Router and IP-packet-transferring method

A router used for receiving an incoming packet and then passing on said packet to a destination router indicated by a destination address of said packet, said router comprising:

• a first judgment unit for forming a judgment as to whether or not the present time is within a time range open to a user transmitting said packet;
• a second judgment unit for comparing a distance to said destination address along a route to be traveled by said packet by way of a predetermined network with a distance to said destination address along a route to be traveled by said packet by way of the Internet only without passing through said predetermined network;
• a third judgment unit for forming a judgment as to whether to pass on said packet to said destination address along said route passing through said predetermined network or said route by way of said Internet only without passing through said predetermined network on the basis of a result of said judgment formed by said first judgment unit and a result of said judgment formed by said second judgment unit;
• and
• an encapsulation unit which is used for creating an encapsulated packet by adding an encapsulation header destined for said predetermined network to said packet in case a result of said judgment formed by said third judgment unit indicates that said packet is to be passed on to said destination address by way of said predetermined network.

A communication network comprising the Internet, an intranet including a first boundary router connected to said Internet and a user network including a second boundary router connected to said Internet wherein:

• said first boundary router includes:
• a decapsulation unit for carrying out a process of decapsulating a first packet into a second packet in the case of said first packet including a predetermined address specified as a destination address;
• a first judgment unit for forming a judgment as to whether or not a user transmitting said first packet is an authorized user;
• a second judgment unit for forming a judgment as to whether or not the present time is within a time range allowed for said user transmitting said first packet;
• and
• a third judgment unit for forming a judgment as to whether or not said second packet obtained as a result of said process of decapsulating said first packet is allowed to pass through said intranet on the basis of a result of said judgment formed by said first judgment unit and a result of said judgment formed by said second judgment unit;
• whereas
• said second boundary router includes:
• a fourth judgment unit for forming a judgment as to whether or not the present time is within a time range open to a user transmitting a third packet;
• a fifth judgment unit for comparing a distance to a destination address of said third packet along a route to be traveled by said third packet by way of said intranet with a distance to said destination address along a route to be traveled by said third packet by way of the Internet only without passing through said intranet;
• a sixth judgment unit for forming a judgment as to whether to pass on said third packet to said destination address along said route passing through said intranet or said route by way of said Internet only without passing through said intranet on the basis of a result of said judgment formed by said fourth judgment unit and a result of said judgment formed by said fifth judgment unit;
• and
• an encapsulation unit which is used for creating an encapsulated packet by adding an encapsulation header destined for said first boundary router to said third packet in case a result of said judgment formed by said sixth judgment unit indicates that said third packet is to be passed on to said destination address by way of said intranet.

A communication method comprising:

• encapsulating a packet and transmitting an encapsulated packet having a destination address of a second edge node included in an intranet by a first edge node included in a user network;
• decapsulating said encapsulated packet by said second edge node included in an intranet;
• forming a judgment as to whether or not a first user having a source address of the decapsulated packet is cataloged in a table for cataloging users allowed to pass though said intranet in a case where a second user having a destination address of said decapsulated packet is not included in said intranet;
• and
• forming a judgment as to whether or not said decapsulated packet is allowed to transmit to an internet after passing through said intranet on the basis of the judgment.