The Research Of Mobile IPv4 Dynamic HA

We have analysed the limitations which would occur under the mobile node(MN)using the static HA(home agent) mode by studying the theory and work procedure of mobile IPv4. So we present the dynamic HA theory which allow the MN changing it' s home agent address and getting other optimum home agent by some methods to improve the problems including too long registration signal time, unsuitable for large scale application and inconsequently network resource used. And we also aim at the key technique of the dynamic HA implemention to study the settlement of each key technique. The key technique include that where the information of a new HA of MN come form? How dynamically allocation a HA to a MN? How distribute the session key to each entity of mobile IP in the dynamic HA mode. And how to resolve handoff problem of HA and the variety home address of MN.As to the problem where a MN can get information of a new HA, we add the new extention —-The Dynamic HA address Extension in the initial registration message to contain the information comes from the dynamic HA allocation message exchanging or re-directed HA exchanging .So that the MN can read information of new HA from the new extention and change it' s HA based the information it got. The theory could help to improve the transmission speed and also achieve load balancing among a group of HAs .To the Requested HA allocation and Key distribution problem,we introduce the AAA servers(using Diameter protocol)in the home network of the MN and foreign networks and make the HAs and FAs as the Diameter clients. In the same time, we extend the Diameter protocol by adding new Diameter Commands and AVPs to support the mobile IPv4 dymaic HA and extend the regeistration meaages by add some useful extentions to contain the address of Requested HA and the key which are assigned by AAA servers. If the MN could accept a MA in the foreign network as it' s HA, the AAAF would assign one in the foreign network to it. If the MN could only accept the MA in it' s home network , the AAAH would assign one in the home network to it. But the messageauthentication keys could only be created and distributed by the AAAH which is the only one trusting entity of the MN. If the AAAH learn that the three entities in th mobile IP require message authentication keys between each other, it would creat two nonces and three keys, and send back to the three entities in the HAR and registration reply message.To the HA handoff problem ,we propose a method to send special registration request message to the old home agent which is adding the address of the new home agent instead of the true care-of address of the MN into the care-of address zone of the registration request message when the MN realized that the address of home agent has changed.By doing so, the old home agent could redirect the data sent to the old home address of the MN to the new agent .To the variety of the home address of a MN problem,we use the NAI instead of the home address of a MN to uniquely identified the MN and introdure the dynamic DNS to shield the home address of the MN which is easily to be achieved without any additional requriement on the CNs.