Communication equipment, communication network system and communication method

The invention provides a communication network system under multilayer NAT environment including a common network and at least one private network. The private network accesses to the common network or other private networks through an address conversion unit. The communication apparatus of the communication network system includes a top-level communication apparatus accessing to the common network and a basic communication apparatus accessing to the private network. The communication apparatus records the user entry information of each system terminal apparatus. The user entry information at least includes a user mark, a user entry point of the system terminal apparatus used by the user in the network accessed by the communication apparatus and a system terminal apparatus access point of the system terminal apparatus used by the user in the network accessed by the communication apparatus. The invention further provides corresponding communication method and communication apparatus. The invention is able to prevent the communication data between users from passing through the common network route, thereby improving the service quality of network application and reducing the pressure to the common network.