网络通讯的七层定义及应用：1實體層 (Physical layer)2、資料鏈結層 (Data link layer)3、網路層 (Network layer)4、傳輸層 (Transport layer)5、會談層 (Session layer)6、展示層 (Presentation layer)7、應用層 (Application layer)-The seven network communication and application of the definition: 1 physi