【正文】 后 暗示 著線纜長度 限制為 大約 25m。這些項(xiàng)目的成本將隨著帶寬的增加而增加。 由于從纜繩的輻射 ，越來越多的信號(hào) 強(qiáng)度 以高數(shù)據(jù)速率的 形式損耗 。 嚴(yán)格地說正是因?yàn)檫@些高費(fèi)用，于是開發(fā)了非屏蔽雙鉸線 (UTP)以太網(wǎng)。高帶寬或關(guān)鍵比特率應(yīng)用例如 VOIP，視頻流，視頻會(huì)議和計(jì)算機(jī)輔助設(shè)計(jì) (CAD)，正逐漸變得普遍。例如，在 1吉比特速度時(shí)，當(dāng)使用流行的 多模光纖還有約 220米長度的限制。我們現(xiàn)在應(yīng)該做什么，可以保證我們新的網(wǎng)絡(luò)設(shè)施不會(huì)成為未來(或許 一點(diǎn)也不遙遠(yuǎn) )的傳統(tǒng)網(wǎng)絡(luò)。 許多 IT 經(jīng)理感到不太確定應(yīng)該跟隨哪些新的技術(shù)。本標(biāo)準(zhǔn)的目的是指定一個(gè)通用的、能夠支持多產(chǎn)品，多廠商環(huán)境的商業(yè)建筑物電信布線系統(tǒng)。線圈應(yīng)該留待日后安裝在每個(gè)樓層。由于兩 個(gè)分開的組織維護(hù)同一組相同的線纜，這將 分離 作用 并且使混亂減到最小 。因?yàn)槟承└f的大廈座位有限，根據(jù)具體情況必須對(duì)原有房屋進(jìn)行評(píng)估。附件 1 外文資料翻譯譯文： 綜合布線的未來 JHMI(約翰斯霍普金斯醫(yī)學(xué)研究所 )前提的分配計(jì)劃將與由 AT＆ T的前提分配制度和國際標(biāo)準(zhǔn)組織的綜合業(yè)務(wù)數(shù)字網(wǎng)指定的標(biāo)準(zhǔn)相一致。對(duì)于新樓宇，每個(gè)小房間應(yīng)該至少可以容納兩個(gè)標(biāo)準(zhǔn) 19機(jī)架。數(shù)據(jù)線將安裝在適當(dāng)?shù)臋C(jī)架式數(shù)據(jù)硬件（如 3274控制器，以太網(wǎng)橋箱等），而語音線（如可能）則將安裝到機(jī)架式語音硬件。以太網(wǎng)電纜必須有隨時(shí)可用的訪問（即不是在管道運(yùn)行），以確保日后使用。 它還提供了一些可以用來為商業(yè)企業(yè)設(shè)計(jì)通訊產(chǎn)品 的 信息。這部分歸結(jié)于制造商的可觀的營銷炒作。 網(wǎng)絡(luò)的單調(diào)上升 1980年以來的數(shù)據(jù)傳輸速率，當(dāng)網(wǎng)絡(luò)速度被由（ clunkety 彈響電傳打字機(jī)）機(jī)械轉(zhuǎn)速機(jī)制決定時(shí)，網(wǎng)絡(luò)已經(jīng)看到了數(shù)據(jù)傳輸速率的單調(diào)上升。當(dāng)使用 50/125μ m 光纖時(shí)，可以增加至約 500米。不同于建筑物的垂直局域網(wǎng) ,水平網(wǎng)絡(luò)的升級(jí)是非常昂貴。這將允許在建筑物內(nèi)使用現(xiàn)有的、低等級(jí)的 3類電話線纜。 相對(duì)較大的外部串?dāng)_影響著弱信號(hào) ,尤其是在線纜末端附近。 現(xiàn)在已經(jīng)開始開發(fā) 6類線纜，以便解決其中一些問題，但是，目前，還沒有批準(zhǔn)任何標(biāo)準(zhǔn)。 這必將是一個(gè)非常殘酷的限制。擴(kuò)展帶寬多模光纖，已經(jīng)制定了一個(gè)改進(jìn)的折射率分布。通過對(duì)比的方式， PC 機(jī)的壽命約為 2 3年，而以太交換機(jī) 3 5年。如果因?yàn)槟壳暗某杀締栴}，在任何給定的項(xiàng)目并不實(shí)際安裝光纖，但至少，在布線內(nèi)容中應(yīng)該預(yù)留光纖的空間，以適應(yīng)未來的應(yīng)用。它是由預(yù)安裝管道保護(hù)的免受損壞。 外文原文： The Future of Structured Cabling The JHMI Premise Distribution Plan will be consistent with standards specified by the ATamp。s when work speeds were dictated by the rotor speed of mechanical mechanisms (clunketyclunk teletypes), the works have seen a monotonous rise in data rates. The rise has followed Moore39。s properties to fluctuations in increasing loss of signal strength at high data rates due to its radiation from the cable. The relatively large effects of external interference on weak signals, particularly near the ends of the cable. This is especially important where data cables share adjacent cable containment with mains wiring. The increased signal coupling between pairs of conductors in the same cable (crosstalk). This situation is exacerbated at the ends of the cable where it is attached to the hardware. At the connector, relatively high power transmit signals are launched into the cable in very close proximity to the receive signals that have already been attenuated by radiation loss along the cable39。D to be worthwhile. Worst case predictions for category 7 at 10gigabit speeds imply a length restriction of about 25m. This would be a severe limitation. Any improvement will be at the expense of costlier transceivers. In any event, these distance constraints at higher data rates are onerous for UTP cabling. Category 7 then, must be at least a fibre solution? Optical Technology Optical technology, on the other hand, is already advanced. It has been improved by the development of extended bandwidth multimode fibre and by the development of the VCSEL laser. The refractive index profile of ordinary multimode fibre does not follow the ideal parabolic variation across the diameter of the core. These fibres have a small index discontinuity located at the axis of the fibre that prevents paraxial rays from being transmitted efficiently. These are the rays that suffer least dispersion and it is low dispersion that permits higher signalling rates to be used. Extended bandwidth multimode fibres have been developed with an improved refractive index profile. They have increased the distance over which gigabit ether may be transmitted by multimode fibres to about 1km. The VCSEL laser is capable of launching paraxial rays along the centre of an optical fibre and is the ideal plement to the use with extended bandwidth fibre. Traditionally, copper works have been cheaper than their optical counterparts, but as data rates increase, the costs of installing these media will converge. This is likely to happen at rates of about Gbs. The Future Obviously, all predictions about future requirements are fraught with difficulty and we must rely heavily on past experience. Errors of judgement when dealing with the horizontal working are expensive and have long lasting consequences. There is usually only one chance to get it right as the lifetime for horizontal wiring is 10 years or more. By way