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Тема |
Re: B-ISDN [re: т] |
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Автор | ni (Нерегистриран) | |
Публикувано | 23.01.03 13:18 |
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Абсолютно вярно.
Broadband integrated services digital network (B-ISDN) is a further development of the narrowband integrated services digital network (N-ISDN) concept. In the early 1980s, it was foreseen that a need would soon arise for services requiring greater bandwidths than those supported by N-ISDN, that is, bandwidths exceeding 2 Mbit/s. A solution to facilitate increased access bandwidth had been sketched out by the mid-1980s. At its core were three fixed-bandwidth high-speed channels, but this was not an ideal solution. The fixed bandwidths (comprising 2 Mbit/s and 140 Mbit/s, for example) would be unsuitable for services that required other capacities. Above all, these fixed-bandwidth channels would not be able to effectively handle services with varying bandwidth requirements. As a result of the introduction of the ATM concept and its apparent bit-rate flexibility, the International Telecommunication Union - Telecommunications Standardization Sector (ITU-T) selected this technique as the basis for B-ISDN services.
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