When it comes to copper cabling, you’ve probably heard of Category 6 as having a bandwidth of 250 MHz and Category 6A as having a bandwidth of 500 MHz. (The bandwidth is often printed on the cable jacket.)  This creates plenty of confusion since we think of bandwidth on the network as expressed in Mb/s or Gb/s. We are not wrong in that mindset – your Category 6A cable may have an operating bandwidth of 500 MHz, while your network may have a bandwidth of 10 Gb/s.

說到銅纜，你可能聽說過6類的帶寬是250MHz，6類的帶寬是500MHz（帶寬通常打印在電纜護(hù)套上。）這造成了大量的混亂，因?yàn)槲覀冋J(rèn)為網(wǎng)絡(luò)上的帶寬是以Mb/s或Gb/s表示的。我們的想法并沒有錯——您的6A類電纜的工作帶寬可能為500 MHz，而您的網(wǎng)絡(luò)的帶寬可能為10 Gb/s。

So why is category cable bandwidth defined as MHz? Good question. Megahertz is the frequency or rate at which a wave will cycle each second, with 1 hertz equal to 1 cycle per second and 1 MHz equal to 1 million cycles per second. The relationship of speed to frequency is a bit complex, but in simple terms, higher frequencies are needed to carry more bits of data. Each data bit is encoded on a carrier frequency, and the amount of data that can be transmitted per second depends on the signal encoding scheme of the active equipment.

那么，有同學(xué)會問為什么類別電纜帶寬定義為Mhz？這是個好問題。兆赫是波每秒循環(huán)的頻率或速率，1赫茲等于每秒1個循環(huán)，1兆赫等于每秒100萬個循環(huán)。速度與頻率的關(guān)系有點(diǎn)復(fù)雜，但簡單來說，需要更高的頻率來承載更多的數(shù)據(jù)位每個數(shù)據(jù)位在載波頻率上被編碼，并且每秒可以發(fā)送的數(shù)據(jù)量取決于有源設(shè)備的信號編碼方案。

Back in the days of Cat 5, the bandwidth and the data rates were the same – 100 MHz cabling could deliver 100 Mb/s.  But designers of network interfaces have been able to develop encoding schemes such as pulse amplitude modulation (PAM) and DSQ128 to go beyond the simple 1:1 relationship of bandwidth to data rate.  By the time Cat 6 came out, they were able to drive 10 Gbps over a cable with a bandwidth of 250 MHz.  This approach is how NBASE-T is able to get 2.5 and even 5 Gbps out of Cat 5e cable and how your cable provider gets you faster internet speeds without recabling the connection to your house.

早在第5類的時代，帶寬和數(shù)據(jù)速率是一樣的——100兆赫的電纜可以傳輸100兆字節(jié)/秒。但是網(wǎng)絡(luò)接口的設(shè)計(jì)者已經(jīng)能夠開發(fā)編碼方案，如脈沖幅度調(diào)制（PAM）和DSQ128，以超越帶寬與數(shù)據(jù)速率的簡單1:1關(guān)系，到Cat 6問世時，他們已經(jīng)能夠通過一根帶寬為250mhz的電纜驅(qū)動10gbps這種方法是NBASE-T如何能夠從5e類電纜中獲得2.5甚至5 Gbps，以及您的電纜供應(yīng)商如何在不重新布線的情況下，為您提供更快的網(wǎng)速。