數據通訊

課程架構

  1. Overview概述
  2. Physical Layer實體層
  3. Data-Link Layer資料鏈結層
  4. Network Layer網路層
  5. Transport Layer傳輸層
  6. Application Layer應用層
  7. Topics Related to All Layers與各層次有關的主題

數據通訊與網路(第五版)專有名詞註記

Chapter1 Introduction

sec1.1 DATA COMMUNICATIONS

  • data 數據：information presented in whatever form is agreed upon by the parties creating and using the data 指由一群人同意產生並使用之任何形式的資訊
  • data communication 數據通訊： the exchange of data between two devices via some form of transmission medium such as a wire cable 兩台設備間透過某種型式的傳輸媒介(如纜線)做數據交換
  • types of data exchanged 數據交換的形式
  • criteria [kraɪˋtɪrɪə] 標準，準則
  • topology 拓撲：湊出來的形狀(不確定)
  • network topologies 網路拓撲：The topology of a network is the geometric representation of the relationship of all the links and linking devices (usually called nodes) to one another. 網路的拓撲是所有的鏈結與設備(通常稱為節點)間的關係之幾何圖形的表現。
  • Local Area Network, LAN 區域網路
  • Wide Area Network, WAN 廣域網路
  • inter- 外部、互
  • intra- 內部
  • internetwork、internet 互連網
  • Internet 網際網路：the largest internet(互連網) in the world
  • telecommunication 電信：includes telephony, telegraph, and television, means communication at a distance 涵蓋電話、電報及電視，其意義為遠方通訊 (tele- is Greek for “far” tele是希臘文，意為遠方)
  • real-time 即時
  • a data communications system 數據通訊系統

效能有四項基本特性

  1. delivery 傳遞：The system must deliver data to the correct destination. 系統必須傳遞數據到正確的目的地。
  2. accuracy 正確：The system must deliver the data accurately. 系統必須正確地傳遞數據。
  3. timeliness[ˋtaɪmlɪnɪs] 即時：The system must deliver data in a timely manner. 系統必須適時傳遞數據。
  4. jitter[ˋdʒɪtɚ] 劇跳：refers to the variation in the packet arrival time 指封包抵達的時間變化

五個構成元件

  1. message 訊息：the information (data) to be communicated 互通的資訊(數據)
  2. sender 傳送者：the device that sends the data message 傳送數據訊息的設備
  3. receiver 接收者：the device that receives the data message 接收數據訊息的設備
  4. transmission medium 傳輸媒介：the physical path by which a message travels from sender to receiver 一條由傳送者到接收者間訊息所經過的實體路徑 EX.twisted-pair wire 雙絞線、coaxial cable 同軸纜線、fiber-optic cable 光纖、radio waves 無線電波
  5. protocol 協定： is a set of rules that govern data communications. 是一組管理數據通訊的準則。 It represents an agreement between the communicating devices. 它代表兩通訊設備間的協議。
  • forms of data representation 數據表示的形式
  1. text 文字：is represented as a bit pattern, a sequence of bits (0s or 1s) 以位元型樣(一系列的0或1)表示 Different sets of bit patterns have been designed to represent text symbols. 位元型樣的不同集合被設計來表示文字符號。Each set is called a code. 每組集合稱為代碼。The process of representing symbols is called coding. 表示符號的過程稱為編碼。
  2. numbers 數字：Numbers are also represented by bit patterns. 也是以位元型樣(一系列的0或1)表示。 The number is directly converted to a binary number to simplify mathematical operations. 直接將數字轉換成二進位表示以簡化數學運算。
  3. images 影像：Images are also represented by bit patterns. 也是以位元型樣(一系列的0或1)表示。An image is composed of a matrix of pixels (picture elements), where each pixel is a small dot. 影像由矩陣的像素(圖像元素)構成，每一個像素是一個小點。The size of the pixel depends on the resolution. 像素的大小取決於所謂的解析度。Each pixel is assigned a bit pattern. 每個像素會被指定一個位元型樣。 The size and the value of the pattern depend on the color of image. 型樣的大小和值與影像色彩有關。
  4. audio 音訊：Audio refers to the recording or broadcasting of sound or music. 指聲音或音樂的錄製或廣播。Audio is continuous, not discrete.
  5. video 視訊：Video refers to the recording or broadcasting of a picture or movie. 指圖像或電影的錄製或廣播。Video can either be produced as a continuous entity (e.g., by a TV camera), or it can be a combination of images, each a discrete entity, arranged to convey the idea of motion. 可以是連續實體(ex.透過攝影機)，或離散實體影像的組合，經安排後以動作的概念傳達出來。
  • Unicode：today, the prevalent coding system 目前流行的編碼系統 Unicode, which uses 32 bits to represent a symbol or character used in any language in the world. 以32個位元來表示全世界使用的各種文字或符號。ASCII constitutes the first 127 characters in Unicode and is also referred to as Basic Latin. Unicode的前127個字元是由ASCII所構成，且Unicode的前127個字元俗稱基本拉丁。
  • American Standard Code for Information Interchange (ASCII) 美國標準資訊交換碼
  • RGB 色光三原色：red 紅色、green 綠色、blue 藍色
  • YCM(YCMK) 物體三原色：yellow 黃色、cyan 青藍色、magenta 洋紅色，YCM三色混合，雖然可以得到黑色，但這種黑色並不 是純黑，所以印刷時要另加黑色（Black），稱YCMK。
  • Data Flow 資料流
  1. Simplex[ˋsɪmplɛks] 單工：單向傳輸
  2. Half-duplex[ˋdjuplɛks] 半雙工：一次只能傳送一個方向，但雙向均支援 EX. Walkie-talkie[ˋwɔkɪˋtɔkɪ] 手提無線電話機、 CB (citizens band) radios 民用波段(CB)電台的無線電波
  3. Full-duplex 全雙工：雙向可同時傳輸 EX. telephone network 電話網路

sec1.2 NETWORKS

  • network 網路：the interconnection of a set of devices capable of communication 一套具有通訊能力的設備之間的互連 ps.設備可指"host 主機(end system 終端系統)"、"connecting device 連線設備"
  • host 主機 = end system 終端系統：large computer 大型電腦、 desktop 桌上型電腦、 laptop 筆記型電腦、 workstation 工作站、 cellular [ˋsɛljʊlɚ] phone 行動電話、 security system 安全系統
  • connecting device 連接設備、互連設備：router 路由器(connects the network to other networks 網路間互連)、switch 交換器(connects devices together 設備互連)、modem 數據機, modulator-demodulator 調變器-解調器(changes the form of data 改變數據形式)
  • breach [britʃ] n.（對法律等的）破壞，違反；（對他人權利的）侵害[C][U]
  • Network Criteria 網路效益評估準則：
  1. Performance 效能：throughput 傳輸量、 delay 延遲
  2. Reliability 可靠度： the frequency of failure 失敗的頻率、 the time it takes a link to recover from a failure 網路鏈結從失敗中恢復所需的時間、 the network’s robustness[roˋbʌstnɪs] in a catastrophe[kəˋtæstrəfɪ] 大災難中網路的堅實程度
  3. Security 安全：protecting data from unauthorized access 保護數據免於未授權的存取、 protecting data from damage and development 保護數據免於受損與變化、 implementing policies and procedures for recovery from breaches and data losses 自受破壞和數據遺失中恢復的實施政策與程序
  • Physical Structures 實體結構：define some network attributes[əˋtrɪbjʊt] 定義一些網路屬性
  1. Type of Connection 連線的型式：point-to-point connection 點對點連線、multipoint / multidrop connection 多點連線
  2. Physical Topology 實體拓撲：Mesh Topology 網狀拓撲、Star Topology 星狀拓撲、Bus Topology 匯流排拓撲、Ring Topology 環狀拓撲
  • point-to-point connection 點對點連線：provides a dedicated link between two devices 提供一條兩點間的專線
  • multipoint / multidrop connection 多點連線：one in which more than two specific devices share a single link 由兩個以上特定設備所分享的單一條鏈結
  • share 分享：spatially shared 空間分享(several devices can use the link simultaneously 多台設備能同時使用鏈結)、timeshared 時間分享(users must take turns 使用者必須輪流)
  • Physical Topology 實體拓撲：refers to the way in which a network is laid out physically. 指網路建置的實體架構。Two or more devices connect to a link; two or more links form a topology. 兩台以上的設備建立一條鏈結，兩條以上的鏈結形成拓撲。
  • Mesh Topology 網狀拓撲：Every device has a dedicated point-to-point link to every other device. 每一台設備都有一條專用(點對點連線)的鏈結連至其他設備。ex. the connection of telephone regional offices 電話區域交換局間的連線
  • Star Topology 星狀拓撲：Each device has a dedicated point-to-point link only to a central controller, usually called a hub. 每部設備都有一條專用(點對點連線)的鏈結只連接到中央控制器，俗稱集線器。ex. High-speed LANs 高速區域網路
  • Bus Topology 匯流排拓撲：The preceding examples all describe point-to-point connections. A bus topology, on the other hand, is multipoint. 匯流排拓撲是多點連線(共享的鏈結)。優點：容易安裝。缺點：不容易找到障礙點及重新連線、不易增加新設備、分接頭處的訊號反射可能降低品質、匯流排上任一點斷線或故障將癱瘓所有傳輸。ex. 傳統乙太網路的區域網路
  • Ring Topology 環狀拓撲：Each device has a dedicated point-to-point connection with only the two devices on either side of it. 每一台設備都有與兩邊設備的點對點專線。優點：容易安裝與重新配置、要增加或減少設備只需牽動兩個接點、隔離故障點很簡單。缺點：unidirectional traffic 單向的訊務流(環上某處的中斷(如關閉某節點(即裝置))就足以停止整個網路)
  • Drop line 支線
  • Tap 分接頭
  • Repeater 增益器：When a device receives a signal intended for another device, its repeater regenerates the bits and passes them along. 將位元訊號再生並往下傳送
  • Token Ring 記號環

sec1.3 NETWORK TYPES

  • internetwork 互連網：a network of networks 網路中的網路
  • Local Area Network, LAN 區域網路： usually privately owned 通常是私人擁有 connects some hosts in a single office, building, or campus 其連結的主機範圍可能位處單一間辦公室、一棟建築或一個園區 Each host in a LAN has an identifier, an address, that uniquely defines the host in the LAN. 區域網路上的每台主機都有識別碼和位址以定義此主機在LAN中的唯一性。
  • Wide Area Network, WAN 廣域網路：不同於LAN受限於規模，WAN可延伸到一個城鎮、一個州、一個國家，甚至是全世界。LAN連接主機、WAN連接互連設備(EX.交換器、路由器、數據機)。A WAN is normally created and run by communication companies and leased by an organization that uses it. WAN通常是由電信公司所建立，並租賃給機構使用。
  • lease[lis] v.租