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An access network is the part of a telecommunications network which connects subscribers to their immediate service provider. It is contrasted with the ''core network'', (for example the Network Switching Subsystem in GSM) which connects local providers to each other. The access network may be further divided between feeder plant or distribution network, and drop plant or edge network. ==Telephone heritage== An access network or outside plant refers to the series of wires, cables and equipment lying between a consumer/business telephone termination point (the point at which a telephone connection reaches the customer) and the local telephone exchange. The local exchange contains banks of automated switching equipment to direct a call or connection to the consumer. The access network is perhaps one of the oldest assets a telecoms operator owns, and is constantly evolving, growing as new customers are connected, and as new services are offered. This makes the access network one of the most complex networks in the world to maintain and keep track of. In 2007–2008 many telecommunication operators experienced increasing problems maintaining the quality of the records which describe the network. In 2006, according to an independent Yankee Group report, globally operators experience profit leakage in excess of €15 Billion each year. The access network is also perhaps the most valuable asset an operator owns, since this is what physically allows them to offer a service. Access networks consist largely of pairs of copper wires, each traveling in a direct path between the exchange and the customer. In some instances, these wires may even be aluminum, the use of which was common in the 1960s and 1970s following a massive increase in the cost of copper. As it happened, the price increase was temporary, but the effect of this decision is still felt today because the aluminum wires oxidize and lose their ability to carry large quantities of data. Access is essential to the future profitability of operators who are experiencing massive reductions in revenue from plain old telephone services, due in part to the opening of historically nationalized companies to competition, and in part to increased use of mobile phones and voice over IP (VoIP) services. Operators offered additional services such as xDSL based broadband and IPTV (Internet Protocol Television) to guarantee profit. The access network is again the main barrier to achieving these profits since operators world wide have accurate records of only 40% to 60% of the network. Without understanding or even knowing the characteristics of these enormous copper spider webs, it is very difficult, and expensive to 'provision' (connect) new customers and assure the data rates required to receive next generation services. Access networks around the world evolved to include more and more optical fiber technology. Optical fibre already makes up the majority of core networks and will start to creep closer and closer to the customer, until a full transition is achieved, delivering value added services over fiber to the home (FTTH). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Access network」の詳細全文を読む スポンサード リンク
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