JP3950915B2 - DATA DISTRIBUTION METHOD, DATA DISTRIBUTION SYSTEM, DATA RECEPTION DEVICE, DATA RELAY DEVICE, DATA RECEPTION DEVICE, AND DATA DISTRIBUTION PROGRAM - Google Patents

Description

  The present invention provides a data distribution system including a data distribution device, a data relay device, and a data reception device, and one or a plurality of the data reception devices from the data distribution device via one or a plurality of the data relay devices. The present invention relates to a data distribution method of distributing data to

  Conventionally, as a distribution method for distributing data from a data distribution apparatus to a data reception apparatus, unicast distribution in which the data distribution apparatus and the data reception apparatus are in a one-to-one relationship, and the data reception apparatus for one data distribution apparatus There are one-to-many multicast distribution and broadcast distribution in which there are multiple. Among these distribution methods, multicast distribution is a distribution method in which a specific number of data receiving devices are data distribution destinations, and broadcast distribution is a distribution method in which an unspecified number of data receiving devices are data distribution destinations. is there. Hereinafter, these unicast distribution, broadcast distribution, and broadcast distribution will be described in detail.

  In unicast distribution, the data receiving apparatus requests data to the data distributing apparatus, the data distributing apparatus transmits data in response, and the data distributing apparatus waits for a data request from the data receiving apparatus. There is push-type distribution that transmits data without any other.

  In multicast distribution and broadcast distribution, when receiving data (program information or the like) accompanying the distribution data, the data receiving apparatus selectively receives the distribution data based on the accompanying information. However, in multicast distribution, the data receiving apparatus notifies the data relay apparatus that relays data from the data distribution apparatus that the data is received. Then, the data relay apparatus that has received the notification transmits the data transmitted from the data distribution apparatus only to the data receiving apparatus that has notified that the data is to be received.

Conventionally, a data transmission apparatus has decided one of unicast distribution, multicast distribution, and broadcast distribution to transmit data.
By Thomas Maufer, translated by Hiroyuki Enomoto, “Introduction to IP Multicast”, first edition, Kyoritsu Publishing Co., Ltd., November 2001 By Dave Kosiur, translated by Yukio Hamada, “Mastering TCP / IP Multicast”, first edition, second edition, Ohm Corporation, December 2000 By Beau Williamson, translated by Comsus, supervised by Cisco Systems, "IP Multicast Network Development Guide Vol. 1", first edition, Softbank Publishing Co., Ltd., July 2001

  Of the above-mentioned distribution methods, multicast distribution and broadcast distribution are compared with unicast distribution when the number of data receiving apparatuses is large and the geographical distribution of the data receiving apparatuses is somewhat dense. Thus, the time required for data distribution is short, the total amount of distribution data is reduced, and the efficiency of data distribution is increased.

  However, on the other hand, in multicast distribution and broadcast distribution, when the number of data receiving devices serving as distribution destinations is small and the geographical distribution of the data receiving devices serving as the distribution destinations is distributed, it is unidirectional. Compared with cast distribution, the efficiency of sufficient data distribution may not be improved. In particular, in multicast distribution, the cost of multicast group management for specifying a receiving destination is generated, and thus it is problematic that sufficient data distribution efficiency cannot be improved as compared with unicast distribution. Hereinafter, this problem will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration example of a conventional data distribution system. The data distribution system shown in the figure includes a content server 210 as a data distribution device, a client 220 as a data reception device, and a router 230 as a data relay device. The content server 210 and the router 230 are connected to a communication network 240 such as the Internet or a wireless network. The clients 220-1 to 220-3 are connected to the router 230-1 via a communication network 250-1 such as a LAN (Local Area Network). Similarly, the clients 220-4 to 220-6 are connected to the router 230-2 via the communication network 250-2, and the clients 220-7 to 220-9 are connected to the router 230- via the communication network 250-3. 3 is connected. Note that the subscript M of the transmission path constituting the communication networks 240 and 250 in the figure indicates that data is transmitted to the transmission path by multicast distribution.

  The content server 210 performs multicast distribution to the client 220. In the figure, among the clients 220 connected to the communication network 250-3, only the client 220-8 is the distribution destination. However, in the conventional data distribution method, data distribution is performed in the entire system in accordance with a distribution method decided by the content server 210 as a data distribution apparatus, so multicast distribution is also performed for the communication network 250-3. For this reason, in the communication network 250-3, a communication cost due to the multicast distribution control protocol occurs, and the total distribution data amount including the communication cost increases.

  The present invention solves the above-described problems, and an object thereof is to provide a data distribution method, a data distribution system, a data relay device, a data reception device, and a data distribution program that improve the efficiency of data distribution. There is.

  To achieve the above object, the present invention provides a data distribution system comprising a data distribution device, a data relay device, and a data reception device connected to a communication network. In a data distribution method for distributing data from a distribution device to one or more data reception devices via one or more data relay devices, the data reception device notifies the data relay device of information related to data reception. The data relay device manages information related to data reception notified from the data receiving device, and distributes data to the data receiving device based on the managed information related to data reception And determining the determined delivery method to the data receiving device, and based on the determined delivery method, Data from a data distribution device is transmitted to the data reception device, and the data reception device receives data from the data relay device based on a distribution method notified from the data relay device. To do.

  According to the present invention, the data distribution apparatus determines one distribution method as in the prior art, and data distribution is not performed in the entire system by the distribution method, but the data relay apparatus is transmitted from the data receiving apparatus. Since the distribution method is determined based on the information related to data reception, the data can be distributed for each data distribution route in accordance with the distribution method according to the status of the data receiving device, and the efficiency of data distribution can be improved. It becomes possible.

  According to a second aspect of the present invention, in the data distribution method according to the first aspect, the information related to the data reception includes identification information of data desired to be distributed by the data reception device, and the data And the identification information of the data distribution method desired by the receiving apparatus.

  According to a third aspect of the present invention, in the data distribution method according to the first or second aspect, the data relay device is configured to transfer the data reception device to the data reception device based on the information on the data reception managed. On the other hand, a distribution method for distributing data is periodically determined.

  In this case, the distribution method can be changed periodically, and even when the status of the data receiving device changes from moment to moment, the data can be distributed with an appropriate distribution method, and the efficiency of data distribution Can be improved.

  According to a fourth aspect of the present invention, in the data distribution method according to any one of the first to third aspects, the data relay device transmits information on the data reception to be managed in the communication network. Notification is made to another data relay device belonging to the host device.

  Further, according to a fifth aspect of the present invention, in the data distribution method according to any one of the first to fourth aspects, the data relay device is another data belonging to a lower level of the own device in the communication network. Information related to data reception notified from the relay device is managed.

  In this case, the data relay device can manage information related to data reception transmitted from the data receiving device under its control, in other words, from the data receiving device that is the distribution destination of data from its own device. In addition, it is possible to appropriately determine a distribution method for distributing data to the data receiving apparatus via another data relay apparatus.

  According to a sixth aspect of the present invention, in the data distribution method according to any one of the first to fifth aspects, the distribution method is any one of unicast distribution, multicast distribution, and broadcast distribution. It is characterized by.

  According to a seventh aspect of the present invention, in the data distribution method according to the sixth aspect, the data relay device is configured such that the number of data receiving devices to which predetermined data from the own device is distributed is a threshold value. In the following cases, the distribution method is determined to be unicast distribution, and when the threshold is exceeded, the distribution method is determined to be multicast distribution or broadcast distribution.

  In this case, the data relay apparatus adopts unicast distribution when the number of data receiving apparatuses to which predetermined data from the own apparatus is distributed is small, and multicast distribution and further broadcast as the number increases. Since the distribution is adopted, it is possible to determine an appropriate distribution method according to the number of data receiving apparatuses that are distribution destinations.

  In addition, the present invention includes a data distribution device, a data relay device, and a data reception device connected to a communication network, and includes one or more data relay devices from the data distribution device. In a data distribution system for distributing data to one or a plurality of the data reception devices via the first data reception information notification unit, the data reception device notifies the data relay device of information related to data reception, Data receiving means for receiving data from the data relay device based on a distribution method notified from the data relay device, and the data relay device manages information related to data reception notified from the data receiving device Data reception information management means for performing the data reception based on the managed data reception information Based on the distribution method determining means for determining the distribution method for distributing data to the device, the distribution method notifying means for notifying the data receiving apparatus of the determined distribution method, and the determined distribution method, And a data transmission means for transmitting data from the data distribution device to the data reception device.

  According to a ninth aspect of the present invention, in the data distribution system according to the eighth aspect, the distribution method determining means sets a distribution method for distributing data to the data receiving device in a cycle. It is characterized by determining automatically.

  According to a tenth aspect of the present invention, in the data distribution system according to the eighth or ninth aspect, the data relay device transmits information on the managed data reception to the own device in the communication network. And a second data reception information notifying unit for notifying other data relay apparatuses belonging to the higher level of the data relay device.

  In addition, according to the present invention, in the data distribution system according to any one of claims 8 to 10, the data reception information management means is another data relay belonging to a lower level of the own device in the communication network. Information related to data reception notified from the apparatus is managed.

  Further, according to a twelfth aspect of the present invention, in the data distribution system according to any one of the eighth to eleventh aspects, the distribution method is any one of unicast distribution, multicast distribution, and broadcast distribution. It is characterized by that.

  Further, according to a thirteenth aspect of the present invention, in the data distribution system according to the twelfth aspect of the present invention, the distribution method deciding means determines the number of data receiving apparatuses that are distribution destinations of predetermined data from the own apparatus. Is less than or equal to a threshold value, the distribution method is determined to be unicast distribution, and when the threshold value is exceeded, the distribution method is determined to be multicast distribution or broadcast distribution.

  Further, the present invention is the data receiving device as described in claim 14, wherein the data receiving device is connected to the communication network and receives data distributed from the data distributing device via one or more data relay devices. Data receiving information notifying means for notifying the data relay apparatus of information related to the data relay apparatus, and data receiving means for receiving data from the data relay apparatus based on a distribution method notified from the data relay apparatus. And

  Further, according to the present invention, the data receiving device according to claim 14 has a communication interface unit having a function of performing communication with another device and a function of performing a communication protocol process. A communication protocol control unit; an application processing unit having a function of operating an application; an input / output processing unit having a function of performing input / output processing via an external peripheral device; and a storage unit having a function of storing information It is characterized by that.

  The present invention also relates to data reception notified from the data receiving device in a data relay device connected to a communication network and distributing data from the data distributing device to the data receiving device. A data reception information management means for managing information; a distribution method determination means for determining a distribution method for distributing data to the data receiving device based on the managed data reception information; A distribution method notifying unit for notifying the data receiving device of the determined distribution method, and a data transmitting unit for transmitting data from the data distribution device to the data receiving device based on the determined distribution method. And

  According to a 17th aspect of the present invention, in the data relay device according to the 16th aspect, the distribution method determining means sets a distribution method for distributing data to the data receiving device in a cycle. It is characterized by determining automatically.

  Further, according to the present invention, as described in claim 18, in the data relay device according to claim 16 or 17, the information related to the managed data reception is transmitted to other information belonging to a higher rank in the communication network. Data reception information notifying means for notifying the data relay device is provided.

  Further, according to the present invention, as described in claim 19, in the data relay device according to any one of claims 16 to 18, the data reception information management means is a device other than a subordinate device of the own device in the communication network. Information relating to data reception notified from the data relay device is managed.

  According to the present invention, the data relay device according to any one of claims 16 to 19 is provided with a communication interface unit having a function of performing communication with other devices, and a communication protocol process. A communication protocol control unit having a function of performing storage and a storage unit having a function of storing information.

  Further, according to a twenty-first aspect of the present invention, in the data relay device according to any one of the sixteenth to twentieth aspects, the distribution method is any one of unicast distribution, multicast distribution, and broadcast distribution. It is characterized by that.

  According to a twenty-second aspect of the present invention, in the data relay apparatus according to the twenty-first aspect, the distribution method determining means is the number of data receiving apparatuses that are distribution destinations of predetermined data from the own apparatus. Is less than or equal to a threshold value, the distribution method is determined to be unicast distribution, and when the threshold value is exceeded, the distribution method is determined to be multicast distribution or broadcast distribution.

  According to a twenty-third aspect of the present invention, there is provided the data for operating the data receiving device connected to the communication network and receiving the data distributed from the data distribution device via one or more data relay devices. In a distribution program, executing a procedure for notifying the data relay device of information related to data reception and a procedure for receiving data from the data relay device based on a distribution method notified from the data relay device It is characterized by.

  According to a twenty-fourth aspect of the present invention, there is provided a data distribution program for operating a data relay apparatus that is connected to a communication network and distributes data from a data distribution apparatus to a data reception apparatus. A procedure for managing information related to data reception notified from the above, a procedure for determining a distribution method for distributing data to the data receiving device based on the information related to data reception managed, and the determination A procedure for notifying the data receiving device of the distributed delivery method and a procedure for transmitting data from the data delivery device to the data receiving device based on the determined delivery method.

  Further, according to the present invention, as described in claim 25, in the data distribution program according to claim 24, the information related to the managed data reception is transmitted to other data belonging to the host device in the communication network. A procedure for notifying the relay apparatus is executed.

  Further, according to the present invention, as described in claim 26, in the data distribution program according to claim 24 or 25, data reception notified from another data relay device belonging to a lower level of the own device in the communication network It is characterized in that a procedure for managing information related to is executed.

  As described above, according to the present invention, it is possible to appropriately determine a distribution method and improve the efficiency of data distribution.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 2 is a diagram illustrating a configuration example of the data distribution system according to the embodiment of this invention. The data distribution system shown in the figure includes a content server 10 as a data distribution apparatus, a client 20 as a data reception apparatus, and a router 30 as a data relay apparatus. The content server 10 and the router 30 are connected to a communication network 40 such as the Internet or a wireless network. The clients 20-1 to 20-3 are connected to the router 30-1 via a communication network 50-1 such as a LAN (Local Area Network). Similarly, the clients 20-4 to 20-6 are connected to the router 30-2 via the communication network 50-2, and the clients 20-7 to 20-9 are connected to the router 30- via the communication network 50-3. 3 is connected. 2 indicates that the data is transmitted to the transmission line by multicast distribution, and the subscript U indicates that the data is transmitted by unicast distribution. It is transmitted to the road.

  In this data distribution system, the client 20 transmits information related to data reception to the router 30. The router 30 uses any one of unicast distribution, multicast distribution, and broadcast distribution as a distribution method for performing data distribution to the client 20 or another router 30 based on the data reception information transmitted from the client 20. The data to be distributed is transmitted from the content server 10 in accordance with the determined distribution method.

  FIG. 2 shows an example in which distribution destinations of distribution data transmitted from the content server 10 are clients 20-1, 20-2, 20-3, 20-4, 20-5, and 20-8. . Specifically, distribution data transmitted from the content server 10 by multicast distribution is sent to the clients 20-1, 20-2, and 20 via the routers 30-7, 30-6, 30-5, and 30-1. -3. At this time, all of the routers 30-7, 30-6, 30-5, and 30-1 perform multicast distribution. Distribution data transmitted by multicast distribution from the content server 10 is sent to the clients 20-4 and 20-5 via the routers 30-7, 30-6, 30-5, and 30-2. At this time, the routers 30-7 and 30-6 perform multicast distribution, and the routers 30-5 and 30-2 perform unicast distribution. Furthermore, distribution data transmitted from the content server 10 by multicast distribution is sent to the client 20-8 via the routers 30-7, 30-6, 30-8, and 30-3. At this time, the router 30-7 performs multicast distribution, and the routers 30-6, 30-5, and 30-2 perform unicast distribution.

  FIG. 3 is a diagram illustrating a detailed configuration example of the client 20. As shown in the figure, the client 20 includes a communication interface unit 61, a communication protocol control unit 62, an application unit 63, an input / output processing unit 64, and a storage device 65.

  The input / output processing unit 64 outputs a signal corresponding to an operation instruction from the user to the application unit 53. The application unit 63 activates an application for receiving distribution data based on a signal corresponding to the operation instruction by the user.

  Specifically, the application unit 63 first acquires information related to distribution data (distribution data related information). The distribution data related information includes information regarding which of unicast distribution, multicast distribution, and broadcast distribution can be used as a data distribution method, information associated with these distribution methods, and the like.

  This distribution data related information is input from the input / output processing unit 64 in response to a user operation instruction, or is acquired from the storage device 65 or the external node that holds the distribution data related information.

  When the distribution data related information is held in an external node, the application unit 63 externally holds information related to distribution data (distribution data related information) via the communication protocol control unit 62 and the communication interface unit 61. To obtain the distribution data related information. The distribution data related information held by the external node includes, for example, information held by the content server 10, net news information held by the news server, mail data held by the mail server, and WWW (World Wide Web) server. Advertising information.

  The application unit 63 that has acquired the distribution data related information in this way selects any one of the unicast distribution, the multicast distribution, and the broadcast distribution as the distribution method, and sends the selected distribution method to the communication protocol control unit 62. Make a notification. Note that the application unit 63 does not have to select a delivery method when the client 20 can receive data delivery by all delivery methods. If the distribution method is not selected, the application unit 63 notifies the communication protocol control unit 62 that there is no selection.

  Further, when the client 20 cannot receive data distribution by any of the distribution methods, for example, the client 20 can receive only data distribution by unicast distribution and broadcast distribution, and can receive data distribution by multicast distribution. If not, the application unit 63 selects a distribution method from which the client 20 can receive data distribution, and notifies the communication protocol control unit 62 of the selected distribution method and the selected distribution method. Notification that it should be forcibly set.

  The communication protocol control unit 62 that has received the notification of the distribution method or the notification of no selection generates a distribution request message as information related to data reception. This distribution request message includes a distribution method type, a data ID, and a data ID type as information corresponding to the distribution method selected by the application unit 63. The distribution method type is information that uniquely identifies the distribution method selected by the application unit 63. When the application unit 63 does not select a distribution method, this distribution method type is not included. The data ID is information for uniquely identifying distribution data requested by the client 20. The data ID type is information for identifying an attribute of the data ID, and includes, for example, a URI (Uniform Resource Indication), a content ID, a multicast session ID, a multicast IP address of a distribution destination, a broadcast channel ID, and the like.

  When the communication protocol control unit 62 receives a notification from the application unit 63 that the selected distribution method should be forcibly set, the communication protocol control unit 62 adds information (for example, a flag) indicating that to the distribution request message. . Hereinafter, a distribution request message to which information indicating that a distribution method should be forcibly set is added is referred to as a forced distribution request message.

  The distribution request message and the forced distribution request message can include a plurality of pieces of information related to the distribution method. For example, when the application unit 63 activates two applications at the same time, selects multicast distribution corresponding to one application, and selects unicast distribution corresponding to the other application, the distribution request message and the forced distribution request message Can include both information corresponding to multicast distribution and information corresponding to unicast distribution.

  Further, the communication protocol control unit 62 transmits the generated distribution request message or forced distribution request message to the router 30 via the communication interface unit 61 when the application unit 63 selects unicast distribution or multicast distribution as the distribution method. To do.

  On the other hand, when the application unit 63 selects broadcast distribution as a distribution method and generates a distribution request message according to the selection, the communication protocol control unit 62 may transmit the distribution request message to the router 30. The reception of distribution data may be awaited without transmission. The distribution request message need not be transmitted because, in the case of broadcast distribution, the client 20 can receive distribution data simply by waiting for reception of distribution data.

  FIG. 4 is a diagram illustrating a detailed configuration of the router 30. As shown in the figure, the router 30 includes a communication interface unit 71, a communication protocol control unit 72, and a storage device 73. Further, the storage device 73 holds a client management table 731 and a distribution method management table 732.

  The communication interface unit 71 receives the distribution request message or the forced distribution request message from the client 20 and outputs it to the communication protocol control unit 72.

  When the received message is a distribution request message, the communication protocol control unit 72 adds a record including information in the distribution request message to the client management table 731 held in the storage device 73.

  FIG. 5 is a diagram illustrating an example of the client management table 731. The client management table 731 associates the distribution data, the client 20 that is the distribution destination of the distribution data, and the distribution method. In the client management table 731 shown in FIG. 5, one record includes a data ID, a data ID type, a client IP address, a distribution method type requested by the client 20 (request distribution method type), and a distribution method type determined by the router 30. (Determined delivery method type) and status information indicating the current state of message exchange between the router 30 and the client 20.

  The communication protocol control unit 72 associates the data ID, data ID type, and distribution method type in the distribution request message with the data ID, data ID type, and request distribution method type of the client management table 731, respectively. Further, the communication protocol control unit 72 associates the source IP address included in the header of the distribution request message with the client IP address of the client management table 731. Furthermore, the communication protocol control unit 72 uses the current state of message exchange between the router 30 and the client 20 as status information. For example, when receiving the distribution request message, the communication protocol control unit 72 sets the status information to “distribution request received” as shown in the third record of the client management table 731 in FIG. The determined distribution method type will be described later. In the client management table 731 shown in FIG. 5, “U” in the request distribution method type and the determined distribution method type indicates unicast distribution, “M” indicates multicast distribution, and “B” indicates broadcast distribution.

  The communication protocol control unit 72 has already included in the client management table 731 a record including the data ID, data ID type and distribution method type in the received distribution request message, and the transmission source IP address of the distribution request message. If so, no record is added.

  After adding the record to the client management table 731, the communication protocol control unit 72 further updates the distribution method management table 732 held in the storage device 73. FIG. 6 is a diagram illustrating an example of the distribution method management table 732. This distribution method management table 732 is a reference for determining a distribution method according to distribution data, the number of clients 20 that are distribution destinations of the distribution data, and the number of clients 20 that are distribution destinations of the distribution data. Is associated with the threshold value. The threshold value can be set to a different value for each multicast address as the corresponding data ID or for each router 30. For example, when a threshold is set for each multicast address, the node that determines the threshold extends SDP (Session Description Protocol) that expresses multicast session information such as a multicast address, a port number, and distribution data. By providing a field including “”, it is possible to notify each router 30 and the client 20 of the threshold value.

  In the distribution method management table 732 shown in FIG. 6, one record includes a data ID, a threshold value, and the number of members (the number of clients serving as distribution destinations). When updating the distribution method management table 732, the communication protocol control unit 72 specifies a record including the data ID in the received distribution request message from the distribution method management table 732, and the number of members in the specified record. Increase by one.

  Further, the communication protocol control unit 72 periodically determines a distribution method at a predetermined timing. Specifically, the communication protocol control unit 72 selects one data ID that is information for identifying distribution data and the client IP address of the client 20 that is the distribution destination of the distribution data specified by the data ID. . Next, the communication protocol control unit 72 specifies a record including the selected data ID from the records in the distribution method management table 732, and determines the distribution method based on the threshold value and the number of members in the specified record. Then, it is determined to be either multicast distribution or broadcast distribution. For example, when the data protocol “224.1277.32.7” and the client IP address “192.168.4.234” are selected, the communication protocol control unit 72 is the first in the distribution method management table 732 shown in FIG. Identify the records. This record has a threshold value of “unicast distribution when the number of members is 2 or less and multicast distribution when the number of members is 3 or more”, and the number of members is “2”. Therefore, the communication protocol control unit 72 converts the distribution data specified by the selected data ID “224.1277.32.7” to the client 20 specified by the selected client IP address “192.168.4.234”. Unicast delivery is determined as the delivery method when delivering to

  After determining the distribution method in this way, the communication protocol control unit 72 then adds the determined communication method to the determined distribution method in the corresponding record in the client management table 731. For example, when the communication protocol control unit 72 distributes the distribution data specified by the data ID “224.127.32.7” to the client 20 specified by the client IP address “192.168.4.234”. 1 is included in the client management table 731 shown in FIG. 5 and includes the data ID “224.1277.32.7” and the client IP address “192.168.4.234”. The decision distribution method in the th record is “U”.

  Next, the communication protocol control unit 72 finds a record having a different request distribution method type and a determined distribution method type from each record of the client management table 731 and extracts a client IP address in the record. The client 20 specified by the extracted client IP address is a client 20 in which the distribution method requested by the client 20 is different from the distribution method determined by the router. For example, in the client management table 731 illustrated in FIG. 5, the communication protocol control unit 72 performs the client IP address “192.168.4.434” in the first record and the client IP address “192” in the second record. .1688.4.12 ".

  Further, the communication protocol control unit 72 generates a distribution request response message and transmits the extracted client IP address as a transmission destination. This delivery request response message includes a decision delivery method type, a data ID, a data ID type, and the like associated with the extracted client IP address in the client management table 731. The communication protocol control unit 72 normally transmits a distribution request response message to the client 20 by unicast distribution. If there is a multicast group to which the client 20 is subscribed, the communication protocol control unit 72 A multicast address may be transmitted as a transmission destination.

  Next, the communication protocol control unit 72 sets the status information associated with the extracted client IP address in the client management table 731 as “distribution request response transmitted”.

  The communication protocol control unit 62 in the client 20 receives this distribution request response message via the communication interface unit 61. Further, the communication protocol control unit 62 recognizes that the distribution method different from the distribution method selected by itself is determined by the determined distribution method type in the distribution request response message, and receives the distribution data by the distribution method. Starts the standby required for At this time, the communication protocol control unit 62 may notify the application unit 63 of the distribution method determined by the router 30. In this case, the application unit 63 can notify the user that the distribution method has been changed by performing a dialog box display or the like through the input / output processing unit 64.

  Note that the communication protocol control unit 72 in the router 30 transmits a distribution request response message to all the clients 20 managed by the client management table 731, and the application unit 63 in the client 20 receives this message. You may do it.

  On the other hand, when the received message is a forced delivery request message, the communication protocol control unit 72 adds a record to the client management table 731 in which information in the forced delivery request message is held in the storage device 73.

  Specifically, as in the case of receiving the distribution request message, the communication protocol control unit 72 sets the data ID, data ID type, and distribution method type in the forced distribution request message to the data ID and data in the client management table 731 respectively. Corresponding to the ID type and the request distribution method type. Further, the communication protocol control unit 72 associates the source IP address included in the header of the distribution request message with the client IP address of the client management table 731. Furthermore, the communication protocol control unit 72 uses the current state of message exchange between the router 30 and the client 20 as status information.

  Note that the communication protocol control unit 72 already includes in the client management table 731 a record including the data ID, the data ID type and the distribution method type in the received forced distribution request message, and the transmission source IP address of the distribution request message. If it is, the record is not added.

  Next, the communication protocol control unit 72 determines the request distribution method type in the record added to the client management table 731 as the determined distribution method type as it is. As a result, the router 30 can distribute the distribution data to the client 20 by the distribution method requested by the client 20.

  Further, the communication protocol control unit 72 generates a forced distribution request response message and transmits the client IP address in the record added to the client management table 731 as a transmission destination. This distribution request response message includes a determined distribution method type, a data ID, a data ID type, and the like in the record added in the client management table 731. Further, the communication protocol control unit 72 sets the status information in the added record to “forced distribution request response transmitted”.

  When the communication protocol control unit 62 in the client 20 receives the forced distribution request response message via the communication interface unit 61, the distribution method selected by the communication protocol control unit 62 is determined by the determined distribution method type in the forced distribution request response message. The router 30 recognizes that it has been determined, and starts waiting for receiving distribution data by the distribution method.

  Also, the communication protocol control unit 62 in the client 20 sends a distribution stop request message as information for notifying the router 30 of the end or stop of data distribution after the end of data distribution or when it is desired to stop the data distribution. Is generated.

  The distribution stop request message includes a data ID and a data ID type as information corresponding to data whose distribution is to be ended or stopped. Further, the communication protocol control unit 62 adds information (for example, a flag) for identifying the distribution stop request message to the distribution stop request message and transmits the information to the router 30 via the communication interface unit 61.

  The communication interface unit 71 in the router 30 receives the delivery stop request message from the client 20 and outputs it to the communication protocol control unit 72. The communication protocol control unit 72 includes, in each record of the client management table 731, a record including the data ID and data ID type in the distribution stop request message and the transmission source IP address included in the header of the distribution stop request message. If there is, delete the record information.

  Further, the communication protocol control unit 72 specifies a record including the data ID in the received distribution stop request message from the records of the distribution method management table 732, and decreases the number of members in the specified record by one.

  Through the above procedure, the client management table 731 and the distribution method management table 732 held in the storage device 73 of the router 30 are updated in accordance with the data reception from the client 20. Hereinafter, the update operation of the client management table 731 and the distribution method management table 732 of the router 30 when data is received from the client 20 will be described with reference to the flowchart of FIG.

  When the communication protocol control unit 72 in the router 30 receives a message from the client 20 via the communication interface unit 71 (step 101), the communication protocol control unit 72 determines whether the received message is a distribution request message (step 101). 102).

  When the message from the client 20 is a delivery request message, the communication protocol control unit 72 includes, in the record of the client management table 731, the data ID, the data ID type, the delivery method type, and the delivery in the delivery request message. It is determined whether there is information that matches the source IP address of the request message (step 103). If there is no information, the data ID, data ID type and distribution method type in these distribution request messages, A record including information on the source IP address included in the header of the distribution request message is added to the client management table 731 (step 104).

  Next, the communication protocol control unit 72 specifies a record including the data ID in the received distribution request message from the distribution method management table 732, and increases the number of members in the specified record by 1 (step 105). ). The operations in steps 101 to 105 described above are performed every time the router 30 receives a message.

  Thereafter, the communication protocol control unit 72 selects one data ID and the client IP address of the client 20 that is the distribution destination of the distribution data specified by the data ID at a predetermined timing. Further, the communication protocol control unit 72 specifies a record including the selected data ID from the distribution method management table 732 and compares the threshold value in the specified record with the number of members to determine the distribution method (step 106). ). Next, the communication protocol control unit 72 adds the determined communication method to the determined distribution method in the corresponding record in the client management table 731 (step 107).

  Further, the communication protocol control unit 72 finds a record having a different request distribution method type and a determined distribution method type from each record of the client management table 731 and extracts a client IP address in the record (step 108). Then, the communication protocol control unit 72 generates a distribution request response message and transmits the extracted client IP address as the transmission destination (step 109). Thereafter, the communication protocol control unit 72 sets the status information associated with the extracted client IP address in the client management table 731 to “distribution request response transmitted” (step 110).

  On the other hand, if the communication protocol control unit 72 determines in step 102 that the message from the client 20 is not a distribution request message, it further determines whether or not the message is a forced distribution request message (step 111).

  When the message from the client 20 is a forced delivery request message, the communication protocol control unit 72 includes, in the record of the client management table 731, the data ID, data ID type, and delivery method type in the forced delivery request message, It is determined whether or not there is information that matches the transmission source IP address of the compulsory distribution request message (step 112). If there is no information, the data ID, data ID type, and distribution method in these compulsory distribution request messages are determined. A record including information on the type and the source IP address included in the header of the distribution request message is added to the client management table 731 (step 112).

  Next, the communication protocol control unit 72 determines the requested distribution method type in the record added to the client management table 731 as the determined distribution method type as it is (step 114).

  Further, the communication protocol control unit 72 generates a forced distribution request response message and transmits the extracted client IP address as a transmission destination (step 115). Thereafter, the communication protocol control unit 72 sets the status information in the added record to “forced distribution request response transmitted” (step 116).

  If the communication protocol control unit 72 determines in step 111 that the message from the client 20 is not a forced delivery request message, the communication protocol control unit 72 further determines whether or not the message is a delivery stop request message (step 117). .

  When the message from the client 20 is a delivery stop request message, the communication protocol control unit 72 includes, in the record of the client management table 731, the data ID, data ID type, and delivery method type in the delivery stop request message, It is determined whether there is information that matches the transmission source IP address of the distribution stop request message (step 118). If there is information, the data ID, data ID type, and distribution method in these distribution stop request messages are determined. A record including information on the type and the source IP address included in the header of the distribution request message is deleted from the client management table 731 (step 119).

  Further, the communication protocol control unit 72 specifies a record including the data ID in the received distribution stop request message from the records in the distribution method management table 732, and decreases the number of members in the specified record by 1 ( Step 120). The operations in steps 111 to 120 described above are performed every time the router 30 receives a message. Thereafter, the processing of steps 106 to 110 described above is performed.

  After the client management table 731 and the distribution method management table 732 are updated in this way, when the communication protocol control unit 72 in the router 30 receives distribution data from the content server 10 or another router 30, the distribution Using the data ID associated with the data as a key, the client management table 731 held in the storage device 73 is searched to identify a record including the data ID. Then, the communication protocol control unit 72 recognizes the distribution method based on the determined distribution method type in the specified record. When the recognized distribution method is different from the distribution method of the received distribution data, the communication protocol control unit 72 converts the recognized distribution method into the recognized distribution method, and sends it to the client 20 corresponding to the client IP address in the specified record. On the other hand, the received distribution data is transmitted. On the other hand, if the recognized distribution method is the same as the distribution method of the received distribution data, the communication protocol control unit 72 receives the received distribution to the client 20 corresponding to the client IP address in the specified record. Send the data as is. The communication protocol control unit 62 in the client 20 receives distribution data transmitted from the router 30 via the communication interface unit 61.

  In the embodiment described above, the router 30 updates the client management table 731 and the distribution method management table 732 based on the received distribution request message, forced distribution request message, and distribution stop request message. You may make it transmit to the other router 30 which belongs to the upper rank of an apparatus.

  For example, in the case of multicast distribution, a multicast tree is usually formed to transmit distribution data. This multicast tree specifies the distribution route of distribution data with the content server 10 and the router 30 having a special function called a rendezvous point as the apex so that multicast packets and the like are not transmitted redundantly. Is. Distribution data by multicast distribution is transferred in the lower direction in order from the top of this multicast tree, and finally reaches the client 20.

  In this multicast distribution, for example, a cost due to a protocol for managing a multicast tree, such as PIM (Protocol Independent Multicast), is required. For this reason, also in the distribution of the distribution data between the routers 30, it is effective to switch the distribution method as appropriate according to the number of members belonging to the multicast group.

  In the case of unicast distribution, a distribution route of distribution data from the content server 10 to each client 20 is set. At this time, distribution data to a plurality of clients 20 may be transferred to the same distribution path. In such a case, it is effective to perform multicast distribution on a distribution route through which distribution data to a plurality of clients 20 is transferred.

  In order to realize the function as described above, the communication protocol control unit 72 in the router 30 sends the received distribution request message, forced distribution request message, and distribution stop request message to other routers that belong to the host device in the multicast tree. 30 and other routers 30 belonging to the host device in the distribution route in unicast distribution.

  The communication protocol control unit 72 in the upper router 30 that has received the message from the lower router 30 updates the client management table 731 and the distribution method management table 732 based on the received message in the same manner as described above. . The distribution method management table 732 is provided for each distribution route toward the lower router 30. Furthermore, the communication protocol control unit 72 in the upper router 30 determines a distribution method, and transmits distribution data from the upper content server 10 or the router 30 to the lower router 30 according to the distribution method.

  For example, consider a case in FIG. 2 where the content server 10 transmits one piece of distribution data. In this case, the communication protocol control unit 72 in the router 30-1 transmits the distribution request message from the clients 20-1, 20-2, and 20-3 to the upper router 30-5. In addition, the communication protocol control unit 72 in the router 30-2 transmits the distribution request message from the clients 20-4 and 20-5 to the router 30-5.

  The communication protocol control unit 72 in the router 30-5 transmits the distribution request message from the routers 30-1 and 30-2 to the upper router 30-6. Also, the communication protocol control unit 72 in the router 30-5 updates the client management table 731 and the distribution method management table 732 based on the distribution request messages from the routers 30-1 and 30-2. At this time, the number of members of the delivery method management table 732 is three for the delivery route to the router 30-1, that is, the clients 20-1, 20-2, and 20-3, and the delivery route to the router 30-2. There are two clients 20-4 and 20-5.

  Further, the communication protocol control unit 72 in the router 30-5 determines the communication method by comparing the number of members with the corresponding threshold in the distribution method management table 732. For example, when the threshold value is “unicast distribution when the number of members is 2 or less, multicast distribution when the number of members is 3 or more”, the communication protocol control unit 72 in the router 30-5 determines the distribution route to the router 30-1. Since there are three members 20-1, 20-2 and 20-3, the distribution method is determined as multicast distribution, and the number of members regarding the distribution route to the router 30-2 is the client 20-4. And 20-5, the distribution method is determined as unicast distribution.

  Further, the communication protocol control unit 72 in the lower router 30 collects the distribution request messages received from the lower router 30 than the client 20 or itself for each corresponding distribution data, and creates a new distribution request message, A forced distribution request message and a distribution stop request message may be generated, and the generated new message may be transmitted to the upper router 30. In this case, the newly generated message includes the data ID, the data ID type, the number of subordinate clients serving as distribution destinations of the distribution data specified by the data ID, and the distribution data specified by the data ID. The distribution method type determined by the router 30 is included.

  The communication protocol control unit 72 in the upper router 30 updates the router management table based on the received message. FIG. 8 shows an example of the router management table. The router management table associates distribution data, a lower router 30 as a distribution destination of the distribution data, and a distribution method for distribution to the lower router 30. In the router management table shown in FIG. 8, one record includes a data ID, a data ID type, a router IP address, the number of clients under the lower router 30, and the type of distribution method determined by the lower router 30 (request distribution method). Type), the type of distribution method determined by the upper router 30 (determined distribution method type), and status information indicating the current state of message exchange between the upper router 30 and the lower router 30.

  The data ID, data ID type, and request distribution method type in the router management table correspond to the data ID, data ID type, and distribution method type in the message from the lower router 30 respectively. The router IP address in the router management table corresponds to the source IP address included in the message header. The number of subordinate clients in the router management table corresponds to the number of subordinate clients in the message. The status information in the router management table corresponds to the current state of message exchange between the upper router 30 and the lower router 30.

  The communication protocol control unit 72 in the upper router 30 adds a record corresponding to the router management table when receiving the distribution request message and the forced distribution request message, and when receiving the distribution stop request message, Delete the corresponding record from the router management table.

  Further, the communication protocol control unit 72 in the upper router 30 updates the distribution method management table 732 held in the storage device 73. Specifically, when receiving the distribution request message and the forced distribution request message, the communication protocol control unit 72 in the upper router 30 determines the number of subordinate clients in the received message in the distribution method management table 732. Of the records, it is added to the number of members of the record having the data ID in the received message. On the other hand, when the communication protocol control unit 72 in the upper router 30 receives the distribution stop request message, the number of members of the record having the data ID in the received message among the records in the distribution method management table 732. Is subtracted from the number of subordinate clients in the received message.

  Further, the communication protocol control unit 72 in the upper router 30 periodically determines a distribution method at a predetermined timing. The specific procedure is almost the same as the procedure for determining the distribution method described above. That is, the communication protocol control unit 72 in the upper router 30 has one data ID that is information for identifying the distribution data and the router IP of the lower router 30 that is the distribution destination of the distribution data specified by the data ID. Select an address. Next, the communication protocol control unit 72 in the upper router 30 identifies a record including the selected data ID from the records in the distribution method management table 732, and distributes it based on the threshold value and the number of members in the identified record. The system is determined as one of unicast distribution, multicast distribution, and broadcast distribution.

  After determining the distribution method in this way, the communication protocol control unit 72 in the next upper router 30 adds the determined communication method to the determined distribution method of the corresponding record among the records in the router management table. To do. Next, the communication protocol control unit 72 in the upper router 30 finds a record in which the request delivery method type and the determined delivery method type are different from each record in the router management table, and extracts the router IP address in the record. To do. The lower level router 30 specified by the extracted client IP address is different from the distribution method determined by the lower level router 30 and the determined distribution method determined by the higher level router 30. Further, the communication protocol control unit 72 in the upper router 30 generates a distribution request response message and transmits the extracted router IP address as a transmission destination. The distribution request response message includes a determined distribution method type, a data ID, a data ID type, and the like associated with the extracted router IP address in the router management table.

  Upon receiving this distribution request response message, the communication protocol control unit 72 in the lower router 30 recognizes that a distribution method different from the distribution method determined by itself is determined, and among the records of the client management table 731 The decision delivery method type of the record having the data ID in the delivery request response message delivery request response message is changed.

  Thereafter, the communication protocol control unit 72 in the lower router 30 finds a record in which the request distribution method type and the determined distribution method type are different from each record in the client management table 731. Then, the communication protocol control unit 72 in the lower router 30 transmits a distribution request response message to the client 20 specified by the client IP address in the record or the router 30 lower than itself.

  The upper router 30 may be connected to the lower router 30 and the client 20. In this case, the upper router 30 holds both the client management table 731 and the router management table.

  When the upper router 30 that holds both the client management table 731 and the router management table refers to either the client management table 731 or the router management table, the upper router 30 also refers to the other table to determine the number of subordinate clients. calculate. Then, the upper router 30 determines the distribution method by adding the calculated number of subordinate clients to the corresponding number of members in the distribution method management table 732 and comparing this number with the corresponding threshold value.

  Alternatively, as shown in FIG. 9, the upper router 30 may hold a node management table in which the client management table 731 and the router management table are combined. In this case, in the node management table, “client IP address” in the client management table 731 and “router IP address” in the router management table are set as “node IP address”, and whether the node is a client. A “node type” indicating whether it is a router is added.

  As described above, the upper router 30 manages the subordinate clients 20 and the lower routers 30 by holding the client management table 731 and the router management table or the node management table as necessary, and appropriately A delivery method can be determined.

  In each of the above embodiments, the communication protocol control unit 62 in the client 20 is an IGMP that is a multicast group management protocol used on the Internet when transmitting a distribution request message, a forced distribution request message, and a distribution stop request message. An IGMP Membership Report message in (Internet Group Management Protocol) can be used.

  Further, the communication protocol control unit 62 in the client 20 may periodically transmit a distribution request message to the router 30. In response to this message, the router 30 can determine whether or not the contents of the client management table 731 and the distribution method management table 732 in the storage device 73 match the state of the client 20.

  Further, the communication protocol control unit 72 in the router 30 may transmit a reception status inquiry message for inquiring the current state of the client 20 to the client 20 as necessary or periodically. In this case, the client 20 returns a delivery request message as a response to the reception status inquiry message. Note that the communication protocol control unit 72 in the router 30 uses an IGMP Source-and-Group-Specific Membership Query message, an IGMP Group-Specific Membership message, or an IGMP Source-and-Group-Membership Query message when multicast delivery is used when sending a delivery status inquiry message. Messages, or these extended messages can be used.

  As described above, the present invention is applied to information transmission / reception between the client 20 and the router 30 and information transmission / reception between the routers 30. Information transmission / reception between the client 20 and the router 30 and information transmission / reception between the routers 30 are also performed. And may be applied to both of them at the same time.

  As described above, in the data distribution system of this embodiment, the client 20 transmits information related to data reception to the router 30. Based on the distribution request message, forced distribution request message, and distribution stop message transmitted from the client 20, the router 30 uses a unicast distribution method for distributing data to the client 20 or another router 30. The data to be distributed is determined from any one of the multicast distribution and the broadcast distribution, and the distribution target data transmitted from the content server 10 is transmitted according to the determined distribution method.

  That is, the router 30 can determine an appropriate distribution method and perform efficient distribution regardless of the distribution method of the content server 10. Specifically, when the distribution method of the content server 10 is multicast distribution, the router 30 determines that the number of members of the multicast group under its own device (the number of clients 20 under the own device in the distribution route) is If the number is small, the distribution method is switched from multicast distribution to unicast distribution. For this reason, it is possible to reduce the communication cost by the control information (IGMP, PIM, etc.) for managing the multicast group, and this is particularly effective in a wireless network with a high communication cost.

  Further, when the router 30 periodically determines the distribution method, it is possible to determine an appropriate distribution method according to an increase or decrease in the number of subordinate members. Furthermore, the router 30 can appropriately set the distribution method between the routers 30 by transmitting a message from the client 20 to the other routers 30 belonging to the host device.

It is a figure which shows the structural example of the conventional data delivery system. It is a figure which shows the structural example of the data delivery system of this embodiment. It is a figure which shows the structural example of a client. It is a figure which shows the structural example of a router. It is a figure which shows an example of a client management table. It is a figure which shows an example of a delivery system management table. It is a flowchart which shows operation | movement of the router at the time of the data reception from a client. It is a figure which shows an example of a router management table. It is a figure which shows an example of a node management table.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Content server 20 Client 30 Router 40, 50 Communication network 61, 71 Communication interface part 62, 72 Communication protocol control part 63 Application part 64 Input / output processing part 65, 73 Storage device 731 Client management table 732 Distribution system management table

Claims (18)

In a data distribution system including a data distribution device, a data relay device, and a data reception device connected to a communication network, one or a plurality of the data from the data distribution device via one or a plurality of the data relay devices In a data distribution method for distributing data to a receiving device,
The data receiving device is:
Notifying the data relay device of information related to data reception,
The data relay device
Managing information related to data reception notified from the data receiving device;
If the information on data reception includes a forced delivery request message that forcibly specifies a delivery method, determine the designated delivery method;
When the data reception information includes a distribution request message that does not specify a distribution method, based on the managed data reception information, determine a distribution method for distributing data to the data receiving device,
Notifying the data receiving device of the determined delivery method,
Based on the determined distribution method, the data from the data distribution device is transmitted to the data reception device,
The data receiving device is:
A data distribution method comprising: receiving data from the data relay device based on a distribution method notified from the data relay device. The data distribution method according to claim 1,
Determining a distribution method for distributing data to the data receiving device based on the managed information regarding data reception when the information regarding data reception includes a distribution stop request message for stopping distribution; A characteristic data distribution method. The data distribution method according to claim 1 or 2,
The information relating to data reception includes data identification information desired to be distributed by the data receiving device and data distribution method identification information desired by the data receiving device. The data distribution method according to any one of claims 1 to 3,
The data relay device
A data distribution method characterized by periodically determining a distribution method for distributing data to the data receiving device based on the information relating to data reception to be managed. The data distribution method according to any one of claims 1 to 4,
The data delivery method according to claim 1, wherein the delivery method is any one of unicast delivery, multicast delivery, and broadcast delivery. The data distribution method according to claim 5, wherein
The data relay device determines the distribution method to be unicast distribution when the number of data receiving devices to which predetermined data from the own device is distributed is equal to or less than a threshold value, and distributes the data when the number exceeds the threshold value. A data distribution method characterized in that a method is determined to be multicast distribution or broadcast distribution. Consists of a data distribution device, a data relay device, and a data reception device connected to a communication network, and distributes data from the data distribution device to one or more data reception devices via one or more data relay devices In the data distribution system that
The data receiving device is:
First data reception information notification means for notifying the data relay device of information related to data reception;
Data receiving means for receiving data from the data relay device based on a delivery method notified from the data relay device;
With
The data relay device
Data reception information management means for managing information related to data reception notified from the data receiving device;
When the information regarding data reception includes a forced distribution request message forcibly specifying a distribution method, the specified distribution method is determined, and when the information regarding data reception includes a distribution request message without specifying a distribution method A distribution method determining means for determining a distribution method for distributing data to the data receiving device based on the managed data reception information;
A delivery method notification means for notifying the data delivery device of the determined delivery method;
Data transmission means for transmitting data from the data distribution device to the data reception device based on the determined distribution method;
A data distribution system comprising: The data distribution system according to claim 7, wherein
The distribution method determining means, when the information related to data reception includes a distribution stop request message for stopping distribution, based on the managed information related to data reception, A data distribution system characterized by determining a distribution method. The data distribution system according to claim 7 or 8,
The data distribution system characterized in that the distribution method determining means periodically determines a distribution method for distributing data to the data receiving device. The data distribution system according to any one of claims 7 to 9,
The data distribution system, wherein the distribution method is any one of unicast distribution, multicast distribution, and broadcast distribution. The data distribution system according to claim 10, wherein
The distribution method determining means determines the distribution method to be unicast distribution when the number of data receiving devices serving as distribution destinations of predetermined data from the own device is equal to or less than a threshold, and exceeds the threshold, A data distribution system, wherein a distribution method is determined to be multicast distribution or broadcast distribution. In a data relay device that is connected to a communication network and distributes data from a data distribution device to a data reception device,
Data reception information management means for managing information related to data reception notified from the data receiving device;
When the information regarding data reception includes a forced distribution request message forcibly specifying a distribution method, the specified distribution method is determined, and when the information regarding data reception includes a distribution request message without specifying a distribution method A distribution method determining means for determining a distribution method for distributing data to the data receiving device based on the managed data reception information;
A delivery method notification means for notifying the data delivery device of the determined delivery method;
Data transmission means for transmitting data from the data distribution device to the data reception device based on the determined distribution method;
A data relay device comprising: The data relay device according to claim 12,
The distribution method determining means, when the information related to data reception includes a distribution stop request message for stopping distribution, based on the managed information related to data reception, A data relay apparatus that determines a distribution method. The data relay device according to claim 12 or 13,
The data relay device according to claim 1, wherein the distribution method determining means periodically determines a distribution method for distributing data to the data receiving device. The data relay device according to any one of claims 12 to 14,
A communication interface unit having a function of performing communication with other devices;
A communication protocol control unit having a function of performing communication protocol processing;
A storage unit having a function of storing information;
A data relay device comprising: The data relay device according to any one of claims 12 to 15,
The data relay apparatus according to claim 1, wherein the distribution method is any one of unicast distribution, multicast distribution, and broadcast distribution. The data relay device according to claim 16, wherein
The distribution method determining means determines the distribution method to be unicast distribution when the number of data receiving devices serving as distribution destinations of predetermined data from the own device is equal to or less than a threshold, and exceeds the threshold, A data relay apparatus, wherein a distribution method is determined to be multicast distribution or broadcast distribution. In a data distribution program for operating a data relay device that is connected to a communication network and distributes data from a data distribution device to a data reception device,
A procedure for managing information related to data reception notified from the data receiving device;
When the information regarding data reception includes a forced distribution request message forcibly specifying a distribution method, the specified distribution method is determined, and when the information regarding data reception includes a distribution request message not specifying a distribution method Determining a delivery method for delivering data to the data receiving device based on managed data reception information;
A procedure for notifying the data receiving apparatus of the determined delivery method;
A procedure for transmitting data from the data distribution device to the data receiving device based on the determined distribution method;
Data distribution program to execute.

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