通信中交换的要领源于电话交换。从通信资源分配的角度来看，交换就是按照某种方式动态地分配传输线路资源的一种运作。当然，这也是一门技术，称之为交换技术。-Exchange of communication essentials from the telephone exchange. Allocation of resources from the communications point of view, the exchange is in some way in accordance wit