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有当今的广域网网络建设中,一般采用层次化建网,网络分为传输、交换及接入三层。传输层主要为业务提供可靠的传输,一般只提供简单的交叉连接,而无交换的功能,在传输层的主要设备是SDH;交换层可以建立在传输层之上,指的对数据进行交换,主要设备是ATM交换机、路由器等;而接入层主要完成对具体业务的接入。
There are today’s wide area network construction, the general use of hierarchical network construction, the network is divided into transmission, exchange and access three. Transport layer is mainly to provide reliable services for the transmission, generally only provide a simple cross-connect, without exchange function, the main equipment in the transport layer is SDH; Exchange layer can be established above the transport layer, refers to the data exchange, The main equipment is ATM switches, routers, etc .; and access layer to complete the specific business access.