Home agent discovery upon changing the mobility management scheme

Abstract

The invention relates to a method for discovering a home agent serving a mobile node upon the mobile node changing its mobility management scheme in a packet-switched network and the implementation of such method in a mobile node or home agent. In order to propose a home agent discover scheme that maintains session continuity in a seamless manner upon a mobile node changing its mobility management scheme, a mobile node comprises information on its location prior to changing the mobility management scheme to one of the first signaling messages transmitted upon changing the mobility management scheme (home agent discovery message). The receiving node uses this information to identify the home agent serving the mobile node or to provide a hint to the home agent where the mobile node is registered in a response message to the mobile node. This approach may also be used for path optimization when a mobile node moves from a trusted to an un-trusted access network.

1 - 32 . (canceled) 
     
     
         33 . A method for discovering a home agent serving a mobile node prior to the mobile node changing its mobility management scheme from a network-based mobility scheme to a client-based mobility scheme, or vice versa, in a packet-switched network, the method being performed by the mobile terminal and comprising:
 transmitting a home agent discovery message to a home agent discovery server, wherein the home agent discovery message comprises information on the mobile node's location prior to changing its mobility management scheme from the network-based mobility scheme to the client-based mobility scheme, or vice versa,   receiving from the home agent discovery server a response message comprising information helping the mobile node to discover the home agent serving the mobile node, and   transmitting another home agent discovery message to a home agent based on the information comprised in the response message received from the home agent discovery server,   wherein the method is performed by the mobile node in response to the mobile node changing its mobility management scheme upon handover from a domain supporting the network-based mobility scheme to a domain supporting the client-based mobility scheme, or vice versa.   
     
     
         34 . The method according to  claim 33 , wherein the home agent discovery server is a home agent, a DHCP server or an Evolved Packed Data Gateway of a 3GPP-based mobile communication system. 
     
     
         35 . The method according to  claim 33 , wherein the mobile node uses an anycast address or a multicast address or a unicast address as the destination address of the home agent discovery message transmitted to the home agent discovery server. 
     
     
         36 . The method according to  claim 34 , wherein the mobile node uses an anycast address or a multicast address or a unicast address as the destination address of the home agent discovery message transmitted to the home agent discovery server. 
     
     
         37 . The method according to  claim 33 , further comprising determining at the home agent discovery server the information to be comprised in the response message based on the location information provided by the mobile node in its home agent discovery message. 
     
     
         38 . The method according to  claim 34 , further comprising determining at the home agent discovery server the information to be comprised in the response message based on the location information provided by the mobile node in its home agent discovery message. 
     
     
         39 . The method according to  claim 33 , further comprising deriving by the mobile node the destination address for the home agent discovery message from the information comprised in the response message received from the home agent discovery server. 
     
     
         40 . The method according to  claims 39 , wherein the information comprised in the response message is redirection information indicating an anycast group address, multicast group address or a unicast address of the home agent. 
     
     
         41 . The method according to  claim 40 , wherein the anycast group address or the unicast address of the home agent is an address of temporary validity and/or is configured for use by the mobile node or a group of mobile nodes only. 
     
     
         42 . The method according to  claim 39 , wherein the mobile node uses the address provided in the response message as the destination address for the home agent discovery message transmitted to the home agent. 
     
     
         43 . The method according to  claim 40 , wherein the mobile node uses the address provided in the response message as the destination address for the home agent discovery message transmitted to the home agent. 
     
     
         44 . The method according to  claim 33 , wherein the home agent discovery message transmitted to the home agent comprises infoniiation on the mobile node's location at initial attach. 
     
     
         45 . The method according to  claim 34 , wherein the home agent discovery message transmitted to the home agent comprises information on the mobile node's location at initial attach. 
     
     
         46 . The method according to  claim 33 , further comprising transmitting by the home agent having received a home agent discovery message a response message comprising information helping the mobile node to discover the home agent serving the mobile node or indicating that the other mobile node is the home agent serving the mobile node. 
     
     
         47 . The method according to  claim 33 , further comprising the step repeating the transmission of a home agent discovery message to other home agents until a home agent indicates in a response message to be the home agent serving the mobile node. 
     
     
         48 . The method according to  claim 33 , wherein either one or all of the home agent discovery messages transmitted by the mobile node comprise a temporary identifier of the mobile node, where the mapping of the temporary identifier to a corresponding non-temporary identifier of the mobile node is only known to home agent and mobile node. 
     
     
         49 . The method according to  claim 47 , further comprising searching a binding cache entry of the mobile node by the home agent receiving a home agent discovery message using the temporary or non-temporary identifier of the mobile node. 
     
     
         50 . The method according to  claim 47 , wherein a home agent having received a home agent discovery message responds to the home agent discovery message by transmitting a response message including information helping the mobile node to discover the home agent serving the mobile node, if there is no binding cache entry for the mobile node in the binding cache of the home agent. 
     
     
         51 . The method according to  claim 48 , wherein a home agent having received a home agent discovery message responds to the home agent discovery message by transmitting a response message including information helping the mobile node to discover the home agent serving the mobile node, if there is no binding cache entry for the mobile node in the binding cache of the home agent. 
     
     
         52 . The method according to  claim 33 , wherein the home agent discovery server is located in a domain in which a client-based mobility management scheme is used and the home agent is located in a domain providing a network-based mobility management scheme. 
     
     
         53 . The method according to  claim 33 , wherein the home agent discovery messages and the response messages thereto are messages of an authentication procedure for authenticating the mobile node. 
     
     
         54 . The method according to  claim 34 , wherein the home agent discovery messages and the response messages thereto are messages of an authentication procedure for authenticating the mobile node. 
     
     
         55 . The method according to  claim 53 , wherein the authentication procedure is restarted based on the information comprised in a response message to a home agent discovery message, if the information comprised in the response message is information helping the mobile node to discover another home agent. 
     
     
         56 . The method according to  claim 54 , wherein the authentication procedure is restarted based on the information comprised in a response message to a home agent discovery message, if the information comprised in the response message is information helping the mobile node to discover another home agent. 
     
     
         57 . A mobile node for discovering a home agent serving the mobile node prior to the mobile node changing its mobility management scheme from a network-based mobility scheme to a client-based mobility scheme, or vice versa, in a packet-switched network, the mobile node comprising:
 a transmitter for transmitting a home agent discovery message to a home agent discovery server, wherein the home agent discovery message comprises information on the mobile node's location prior to changing the mobility management scheme from the network-based mobility scheme to the client-based mobility scheme, or vice versa, and   a receiver for receiving from the home agent discovery server a response message comprising information helping the mobile node to discover the home agent serving the mobile node,   wherein the transmitter is configured to transmit another home agent discovery message to a home agent based on the information comprised in the response message received from the home agent discovery server,   wherein the mobile node is configured to change the mobility management scheme upon handover from a domain supporting the network-based mobility scheme to a domain supporting the client-based mobility scheme, or vice versa.   
     
     
         58 . The mobile node according to  claim 57 , further comprising a processing unit for deriving by the mobile node the destination address for the home agent discovery message from the information comprised in the response message received from the home agent discovery server. 
     
     
         59 . The mobile node according to  claim 58 , wherein the mobile node is configured to use the address provided in the response message as the destination address for the home agent discovery message transmitted to the home agent by its transmitter. 
     
     
         60 . The mobile node according to  claim 57 , further comprising a processing unit for determining information related to the location of the mobile node and for storing the location information in a storage comprised by the mobile node. 
     
     
         61 . A home agent for use in a packet-switched network, the home agent comprising:
 a receiver for receiving a home agent discovery message from a mobile node, wherein the home agent discovery message comprises information on the mobile node's location prior to changing the mobility management scheme from a network-based mobility scheme to a client-based mobility scheme, or vice versa,   a binding cache for maintaining bindings of plural mobile nodes served by the home agent,   a processing unit for determining whether a binding cache entry exists for the mobile node from which the home agent discovery message has been received,   wherein the processing unit is configured to determine, based on the location information comprised in the home agent discovery message, information helping the mobile node to discover the home agent serving the mobile node, if no binding cache entry exists for the mobile node and to cause a transmitter of the home agent to transmit a response message comprising the information helping the mobile node to discover the home agent serving the mobile node to the mobile node from which the home agent discovery message has been received.