【導(dǎo)讀】通信管道對于每一個通信系統(tǒng)來說是一個至關(guān)重要的元素。這些管道實際上把數(shù)據(jù)從一。臺計算機傳輸?shù)搅硪慌_。一類是有線，另一類是無線。物理連接使用固體介質(zhì)連接、發(fā)送和接收設(shè)備。你所看到的電話線，是由上百根銅線纏繞而成的雙絞線。當然也可以插在手機和電腦上。電話線作為一個標準傳輸媒介，多年一來一直在負責語音和。然而,他們現(xiàn)在已經(jīng)被更先進、可靠的媒體所淘汰了。在傳輸能力方面,一個同軸電纜是雙絞線傳輸容量的80倍。軸電纜先主要用于提供電視信號以及連接網(wǎng)絡(luò)的電腦..光纖電纜傳輸數(shù)據(jù)是由光脈沖在細小的玻璃導(dǎo)管內(nèi)進行的。光纖電纜的傳輸速度已經(jīng)超過雙絞線26000倍。與同軸電纜相比,光纖更輕，傳輸更快。迅速取代電纜電話線路。紅外技術(shù)使用紅外光波在短距離通信。它有時被稱為視距通信，因為光只能沿直線傳播。這就要求發(fā)送和接收設(shè)備必須沒有任何障礙物阻止。一個便攜式設(shè)備，如筆記本電腦或掌上電腦桌面計算機上傳輸數(shù)據(jù)。

　　

【正文】 聯(lián)網(wǎng)上單獨發(fā)送 ,可能旅行不同的路線到一個共同的目標。在接收端 ,包成正確的順序重新組裝。 NETWORK ARCHITECTURE Network architecture describes how a work is arranged and how resources are coordinated and enpasses a variety of different work specifics, including work configurations and configurations describe the physical arrangement of the work. Network strategies define how information and resources are shared. 網(wǎng)絡(luò)體系結(jié)構(gòu)描述了一個網(wǎng) 絡(luò)安排和資源協(xié)調(diào)和共享。它包含了各種不同的網(wǎng)絡(luò)細節(jié) ,包括網(wǎng)絡(luò)配置和策略。網(wǎng)絡(luò)配置描述物理安排網(wǎng)絡(luò)。網(wǎng)絡(luò)策略定義信息和資源共享。 CONFIGURATIONS A work can be arranged or configured in several different ways. This arrangement is called the work39。s four principal work topologies are star, bus, ring, and hierarchical. 一個網(wǎng)絡(luò)可以安排或配置在 幾種不同的方式。這樣的安排被稱為網(wǎng)絡(luò)的拓撲結(jié)構(gòu)。四項主要的網(wǎng)絡(luò)拓撲是明星 ,巴士 ,戒指 ,和層次。 In a star work, a number of small puters or peripheral devices are linked to a central unit.(See Figure 918.) The central unit is the work hub and is typically a host puter or file server. 在一個星形網(wǎng)絡(luò) ,一些小型計算機或外圍設(shè)備被連接到一個中央單位。 中央單位是網(wǎng)絡(luò)中心 ,通常是一個主機或文件服務(wù)器。 All munications pass through this central unit. Control is maintained by polling. That is, each connecting device is asked (polled) whether it has a message to send. Each device is then in turn allowed to send its message 所有通信通過這個中央單位 。控制是由輪詢。即 ,每個連接裝置 是問 (“調(diào)查 ”)是否有一個消息發(fā)送。每個裝置 ,然后反過來允許發(fā)送的信息 One particular advantage of the star topology is that it can be used to support a timesharing system. That is,several users can share resources (time) on a central puter. The star is a mon topology for linking microputers to a mainframe that allows access to an anization39。s database. 一個特定的優(yōu)勢是 ,它星型 拓樸結(jié)構(gòu)可以用于支持分時系統(tǒng)。那是 ,幾個用戶可以共享資源(時間 )在一個中央計算機。星是一種常見的拓撲結(jié)構(gòu)為連接微機到主機 ,允許訪問一個組織的數(shù)據(jù)庫。 In a bus work each device in the work handles its own munications control. There is no host puter. All munications travel along a mon connecting cable called a bus or backbone. (See Figure 919.) As the information formation is intended for it. 在總線網(wǎng)絡(luò)每個設(shè)備在網(wǎng)絡(luò) 中處理它自己的通信控制。沒有主機。所有通信沿著一個共同的連接電纜稱為總線或骨干。隨著信息形成適用于它。 The bus work is typically used when only a few microputers are to be linked arrangement is mon for sharing data stored on different microputers. Because a star work typically provides a more direct path to shared resources,it is more efficient than a bus work for sharing these , a bus work is easy to install and is less expensive. 總線網(wǎng)絡(luò)通常用在當只有很 少的微機都聯(lián)系到一起。這樣的安排是常見的共享數(shù)據(jù)存儲在不同的微型計算機。因為一個星形網(wǎng)絡(luò)通常提供了一個更直接的路徑共享資源 ,它是更有效的比一個總線網(wǎng)絡(luò)共享這些資源。然而 ,一個總線網(wǎng)絡(luò)易于安裝和不昂貴的。 In a ring work, each device is connected to two other devices, forming a ring.(See Figure 920.) There is no central file server or puter. Messages are passed around the ring until they reach the correct destination. With microputers, the ring arrangement is the least frequently used of the four works. However, it often is used to link mainframes, especially over wide geographical areas. These mainframes tend to operate fairly autonomously. They perform most or all of their own processing and only occasionally share data and programs with other mainframes. 在一個環(huán)網(wǎng)絡(luò) ,每個設(shè)備被連接到其他兩個設(shè)備 ,形成一個環(huán)。 沒有中央文件服務(wù)器或計算機。消息被傳遞在環(huán)直到他們到達正確的目的地。用微型計算機 ,戒指的安排是最常用的四種網(wǎng)絡(luò)。然而 ,它通常是用來連接主機 ,尤其是在廣泛的地理區(qū)域。這些大型機往往相當獨立地運作。他們表演的大多數(shù)或所有他們自己處理 ,只有偶爾分享數(shù)據(jù)和程序與其他主機。 A ring work is useful in a decentralized anization because it makes possible a distributed data processing system. That is,puters can perform processing tasks at their own dispersed locations,However, they also can share programs, data,and other resources with each other. 一個環(huán)網(wǎng)絡(luò)是有用的在一個 分散的組織 ,因為它使可能的分布式數(shù)據(jù)處理系統(tǒng) 。那是 ,電腦可以執(zhí)行處理任務(wù)在自己的分散的位置 ,然而 ,他們也可以共享程序、數(shù)據(jù)和其他資源 ,與對方。 The hierarchical work consists of several puters linked to a central host puter, just like a star work. However, these other puters are also hosts to other, smaller puters or to peripheral devices. (See Figure 921.) 層次網(wǎng)絡(luò)由多個計算機連接 到一個中央主機電腦 ,就像一個星形網(wǎng)絡(luò)。然而 ,這些其他的電腦也主機 ,其它的小電腦或外圍設(shè)備。 Thus, the host at the top of the hierarchy could be a mainframe. The puters below the mainframe could be miniputers, and those below, microputers. The hierarc hical work allows various puters to share databases, processing power, and different output devices. 因此 ,主持人最高等級的可 以是一個主機。下面的電腦主機可以小型機 ,下面 ,微型計算機。層次網(wǎng)絡(luò)允許各種電腦共享數(shù)據(jù)庫、處理能力和不同輸出設(shè)備。 A hierarchical work is useful in centralized anizations. For example,different departments within an anization may have individual microputers connected to departmental miniputers. The miniputers in turn may be connected to the corporation39。s mainframe, which contains data and programs accessible to all. 一個層次網(wǎng)絡(luò)是有用的在 集中組織。例如 ,不同的部門在一個組織中可能存在個人微型計算機連接到部門的小型計算機。小型機的反過來又可以連接到公司的主機 ,它包含數(shù)據(jù)和程序都可接受。 For a summary of the work configurations, see Figure 922. 對于一個總結(jié)的網(wǎng)絡(luò)配置 ,見圖 922。