Patent ID: 8015603

Claim:
A method for packet transmission in a Mobile Internet Protocol (MIP) network, comprising: sending, by a mobile terminal apparatus to a Home Agent (HA), a first Firewall Detection (FD) packet encapsulated with IP security (IPsec) protocol and a second FD packet encapsulated with IPsec protocol and User Datagram Payload (UDP) protocol; determining whether there is a firewall blocking an IPsec packet between the mobile terminal apparatus and the HA by way of determining whether a Firewall Detection Reply (FDR) packet received from the HA corresponds to the first FD packet encapsulated with the IPsec protocol or the second FD packet encapsulated with the IPsec protocol and the UDP protocol, wherein said determining whether there is a firewall blocking the IPsec packet comprises: determining that there is no firewall blocking the IPsec packet when the FDR packet received corresponds to the first FD packet; and determining that there is the firewall blocking the IPsec packet when the FDR packet received corresponds to the second FD packet; encapsulating packets with the UDP protocol and performing binding update and packet exchange if there is the firewall blocking the IPsec packet; and performing binding update and packet exchange if there is no firewall blocking the IPsec packet.