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随着计算机通信技术的不断发展,要求租用数据专线的用户与日俱增,对传输速率高、质量可靠的数据信息需求量越来越大。现有通信网的模拟信道已很难满足计算机通信及数据传输的要求。数字数据网(Digital Data Network,简称DDN)正是在这种情况下应运而生,并迅速发展起来。 DDN主要作用是向用户提供专用的数字数据传输信道,为用户建立专用数据网提供条件。DDN可向用户提供图像通信、数字电话通信、数据广播通信、计算机局域网互联、计算机远程通信等多种服务。DDN还可以为公用分组数据交换网(PSPDN)提供用户与
With the continuous development of computer communication technology, the number of subscribers leasing data leased line is increasing day by day, and the demand for data information with high transmission rate and reliable quality is increasing. The existing communication network analog channel has been difficult to meet the requirements of computer communications and data transmission. It is precisely under such circumstances that the Digital Data Network (DDN) came into being and rapidly developed. DDN main role is to provide users with a dedicated digital data transmission channel for users to establish a dedicated data network to provide the conditions. DDN can provide users with image communications, digital telephony, data broadcast communications, computer LAN interconnection, computer remote communications and other services. DDN also provides users and users for the Public Packet Data Network (PSPDN)