JP2006319495A - Distribution system, node device and method for complementing data packet or the like - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a distribution system capable of complementing a defective data packet more efficiently without shouldering a large burden on a specific device such as a distribution server, and the like, to provide a node device, and to provide a method for complementing the data packet or the like. <P>SOLUTION: In the distribution system, a plurality of the node devices are connected through communication paths while forming a plurality of hierarchies, and a plurality of the continuous data packets are distributed while being relayed in the downstream direction from an upstream direction. The distribution system has a packet receiving means for receiving a plurality of the distributed continuous data packets, and a defective packet presence discriminating means for discriminating whether or not there is a defective data packet. The distribution system further has an complement demand transmission means for transmitting the complement demand information of the defective data packet to the node devices excepting the node device positioned in its own downstream when the defective data packet is discriminated and an complementing packet receiving means for receiving the data packet being replied to the complement demand transmission means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technical field such as a missing data packet compensation method in a content distribution system or the like in which a plurality of continuous data packets forming a content unit are distributed while being relayed by a node device from upstream to downstream.

  As this type of content distribution system, Patent Document 1 discloses a stream data distributed distribution system, in which each node device has topology information for recognizing a network connection relationship, Each node device is connected to the upstream (upper layer) node device recognized by the topology information, receives the stream data transmitted from the upstream node device, and forwards (relays) it to the downstream (lower layer) node device ).

In such a content distribution system, a communication that does not perform delivery confirmation such as UDP (User Datagram Protocol) is used for communication between node devices, and each node device freely participates in and leaves the network (for example, Therefore, data packets are lost at a certain rate in the content received by each node device.
JP 2003-169089 A

  By the way, as described above, when a data packet loss occurs, for example, a method of acquiring and complementing the missing data packet from a distribution server that is a content distribution source can be considered. There is a problem that access to the distribution server is concentrated and imposes a heavy burden.

  The present invention has been made in view of the above problems and the like, and a distribution system, a node device, and the like that can complement missing data packets without imposing a heavy burden on a specific device such as a distribution server. It is another object of the present invention to provide a data packet complementing method and the like.

  In order to solve the above-mentioned problem, according to the first aspect of the present invention, a plurality of node devices are connected via a communication path while forming a plurality of hierarchies, and a plurality of continuous data packets are directed from upstream to downstream. In the node device included in the distribution system that is distributed while being relayed by the node device, the packet receiving unit that receives the plurality of continuous data packets that have been distributed and the missing data based on the received data packet A missing packet presence / absence judging means for judging whether or not there is a data packet, and a node other than a node device located downstream of the node when the missing packet presence / absence judging means determines that there is the missing data packet Complement request transmission means for transmitting complement request information of the missing data packet to the device, and the complement request Characterized in that it and a complementary packet receiving means for receiving a data packet sent back from the node device relative distribution.

  According to the present invention, since it is configured to transmit the complement request information of the missing data packet to a node device other than the node device located downstream of itself, a large burden is placed on a specific device such as a distribution server. It is possible to compensate for missing data packets without imposing.

  According to a second aspect of the present invention, in the node device according to the first aspect, the complement request transmitting means is an upstream located on a communication path from itself to a distribution source device that is a distribution source of the data packet. One of the first node device and the second node device other than the node device located on the downstream side of the communication path is selected with a preset probability, The complement request information is transmitted to the selected node device.

  According to the present invention, any one of the first node device and the second node device is selected with a preset probability, and the supplement request information is sent to the selected node device. Since it is configured to transmit, a data packet can be complemented efficiently in a wide range without imposing a burden on a specific node device.

  According to a third aspect of the present invention, in the node device according to the second aspect, the probability that the first node device is selected is set higher than the probability that the second node device is selected. Features.

  According to the present invention, in a situation where the supplement request information is repeatedly transferred, convergence near the distribution source device with little packet loss can be accelerated, so that data packets can be supplemented more quickly.

  According to a fourth aspect of the present invention, in the node device according to the second or third aspect, the second node device is a node device in a hierarchy higher than or equal to itself.

  According to the present invention, since complementary request information is always transferred to other node devices on the upper layer side with reference to its own device, it is possible to avoid the loop of complementary request information from being transferred.

  According to a fifth aspect of the present invention, in the node device according to any one of the second to fourth aspects, the plurality of node devices have a communication path while forming a plurality of hierarchies with the distribution source device as a vertex. The second node device is a communication path branched from the distribution source device, and is different from the communication route from itself to the distribution source device of the data packet. It is located on a communication path.

  According to the fifth aspect of the present invention, since the transfer processing of the supplement request information is converged to a single distribution source device, the data packet can be complemented more reliably.

  According to a sixth aspect of the present invention, in the node device according to any one of the first to fifth aspects, the storage unit that temporarily stores the received data packet and the plurality of units that form a unit of content When the missing data packet is supplemented by the supplement request information, the complete content data is restored by using the plurality of data packets stored in the storage means and the supplement packet. And recording means for recording on a recording medium.

  According to the sixth aspect of the present invention, since the purchased content can be restored by diverting the distributed stream, it is possible to reduce the amount of data communication related to the content purchase.

  A seventh aspect of the present invention is a node device comprising complementary request information receiving means for receiving the complementary request information transmitted from the node device according to any one of the first to sixth aspects, wherein the reception is received. Packet presence / absence determining means for determining whether or not the data packet indicated by the supplement request information is included, and when the packet presence / absence determining means determines that the data packet is included, Data packet return means for returning the data packet to the node device that has transmitted the complement request information.

  According to the present invention, when there is a data packet indicated in the supplement request information, the node device that has received the supplement request information returns the data packet to the node device that has transmitted the supplement request information. Missing data packets can be complemented without imposing a heavy burden on a specific device such as a distribution server.

  The invention according to claim 8 is the node device according to claim 7, other than the node device located downstream of itself when the packet presence / absence determining unit determines that the data packet is not included. Further, a supplement request transfer means for transferring the supplement request information to the node device is provided.

  According to the present invention, the node device that has received the supplement request information is a node device other than the node device that is located downstream of the node device that has received the supplement request information when there is no data packet indicated by the supplement request information. The supplement request information is transferred to the device, that is, the supplement request information is transferred up to the node device having the missing data packet, so that the missing data packet of the complement request source is complemented in a specific node device. Even if it is not possible, the complementary processing can be supplemented by another node device.

  The invention according to claim 9 is a node device comprising supplement request information receiving means for receiving the complement request information transmitted from the node device according to any one of claims 1 to 6, wherein the complement request The information includes a missing packet list in which packet identification information corresponding to each of the plurality of missing data packets is described, and whether or not each of the data packets indicated by the missing packet list is included. A packet presence / absence judging means for judging whether the data packet is judged to be present by the packet presence / absence judging means, a data packet replying means for replying to the node device that sent the complementary request information, and data relating to the reply Missing packet that deletes packet identification information corresponding to the packet from the missing packet list and updates the missing packet list The packet identification information is still determined by the packet update information, the packet identification information presence / absence determination means for determining whether or not the packet identification information is still described in the updated lost packet list, and the packet identification information presence / absence determination means. If it is determined that it is described, complementary request transfer means for transferring the complementary request information including the updated missing packet list to a node device other than the node device located downstream of itself, It is characterized by providing.

  According to the present invention, since the supplement request information is continuously transferred in an appropriately updated form until all of the data packets indicated in the supplement request information can be supplemented, a load is not imposed on a specific node device, and Can reliably complement data packets in a wide range.

  According to a tenth aspect of the present invention, in the node device according to the eighth or ninth aspect, the complementary request transfer means is located on a communication path from itself to a distribution source device that is a distribution source of the data packet. The first node device upstream and the second node device other than the node device located on the downstream side of the communication path are selected with a preset probability. The complement request information is transferred to the selected node device.

  According to the present invention, any one of the first node device and the second node device is selected with a preset probability, and the supplement request information is sent to the selected node device. Since it is configured to transmit, a data packet can be complemented more efficiently in a wide range without imposing a burden on a specific node device.

  According to an eleventh aspect of the present invention, in the node device according to the tenth aspect, the probability that the first node device is selected is set higher than the probability that the second node device is selected. Features.

  According to the present invention, in a situation where the supplement request information is repeatedly transferred, convergence near the distribution source device with little packet loss can be accelerated, so that data packets can be supplemented more quickly.

  According to a twelfth aspect of the present invention, in the node device according to the tenth or eleventh aspect of the invention, the second node device is a node device having a hierarchy higher than or equal to itself.

  According to the present invention, since complementary request information is always transferred to other node devices on the upper layer side with reference to its own device, it is possible to avoid the loop of complementary request information from being transferred.

  The invention according to claim 13 is the node device according to any one of claims 10 to 12, wherein the plurality of node devices have a communication path while forming a plurality of hierarchies with the distribution source device as a vertex. The second node device is a communication path branched from the distribution source device, and is different from the communication route from itself to the distribution source device of the data packet. It is located on a communication path.

  According to the present invention, since the transfer processing of the supplement request information is converged to a single distribution source device, the data packet can be complemented more reliably.

  A program according to a fourteenth aspect causes a computer to function as the node device according to any one of the first to sixth aspects.

  A program according to a fifteenth aspect causes a computer to function as the node device according to any one of the seventh to thirteenth aspects.

  According to a sixteenth aspect of the present invention, a plurality of node devices are provided, the plurality of node devices are connected via a communication path while forming a plurality of hierarchies, and a plurality of continuous data packets are directed from upstream to downstream. In the distribution system distributed while being relayed by the node device, one of the node devices is missing based on the received data packet and packet receiving means for receiving the plurality of continuous data packets distributed. A missing packet presence / absence judging means for judging whether or not there is a lost data packet; and when the missing packet presence / absence judging means judges that there is the missing data packet, Complement request transmission means for transmitting complement request information indicating a complement request for the missing data packet to the node device And a supplement packet receiving means for receiving a data packet returned from the other node device in response to the complement request information, wherein the other node device transmits the complement transmitted from the first node device. Complement request information receiving means for receiving request information, packet presence / absence determining means for determining whether or not the missing data packet indicated by the received complement request information is included, and packet presence / absence determining means When it is determined that the data packet is included, data packet return means is provided for returning the data packet to the one node device.

  According to a seventeenth aspect of the present invention, in the distribution system according to the sixteenth aspect, when the other node device is determined not to have the data packet by the packet presence / absence determining means, It further comprises supplement request transfer means for transferring the supplement request information to a node device other than the node device located downstream.

  In the invention according to claim 18, a plurality of node devices are connected via a communication path while forming a plurality of hierarchies, and a plurality of continuous data packets are distributed while being relayed by the node device from upstream to downstream. A method of complementing data packets in a distributed system, the step of receiving a plurality of continuous data packets distributed in one of the node devices, and the receiving of data in the one node device A step of determining whether or not there is a missing data packet based on the packet; and if it is determined in the one node device that the missing data packet is present, a position downstream of the one node device A process of transmitting complement request information indicating a complement request for the missing data packet to a node device other than the node device to perform Receiving the supplement request information transmitted from the one node device in the other node device, and the missing data indicated by the received supplement request information in the other node device. A step of determining whether or not the data packet is included; and when the other node device determines that the data packet is included, the data packet is sent to the one node device. A step of returning, and a step of receiving, in the one node device, a data packet returned from the other node device.

  According to a nineteenth aspect of the present invention, in the data packet complementing method according to the eighteenth aspect, when the other node device determines that the data packet is not included, the other node device. The method further comprises a step of transferring the complement request information to a node device other than the node device located downstream of the node device.

  According to the present invention, the configuration is such that the complement request information of the missing data packet is transmitted to the node device other than the node device located downstream of the node device, and the packet is complemented from the node device. Missing data packets can be complemented without imposing a heavy burden on specific devices such as servers.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, the best embodiment of the invention will be described with reference to the drawings. The embodiment described below is an embodiment when the present invention is applied to a tree-type content distribution system.

[1. Configuration of tree-type content distribution system]
First, with reference to FIG. 1, a schematic configuration and functions of the tree-type content distribution system will be described.

  FIG. 1 is a diagram illustrating an example of a connection mode of each device in the tree-type content distribution system according to the present embodiment.

  As shown in the lower frame 101 of FIG. 1, IX (Internet eXchange) 5, ISP (Internet Service Provider) 6, DSL (Digital Subscriber Line) line operator (device) 7, FTTH (Fiber To The Home) line A network (real world network) 10 such as the Internet is constructed by a business operator (device) 8, a router (not shown), a communication line (for example, a telephone line, an optical cable, etc.) 9, and the like. In the lower frame 101 of FIG. 1, the thickness of the solid line corresponding to each communication line 9 represents the bandwidth (for example, data transfer rate) of each communication line 9.

  The tree-type content distribution system S according to the present embodiment includes a broadcasting station device 1 as a distribution source device that is a distribution source of a plurality of continuous data packets that form a unit of content, and a plurality of node devices 2a, 2b, and 2c. , 2d, etc., and is configured as shown in the upper frame 100 of FIG. 1 on the basis of the network 10 as shown in the lower frame 101 of FIG. A plurality of node devices are connected as a tree via a communication path while forming a plurality of hierarchies (four hierarchies in the example of FIG. 1), and the plurality of continuous data packets are upstream (upper hierarchies). Are distributed while being relayed (transferred) by each node device in the downstream (lower hierarchy) direction. In the following description, when any one of the node devices 2a, 2b, 2c, 2d... Is shown, the node device 2 may be referred to for convenience.

  A node device 2 shown in the upper frame 100 of FIG. 1 is a node device 2 that participates in the tree-type content distribution system S. In order to participate in the tree-type content distribution system S, a node that has not participated It is necessary for the device to make a participation request to the connection destination introduction (inquiry) server 3 and to be authenticated by the connection destination introduction (inquiry) server 3 that there is an authority to participate. This connection destination introduction (inquiry) server 3 has location information (for example, IP (Internet Protocol) address and port number (standby port number)) of the broadcast station apparatus 1 and the node apparatus 2 participating in the tree-type content distribution system S. ) And topology (connection mode) information between the broadcast station apparatus 1 and the node apparatus 2 and each node apparatus 2 in the tree-type content distribution system S are managed using a database. After performing the authentication in response to the participation request, the location information of the node device 2 that has already participated (selected in consideration of the tree topology) is notified to the node device. . The node device that has received the notification of the location information establishes a connection with the node device 2 that has already participated based on the location information, and thereby participates in the tree-type content distribution system S.

  Note that the tree-like topology indicates the maximum number of connections and the balance (symmetry) of the downstream node devices 2 directly connected to each node device 2, and the locality between the node devices 2 (proximity on the network 10 ( The number of hops (the number of intervening routers is so high that it is small) is determined.

  In addition, when the node device 2 that has already participated is turned off or has a communication failure, the node device 2 leaves the tree-type content distribution system S, and is thus directly connected to the node device 2 that has left the node. The downstream node device 2 or the like acquires the location information of the already participating node device 2 as a new connection destination from the connection destination introduction (inquiry) server 3 and establishes a connection.

  Furthermore, a tree-like topology in the tree-type content distribution system S is formed for each broadcasting station apparatus, in other words, for each broadcasting channel (only one broadcasting channel is shown in the upper frame 100 in FIG. 1). (However, in some cases, one broadcast station apparatus can cover a plurality of broadcast channels.) For example, when the user switches the broadcast channel in the already participating node apparatus 2, the node apparatus 2 The location information of the node device 2 that has already participated in the broadcast channel after switching is acquired from the connection destination introduction (inquiry) server 3 to establish a connection. The broadcast channel switching control is not directly related to the present invention, and thus detailed description thereof is omitted.

  In such a tree-type content distribution system S, a plurality of data packets stream-distributed from the broadcasting station apparatus 1 are relayed by each node apparatus in the upstream to downstream direction (for example, the upper part of FIG. 1). When any one or a plurality of data packets are lost in the node device 2a → the node device 2c → the node device 2g → the node device 2o) shown in the frame 100, the node device 2 that recognizes the loss of the data packet is The missing data packet complement request information is transmitted to node devices 2 other than the node device 2 located downstream of itself (the own node device). In contrast, when the node device 2 that has received the supplement request information has a data packet indicated by the supplement request information, the node device 2 transmits the data to the node device 2 that is the transmission source of the supplement request information. When the packet is returned and the data packet is not included, the supplement request information is transferred to the node device 2 other than the node device 2 located downstream of the packet. Thus, the supplement request information is transferred until it reaches the node device 2 having the data packet indicated therein (if there are a plurality of missing data packets, all data packets can be complemented). Forwarded). Then, the node device 2 that is the transmission source of the complement request information receives the data packet returned from the other node device 2 in response to the complement request information, and complements the missing packet in its own device. To do.

  Here, the transmission destination (or transfer destination) of the complement request information is set as “a node device other than the node device located downstream of itself” because the node device 2 located downstream of itself is missing on the upstream side of itself. This is because the data packet cannot be supplemented even if the supplement request information is transmitted (or transferred) to these devices. For example, node devices 2g, 2h, 2o, 2p, 2q, and 2r correspond to node devices located downstream of the node device 2c in the upper frame 100 of FIG. 1 (of these, the node devices 2g and 2h are , A downstream node device that is directly connected to the node device 2c when viewed from the node device 2c).

  As a destination of transmission (or transfer) of the complement request information, any node device 2 other than the node device 2 located downstream of itself may be used. However, a burden is imposed on the broadcast station device 1 and the upstream node device 2 as much as possible. In order to make it possible to complement the data packet more efficiently, it is assumed that the node device 2 closer to the broadcast station device 1 in a tree-like topology is less likely to lose data packets. Each node device 2 includes an upstream node device 2 (an example of a first node device, hereinafter referred to as an “upstream node device”) to which it directly connects the complement request information, and a broadcast station device for data packets from the node device 2 A node device 2 other than the node device 2 located on the communication path up to 1 and downstream of itself (an example of a second node device, hereinafter, “distant node device”) Say) and any selected one of a node 2 at a preset probability, transmission to the selected node 2 (or transfer) it is desirable to.

  This is because the tree-like topology is formed in consideration of the locality between the node devices 2, so that the upstream node device (for example, the upstream node device of the node device 2c in the upper frame 100 of FIG. The node device 2a) is often close to the network (for example, the number of pops is small). Therefore, there is a possibility that the missing data packet can be quickly acquired. Since the node device 2 (particularly the upstream node device) located on the communication path up to the possibility of missing the same data packet, if it is a far node device located on another communication path, This is because the possibility that the self has a missing data packet is high. The location information of the remote node device is acquired from the connection destination introduction (inquiry) server 3.

  FIG. 2 is a diagram illustrating a state in which the complement request information is transferred toward the broadcast station apparatus 1. In the example of FIG. 2, the node device 2af transmits complement request information to the node device 2ae serving as the upstream node device, and the node device 2ae is a communication path branched from the broadcast station device 1 and is self- The supplement request information is transmitted to the node device 2y as a remote node device located on a communication path different from the communication path from the broadcast station device 1 to the broadcast station device 1. The node device 2y located on a communication path branched from the broadcast station apparatus 1 and different from the communication path from itself to the broadcast station apparatus 1 is completely a packet complement request source. Since it is located in a different route, it is highly likely that it has a missing data packet.

  In the example of FIG. 2, the probability (1-β) that the upstream node device is selected is set slightly higher (β <0.5) than the probability (β) that the far node device is selected. Further, when the complement request information is transmitted (or transferred) to the remote node device, the hierarchy of the transmission source (transfer source) node device and the transmission destination (transfer destination) far node device is the same or one level higher. (Upstream) level. As a result, more node devices can be used until the complement request information is transferred to the broadcast station device 1 (if all data packets can be complemented, the transfer ends in the distribution source device (broadcast station device)). Thus, the data packet can be complemented more efficiently in a wide range while suppressing the burden on the broadcasting station device 1 and the upstream node device 2.

  When the supplement request information is transmitted (or transferred) to the remote node device, the hierarchy of the remote node device of the transmission destination (transfer destination) is higher than the hierarchy of the node device 2 of the transmission source (transfer source). In the lower (downstream) hierarchy, there is a possibility that the transfer of the supplement request information may loop.

  FIG. 3 is a diagram illustrating a state in which the transfer of the supplement request information is looped. As shown in FIG. 3, the hierarchy of the remote node device (for example, the node device 2w) of the transmission destination (transfer destination) is the hierarchy (for example, the first of the node devices (for example, the node device 2c) of the transmission source (transfer source). When the layer is lower (downstream) than the second layer (for example, the fourth layer), there is a problem that the transfer of the complement request information loops, and all data packets cannot be complemented. In order to avoid such a problem, each node device 2 compares the hierarchy of the remote node device of the transmission destination (transfer destination) with its own hierarchy when transmitting or transferring the complement request information. If the hierarchy of the remote node device is lower (downstream), the probability (1-β) that the upstream node device is selected is temporarily increased to facilitate selection of the upstream node device, or the own node The location information of the remote node device located in the upper (upstream) layer is acquired from the connection destination introduction (inquiry) server 3, and the supplement request information is transmitted or transferred to this.

[2. Configuration of broadcasting station equipment]
Next, the configuration and function of the broadcast station apparatus 1 will be described with reference to FIG.

  FIG. 4 is a diagram illustrating a schematic configuration example of the broadcast station apparatus 1.

  As shown in FIG. 4, the broadcast station apparatus 1 includes a CPU having a calculation function, a working RAM, various data and programs (including an OS (operating system) and various applications), a ROM, and the like. 11, a storage unit 12 composed of an HDD or the like for storing and saving content data (for example, compressed video data or music data), and encryption for encrypting content data using an encryption key Communication accelerator 15, communication unit 15 for controlling communication of information between node device 2 and the like through network 10, and receiving an instruction from the operator and giving an instruction signal corresponding to the instruction to control unit 11 An input unit (for example, a keyboard, a mouse, etc.) 16, and these components are connected to the bus 17. They are connected with each other.

  The control unit 11 controls the entire broadcast station apparatus 1 by executing a program stored in the storage unit 12 or the like by the CPU, and encrypts content data stored and stored in the storage unit 12 using an encryption key. The data is encrypted by the accelerator 13, the content data is divided into a predetermined amount of data, and a plurality of continuous data packets are generated, and this is transmitted to the node device 2 (example in the upper frame 100 in FIG. 1) via the communication unit 15. Then, stream distribution is performed to the node devices 2a and 2b). In the payload portion of each data packet, packet numbers (sequence numbers consecutive in the order of distribution) that are continuous from the beginning of the content data are described (embedded). In the payload portion of each data packet, packet type information indicating whether or not the data packet is a complementary data packet is described (embedded).

  In addition, the control unit 11 determines the distribution destination of the content data with reference to the connection mode table stored in the storage unit 12. In this connection mode table, at least the IP address and port number of the node device 2 connected to the broadcast station device 1 (in other words, the node device 2 that is the distribution destination of the content data) are described.

[3. Node device configuration]
Next, the configuration and function of the node device 2 will be described with reference to FIG.

  FIG. 5 is a diagram illustrating a schematic configuration example of the node device 2.

  As shown in FIG. 5, the node device 2 includes a CPU 21 having a calculation function, a working RAM, a ROM that stores various data and programs (including an OS (operating system) and various applications), and the like. A storage unit 22 composed of an HDD or the like for storing various data and programs, a buffer memory 23 as storage means for temporarily storing (storing) received content data (data packets), and a buffer memory 23 A decryption accelerator 24 for decrypting the encrypted content data stored in the content data using a decryption key, and video data (video information) and audio data (audio information) included in the decrypted content data Decoder unit 25 that decodes (reproduces data, etc.) and reproduces, and A video processing unit 26 that performs predetermined drawing processing on the video data and outputs the video signal; and a display unit 27 such as a CRT or a liquid crystal display that displays video based on the video signal output from the video processing unit 26. The reproduced audio data is converted into an analog audio signal by D (Digital) / A (Analog) conversion, amplified by an amplifier and output, and the audio signal output from the audio processing unit 28 A communication unit 29a for controlling communication between the broadcast station apparatus 1 and other node apparatuses 2 through the network 10, and various instructions from the user (viewer). An input unit (for example, a mouse, a keyboard, an operation panel, or a remote controller) 29b for giving an instruction signal to the control unit 21, and an IC card 29e An IC card slot 29c for mounting and electrically connecting, a control unit 21, a storage unit 22, a buffer memory 23, a decoding accelerator 24, a decoder unit 25, a communication unit 29a, an input unit 29b, The IC card slot 29c is connected to each other via a bus 29e. As the node device 2, for example, an STB (Set Top Box) or a personal computer is applicable.

  The IC card 29e has tamper resistance (that is, tampering measures are taken so that confidential data cannot be read by unauthorized means and cannot be easily analyzed). It is distributed to users from operators. The IC card 29e includes an IC card controller including a CPU, a tamper-resistant nonvolatile memory (for example, EEPROM), and the like. The nonvolatile memory includes a user ID and encrypted content data. A decryption key, a digital certificate, and the like for decrypting are stored. When the node device participates in the tree-type content distribution system S, the digital certificate is transmitted to the connection destination introduction (query) server 3 together with a participation request (including location information of the node device).

  The buffer memory 23 is composed of, for example, a FIFO (First In First Out) ring buffer memory. Under the control of the control unit 21, the buffer memory 23 temporarily stores the content data received through the communication unit 29a in the storage area indicated by the reception pointer. Is accumulating.

  The control unit 21 performs overall control of the entire node device 2 by reading and executing a program stored in the storage unit 22 or the like by the CPU, and receives a plurality of data packets distributed from upstream through a communication unit 29a. Is received and written to the buffer memory 23, and the data packets stored in the buffer memory 23 (data packets received in the past for a predetermined time) are read and transmitted (transferred) to the downstream node device 2 through the communication unit 29a. In addition, the data packets stored in the storage area of the buffer memory 23 indicated by the playback pointer are read out and output to the decoding accelerator 24 and the decoder unit 25 via the bus 29d. ing. The program may be downloaded from a predetermined server on the network 10, for example, or may be recorded on a recording medium such as a CD-ROM and read via a drive of the recording medium. It may be.

  Further, the control unit 21 determines whether or not there is a missing data packet based on the data packet received and accumulated in the buffer memory 23 as the missing packet presence / absence judging means. When it is determined that there is a packet (for example, when data packets with packet numbers “1”, “2”, “4”, “5”, “6” are stored in the buffer memory 23, “ It is determined that the data packet to which the packet number of 3 ″ is assigned is missing), and as described above, as the complement request transmission unit, the node device 2 other than the node device 2 located downstream of itself is The complement request information of the missing data packet is transmitted through the communication unit 29a, and the data packet returned from the other node device 2 is transmitted to the complement request information. It adapted to receive a complementary packet receiver via parts 29a.

  Here, the supplement request information includes, for example, a missing packet list (for example, a packet number and content ID (ID uniquely assigned to each content data) as packet identification information corresponding to the missing data packet). Packet loss list) and a plurality of missing data packets, a packet number and a content ID corresponding to each missing data packet are described.

  Further, the control unit 21 receives the supplement request information transmitted or transferred from the other node device 2 as a supplement request information receiving unit through the communication unit 29a, and is included in the supplement request information as a packet presence / absence determining unit. It is determined whether or not the data packet indicated by the missing packet list is included (for example, the packet number and content ID described in the missing packet list, and the packet number and content of the data packet stored in the buffer memory 23) If it is determined that the data packet is included, the data packet is returned to the node device 2 that is the transmission source of the complement request information. A packet is sent back through the communication unit 29a.

  Then, the control unit 21 updates the missing packet list by deleting the packet number corresponding to the complementary data packet related to the reply from the missing packet list as the missing packet list update unit, and further includes packet identification information. As the presence / absence determining means, it is determined whether or not the packet number of the data packet is still described in the updated missing packet list, and when it is determined that it is still described (for example, a plurality of data packets are included in the missing packet list). When the corresponding packet number and content ID are described, and only some of the data packets are returned to the source node device 2), as a supplement request transfer means, as described above, The above complement request information is transmitted to the node device 2 other than the node device 2 located downstream of itself. It adapted to forward through 9a.

[4. Connection destination referral server configuration, etc.]
Next, the configuration and function of the connection destination introduction (inquiry) server 3 will be described with reference to FIG.

  FIG. 6 is a diagram illustrating a schematic configuration example of the connection destination introduction (inquiry) server 3.

  As shown in FIG. 6, the connection destination introduction (inquiry) server 3 includes a CPU having a calculation function, a working RAM, various data and programs (including an OS (operating system) and various applications), a ROM, and the like. A control unit 35, a storage unit 36 composed of an HDD or the like for storing and storing various data, and a communication unit 37 for controlling communication of information with the node device 2 and the like through the network 10. , And these components are connected to each other via a bus 38.

  In the storage unit 36, the location information of the broadcast station apparatus 1 and the node apparatus 2 participating in the tree type content distribution system S, the broadcast station apparatus 1, the node apparatus 2, and each node apparatus 2 in the tree type content distribution system S are stored. A database that stores topology information between them is constructed.

  The control unit 35 performs overall control of the connection destination introduction (inquiry) server 3 by executing a program stored in the storage unit 36 or the like by the CPU, and when there is a participation request from a non-participating node device, The authentication described above, for example, the validity of the digital certificate added to the participation request is determined, and if valid, the location information of the node device and the digest of the digital certificate (for example, the digital certificate is stored in a predetermined hash) A hash value hashed by a function) is stored in the database. It should be noted that the digest of the digital certificate is used as a session key when there is an inquiry about the connection destination from the node device due to a reception failure or the like in the node device (this eliminates the need for authentication). ).

  In addition, when the authentication is valid, the control unit 35 provides the location information and the hierarchy level information (that is, the upstream level information) of the plurality of upstream node devices that are connection destination candidates to the node device that has requested the participation. Communicates information indicating how many layers the node device exists) and location information and layer level information of the distant node device (that is, information indicating how many layers the distant node device exists) The data is transmitted through the unit 37. In the node device that has received the location information, the physical proximity of the plurality of upstream node devices that are connection destination candidates on the network 10 is compared, and the upstream node device that is present at the closest position is selected, A connection request is made to the upstream node device and the connection is established, and the location information of the upstream node device with which the connection has been established is transmitted (returned) to the connection destination introduction (inquiry) server 3. On the other hand, the control unit 35 stores topology information regarding the node device in the database.

[5. Operation of tree-type content distribution system]
Next, the operation of the tree-type content distribution system S when a missing data packet is complemented will be described with reference to FIGS.

  FIG. 7 is a flowchart showing processing in the control unit 21 of the node device 2 that is the source of the supplement request information, FIG. 8 is a flowchart showing details of the packet supplement processing in FIG. 7, and FIGS. FIG. 11 is a flowchart showing a process in the control unit 11 of the broadcast station apparatus 1 that has received the complement request information.

  In the processing shown in FIG. 7, the non-participating node device makes a participation request to the connection destination introduction (inquiry) server 3, and the location information and hierarchy level information of a plurality of upstream node devices that are connection destination candidates, It starts by acquiring the location information and hierarchy level information of the remote node device and establishing a connection with the upstream node device (recognizing how many layers the node device is in), and the control unit 21 A data packet related to the content data transmitted from the node device is received through the communication unit 29a (step S1), and the received data packet is transmitted from the other node device 2 according to the complement request information. For example, with reference to packet type information described in the payload portion of the packet (step S2).

  If the received data packet is not a complementary data packet (step S2: N), the control unit 21 determines whether or not the received data packet is a packet that has been received before, For example, it is determined whether or not the packet number of the received data packet matches the packet number of the data packet stored in the buffer memory 23 (step S3).

  If the received data packet is not a packet that has been received before (for example, if the data packet having the same packet number as the received data packet is not stored in the buffer memory 23) (step S3). : N), the control unit 21 inserts and writes the received data packet in the buffer memory 23 (step S4).

  Next, the control unit 21 determines whether or not the currently set device mode (state) is the complement mode (purchase mode) (step S5).

  Here, the complement mode is a mode for purchasing content data. For example, the complement mode is controlled by a user operating the input unit 29b to input a content purchase instruction (for example, pressing a purchase button). Set by the unit 21.

  If the currently set device mode is not the complementary mode (step S5: N), the control unit 21 causes the data packet stored in the buffer memory 23 (due to withdrawal of a node device located upstream, etc.). In consideration of the case where the stream is interrupted, a data packet received in the past for a predetermined time so as not to be affected by this is read and transmitted (transferred) to the downstream node device 2 through the communication unit 29a (step S6).

  Next, the control unit 21 reads out a predetermined amount of data packets stored in the storage area of the buffer memory 23 indicated by the playback pointer, and uses the decryption accelerator 24 previously obtained from the IC card 29e to decrypt the accelerator 24. Is decoded and output to the decoder unit 25 (step S7). A predetermined amount of data packet output to the decoder unit 25 is reproduced, the video data and the like are displayed on the display unit 27 via the video processing unit 26, and the audio data is displayed on the speaker 29 via the audio processing unit 28. Is output as sound waves.

  In step S8, the control unit 21 determines whether or not to stop receiving content data. If the reception of content data is not stopped (step S8: N), the control unit 21 returns to step S1 and repeats the same processing as described above. On the other hand, when reception of content data is to be stopped (step S8: Y), for example, when distribution (broadcasting) of a content unit (for example, one movie or one song) is completed, or input from the user If there is a content data reception stop instruction or the like via the unit 29b, the process ends.

  On the other hand, when the received data packet is a complementary data packet in step S2 (step S2: Y), the control unit 21 proceeds to step S9.

  In step S9, the control unit 21 determines whether or not the currently set device mode (state) is the above-described complement mode. If the device mode is the complement mode (step S9: Y), reception is performed. The complemented data packet is inserted into a complementary buffer (a buffer different from that for a normal data packet) in the buffer memory 23 and written (step S10), and the process returns to step S1. On the other hand, when the mode is not the complement mode (step S9: N), the control unit 21 discards the received complement data packet (step S11) and returns to step S1. In other words, when the mode is not the complement mode, the data packet for complementation is not necessary, so that the packet is discarded, so that the capacity of the buffer memory 23 can be secured.

  In step S3, when the received data packet is a packet that has been received before (step S3: Y), the control unit 21 discards the duplicate data packet (step S11). Return to step S1.

  In step S5, when the currently set device mode is the complementary mode (step S5: N), the control unit 21 checks for a missing (missing) data packet, and if there is any missing. (For example, if the data packet received this time is not the data packet to be received next to the data packet received last time), the packet number of the missing data packet is described in the missing packet list of the content data (that is, missing) The registered data packet is registered in the missing packet list) (step S12). For example, the inspection of the missing data packet includes a packet number (in the payload portion) of the received data packet and a sequence counter held by the node device 2 (represented by the packet number of the data packet to be received next). Counter).

  Next, the control unit 21 determines whether or not packet numbers of a predetermined number (for example, 10) or more of data packets are described (registered) in the missing packet list (step S13), and the predetermined number or more of data packets are determined. If no packet number is described (step S13: N), the process proceeds to step S6, and if a packet number of a predetermined number or more of data packets is described (that is, a predetermined number or more of data packets are missing) If (Yes), the packet complementing process in step S14 is performed.

  In the packet complementing process, as shown in FIG. 8, first, the control unit 21 adjusts a threshold value β of a preset probability (step S111). More specifically, the control unit 21 refers to the hierarchy level information of the remote node device acquired from the connection destination introduction (inquiry) server 3 and compares its own node device 2 and the hierarchy with the hierarchy of the remote node device. Then, when the level of the remote node device is lower (downstream) than the level of its own node device 2, the threshold β is adjusted to be temporarily lowered (upstream is easily selected). In addition, when the hierarchy of the remote node apparatus is not lower (downstream) than the hierarchy of its own node apparatus 2, the threshold value β is maintained as it is.

  Next, the control unit 21 acquires the random value R generated by the random number generator (step S112), determines whether or not the random value R is equal to or greater than the threshold value β (step S113), and the random value R is If it is equal to or greater than the threshold β (step S113: Y), the upstream node device is selected and the supplement request information including the missing packet list is transmitted to the upstream node device through the communication unit 29a (step S114). Returning to the process of FIG. On the other hand, if the random value R is not equal to or greater than the threshold β (step S113: N), the remote node device is selected and the complementary request information including the missing packet list is transmitted to the remote node device through the communication unit 29a ( Step S115), the process returns to the process of FIG.

  As described above, when the complement mode is set, the complement request information is transmitted to the other node device 2, and the complement data packet transmitted according to the complement request information is stored in the buffer memory 23. It will be accumulated in the buffer for completion. When the complement completion information (from the processing of steps S25, S45, and S53 described later) transmitted from the other node device 2 or the broadcasting station device 1 is received, the control unit 12 stores the information in the buffer memory 23. Extract (use) multiple data packets (normal data packets) and complementary data packets (data packets stored in the complementary buffer) to restore complete content data, Is recorded on the HD in the storage unit 22 as another recording medium (for example, for purchase of content data).

  Next, the process shown in FIG. 9 is started in the upstream node device or the remote node device that has received the supplement request information. Note that the process shown in FIG. 9 is a process in the control unit 21 of the node apparatus 2 that is not directly connected to the broadcast station apparatus 1.

  In the process of FIG. 9, the control unit 21 determines whether or not the data packet indicated by the missing packet list included in the complement request information is present (there is a data packet that can be complemented) (for example, a missing packet). When the packet number and content ID described in the list are compared with the packet number and content ID of the data packet stored in the buffer memory 23 (step S21), and there is no data packet that can be complemented (Step S21: N), the process proceeds to Step S24. In step S21, if there is no data packet that can be complemented in the buffer memory 23, it is determined whether or not the content data relating to the data packet is recorded in the HD in the storage unit 22. The recorded content data may be packetized, and the supplementary data packet may be extracted from the packet and transmitted (returned) to the node device 2 that is the transmission source of the complement request information. good.

  On the other hand, when there is a data packet that can be complemented (step S21: Y), the control unit 21 reads the data packet for complementation from the buffer memory 23 and transmits the complement request information transmission source through the communication unit 29a. Transmit (reply) to the node device 2 (step S22). And the control part 21 deletes the packet number corresponding to the data packet which concerns on the said reply from the said missing packet list, updates the said missing packet list (step S23), and transfers to step S24.

  In step S24, the control unit 21 determines whether or not the packet number of the data packet is still described in the updated missing packet list. If the packet number of the data packet is not described in the missing packet list (step S24: N), since all the missing data packets are transmitted, the control unit 21 complements the data packet. Completion information is transmitted to the node device 2 that is the transmission source of the supplement request information through the communication unit 29a (step S25), and the process ends.

  On the other hand, when the packet number of the data packet is still described in the updated lost packet list (step S24: Y), the control unit 21 determines the threshold β of the probability set in advance as in step S111. (Step S26), and then, the random number value R generated by the random number generator is acquired (Step S27), and it is determined whether or not the random number value R is equal to or greater than the threshold value β (Step S28). If the random value R is greater than or equal to the threshold β (step S28: Y), the control unit 21 selects the upstream node device and selects the above-mentioned missing packet list (if updated, the updated missing packet list). ) Is transmitted (transferred) to the upstream node device through the communication unit 29a (step S29), and the process ends. On the other hand, if the random value R is not equal to or greater than the threshold value β (step S28: N), a complementary request including the above-described missing packet list (if updated, missing packet list after update) is selected. Information is transmitted to the remote node device through the communication unit 29a (step S29a), and the process ends.

  Note that the processing shown in FIG. 9 is performed in the node device 2 existing in the transfer path of the supplement request information.

  By the way, when the upstream node device or the remote node device that has received the supplement request information is the node device 2 that is directly connected to the broadcast station device 1, the processing shown in FIG. 10 is performed.

  In the process of FIG. 10, the process from step S41 to S45 is the same as the process from step S21 to S25 shown in FIG. In step S46, the control unit 21 transmits complement request information including the missing packet list (updated missing packet list if updated) to the broadcasting station device 1 through the communication unit 29a. Exit.

  Next, the process shown in FIG. 11 is started in the broadcasting station apparatus 1 that has received the supplement request information, and the control unit 11 supplements from the master content data based on the packet number and content ID described in the missing packet list. Data packet is acquired (step S51), and the complementary data packet is transmitted (returned) to the node device 2 that is the transmission source of the complementary request information through the communication unit 29a (step S52). Is transmitted to the node device 2 that is the transmission source of the supplement request information (step S53), and the process is terminated.

  In the processing shown in FIG. 7 in the above embodiment, a data packet missing check is performed during distribution of content data related to one unit of content, and a supplement request is made when a predetermined number or more of data packets are missing. Although an example in which information is transmitted to another node device 2 has been described, as another example, content data related to one unit of content is received to the end (in other words, buffering is completed). The supplement request information may be transmitted to another node device 2.

  FIG. 12 is a flowchart showing processing in the control unit 21 of the node device 2 that is the transmission source of the complement request information in this case.

  In the process shown in FIG. 12, for example, after the content data related to one unit of content is buffered to the end, for example, the user operates the input unit 29b to input a content purchase instruction (for example, press the purchase button). ) To begin.

  First, the control unit 21 determines (inspects) whether or not there is a missing data packet among a plurality of data packets constituting the content data stored in the buffer memory 23 (step S62). If there is a missing data packet (step S62: Y), for example, if there is a location where the continuity of the packet number is interrupted, the control unit 21 identifies the missing data packet, the packet number, and the content A missing packet list in which the content ID of the data is described is created (step S63), and the packet complementing process in step S64 is performed.

  Note that the packet complementing process in step S64 (refer to FIG. 8 for details) is the same as the packet complementing process in step S14 described above, and a duplicate description will be omitted. In addition, when the complement request information is transmitted in the process of FIG. 12, the processes of the other node devices 2 and the like are the same as the processes shown in FIGS.

  Next, the control unit 21 receives a complementary data packet transmitted (returned) from the other node device 2 or the like in response to the above-described complement request information (step S65), and uses this as a complement data in the buffer memory 23. The complete content data is restored using a plurality of data packets stored in the buffer memory 23 and stored in the buffer memory 23 and the complementary data packet (complement packet), and this is used as a recording means for other recording. Recording is performed on the HD in the storage unit 22 as a medium (for example, for purchase of content data) (step S66).

  If there is no missing data packet in step S62 (step S62: Y), complete content data is restored using a plurality of data packets stored in the buffer memory 23, and this is used as recording means. Recording is performed on the HD in the storage unit 22 as another recording medium (for example, for purchase of content data).

  Next, the control unit 21 obtains a license certificate for reproducing the recorded content data from, for example, a license server (not shown) (step S67), and notifies the user that the purchase of the content data has been completed. (For example, by display or audio output) (step S68), and the process ends. Thereby, even when there is a missing data packet in the distributed content data, the user can complete the missing data packet and purchase it in a complete form.

  Note that the content data recorded (purchased) in this way is decrypted by the decryption accelerator 24 under the control of the control unit 21, for example, when a reproduction instruction is given from the user via the input unit 29b. The video data and the like are decoded and reproduced by the decoder unit 25 and displayed on the display unit 27 via the video processing unit 26, and the audio data is output as sound waves from the speaker 29 via the audio processing unit 28. Become.

  As described above, according to the above-described embodiment, the supplement request information transmitted from the node device that supplements the missing data packet is transferred until the node device 2 having the data packet indicated therein arrives. Therefore, the data packet can be complemented more efficiently. In addition, since the supplement request information is transmitted or transferred at each node device by selecting either the upstream node device or the remote node device with a preset probability, the broadcast station device 1 and The data packet can be complemented more efficiently in a wide range while suppressing the burden on the upstream node device 2.

  In the above embodiment, when the node device 2 that is the source of the supplement request information changes the upstream node device to be connected and raises the layer level (for example, from the fourth layer to the second layer), for example, If the complementary request information is transmitted to the far node device that is recognized from the beginning, the far node device may be in a lower hierarchy than itself, and therefore there is a possibility that the transfer of the complementary request information loops (FIG. 3). See). The operation of the node device 2 for avoiding this will be described.

  FIG. 13 shows an operation state for avoiding a loop for transferring complementary request information when the node device 2 that is the source of the complementary request information changes the connected upstream node device and raises the hierarchical level. FIG.

  In the example of FIG. 13, the node device 2r that is the source of the supplement request information requests an introduction request instead of the supplement request information to the remote node device 2w that it recognizes from the beginning when the hierarchical level is raised. The remote node device 2w that has transmitted information (including its own location information and hierarchy level information) and received the introduction request information transfers the introduction request information to its own upstream node device 2k, and the upstream Since the node device 2k compares the own layer and the layer of the source node device 2r and is not the same layer, the node device 2k transfers the introduction request information to the upstream upstream node device 2e, and the upstream node device 2e is the same hierarchy comparing its own hierarchy and the hierarchy of the transmission source node apparatus 2r, and therefore, the introduction response including its own location information and hierarchy level information is given to the transmission source node apparatus 2r. It is adapted to transmit the information. As a result, even when the node device 2r that is the transmission source of the supplement request information changes the upstream node device to be connected and raises the hierarchical level, the node device 2 that is the transmission source retains the location information of the new remote node device. Etc. can be acquired efficiently, and supplement request information can be transmitted to a new remote node device.

  In the above embodiment, as an example of the first node device, an upstream node device directly connected to itself is used. However, any upstream device positioned on the communication path from itself to the broadcasting station device 1 is used. It may be a node device.

It is a figure which shows an example of the connection aspect of each apparatus in the tree type content delivery system which concerns on this embodiment. It is a figure which shows a mode that supplement request information is transferred toward the broadcast station apparatus 1 direction. It is a figure which shows a mode that transfer of complementation request information loops. 1 is a diagram illustrating a schematic configuration example of a broadcast station device 1. FIG. 3 is a diagram illustrating a schematic configuration example of a node device 2. FIG. FIG. 2 is a diagram showing an example of a schematic configuration of a connection destination introduction (inquiry) server 3. It is a flowchart which shows the process in the control part 21 of the node apparatus 2 of the transmission origin of complement request information. It is a flowchart which shows the detail of the packet complementation process in FIG. It is a flowchart which shows the process in the control part 21 of the node apparatus 2 which received the complement request information. It is a flowchart which shows the process in the control part 21 of the node apparatus 2 located downstream of the broadcast station apparatus 1 which received the complement request information. It is a flowchart which shows the process in the control part 11 of the broadcasting station apparatus 1 which received the complement request information. It is a flowchart which shows the process in the control part 21 of the node apparatus 2 of the transmission origin of the complement request information in this case. It is a figure which shows the mode of the operation | movement for avoiding the loop of the transfer of complementation request information when the node apparatus 2 of the transmission source of complementation request information changes the upstream node apparatus to connect and raises a hierarchy level.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Broadcast station apparatus 2 Node apparatus 3 Connection destination introduction (inquiry) server 4 Communication path 10 Network 11 Control part 12 Storage part 13 Encryption accelerator 15 Communication part 16 Input part 17 Bus 21 Control part 22 Storage part 23 Buffer memory 24 Decoding Accelerator 25 Decoder unit 26 Video processing unit 27 Display unit 28 Audio processing unit 29 Speaker 29a Communication unit 29b Input unit 29c IC card slot 29d Bus 35 Control unit 36 Storage unit 37 Communication unit 38 Bus S Tree type content distribution system

Claims (19)

The node included in a distribution system in which a plurality of node devices are connected via a communication path while forming a plurality of hierarchies, and a plurality of continuous data packets are distributed while being relayed by the node device from upstream to downstream In the device
Packet receiving means for receiving the plurality of continuous data packets that have been distributed;
Based on the received data packet, a missing packet presence / absence judging means for judging whether or not there is a missing data packet;
When the missing packet presence / absence judging unit determines that there is the missing data packet, the complement request information of the missing data packet is transmitted to a node device other than the node device located downstream of itself. Complementary request transmission means;
Complementary packet receiving means for receiving a data packet returned from the node device in response to the complementary request information;
A node device comprising: The node device according to claim 1,
The complementary request transmission means includes an upstream first node device positioned on a communication path from itself to a distribution source device that is a distribution source of the data packet, and is positioned on a communication path other than the communication path and downstream Any one of the second node devices other than the node device located in the node device is selected with a preset probability, and the complement request information is transmitted to the selected node device. Node device. The node device according to claim 2,
The node device, wherein the probability that the first node device is selected is set higher than the probability that the second node device is selected. The node device according to claim 2 or 3,
The node device, wherein the second node device is a node device in the same or higher layer as itself. In the node apparatus as described in any one of Claims 2 thru | or 4,
The plurality of node devices are connected in a tree shape via a communication path while forming a plurality of hierarchies with the distribution source device as a vertex.
The second node device is a communication route branched from the distribution source device, and is located on a communication route different from a communication route from itself to the distribution source device of the data packet. Node device to perform. In the node apparatus as described in any one of Claims 1 thru | or 5,
Storage means for temporarily storing the received data packet;
Of the plurality of data packets forming a unit of content, when a missing data packet is supplemented by the supplement request information, a complete data is stored using the plurality of data packets stored in the storage unit and the supplement packet. Recording means for restoring the content data and recording it on another recording medium;
A node device further comprising: A node device comprising supplement request information receiving means for receiving supplement request information transmitted from the node device according to any one of claims 1 to 6,
A packet presence / absence determining means for determining whether or not the data packet indicated by the received complement request information is included;
When it is determined by the packet presence / absence determining means that the data packet is included, a data packet return means for returning the data packet to the node device that has transmitted the complement request information;
A node device comprising: The node device according to claim 7, wherein
Complement request transfer means for transferring the complement request information to a node device other than the node device located downstream of the node device when the packet presence / absence determination unit determines that the data packet is not included. A node device further comprising: A node device comprising supplement request information receiving means for receiving supplement request information transmitted from the node device according to any one of claims 1 to 6,
The supplement request information includes a missing packet list in which packet identification information corresponding to each of a plurality of missing data packets is described,
A packet presence / absence determining means for determining whether or not each of the data packets indicated in the missing packet list is included;
A data packet return means for returning a data packet determined to be present by the packet presence / absence determining means to the node device that transmitted the complement request information;
A missing packet list update means for deleting the packet identification information corresponding to the data packet related to the reply from the missing packet list and updating the missing packet list;
Packet identification information presence / absence determining means for determining whether or not the packet identification information is still described in the updated lost packet list;
If it is determined by the packet identification information presence / absence determining means that the packet identification information is still described, the updated lost packet list is sent to a node device other than the node device located downstream of itself. Complementary request transfer means for transferring the complementary request information including:
A node device comprising: The node device according to claim 8 or 9,
The complementary request transfer means includes an upstream first node device located on a communication path from itself to a delivery source device that is a delivery source of the data packet; Any one of the second node devices other than the node device located in the node device is selected with a preset probability, and the complement request information is transferred to the selected node device. Node device. The node device according to claim 10,
The node device, wherein the probability that the first node device is selected is set higher than the probability that the second node device is selected. The node device according to claim 10 or 11,
The node device, wherein the second node device is a node device in the same or higher layer as itself. The node device according to any one of claims 10 to 12,
The plurality of node devices are connected in a tree shape via a communication path while forming a plurality of hierarchies with the distribution source device as a vertex.
The second node device is a communication route branched from the distribution source device, and is located on a communication route different from a communication route from itself to the distribution source device of the data packet. Node device to perform.   A program for causing a computer to function as the node device according to any one of claims 1 to 6.   A program for causing a computer to function as the node device according to any one of claims 7 to 13. A plurality of node devices, the plurality of node devices are connected via a communication path while forming a plurality of layers, and a plurality of continuous data packets are distributed while being relayed by the node device from upstream to downstream. In the distribution system
The one node device is
Packet receiving means for receiving the plurality of continuous data packets that have been distributed;
Based on the received data packet, a missing packet presence / absence judging means for judging whether or not there is a missing data packet;
If the missing packet presence / absence determining unit determines that there is the missing data packet, a complement request indicating a complement request for the missing data packet is issued to a node device other than the node device located downstream of itself. Complementary request transmission means for transmitting information;
Complement packet receiving means for receiving a data packet returned from another node device in response to the complement request information,
The other node device is:
Complementary request information receiving means for receiving the complementary request information transmitted from the one node device;
A packet presence / absence determining means for determining whether or not the missing data packet indicated by the received complement request information is included;
When it is determined by the packet presence / absence determining means that the data packet is included, a data packet return means for returning the data packet to the one node device;
A distribution system comprising: The distribution system according to claim 16, wherein
The other node device is:
Complement request transfer means for transferring the complement request information to a node device other than the node device located downstream of the node device when the packet presence / absence determination unit determines that the data packet is not included. A distribution system further comprising: Complementing data packets in a distribution system in which a plurality of node devices are connected via a communication path while forming a plurality of hierarchies, and a plurality of continuous data packets are distributed while being relayed by the node device from upstream to downstream. A method,
Receiving the plurality of continuous data packets distributed in one of the node devices;
In the one node device, based on the received data packet, determining whether there is a missing data packet;
When it is determined in the one node device that there is the missing data packet, a complement request for the missing data packet is requested to a node device other than the node device located downstream of the one node device. Transmitting the supplement request information indicating
In the other node device, receiving the complement request information transmitted from the one node device;
In the other node device, determining whether or not the missing data packet indicated by the received supplement request information is included;
When the other node device determines that the data packet is included, the step of returning the data packet to the one node device;
In the one node device, receiving a data packet returned from the other node device;
A method of complementing a data packet comprising: The method of complementing data packets according to claim 18,
When it is determined that the other node device does not have the data packet, the complement request information is transferred to a node device other than the node device located downstream of the other node device. A data packet complementing method, further comprising a step.

Images