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提起以太网,人们一般都把它和5类线缆联系起来。现在的计算机局域网都采用以太网技术,按照当前流行的方式部署以太网,就意味着先要完成一个庞大的结构化布线工程。由于布线工程技术性较强,因此一般都要请专业的公司来完成,这使成本很高。然而,发展相对成熟的电信业却能提供密集的电话线设施,能使这一突出问题通过另一种途径得以改观。电话线具有价廉(3类线)和布线方便等优势,即使重新布线,成本也很低。这样看来,如果利用现有的电话线实现以太网的部署,真是再好不过了。可是,带宽能满足需求吗? 一般应用以太网,用户终端的数据传输速率至少是10Mbps。由于交换机成本的降低,不少用户终端的速率已经达到100Mbps。其实,10Mbps的速率完全可以满足一般应用的需求。但是,对于社区用户、商业办公楼和宾馆来说,目前的宽带接入方案还不十分理想,这也就是人们常说的“最后一公里”问题。即使是企业网,由于现有的以太网技术要求采用5类或更高级的线缆进行布线,所以对一些特殊场所并不是很适合。例如,一些环境差的制造车间和特殊建筑等都不允许进行大规模布线。针对这些问题,人们把目光集中在长距离以太网解决方案上,这一方案的关键是采用VDSL技术。
Lift the Ethernet, people generally put it and Category 5 cable link. Today’s computer LANs all employ Ethernet technology, deploying Ethernet in the current fashion, which means completing a large structured cabling project first. Due to the strong technical wiring, it is generally necessary to ask a professional company to complete, which makes the cost is high. However, the development of a relatively mature telecommunications industry can provide intensive telephone line facilities that can make this outstanding issue another way. Telephone lines have the advantages of low cost (category 3 line) and easy wiring, the cost is very low, even if re-wiring. In this way, it would be great if Ethernet was deployed using an existing phone line. However, the bandwidth to meet the demand? General application of Ethernet, user terminal data transfer rate of at least 10Mbps. Due to the lower switch costs, many user terminals have reached the rate of 100Mbps. In fact, the rate of 10Mbps fully meet the needs of general applications. However, for the community users, commercial office buildings and hotels, the current broadband access solutions are not yet ideal, which is often referred to as the “last mile” issue. Even for corporate networks, existing Ethernet technologies require Category 5 or higher cabling for routing and are not suitable for some special places. For example, some poor manufacturing plants and special buildings do not allow large-scale wiring. In response to these issues, people focus on long-distance Ethernet solutions, the key to this program is the use of VDSL technology.