1. A method for transferring subscriber location information in a network communication system, comprising: determining, by a network access device, the subscriber location information when a subscriber accesses the network, wherein the subscriber location information comprises an identifier of the network access device, a slot number of the subscriber interface board, and a port number of a port of the subscriber interface board in the network access device; converting, by the network access device, the subscriber location information into a code in an encoding format of a content of a field in a packet sent from the subscriber; replacing, by the network access device, the content of the field in the packet with the subscriber location information code, and transferring the packet in the network communication system, wherein said subscriber location information code comprises: one or more indexes of broadband access device number, device frame number, slot number, and port number that are required to identify the subscriber location information; an index of MAC address of the subscriber terminal; an index of subscriber type of the subscriber terminal; and one or more indexes of priority and protocol encapsulation mode that describe subscriber characteristics.