissions ( 傳輸 ) are tunneled ( 通往 ) through the Internet Tunneling ( 通道 ) – one network uses another to send data
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Data Communications HardwareData communications or telecommunications ( 電信 ) – distribution ( 播散 ) of data
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Data Communications Hardware Server ( 伺服 ) computers – central computers that control the network Client ( 客戶 ) computers – computers, linked to a server, that create ( 產生 ) the network
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Data Communications Hardware Proxy ( 代理 ) server computers – handle some requests ( 要求 ), hand others to the actual server computers
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Data Communications Hardware Telephone-link modem ( 數據機 ) – converts ( 轉換 ) analog signals ( 類比信號 ) to digital ( 數位 ) and digital signals to analog Analog – voice communication, such as over a telephone lineDigital – 1’s and 0’s used to represent data in a computer
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Data Communications Hardware Modem
Internal ( 內裝 )External ( 外接 )Voice/data/fax modem
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Data Communications Hardware Cable modem – provides Internet access via cable television lines DSL (Digital Subscriber Line) – Internet access via special ( 特殊 ) line provided ( 提供 ) by a telephone company Satellite ( 衛星 ) modem – Internet access via communications satellite
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Data Communications Hardware Network interface card (NIC) – also called network card and network adapter
Needed to connect a personal computer to a network Ethernet ( 乙太網 ) – de facto ( 事實上的 ) standard ( 標準 )
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Data Communications Hardware Gateway ( 閘道 ) – allows ( 允許 ) for communication between networks using different ( 不同 ) protocols ( 協定 ) Router ( 路由器 ) – routes ( 安排傳送 ) messages ( 訊息 ) to the appropriate ( 適當 ) destination ( 目的地 )Gateway router – both functions in one device
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Data Communications Hardware Message
Source ( 來源 ) – device that sends ( 送 ) the messageDestination – device that receives ( 接收 ) the message Handshaking ( 握手 ) – router establishes ( 建立 ) the connection between the source and the destination
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Data Communications Hardware Network address – assigned to each computer on a network; used to send messages to the appropriate destination Backbone ( 主榦 ) – the routers, gateways, and other equipment that link the computers of the network
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Data Communications Hardware Hub – expands the number of nodes on a network
Half-duplex ( 半雙工 ) – data can only be sent in one direction at a time
Switch ( 交換器 ) – acts like a hub for a local area network (LAN)
Full-duplex ( 全雙工 )– data can be sent in both directions at once
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Data Communications Hardware Terminals ( 終端機 )
Video Display ( 顯示 )Terminal – input/output deviceThin ( 輕 ) client – smart terminal, capable ( 能夠 ) of some processing
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Data Communications Hardware Telephony ( 電話電腦 ) – integration ( 整合 ) of telephones and computers
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Data Communications HardwareAutomatic Teller Machine (ATM, 自動櫃員機 ) – used in banking ( 銀行 ) Point-of-Sale (POS, 銷售點 ) terminals – used in retail ( 零售 )
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The Data Communications ChannelCommunications channel – media ( 媒體 ) a message must pass through on a network
LineLinkPipe ( 管路 )
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The Data Communications ChannelTransmission media ( 媒體 )Measured ( 量測 ) in bits per second (bps)
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The Data Communications ChannelTwisted-pair wire ( 絞線 )
POTS (plain old telephone services)Digital Subscriber Line (DSL)
Cat5 cabling – uses four twisted pairs of wire; speeds of up to 100 M bps Cat5e cabling – speeds of up to 1 G bps
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The Data Communications ChannelCoaxial cable ( 同軸電纜 ) – high capacity channel, capable of speeds up to 10 M bpsFiber optic cable ( 光纖電纜 ) – carries ( 載 ) data as electrical signals
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The Data Communications ChannelWireless ( 無線 ) communication
Microwave ( 微波 ) signal – sent from one transmitter ( 發射器 ) to anotherRadio frequency (RF, 射頻 ) signal – line-of-sight
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The Data Communications ChannelCommunications satellite – repeater ( 強波器 ) for microwave transmissions in geosynchronous orbit ( 地球同步軌道 )Geosynchronous orbit – 22,300 miles above the earth
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The Data Communications ChannelWireless networks
Access points (AP, 擷取點 ) – college campuses ( 校園 ), coffee shops, local area networks
Wi-Fi – approximately ( 大約 ) 300 foot range ( 範圍 )Bluetooth – approximately 30 foot range
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The Data Communications ChannelWireless Application ( 應用 ) Protocol (WAP)
Internet access standard for wireless devices such as cell phones
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The Data Communications ChannelFuture of wireless
Multichannel Multipoint ( 多通路多點 ) Distribution Service (MMDS)Local Multipoint Distribution Service (LMDS)
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The Data Communications ChannelCommon carriers
Examples: AT&T, Sprint, MCIPrivate line (leased ( 租賃 ) line) – charge based on channel capacity and distance ( 距離 )Switched ( 交換 ) line (dialup line) – time and distance charge
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The Data Communications ChannelCommunications protocols ( 通訊協定 ) – rules established to govern ( 管理 ) the way data are transmitted in a computer network Asynchronous transmission ( 非同步通訊 ) – data sent on an as-needed ( 隨需求 ) basisSynchronous transmission ( 同步通訊 ) – source and destination operate in timed synchronization
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NetworksNode – terminal, PC, or any device connected to a network
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NetworksTypes of Networks
Personal ( 個人 ) Area Network (PAN) – connects cell phones or other electronics to the networkLocal Area Network (LAN) – nodes are in close proximity ( 近範圍 )
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NetworksTypes of Networks
Metropolitan ( 大都市 ) Area Network (MAN) – network that encompasses ( 包含 ) a cityWide ( 廣域 ) Area Network (WAN) – nodes of the network are geographically ( 地理 ) distant ( 遠 )
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NetworksLAN resources ( 資源 ) that can be shared
Applications software Links to other LANs Communications capabilities I/O devices Storage devices Add-on boards ( 外加板 )
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NetworksLAN access methods
Network Access Method – rule that a network uses to determine priorities
Logical topology ( 網路拓撲 )
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NetworksEthernet – widely used network access method; uses Carrier ( 載波 ) Sense ( 感覺 ) Multiple Access/Collision ( 衝突 ) Detection ( 偵測 ) (CSMA/CD protocol)Token ( 標記 ) Access Method
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NetworksServers
File server – stores programs and data to be shared via the networkPrint server – handles print jobsCommunication server – provides access to other networksLAN server – PC designed to be server
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NetworksLAN software
Network operating system (NOS)Peer-to-peer (P2P)Dedicated ( 專用 ) server
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NetworksLAN software
Peer-to-peer LAN – all PCs are equal in the networkClient/server LAN – NOS resides on the server computer
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NetworksApplication software for LANs
Client/server LAN applications softwareFront-end ( 前端 ) application software – user interface and applications software processed locally ( 局部 )Back-end ( 後端 ) application software – handles tasks associated with storage and maintenance ( 維護 ) of databases
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NetworksApplication software for LANs
Download ( 下載 ) (server-to-client)Upload ( 上載 ) (client-to-server)
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NetworksShared ( 共享 ) applications software
Groupware ( 群體 ) – allows a group of people to work on a project ( 計畫 )
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NetworksShared applications software
Electronic mail (e-mail)Instant messagingCalendar ( 行事曆 ) and scheduling ( 日程表 )Brainstorming ( 腦力激盪 )Shared whiteboarding ( 白板討論 )
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NetworksShared applications software
Setting priorities ( 優先次序 )Electronic conferencing ( 電子會議 )Electronic forms ( 書表 )
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NetworksHome network – small LAN in the home
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NetworksHome network technologies
WiredWirelessHome phoneline networking (HomePNA or HPNA) – uses existing telephone lines to create the networkHomePlug – uses electrical lines to connect computers in the network
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NetworksHome network decisions
How many computers? Where will they be placed?How much do you want to spend ( 花費 )?What is your networking expertise ( 專業 )?Do you expect ( 預期 ) the network to grow?What applications ( 應用程式 ) do you want to run?
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NetworksSteps to installing ( 安裝 ) a home network
Install network interface cardsSet up communication hardwareLink PCs to router/hub/switchSet up network softwareIdentify files/printers to be sharedSet up Internet connection sharing
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Computers Chapter 6 – Networks and Networking
Lesson Summary• Apply the concept of connectivity to
your life• Understand data communications
hardware• Identify data transmission services• Understand the various network
topologies• Recognize the potential of home
networking
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