Patent ID: 7447183

Claim:
A Home Agent, comprising: a processor; and a memory, at least one of the processor or the memory being for: receiving a registration request packet from a mobile node; determining from the registration request packet whether the mobile node needs an IP address; and determining whether the Home Agent has previously assigned an IP address to the mobile node when it is determined that the mobile node needs an IP address; when the Home Agent determines that the Home Agent has previously assigned an IP address to the mobile node, obtaining the IP address previously assigned to the mobile node, composing a registration reply including the IP address previously assigned to the mobile node and sending the registration reply to the mobile node; and when the Home Agent determines that the Home Agent has not previously assigned an IP address to the mobile node, assigning an IP address to the mobile node, composing a registration reply including the IP address and sending the registration reply to the mobile node; wherein the registration request packet further includes an ID indicator, the ID indicator indicating that the mobile node has an IP address when the ID indicator is in a first state, and otherwise indicating that the mobile node does not have an IP address.