横向兼容 meaning in Chinese

transverse compatibility

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之所以具有强大的生命力和广泛的适应性,主要有两个原因:提供统一标准的光接口和电接口,使不同厂家设备实现横向兼容;采用同步复用方式和灵活的映射结构,以基本传输模块stm - 1为桥梁,与原有的pdh信号实现纵向的前向兼容,与atm 、 fddi等数字体制实现后向兼容。