Patent ID: 7342932

Claim:
A packet transmission system comprising: a home agent providing a home link and a home address to a mobile node; one or more access routers, each providing a foreign link and a c/o address to the mobile node when the mobile node has moved into the corresponding foreign link; and one or more mobility support routers that relay a packet to a destination between the mobile node and the home agent or a counterpart correspondent node wherever the mobile node is located, the mobility support router configured to acquire a first registration request addressed to the home agent and/or the counterpart correspondent node when the mobile node has moved into a first foreign link, store a first entry having the home address of the mobile node and the c/o address contained in the acquired first registration request, and update the first registration request changing the c/o address to its own address to pass the updated first registration request toward the home agent and/or the counterpart correspondent node; wherein each of the one or more mobility support routers processes the first registration request prior to relaying the first registration request (a) in a case when the first registration request contains the address of the mobility support router processing the first registration request, and (b) in a case when the first registration request is not addressed to the mobility support router processing the first registration request.