X.25的用户选用设施是当今国际上标准公用分组数据交换网提供的。大家对X.25的基本格式已比较熟悉,但对X.25的用户选用设施尚了解不多。因此,笔者结合个人的经验与理解,对X.25的用户选用设施加以介绍,希望能给大家一个较为直观的理解,特别是对那些涉及网络运行和管理的因素。 X.25 user-selected facilities are now available on the international standard public packet data exchange network. The basic format of X.25 has been more familiar to everyone, but X.25 users choose to use the facility is still not much. Therefore, the author combined with personal experience and understanding of the X.25 user selection facilities to be introduced, hoping to give you a more intuitive understanding, especially for those involved in network operation and management factors.