Tag conversion apparatus

1. A tag conversion apparatus comprising:

a plurality of ports for communications via networks; and

a controller configured to

hold tag conversion information associating addresses of communication apparatuses and information on tags of tagging schemes for network separation,

analyze a frame input from one of the plurality of ports and determine a current tagging scheme of the frame,

determine a tagging scheme associated with a destination address of the frame based on the tag conversion information,

convert the frame to a frame of the tagging scheme associated with the destination address based on the tag conversion information when the tagging scheme associated with the destination address and the current tagging scheme are different, and

output the converted frame from one of the plurality of ports.

2. The tag conversion apparatus according to claim 1 ,

wherein the controller is configured to receive a plurality of frames with different tag identifiers of a same or different single tagging schemes,

wherein the controller is configured to convert the plurality of frames to frames of a multiple tagging scheme,

wherein each of the frames of the multiple tagging scheme includes a first type tag identifier and a second type tag identifier,

wherein the frames of the multiple tagging scheme include a common first type tag identifier, and

wherein the controller is configured to output the frames of the multiple tagging scheme from one of the plurality of ports.

3. The tag conversion apparatus according to claim 1 ,

wherein each of the communication apparatuses belongs to a domain in which frames are transferred by a tagging scheme,

wherein the tag conversion information is configured to associate the addresses with information on tags in tagging schemes of domains to which the addresses belong and information on relay tags in a relay tagging scheme used for frame transfer between tag conversion apparatuses,

wherein the relay tagging scheme is a multiple tagging scheme including a first type tag identifier and a second type tag identifier, and

wherein the controller is configured to convert the frame to a frame of the relay tagging scheme associated with the destination address based on the tag conversion information when the frame is to be transferred to the destination address via another tag conversion apparatus.

4. The tag conversion apparatus according to claim 3 , wherein entries of the first type tag identifier is less than entries of the second type tag identifier in the tag conversion information.

5. The tag conversion apparatus according to claim 1 ,

wherein the tag conversion information contains information on net groups to which the communication apparatuses belong,

wherein each of the net groups consists of one or more communication apparatuses permitted to communicate with each other,

wherein the controller is configured to determine a destination net group to which a communication apparatus of a destination address of a received frame and a source net group to which a source communication apparatus of the received frame based on the tag conversion information, and

wherein the controller is configured to discard the received frame when the source net group and the destination net group are different.

6. A system comprising:

the tag conversion apparatus according to claim 1 ; and

a management apparatus configured to manage the tag conversion apparatus,

wherein each of the communication apparatuses belongs to a domain in which frames are transferred by a tagging scheme,

wherein the management apparatus is configured to hold management information containing address information of the communication apparatuses and domain information of the communication apparatuses,

wherein the management apparatus is configured to create the tag conversion information based on the management information, and

wherein the tag conversion information contains the address information and tag identifier information of the communication apparatuses.

7. A system comprising:

the tag conversion apparatus according to claim 1 ; and

a management apparatus configured to manage the tag conversion apparatus,

wherein the management apparatus is configured to hold the tag conversion information, and management information containing address information of the communication apparatuses and domain information of the communication apparatuses,

wherein the management apparatus is configured to update the tag conversion information based on an update of the management information, and

wherein the management apparatus is configured to set the updated tag conversion information in the tag conversion apparatus.

8. A method comprising:

analyzing an input frame and determining a current tagging scheme for network separation of the frame;

determining a tagging scheme associated with a destination address of the frame based on tag conversion information associating addresses of communication apparatuses and information on tags of tagging schemes,

converting the frame to a frame of the tagging scheme associated with the destination address based on the tag conversion information when the tagging scheme associated with the destination address and the current tagging scheme are different, and

outputting the converted frame.

9. The method according to claim 8 , further comprising:

receiving a plurality of frames with different tag identifiers of a same or different single tagging schemes; and

converting the plurality of frames to frames of a multiple tagging scheme, and

outputting the frames of a multiple tagging scheme,

wherein each of the frames of the multiple tagging scheme includes a first type tag identifier and a second type tag identifier, and

wherein the frames of the multiple tagging scheme include a common first type tag identifier.

10. The method according to claim 8 ,

wherein each of the communication apparatuses belongs to a domain in which frames are transferred by a tagging scheme,

wherein the tag conversion information is configured to associate the addresses with information on tags in tagging schemes of domains to which the addresses belong and information on relay tags in a relay tagging scheme used for frame transfer between tag conversion apparatuses,

wherein the relay tagging scheme is a multiple tagging scheme including a first type tag identifier and a second type tag identifier, and

wherein the method comprising converting the frame to a frame of the relay tagging scheme associated with the destination address based on the tag conversion information when the frame is to be transferred to the destination address via another tag conversion apparatus.

11. The method according to claim 10 , wherein entries of the first type tag identifier is less than entries of the second type tag identifier in the tag conversion information.

12. The method according to claim 8 ,

wherein the tag conversion information contains information on net groups to which the communication apparatuses belong,

wherein each of the net groups consists of one or more communication apparatuses permitted to communicate with each other, and

wherein the method further comprising:

determining a destination net group to which a communication apparatus of a destination address of a received frame and a source net group to which a source communication apparatus of the received frame based on the tag conversion information, and

discarding the received frame when the source net group and the destination net group are different.

13. The method according to claim 8 ,

wherein each of the communication apparatuses belongs to a domain in which frames are transferred by a tagging scheme, and

wherein the method further comprising:

referring to management information containing address information of the communication apparatuses and domain information of the communication apparatuses; and

creating the tag conversion information containing the address information and tag identifier information of the communication apparatuses based on the management information.

14. The method according to claim 8 ,

wherein each of the communication apparatuses belongs to a domain in which frames are transferred by a tagging scheme, and

wherein the method further comprising updating the tag conversion information based on an update of the management information containing address information of the communication apparatuses and domain information of the communication apparatuses.