Patent ID: 8693502

Claim:
A method for accessing a Packet Data Serving Node (PDSN), which comprises: a terminal directly accessing a service server to register through a Wireless Fidelity (WIFI) module; said terminal receiving parameter information returned from said service server after registering successfully; said terminal starting a Point-to-Point Protocol (PPP) module that encapsulates a request packet with a PPP header to generate a first data packet wherein said request packet contains information for establishing a PPP link with the PDSN; said terminal starting a TUNNEL module, and according to said parameter information, further encapsulating said first data packet with one layer of TUNNEL header to generate a second data packet, wherein said PPP module and said TUNNEL module communicate through a pair of virtual terminal equipment; an Internet Protocol (IP) protocol stack of said terminal further encapsulating said second data packet with one layer of IP header based on a WIFI link to generate a third data packet, and sending said third data packet to a Wireless Access Gateway (WAG) through said WIFI link; after receiving said third data packet, said WAG analyzing and dropping the IP header and TUNNEL header of said third data packet to recover the first data packet, and sending a recovered first data packet to said PDSN; and after receiving said recovered first data packet, said PDSN carrying out analysis processing, and establishing a link connection between said PDSN and said terminal; wherein after the step of establishing the link connection between said PDSN and said terminal, said method further comprises: said terminal generating a new PPP network interface, said terminal obtaining a local IP address Local-IP allocated by said PDSN; and said terminal setting a routing for the WIFI network interface with the destination address as the WAG-IP, accessing the original default routing of said WIFI network interface, and changing the original default routing of said terminal from the setting of WIFI network interface to that of the PPP network interface, thereby forming a data packet interacting channel of the PPP link based on said WIFI link.