Prefix and IP address management scheme for router and host in network system

A router for connecting one or a plurality of hosts and Internet through an accessing communication path of a provider, the router comprising:

• a management unit configured to manage one or a plurality of first type prefixes and their valid periods, and one or a plurality of second type prefixes that have shorter valid periods than the first type prefixes and their valid periods, which are allocated from the provider;
• a request unit configured to request allocation of one or a plurality of new second type prefixes to the provider, before all of the second type prefixes managed by the management unit become invalid;
• and
• an advertisement unit configured to advertise periodically the first type prefixes that are still within their valid periods and information regarding the valid periods of the first type prefixes that is to be informed to the hosts, and the second type prefixes that are still within their valid periods and information regarding the valid periods of the second type prefixes that is to be informed to the hosts.

A host for accessing Internet via a router for connecting each host and the Internet through an accessing communication path of a provider, the host comprising:

• a generation unit configured to generate one or a plurality of first type IP addresses and one or a plurality of second type IP addresses, respectively according to first type prefixes and second type prefixes that have shorter valid periods than the first type prefixes, which are advertised from the router in an identical link;
• a management unit configured to manage the first type IP addresses and the second type IP addresses generated by the generation unit, and valid periods of the first type IP addresses and the second type IP addresses that are determined according to latest information regarding valid periods of the first type prefixes from which the first type IP addresses are generated and latest information regarding valid periods of the second type prefixes from which the second type IP addresses are generated, which are advertised from the router;
• and
• a selection unit configured to select one IP address to be used as a source address of the each host from the first type IP addresses and the second type IP addresses that are still within their valid periods, at a start of communications by the host.

A prefix management method at a router for connecting one or a plurality of hosts and Internet through an accessing communication path of a provider, the prefix management method comprising:

• managing one or a plurality of first type prefixes and their valid periods, and one or a plurality of second type prefixes that have shorter valid periods than the first type prefixes and their valid periods, which are allocated from the provider;
• requesting allocation of one or a plurality of new second type prefixes to the provider, before all of the second type prefixes managed by the managing step become invalid;
• and
• advertising periodically the first type prefixes that are still within their valid periods and information regarding the valid periods of the first type prefixes that is to be informed to the hosts, and the second type prefixes that are still within their valid periods and information regarding the valid periods of the second type prefixes that is to be informed to the hosts.

An IP address management method at a host for accessing Internet via a router for connecting each host and the Internet through an accessing communication path of a provider, the IP address management method comprising:

• generating one or a plurality of first type IP addresses and one or a plurality of second type IP addresses, respectively according to first type prefixes and second type prefixes that have shorter valid periods than the first type prefixes, which are advertised from the router in an identical link;
• managing the first type IP addresses and the second type IP addresses generated by the generating step, and valid periods of the first type IP addresses and the second type IP addresses that are determined according to latest information regarding valid periods of the first type prefixes from which the first type IP addresses are generated and latest information regarding valid periods of the second type prefixes from which the second type IP addresses are generated, which are advertised from the router;
• and
• selecting one IP address to be used as a source address of the each host from the first type IP addresses and the second type IP addresses that are still within their valid periods, at a start of communications by the host.

A computer program product for causing a computer to function as a router for connecting one or a plurality of hosts and Internet through an accessing communication path of a provider, the computer program product comprising:

• a first computer program code for causing the computer to manage one or a plurality of first type prefixes and their valid periods, and one or a plurality of second type prefixes that have shorter valid periods than the first type prefixes and their valid periods, which are allocated from the provider;
• a second computer program code for causing the computer to request allocation of one or a plurality of new second type prefixes to the provider, before all of the second type prefixes managed by the first computer program code become invalid;
• and
• a third computer program code for causing the computer to advertise periodically the first type prefixes that are still within their valid periods and information regarding the valid periods of the first type prefixes that is to be informed to the hosts, and the second type prefixes that are still within their valid periods and information regarding the valid periods of the second type prefixes that is to be informed to the hosts.

A computer program product for causing a computer to function as a host for accessing Internet via a router for connecting each host and the Internet through an accessing communication path of a provider, the computer program product comprising:

• a first computer program code for causing the computer to generate one or a plurality of first type IP addresses and one or a plurality of second type IP addresses, respectively according to first type prefixes and second type prefixes that have shorter valid periods than the first type prefixes and their valid periods, which are advertised from the router in an identical link;
• a second computer program code for causing the computer to manage the first type IP addresses and the second type IP addresses generated by the first computer program code, and valid periods of the first type IP addresses and the second type IP addresses that are determined according to latest information regarding valid periods of the first type prefixes from which the first type IP addresses are generated and latest information regarding valid periods of the second type prefixes from which the second type IP addresses are generated, which are advertised from the router;
• and
• a third computer program code for causing the computer to select one IP address to be used as a source address of the each host from the first type IP addresses and the second type IP addresses that are still within their valid periods, at a start of communications by the host.