Multicast data communication method, multicast data communication system, repeater, repeating method, and medium for storing repeating programs

• US 20020169833A1
• Filed: 04/05/2002
• Published: 11/14/2002
• Est. Priority Date: 04/09/2001
• Status: Active Grant

• Current Assignee: Nippon Telegraph and Telephone Corporation
• Original Assignee: Nippon Telegraph and Telephone Corporation
• Inventors: Takahashi, Noriyuki, Murooka, Takahiro, Ishihara, Shinya, Inoue, Takeru, Miyazaki, Toshiaki, Tani, Seiichiro
• Granted Patent: US 7,313,596 B2
• Time in Patent Office: Days
• US Class Current: 709/205
• CPC Class Codes: H04L 12/185 with management of multicast group membership
• CPC Class Codes: H04L 12/1854 with non-centralised forwarding system, e.g. chaincast

Abstract

A multicast data communication system is provided that has high security, and prevents problems such as an attack by a malicious user creating a great number of meaningless tables at nodes in the network. Clients regularly transmit request packets toward a server; a node receives the request packet, and subsequently receives a delivery-table-creation packet or a delivery packet from the server; if the node has no delivery table corresponding to the server, the node creates the delivery table, registers the addresses of the clients, and their request packet arrival times, and regularly transmits the request packet toward the server; when the node has received a delivery packet from the server, the node duplicates and delivers the delivery packet only to those clients whose request packet arrival times, registered in the delivery table, are within a fixed period from the arrival of the delivery packet.

Claims

1. A multicast data communication system which uses a network capable of unicast communication to multicast data via one or more repeaters provided on a unicast delivery path from a transmitter to a plurality of receivers,

each receiver comprising a unit for transmitting a request message with the transmitter as the destination at a time interval which is shorter than a predetermined value;

the transmitter comprising a unit which determines whether a node adjacent to the receiver side is continuing to request receipt of the data, based on whether a receive interval of the request message is shorter than a predetermined time interval, and a unit which transmits the data toward the receivers when it has been determined that a node adjacent to the receiver side is continuing to request receipt of the data; and

each repeater comprising a unit which creates a delivery table for registering one or more nodes adjacent to the receiver side where the data should be delivered to when, after the request message has been received from the node adjacent to the receiver side, the data or a delivery-table-creation packet has been received from a node adjacent to the transmitter side;

a unit which registers the node adjacent to the receiver side which transmitted a request message after the delivery table was created, in the delivery table;

a unit which determines whether the node adjacent to the receiver side is continuing to request receipt of the data, based on whether a receive interval of the request messages is shorter than a predetermined time interval; and

a unit which, when it has been determined that the node adjacent to the receiver side is continuing to request receipt of the data, transmits a request message with the transmitter as the destination at a time interval which is shorter than a predetermined value, and in addition, replicates the data, sent from the node adjacent to the transmitter side, and delivers the replicated data to the nodes adjacent to the receiver side, which are registered in the delivery table.

2. The multicast data communication system according to claim 1, wherein

the request message comprises path information which represents the path from one of the receivers to one of the repeaters or the transmitter where the request message was received;

the receiver transmits the request message containing information identifying itself as the path information;

when the node adjacent to the receiver side, which transmitted the request message, is not registered in the delivery table, the transmitter creates a delivery-table-creation packet containing the path information in the request message, and transmits the delivery-table-creation packet toward the receiver in accordance with the path information;

the repeater further comprises a unit which determines whether the delivery table has been created, and, in the case where the delivery table has been created, when the node adjacent to the receiver side, which transmitted the request message, is not registered in the delivery table, the repeater creates a delivery-table-creation packet containing the path information in the request message, and transmits the delivery-table-creation packet toward the receiver in accordance with the path information; and

in the case where the delivery table has not been created, the repeater creates new path information, in which information identifying itself is added to the path information in the request message sent from the node adjacent to the receiver side, and transmits a request message containing the new path information with the transmitter as the destination, and, when the delivery-table-creation packet has been sent from the node adjacent to the transmitter side, forwards the delivery-table-creation packet to the node adjacent to the receiver side in accordance with the path information in the delivery-table-creation packet, and creates the delivery table.

3. The multicast data communication system according to claim 2,

the repeater further comprising:

a unit which determines whether the repeater has reached a high load state, exceeding a predetermined load; and

a unit which, while the high load state has been determined, forwards the request message with the transmitter as the destination without registering a node adjacent to the receiver side, which is not registered in the delivery table, in the delivery table when the request message is sent from one of the nodes adjacent to the receiver side, in the delivery table.

4. The multicast data communication system according to claim 2, wherein

the request message contains preference information representing a correlation between the preferences of users corresponding to the receivers and the costs of transforming the data;

and

the repeater further comprising;

a transformation information memory unit which stores in advance transformation information, needed for transforming data delivered to the receivers, over a plurality of required categories;

a transformation-instruction table which defines in advance categories of the transformation information, relating to the nodes adjacent to the receiver side, for each of the nodes adjacent to the receiver side, based on the preference information in the request messages sent from the nodes adjacent to the receiver side;

a transformation unit which consults the transformation-instruction table and selects categories of the transformation information to be used relating to the nodes adjacent to the receiver side, in accordance with the data sent from the nodes adjacent to the transmitter side, reads the transformation information stored in the transformation information memory unit in correspondence with the selected categories, and transforms the data by using the transformation information which is read; and

a transmitting unit which transmits the data, which is transformed by the transformation unit, to each node adjacent to the receiver side.

5. The multicast data communication system according to claim 4, wherein

the transformation unit selects the categories based on information representing the load state of each of the repeaters, or the load state of a communication link between the repeaters, in addition to the preference information.

6. The multicast data communication system according to claim 4, further comprising

a preference information extraction unit which extracts the preference information from the request message sent from a node adjacent to the receiver side;

a preference information memory unit which stores the preference information which is extracted;

a preference information aggregation unit which creates new preference information by aggregatively performing a predetermined calculation to the preference information, stored in the preference information memory unit, and updates the transformation-instruction table in accordance with the new preference information; and

a unit which transmits the new preference information to the node adjacent to the transmitter side.

7. The multicast data communication system according to claim 1, wherein

the repeater further comprises a unit which determines whether the delivery table has been created;

and, in the case where the delivery table has not been created, the repeater updates the source of the request message, sent from one of the nodes adjacent to the receiver side, to itself, and forwards the request message to the node adjacent to the transmitter side, and in addition, creates the delivery table when the data has been sent from the node adjacent to the transmitter side, and discards the data; and

in the case where the delivery table has been created, the repeater registers the source node adjacent to the receiver side, which transmitted the request messages, in the delivery table.

8. The multicast data communication system according to claim 7,

the repeater further comprising:

a unit which determines whether the repeater has reached a high load state, exceeding a predetermined load; and

a unit which, while the high load state has been determined, forwards the request message with the transmitter as the destination without registering a node adjacent to the receiver side, which is not registered in the delivery table, in the delivery table when the request message is sent from one of the nodes adjacent to the receiver side, in the delivery table.

9. The multicast data communication system according to claim 7, wherein

the request message contains preference information representing a correlation between the preferences of users corresponding to the receivers and the costs of transforming the data;

and

the repeater further comprising;

a transformation information memory unit which stores in advance transformation information, needed for transforming data delivered to the receivers, over a plurality of required categories;

a transformation-instruction table which defines in advance categories of the transformation information, relating to the nodes adjacent to the receiver side, for each of the nodes adjacent to the receiver side, based on the preference information in the request message sent from the node adjacent to the receiver side;

a transformation unit which consults the transformation-instruction table and selects a categories of the transformation information to be used relating to the nodes adjacent to the receiver side, in accordance with the data sent from the nodes adjacent to the transmitter side, reads the transformation information stored in the transformation information memory unit in correspondence with the selected categories, and transforms the data by using the transformation information which is read; and

a transmitting unit which transmits the data, which is transformed by the transformation unit, to each node adjacent to the receiver side.

10. The multicast data communication system according to claim 9, wherein

the transformation unit selects the categories based on information representing the load state of each of the repeaters, or the load state of a communication link between the repeaters, in addition to the preference information.

11. The multicast data communication system according to claim 9, further comprising

a preference information extraction unit which extracts the preference information from the request message sent from a node adjacent to the receiver side;

a preference information memory unit which stores the preference information which is extracted;

a preference information aggregation unit which creates new preference information by aggregatively performing a predetermined calculation to the preference information, stored in the preference information memory unit, and updates the transformation-instruction table in accordance with the new preference information; and

a unit which transmits the new preference information to the node adjacent to the transmitter side.

13. The multicast data communication method according to claim 12, wherein

the receiver transmits the request message containing information identifying itself as path information;

when the node adjacent to the receiver side, which transmitted the request message, is not registered in the delivery table, the transmitter creates the delivery-table-creation packet containing the path information in the request message, and transmits the delivery-table-creation packet toward the receiver in accordance with the path information;

a repeater which is located on the path from the receiver to the repeater where the delivery table is created, but which has not created the delivery table, creates new path information, adding information identifying itself to the path information in the request message sent from the node adjacent to the receiver side, and transmits a request message containing the new path information with the transmitter as the destination,

at the time that the request message has arrived at the transmitter or the one of the repeaters where the delivery table is created, when the node adjacent to the receiver side, which transmitted the request message, is not registered in the delivery table, the transmitter or the repeater creates a delivery-table-creation packet containing the path information in the request message, and transmit the delivery-table-creation packet toward the receiver in accordance with the path information; and

when the delivery-table-creation packet has been sent from the node adjacent to the transmitter side, a repeater, which is located on the path from the repeater where the delivery table is created to the receiver, but which has not created the delivery table, forwards the delivery-table-creation packet to the node adjacent to the receiver side in accordance with the path information in the delivery-table-creation packet, and creates the delivery table.

14. The multicast data communication method according to claim 12, wherein

a repeater, which is located on the path from one of the receivers to the repeater where the delivery table is created, but which has not created the delivery table, updates the source of the request message, sent from one of the nodes adjacent to the receiver side, to itself, and forwards the request message to the node adjacent to the transmitter side;

when the request message arrives at the repeater where the delivery table is created, the repeater registers the source node adjacent to the receiver side, which transmitted the request messages, in the delivery table, and transmits the data to the node adjacent to the receiver side; and

a repeater, which is located on the path from the repeater where the delivery table is created to the one of the receivers, but which has not created the delivery table, receives the data, transmitted from the node adjacent to the transmitter side, creates the delivery table and discards the data.

16. The repeater according to claim 15, wherein

the request message comprises path information which represents the path from one of the receivers to one of the repeaters or the transmitter where the request message was received;

the repeater further comprises a unit which determines whether the delivery table has been created;

in the case where the delivery table has been created, when the node adjacent to the receiver side, which transmitted the request message, is not registered in the delivery table, the repeater extracts path information, representing the path from the receiver to the repeater itself, from the request message, creates a delivery-table-creation packet containing the path information, and transmits the delivery-table-creation packet toward the receiver in accordance with the path information; and

in the case where the delivery table has not been created, the repeater creates new path information, in which information identifying itself is added to the path information in the request message sent from the node adjacent to the receiver side, and transmits a request message containing the new path information with the transmitter as the destination, and, when the delivery-table-creation packet has been sent from the node adjacent to the transmitter side, forwards the delivery-table-creation packet to the node adjacent to the receiver side in accordance with the path information in the delivery-table-creation packet, and creates the delivery table.

17. The repeater according to claim 16, further comprising

a unit which determines whether the repeater has reached a high load state, exceeding a predetermined load;

and

a unit which, while the high load state has been determined, forwards the request message with the transmitter as the destination without registering a node adjacent to the receiver side, which is not registered in the delivery table, in the delivery table when the request message is sent from one of the nodes adjacent to the receiver side, in the delivery table.

18. The repeater according to claim 16, further comprising

a transformation information memory unit which stores in advance transformation information, needed for transforming data delivered to the receivers, over a plurality of required categories;

a transformation-instruction table which defines in advance categories of the transformation information, relating to the nodes adjacent to the receiver side, for each of the nodes adjacent to the receiver side, based on the preference information, which represents a correlation between the preferences of users corresponding to the receivers and the costs of transforming the data, the preference information being contained in the request messages sent from the nodes adjacent to the receiver side;

a transformation unit which consults the transformation-instruction table and selects categories of the transformation information to be used relating to the nodes adjacent to the receiver side, in accordance with the data sent from the nodes adjacent to the transmitter side, reads the transformation information stored in the transformation information memory unit in correspondence with the selected categories, and transforms the data by using the transformation information which is read; and

a transmitting unit which transmits the data, which is transformed by the transformation unit, to each node adjacent to the receiver side.

19. The repeater according to claim 18, wherein

the transformation unit selects the categories based on information representing the load state of each of the repeaters, or the load state of a communication link between the repeaters, in addition to the preference information.

20. The repeater according to claim 18, further comprising

a preference information extraction unit which extracts the preference information from the request message, sent from a node adjacent to the receiver side;

a preference information memory unit which stores the preference information which is extracted;

a preference information aggregation unit which creates new preference information by aggregatively performing a predetermined calculation to the preference information, stored in the preference information memory unit, and updates the transformation-instruction table in accordance with the new preference information; and

a unit which transmits the new preference information to the node adjacent to the transmitter side.

21. The repeater according to claim 15, further comprising a unit which determines whether the delivery table has been created;

and wherein

in the case where the delivery table has not been created, the repeater updates the source of the request message, sent from one of the nodes adjacent to the receiver side, to itself, and forwards the request message to the node adjacent to the transmitter side, and in addition, creates the delivery table when the data has been sent from the node adjacent to the transmitter side, and discards the data; and

in the case where the delivery table has been created, the repeater registers the source node adjacent to the receiver side, which transmitted the request messages, in the delivery table.

22. The repeater according to claim 21, further comprising

a unit which determines whether the repeater has reached a high load state, exceeding a predetermined load;

and

a unit which, while the high load state has been determined, forwards the request message with the transmitter as the destination without registering a node adjacent to the receiver side, which is not registered in the delivery table, in the delivery table when the request message is sent from one of the nodes adjacent to the receiver side, in the delivery table.

23. The repeater according to claim 21, further comprising

a transformation information memory unit which stores in advance transformation information, needed for transforming data delivered to the receivers, over a plurality of required categories;

a transformation-instruction table which defines in advance categories of the transformation information, relating to the nodes adjacent to the receiver side, for each of the nodes adjacent to the receiver side, based on the preference information, which represents a correlation between the preferences of users corresponding to the receivers and the costs of transforming the data, the preference information being contained in the request messages sent from the nodes adjacent to the receiver side;

a transformation unit which consults the transformation-instruction table and selects categories of the transformation information to be used relating to the nodes adjacent to the receiver side, in accordance with the data sent from the nodes adjacent to the transmitter side, reads the transformation information stored in the transformation information memory unit in correspondence with the selected categories, and transforms the data by using the transformation information which is read; and

a transmitting unit which transmits the data, which is transformed by the transformation unit, to each node adjacent to the receiver side.

24. The repeater according to claim 23, wherein

the transformation unit selects the categories based on information representing the load state of each of the repeaters, or the load state of a communication link between the repeaters, in addition to the preference information.

25. The repeater according to claim 23, further comprising

a preference information extraction unit which extracts the preference information from the request message sent from a node adjacent to the receiver side;

a preference information memory unit which stores the preference information which is extracted;

a preference information aggregation unit which creates new preference information by aggregatively performing a predetermined calculation to the preference information, stored in the preference information memory unit, and updates the transformation-instruction table in accordance with the new preference information; and

a unit which transmits the new preference information to the node adjacent to the transmitter side.

27. The repeating method according to claim 26, further comprising the steps of:

until the delivery table is created, creating new path information, in which information identifying the repeater itself is added to the path information in the request message sent from the node adjacent to the receiver side, and transmitting a request message containing the new path information with the transmitter as the destination, and thereafter, when the delivery-table-creation packet created by the transmitter or a repeater which has created the delivery table has been sent from the node adjacent to the transmitter side, forwarding the delivery-table-creation packet to the node adjacent to the receiver side in accordance with the path information in the delivery-table-creation packet, and creating the delivery table; and

after creating the delivery table, when the request message has been sent from the node adjacent to the receiver side, in the case where the node adjacent to the receiver side is not registered in the delivery table, extracting path information, representing the path from the receiver to the repeater itself, from the request message, creating a delivery-table-creation packet containing the path information, and transmitting the delivery-table-creation packet toward the receiver in accordance with the path information.

28. The repeating method according to claim 26, further comprising the steps of:

until the delivery table is created, updating the source of the request message, sent from one of the nodes adjacent to the receiver side, to the repeater itself, and forwarding the request message to the node adjacent to the transmitter side, and thereafter, creating the delivery table when the data has been sent from the node adjacent to the transmitter side, and discarding the data; and

after creating the delivery table, registering the source node adjacent to the receiver side, which transmitted the request messages, in the delivery table, and in addition, transmitting the data to the node adjacent to the receiver side.

12. A multicast data communication method which uses a network capable of unicast communication to multicast data via one or more repeaters provided on a unicast delivery path from a transmitter to a plurality of receivers, the method comprising the steps of:

each receiver transmitting a request message with the transmitter as the destination at a time interval which is shorter than a predetermined value;

each repeater creating a delivery table for registering one or more nodes adjacent to the receiver side where the data should be delivered to when, after the request message has been received from the node adjacent to the receiver side, the data or a delivery-table-creation packet has been received from a node adjacent to the transmitter side;

the transmitter determining whether a node adjacent to the receiver side is continuing to request receipt of the data, based on whether a receive interval of the request messages is shorter than a predetermined time interval, transmitting the data to the node adjacent to the receiver side which are continuing to request receipt of the data, and terminating the delivery of the data to the node adjacent to the receiver side which have stopped requesting receipt of the data;

each repeater registering the node adjacent to the receiver side which transmitted a request message after the delivery table was created, in the delivery table; and

each repeater determining whether the node adjacent to the receiver side is continuing to request receipt of the data, based on whether a receive interval of the request messages is shorter than a predetermined time interval; and

, when it has been determined that the node adjacent to the receiver side is continuing to request receipt of the data, transmitting a request message with the transmitter as the destination at a time interval which is shorter than a predetermined value, replicating the data, sent from the node adjacent to the transmitter side, and delivering the replicated data to the nodes adjacent to the receiver side, which are registered in the delivery table.

15. A repeater in a multicast data communication system, which uses a network capable of unicast communication to multicast data from a transmitter to a plurality of receivers, the repeater being provided on a unicast delivery path from the transmitter to the plurality of receivers, and comprising:

a unit which creates a delivery table for registering one or more nodes adjacent to the receiver side where the data should be delivered to when, after the request message, sent by one of the plurality of receivers with the transmitter as the destination at a time interval which is shorter than a predetermined value, has been received from the node adjacent to the receiver side, the data or a delivery-table-creation packet has been received from a node adjacent to the transmitter side;

a unit which registers the node adjacent to the receiver side which transmitted a request message after the delivery table was created, in the delivery table;

a unit which determines whether the node adjacent to the receiver side is continuing to request receipt of the data, based on whether a receive interval of the request message is shorter than a predetermined time interval; and

a unit which, when it has been determined that the node adjacent to the receiver side is continuing to request receipt of the data, transmits a request message with the transmitter as the destination at a time interval which is shorter than a predetermined value, and in addition, replicates the data, sent from the node adjacent to the transmitter side, and delivers the replicated data to the nodes adjacent to the receiver side, which are registered in the delivery table.

26. A repeating method, applied when using a network capable of unicast communication to multicast data from a transmitter to a plurality of receivers, the data being repeated via one or more repeaters provided on a unicast delivery path from the transmitter to the plurality of receivers, the method comprising the steps of:

receiving request messages, sent by the plurality of receivers with the transmitter as the destination at a time interval which is shorter than a predetermined value;

creating a delivery table for registering one or more nodes adjacent to the receiver side where the data should be delivered to when, after the request message has been received from the node adjacent to the receiver side, the data or a delivery-table-creation packet has been received from a node adjacent to the transmitter side;

registering the node adjacent to the receiver side, which transmitted a request message after the delivery table was created, in the delivery table;

determining whether the node adjacent to the receiver side is continuing to request receipt of the data, based on whether a receive interval of the request message is shorter than a predetermined time interval; and

when it has been determined that the node adjacent to the receiver side is continuing to request receipt of the data, transmitting a request message with the transmitter as the destination at a time interval which is shorter than a predetermined value, and in addition, replicating the data, sent from the node adjacent to the transmitter side, and delivering the replicated data to the nodes adjacent to the receiver side, which are registered in the delivery table.

29. A computer-readable medium which stores repeating programs for repeating data when using a network capable of unicast communication to multicast data from a transmitter to a plurality of receivers, the data being repeated on a unicast delivery path from the transmitter to the plurality of receivers,

the repeating program comprising the steps of:

a step of receiving request messages, sent by the plurality of receivers with the transmitter as the destination at a time interval which is shorter than a predetermined value;

a step of creating a delivery table for registering one or more nodes adjacent to the receiver side where the data should be delivered to when, after the request message has been received from the node adjacent to the receiver side, the data or a delivery-table-creation packet has been received from a node adjacent to the transmitter side;

a step of registering the node adjacent to the receiver side, which transmitted the request message after the delivery table was created, in the delivery table;

a step of determining whether the node adjacent to the receiver side is continuing to request receipt of the data, based on whether a receive interval of the request message is shorter than a predetermined time interval; and

a step of, when it has been determined that the node adjacent to the receiver side is continuing to request receipt of the data, transmitting a request message with the transmitter as the destination at a time interval which is shorter than a predetermined value, and in addition, replicating the data, sent from the node adjacent to the transmitter side, and delivering the replicated data to the nodes adjacent to the receiver side, which are registered in the delivery table.