IP communications involves the transmission of information in packets on an as-needed basis.The route a packet of information follows can and does change throughout the transaction,unlike the fixed path of a circuit.

• IP通信发展到按需求以包的形式进行信息传输，与电路（交换）中固定通道不一样，在一次交易中信息包经过的路由是可以并一定是改变的。