pdh physical interface 中文意思是什麼
pdh physical interface
解釋
準同步數字系列物理介面-
On physical layer, it consists of a variety of ne ( network elements ) with different functions connected by optical fibre cables. compared with pdh, sdh is more widely used in fibre optical communication system these days. the reasons of the wide applicability of sdh are : first, it provides worldwide standards for electrical interface and optical interface, which can promote multi - vendor interoperability ; second, it has the feature of synchronous multiplexing and flexible mapping mechanism, so it can use stm - 1 signal to bundle atm cells, fddi signals as well as pdh signals
Sdh之所以具有強大的生命力和廣泛的適應性，主要有兩個原因:提供統一標準的光介面和電介面，使不同廠家設備實現橫向兼容;採用同步復用方式和靈活的映射結構，以基本傳輸模塊stm - 1為橋梁，與原有的pdh信號實現縱向的前向兼容，與atm 、 fddi等數字體制實現後向兼容。
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