Mobile node, mobile agent and network system

A communication method by a mobile terminal moving between networks, comprising the steps of:

• receiving a first IPv4 message from a second movement assistance apparatus, when said mobile terminal has moved from a first network executing communications by using at least an IPv6 to said second network executing communications by using an IPv4;
• detecting that said mobile terminal has moved to said second network from said first network, based on information included in said first IPv4 message;
• acquiring a first IPv4 address on said second network;
• and
• transmitting a second IPv4 message for requesting registration of said first IPv4 address to a first movement assistance apparatus connected to said first network.

A communication method executed by a mobile terminal moving between networks, comprising the steps of:

• receiving a first message on a second network, when said mobile terminal has moved from a first network executing communications by using at least an IPv6 to said second network;
• detecting that said mobile terminal has moved to said second network from said first network, based on information included in said first message;
• acquiring a first IP address to be used on said second network;
• creating a first IPv6 message for requesting registration of said first IP address to a first movement assistance apparatus connected to said first network;
• creating a second message by capsulizing said first IPv6 message into a first IPv4 message, if said second network executes communications by said IPv4;
• and
• transmitting said second message to said first movement assistance apparatus.

A communication method executed by a mobile terminal moving between networks, comprising the steps of:

• receiving a message on a second network, when said mobile terminal has moved from a first network executing communications by using at least an IPv6 to said second network;
• detecting that said mobile terminal has moved to said second network from said first network, based on information included in said message;
• acquiring an IPv6 address to be used on said second network, if said second network executes communications by using said IPv6;
• creating an IPv6 message for requesting registration of said IPv6 address to a movement assistance apparatus connected to said first network;
• and
• transmitting said IPv6 message to said movement assistance apparatus.

An address registration method by a mobile terminal existing on a first network executing communications by using at least an IPv6, said mobile terminal executing communications by using said IPv6 and an IPv4, comprising the steps of:

• receiving a first message from an arbitrary apparatus connected to a second network, when said mobile terminal has moved from said first network to said second network;
• detecting that said mobile terminal has moved to said second network from said first network, based on information included in said first message;
• acquiring an IP address on said second network;
• creating a first IPv6 message for requesting registration of said IP address to a movement assistance apparatus connected to said first network and holding movement information of said mobile terminal;
• creating a second message by capsulizing said first IPv6 message into a first IPv4 message including an IPv4 address of said movement assistance apparatus as a destination address, when said second network executes communications by using said IPv4;
• and
• transmitting said second message.

An address registration method by a mobile terminal existing on a first network executing communications by using at least an IPv6, said mobile terminal being movable to another network, comprising the steps of:

• receiving a first IPv4 message from an arbitrary apparatus connected to a second network, when said mobile terminal has moved from said first network to said second network executing communications by using an IPv4;
• detecting that said mobile terminal has moved to said second network from said first network, based on information included in said first IPv4 message;
• acquiring an IPv4 address to be used on said second network;
• creating an IPv6 message for requesting registration of said IPv4 address to a movement assistance apparatus connected to said first network and holding movement information of said mobile terminal;
• creating an IPv4 message by capsulizing said IPv6 message into an IPv4 message including an IPv4 address of said movement assistance apparatus as a destination address;
• and
• transmitting said IPv4 message.