WO2006120836A1

WO2006120836A1 - Distribution system, node device, data packet retransmitting method, and so forth

Info

Publication number: WO2006120836A1
Application number: PCT/JP2006/307918
Authority: WO
Inventors: Yasushi Yanagihara; Yuji Kiyohara; Hiroaki Suzuki; Kentaro Ushiyama; Hideki Matsuo; Koichi Iijima
Original assignee: Brother Kogyo Kabushiki Kaisha; Xing Inc.
Priority date: 2005-05-11
Filing date: 2006-04-14
Publication date: 2006-11-16
Also published as: JP4736527B2; JP2006319495A

Abstract

A distribution system for efficiently retransmitting a missing data packet without burdening a specific device such as a distribution server with a heavy load, a node device, and a data packet retransmitting method are disclosed. In a distributing system where node devices form layers and are interconnected through communication channels and consecutive data packets are distributed through the node devices in a direction from the upstream side to the downstream side, each node device comprises packet receiving means for receiving the distributed consecutive data packets, missing packet detecting means for detecting a missing data packet, if any, in the received data packets, retransmission request sending means for sending information on missing data packet retransmission request to the other node devices than the node devices located on the downstream side, and retransmitted packet receiving means for receiving data packet retransmitted from the node device in response to the retransmission request information.

Description

Specification

Distribution system, node device, data packet complementing method, etc.

Technical field

[0001] The present invention relates to a method for complementing a missing data packet 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. Technical field.

Background art

As a content distribution system of this type, Patent Document 1 discloses a stream data distributed distribution system, which has topology information for each node device to recognize 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 receives it from the downstream (lower layer) node device. It will be transferred (relayed) to.

[0003] In a content distribution system that works, communication between node devices uses a protocol that does not perform delivery confirmation, such as UDP (User Data Protocol), and each node device is connected to the network. Since it is possible to join and leave freely (for example, power ON / OFF), data packets are dropped at a certain rate in the content received by each node device.

Patent Document 1: JP 2003-169089

Disclosure of the invention

Problems to be solved by the invention

[0004] By the way, as described above, when a missing data packet occurs, for example, a method of acquiring and complementing the missing data packet from the distribution sano that is a content distribution source can be considered. There is a problem that access to the distribution server by multiple node devices is concentrated and a heavy burden is imposed.

[0005] The present invention has been made in view of the above problems and the like, and is capable of complementing a missing data packet without imposing a heavy burden on a specific device such as a distribution server. It is an object to provide a communication system, a node device, a data packet complementing method, and the like.

Means for solving the problem

[0006] In order to solve the above problem, according to one 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 transmitted from upstream to downstream. Packet receiving means for receiving the plurality of continuous data packets distributed to the node device included in the distribution system distributed while being relayed by the node device in the direction; and the received data packet Based on the above, if there is a missing packet presence / absence judging means for judging whether or not there is a missing data packet and the missing packet presence / absence judging means judges that there is the missing data packet, it is located downstream of itself. Complement request transmission means for transmitting the complement request information of the missing data packet to a node device other than the node device; Supplementary packet receiving means for receiving a data packet in which the node device power is also returned in response to the supplement request information.

[0007] According to the present invention, the configuration is such that the complement request information of the missing data packet is transmitted to a node device other than the node device located downstream of itself. It is possible to compensate for missing data packets without imposing a heavy burden on these devices.

[0008] Further, the complement request transmitting means is located on the communication path from itself to the distribution source apparatus that is the distribution source of the data packet, and on the other side of the communication path. In addition, any one of the second node devices other than the node device located downstream of itself is selected with a preset probability, and the complement request information is transmitted to the selected node device. It is characterized by that.

[0009] According to the present invention, either one of the first node device and the second node device is selected with a preset probability, and the complement is selected for the selected node device. Since the completion request information is transmitted, it is possible to complement the data packet efficiently in a wide range without imposing a burden on a specific node device.

[0010] Further, the probability that the first node device is selected is the probability that the second node device is selected. It is characterized by being set higher than the rate.

[0011] According to the present invention, in a situation where complementary request information is repeatedly transferred, convergence near the distribution source device can be accelerated with little packet loss, so that data packets can be complemented more quickly. Can do.

[0012] Further, the second node device is a node device of a hierarchy higher than or equal to the own hierarchy.

[0013] According to the present invention, since the complement request information is always transferred to other node devices on the upper layer with reference to its own device, it is possible to avoid the loop of the supplement request information from being looped.

[0014] Further, 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, and the second node device is the distribution source device The communication path is branched from the communication path, and is located on a different communication path from the communication path from itself to the distribution source device of the data packet.

[0015] According to the present invention, the transfer process of the supplement request information complements the data packet on the communication path that is separate from the communication path including itself, so that the data packet is more reliably completed. be able to.

[0016] Further, when the received data packet is temporarily stored, and a missing data packet among the plurality of data packets forming a content unit is supplemented by the completion request information In addition, the recording apparatus further comprises recording means for restoring the complete content data using a plurality of data packets stored in the storage means and the complementary packet, and recording it on another recording medium.

[0017] According to the present invention, the purchased content can be restored by diverting the distributed stream, so that it is possible to reduce the amount of data communication related to the content purchase.

[0018] Further, it is a node device including a supplement request information receiving unit that receives the supplement request information, and determines whether or not the data packet indicated by the received supplement request information is included. When the packet presence / absence determining unit and the packet presence / absence determining unit determine that the data packet is included, the data packet is returned to the node device that transmitted the complement request information. Data packet return means It is characterized by that.

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. Therefore, it is possible to supplement missing data packets without imposing a heavy burden on a specific device such as a distribution server.

[0020] If the packet presence / absence determining unit determines that the data packet is not included, the complement request information is transferred to a node device other than the node device located downstream of itself. And a supplement request transfer means.

[0021] According to the present invention, the node device that has received the supplement request information is a node that is located downstream of the node device that has received the supplement request information when there is no data packet indicated in the supplement request information. The supplement request information is transferred to a node device other than the device, that is, the supplement request information is transferred up to the node device having the missing data packet. Even if the missing data packet of the request source cannot be complemented, the complement processing can be supplemented by another node device.

[0022] In addition, the node device includes a supplement request information receiving unit that receives the supplement request information. The supplement request information includes packet identification information corresponding to each of a plurality of missing data packets. A missing packet list is included, and it is determined that there is a packet presence / absence determining means for determining whether or not each of the data packets indicated by the missing packet list has power and a packet presence / absence determining means. A data packet return means for returning the received data packet to the node device that transmitted the complement request information, and the packet identification information corresponding to the data packet related to the reply is deleted from the missing packet list and the missing packet list And a lost packet list update means for updating the packet, and the packet is added to the updated lost packet list. If the packet identification information presence / absence determining means for determining whether or not the other information is still described and the packet identification information presence / absence determining means determine that the packet identification information is still described, Complement request transfer means for transferring the supplement request information including the updated lost packet list to a node device other than the node device located downstream. [0023] 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 burden is placed on a specific node device. Data packets can be complemented reliably over a wide range.

[0024] Further, the complementary request transfer means includes a first node device upstream located on a communication path from itself to a distribution source apparatus that is a distribution source of the data packet, and a position other than the communication path. In addition, any one of the second node devices other than the node device located downstream of itself is selected with a preset probability, and the complement request information is transferred to the selected node device. It is characterized by that.

[0025] According to the present invention, either one of the first node device and the second node device is selected with a preset probability, and the complement is selected for the selected node device. Since it is configured to transmit complete request information, it is possible to complement a data packet more efficiently in a wide range without imposing a burden on a specific node device.

[0026] The probability that the first node device is selected is set to be higher than the probability that the second node device is selected.

[0027] According to the present invention, it is possible to accelerate the convergence near the distribution source apparatus with little packet loss in a situation where the supplemental request information is repeatedly transferred. Can be complemented.

[0028] Further, the second node device is a node device of a hierarchy higher than or equal to itself.

[0029] According to the present invention, since the complement request information is always transferred to other node devices on the upper layer with reference to its own device, it is possible to avoid the loop of the supplement request information from being looped.

[0030] 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, and the second node device is the distribution source device The communication path is branched from the communication path, and is located on a different communication path from the communication path from itself to the distribution source device of the data packet.

[0031] According to the present invention, the transfer process of the complementary request information is separated from the communication path including itself. Because it complements the data packet, it can complete the data packet more reliably.

[0032] A program according to another aspect of the present invention causes a computer to function as the node device.

[0033] A program according to another aspect of the present invention causes a computer to function as the node device.

[0034] Further, in still another 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 transmitted. In the distribution system that is distributed while being relayed by the node device from upstream to downstream, the one node device includes a packet receiving unit that receives the plurality of continuous data packets that have been distributed, and the received Based on the data packet, if there is a missing packet presence / absence judging means for judging whether or not there is a missing data packet and the missing packet presence / absence judging means judges that there is the missing data packet, Complement request information indicating a complement request for the missing data packet is transmitted to a node device other than the node device located at Completion request transmission means, Complementary packet reception means for receiving a data packet returned from the other node device power in response to the complement request information, wherein the other node device is the first node device. Complementary request information receiving means for receiving the complementary request information transmitted from the packet, and packet presence / absence determining means for determining whether or not the missing data packet indicated by the received complementary request information is included. And a data packet return means for returning the data packet to the one node device when it is determined by the packet presence / absence determining means that the data packet is included. To do.

[0035] In addition, when the other node device determines that the data packet is not included by the packet presence / absence determining unit, the node device other than the node device located downstream thereof The supplement request transfer means for transferring the complement request information is further provided.

[0036] Further, according to still another 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. A method of complementing a data bucket in a distribution system that is distributed while being relayed by the node device, the step of receiving the plurality of continuous data packets distributed in the node device of 1, Determining whether there is a missing data packet based on the received data packet,

When it is determined that the missing data packet is present in the one node device, the missing data packet is complemented for node devices other than the node device located downstream of the one node device. Transmitting the supplement request information indicating the request; receiving the supplement request information transmitted from the one node device in the other node device; and receiving the supplement in the other node device. The step of determining whether or not the data packet has the missing data packet indicated by the request information, and when the other node device determines that the data packet is included, A step of returning the data packet to the node device of 1, and the data packet sent back to the other node device in the node device of 1. Receiving a network.

[0037] On the other hand, if it is determined that the data packet is present, the supplement request information is transferred to a node device other than the node device located downstream of the other node device. The method further includes a step of sending.

The invention's effect

[0038] According to the present invention, the complement request information of the missing data packet is transmitted to a node device other than the node device located downstream of itself, and the node device power packet is complemented. As a result, it is possible to compensate for missing data packets without imposing a heavy burden on specific devices such as distribution servers.

Brief Description of Drawings

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

FIG. 2 is a diagram showing a state in which supplement request information is transferred in the direction of the broadcasting station device 1 in a direction.

FIG. 3 is a diagram showing a state in which the transfer of supplement request information loops. FIG. 4 is a diagram showing a schematic configuration example of a broadcasting station device 1.

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

FIG. 6 is a diagram showing a schematic configuration example of a connection destination introduction server 3.

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 complementing process in FIG.

FIG. 9 is a flowchart showing processing in the control unit 21 of the node device 2 that has received the complement request information.

FIG. 10 is a flowchart showing processing in the control unit 21 of the node device 2 located downstream of the broadcast station device 1 that has received the complement request information.

FIG. 11 is a flowchart showing processing in the control unit 11 of the broadcast station apparatus 1 that has received the supplement request information.

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

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

Explanation of symbols

1 Broadcasting station equipment

2-node device

3 Destination introduction server

9 Communication path

10 network

11 Control unit

12 Memory

13 Encryption accelerator

15 Communications department

16 Input section 17 Bus

21 Control unit

22 Memory unit

23 Noffer memory

24 Decryption accelerator

25 Decoder part

26 Video processor

27 Display

28 Audio processor

29 Speaker

29a Communication Department

29b Input section

29c IC card slot

29d bus

35 Control unit

36 Memory

37 Communications Department

38 bus

S-tree type content 酉 S system

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the best embodiment of the present 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.

[0042] [1. Configuration of tree-type content distribution system, etc.]

First, the outline structure and functions of the tree-type content distribution system will be described with reference to FIG.

FIG. 1 is a diagram showing an example of a connection mode of each device in the tree-type content distribution system according to the present embodiment. [0044] As shown in the lower frame 101 of FIG. 1, IX (Internet eXchange) 5, ISP (Internet Service Provider) 6, DSL (Digital Subscriber Line) line provider (device) 7, FTTH (Fiber To The A network (real world network) 10 such as the Internet is constructed by a home (line device) (device) 8, a router (not shown), and a communication line (eg, telephone line, optical cable, etc.) 9. In the lower frame 101 of FIG. 1, the thickness of the solid line corresponding to each communication line 9 represents the bandwidth of each communication line 9 (for example, the data transfer rate).

[0045] The tree-type content distribution system S according to the present embodiment includes a broadcast station device 1 as a distribution source device that is a distribution source of a plurality of continuous data packets forming a unit of content, and a plurality of node devices 2a, 2b, 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 in a tree shape via a communication path while forming a plurality of hierarchies (four hierarchies in the example shown in FIG. 1), with the above (vertical) as the top (top). It is distributed while being relayed (transferred) by each node device from (upper layer) to downstream (lower layer). In the following description, when any one of the node devices 2a, 2b, 2c, 2d... Is indicated, it may be referred to as a node device 2 for convenience.

The node device 2 shown in the upper frame 100 of FIG. 1 is the node device 2 participating in the tree type content distribution system S, and the node device that has not participated in the tree type content distribution system S. When participating, a connection request is made to the connection destination introduction server 3 and authentication regarding the participation authority is received from the connection destination introduction server 3. The connection destination introduction server 3 includes location information (for example, IP (Internet Protocol) address and port number (standby port number;)) of the broadcast station device 1 and the node device 2 participating in the tree-type content distribution system S. ) And topology (connection mode) information between the broadcasting station device 1 and the node device 2 and each node device 2 in the tree-type content distribution system S are managed using a database. After performing the above authentication in response to the participation request, the location information of the already participating node device 2 (selected in consideration of the tree-like topology) that is the connection destination is notified to the node device. The node device that has received the location information notification Based on the location information, a connection is established with the node device 2 that has already participated, and as a result, participation in the tree-type content self-trust system S is made.

[0047] It should be noted that the tree topology is the maximum number of connections and balance (symmetry) of the downstream node devices 2 that are directly connected to each node device 2, as well as the locality between the node devices 2 (on the network 10). It is determined in consideration of proximity (the number of hops (the number of intervening routers) is small! / ヽ is high).

[0048] 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. In other words, the downstream node device 2 or the like directly connected to the withdrawn node device 2 acquires the location information of the already participating node device 2 as a new connection destination from the connection destination introduction server 3. Establish a connection.

[0049] Furthermore, a tree-like topology in the tree-type content distribution system S is formed for each broadcast station device, in other words, for each broadcast channel (in the upper frame 100 of Fig. 1, only one broadcast channel is formed). (However, there are cases where a single broadcasting station device can cover multiple broadcasting channels). For example, when the broadcast channel is switched by the user in the node device 2 that has already participated, the node device 2 acquires the location information of the node device 2 that has already participated in the broadcast channel after the switch from the connection destination introduction server 3. To establish a connection. The broadcast channel switching control has a direct relationship with the present invention, and therefore will not be described in detail.

[0050] In such a tree-type content distribution system S, a plurality of data packets stream-distributed from the broadcasting station apparatus 1 are on a communication path (for example, shown in FIG. (1) Node device 2 & → Node device 2c → Node device 2g → Node device 2o) shown in the upper frame 100 in FIG. 1 is missing one or more data packets. The node device 2 that recognizes transmits the complement request information of the missing data packet to the node devices 2 other than the node device 2 located downstream of the node device (self-node device). On the other hand, when the node device 2 that has received the supplement request information has the data packet indicated by the supplement request information, the node device 2 transmits the supplement request information to the node device 2 that is the transmission source of the supplement request information. Send data packet back If 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 itself. Thus, the supplement request information has the data packet indicated therein and is transferred until it reaches the node device 2 (if there are a plurality of missing data packets, all the data packets are transmitted). Will be transferred until it can be completed). Then, the node device 2 that is the transmission source of the supplement request information receives the data packet returned from the other node device 2 in response to the supplement request information, and is lost to its own device. Complement the packet.

Here, the transmission destination (or transfer) destination of the supplement request information is “node device other than the node device located downstream of itself” because the node device 2 located downstream of itself Since the missing packet is not delivered to the upstream side (missing packet is chained), even if the supplement request information is sent (or forwarded) to these devices, the data packet cannot be complemented. It is. For example, node devices 2g, 2h, 2o, 2p, 2q, and 2r are applicable as node devices located downstream of the node device 2c in the upper frame 100 of FIG. 1 (of these, the node devices 2g and 2g). 2h is a downstream node device directly connected to the node device 2c when viewed from the node device 2c).

[0052] 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. As much as possible, the broadcasting station device 1 and the upstream node device 2 (The node device 2 closer to the broadcasting station device 1 in the tree-like topology is assumed to have fewer data packets missing), and the data packets can be complemented more efficiently. In addition, for example, each node device 2 broadcasts from the upstream node device 2 (an example of a first node device, hereinafter referred to as an “upstream node device”) to which the above-mentioned complementary request information is directly connected. Node device 2 other than node device 2 located on the communication path leading to station device 1 and located downstream of itself (an example of a second node device, hereinafter referred to as “far node device”) Or Select square the node 2 at a preset probability, sent to the selected node 2 (or transfer) it is desirable to.

[0053] This is formed in consideration of the locality between each node device 2 in the form of a tree-like topology. Therefore, the upstream node device (for example, the node device in the upper frame 100 in FIG. 1) The upstream node device of 2c is often the node device 2a) (for example, the number of pops is small). Therefore, there is a possibility that the lost data packet can be acquired quickly, while from the self Since node device 2 (especially upstream node device) located on the communication path leading to broadcast station device 1 for data packets may be missing the same data packet, it is located on another communication route. This is because a remote node device that has a high probability of having a data packet missing from itself is high. The location information of the remote node device is acquired from the connection destination introduction server 3.

FIG. 2 is a diagram showing a state in which the supplement request information is transferred toward the broadcast station apparatus 1 direction. In the example of FIG. 2, the node device 2af transmits the complement request information to the node device 2ae 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 that is branched from the broadcasting station apparatus 1 and is different from the communication path from itself to the broadcasting station apparatus 1 is the packet complement request source. Since it is located in a completely different route, it is highly likely that it will have a missing data packet.

[0055] In the example of FIG. 2, the probability (1) that the upstream node device is selected is set slightly higher (ι8 to 0.5) than the probability (ι8) that the far node device is selected. Furthermore, when the supplement request information is transmitted (or transferred) to the remote node device, the hierarchy of the source (transfer source) node device and the destination (transfer destination) remote node device is the same or one. It is the upper (upstream) hierarchy. As a result, until the above complement request information is transferred to the broadcast station apparatus 1 (if all data packets can be complemented, the transfer ends at the distribution source apparatus (broadcast station apparatus)), more The data packet is transferred to the node device, and 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.

[0056] When complementary 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 that of the node device 2 of the transmission source (transfer source). If the hierarchy is lower (downstream) than the hierarchy, there is a possibility that the transfer of complementary request information may loop. FIG. 3 is a diagram showing a state in which the transfer of the complement request information loops. 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 of the node device (for example, the node device 2c) of the transmission source (transfer source) (for example, When the layer is lower (downstream) than the second layer (for example, the fourth layer), there is a problem that the transfer of the supplement 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 complementary request information, and If the hierarchy of the far-end node device is lower (downstream) than the hierarchy, temporarily increase the probability (1—) that the upstream node device is selected to make it easier to select the upstream node device, or The location information of the remote node device located in the hierarchy higher (upstream) than the hierarchy is acquired from the connection destination introduction server 3, and the completion request information is transmitted or transferred to this.

[0058] [2. Configuration of broadcasting station apparatus]

Next, the configuration and function of the broadcast station apparatus 1 will be described with reference to FIG.

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

As shown in FIG. 4, the broadcast station apparatus 1 is configured with a CPU having a calculation function, a working RAM, various data, a ROM and the like for storing programs (including an OS (operating system) and various applications). Control unit 11, HDD 12 for storing and saving content data (for example, compressed video data and music data), etc., and encryption of content data using encryption key And an encryption accelerator 13 for communication, a communication unit 15 for controlling communication of information between the node device 2 and the like through the network 10, and an instruction signal corresponding to the instruction received from the operator. An input unit (for example, a keyboard, a mouse, etc.) 16 provided to the control unit 11 is configured, and these components are connected to each other via a bus 17.

[0061] The control unit 11 performs overall control of the broadcasting station apparatus 1 by the CPU executing a program stored in the storage unit 12 or the like, and uses the encryption key for content data stored and stored in the storage unit 12. Then, encryption is performed by the encryption accelerator 13, and the content data is divided into a predetermined amount of data to generate a plurality of continuous data packets. The stream is distributed to the node device 2 (in the example in the upper frame 100 of FIG. 1, the node devices 2a and 2b). In the payload portion of each data packet, the packet number (sequence number consecutive in the order of distribution) of the content data is 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).

[0062] 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 to which content data is distributed) are described.

[0063] [3. Configuration of node device, etc.]

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.

[0065] As shown in FIG. 5, the node device 2 has 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. Configured control unit 21, HDD etc. that stores various data and programs, etc. Configured storage unit 22, and buffer memory as storage means for temporarily storing (storing) received content data (data packets) 23, a decryption accelerator 24 for decrypting encrypted content data stored in the notifier memory 23 using a decryption key, and video data included in the decrypted content data (Video information) and audio data (Audio information) etc. are decoded (Data decompression etc.) and reproduced, and the reproduced video data etc. The video processing unit 26 that performs predetermined drawing processing and outputs the video signal, the 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, and the above-described playback Audio data is converted to analog audio signal by D (Digital) / A (Analog) conversion, then amplified by amplifier and output, and audio signal output from the audio processing unit 28 is output as sound wave A communication unit 29a for controlling communication between the speaker 29 to be connected to the broadcasting station device 1 and other node devices 2 through the network 10, and the user Inputs various instructions from the (viewer) and gives the instruction signal to the control unit 21 (for example, a mouse, keyboard, operation panel, or remote control) 29b and an IC card 29e are attached electrically. An IC card slot 29c for connection, and includes a control unit 21, a storage unit 22, a nota memory 23, a decryption accelerator 24, a decoder unit 25, a communication unit 29a, an input unit 29b, and an 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.

[0066] The IC card 29e is tamper-resistant (that is, tampering is taken so that confidential data cannot be read by unauthorized means and cannot be easily analyzed). Content distribution system S operator is distributed to users. The IC card 29e includes an IC card controller composed of a CPU, a tamper-resistant nonvolatile memory (for example, EEPROM), etc., and a user ID and an encrypted key are stored in the nonvolatile memory. A decryption key, a digital certificate, and the like for decrypting the content data 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 server 3 together with a participation request (including the location information of the node device).

[0067] The buffer memory 23 is composed of, for example, a FIFO (First In First Out) format ring buffer memory, and is received through the communication unit 29a in the storage area indicated by the reception pointer under the control of the control unit 21. Content data is temporarily stored.

[0068] In the control unit 21, the CPU reads and executes a program stored in the storage unit 22 and the like so as to control the entire node device 2, and the communication unit transmits a plurality of data buckets to which upstream power is also distributed. Received as a packet receiving means through 29a and written to the buffer memory 23 and read out the data packets stored in the buffer memory 23 (data packets received in the past for a certain period of time), and downstream node devices through the communication unit 29a In addition, the data packet stored in the storage area of the buffer memory 23 indicated by the playback pointer is read out, and the decoding key separator 24 and the decoder are read out via the bus 29d. Output to part 25. The above program may be downloaded with a predetermined server power on the network 10, for example. For example, it may be recorded on a recording medium such as a CD-ROM and read through a drive of the recording medium.

[0069] 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. (For example, data packets with packet numbers “1”, “2”, “4”, “5”, “6” are accumulated in the buffer memory 23, In this case, it is determined that the data packet with the packet number “3” is missing). 2 transmits the complement request information of the missing data packet through the communication unit 29a, and transmits the data packet returned from the other node device 2 to the supplement request information through the communication unit 29a. It is designed to receive data as a packet receiving means.

Here, in the supplement request information, for example, a packet number as a packet identification information corresponding to a missing data packet, a content ID (an ID uniquely assigned to each content data), and the like are described. Includes missing packet list (packet loss list)! / If there are multiple missing data packets, the packet number and content ID corresponding to each missing data packet will be described.

In addition, 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 uses the supplement request information as a packet presence / absence determination unit. It is determined whether or not the data packet indicated by the missing packet list included in the request information is possessed (for example, the packet number and the content ID described in the missing packet list and the buffer memory 23 are stored. If it is determined that the data packet is present, the data packet return means serves as a data packet return means for the node device 2 that is the transmission source of the complementary request information. The data packet is returned as a complementary data packet through the communication unit 29a.

[0072] Then, the control unit 21 deletes 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. The dropped packet list is updated, and further, as a packet identification information presence / absence determining means, it is determined whether or not the packet number of the data packet is still described in the updated lost packet list, and it is determined that it is still described. Case (for example, packet numbers and content IDs corresponding to multiple data packets are described in the missing packet list, and only some data packets are returned to the source node device 2) As described above, the supplement request information is transferred through the communication unit 29a to the node device 2 other than the node device 2 located downstream of itself as a supplement request transfer means.

[0073] [4. Configuration of connection destination introduction server]

Next, the configuration and function of the connection destination introduction server 3 will be described with reference to FIG.

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

[0075] As shown in FIG. 6, the connection destination introduction server 3 also has 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 communication unit for controlling communication of information between the configured control unit 35, a storage unit 36 configured to store and store various data and the like, and a node device 2 and the like through the network 10. 37, and these components are connected to each other through a nose 38.

[0076] In the storage unit 36, the location information of the broadcasting station device 1 and the node device 2 participating in the tree type content distribution system S, the broadcasting station device 1 and the node device 2 in the tree type content distribution system S, and A database in which topology information between the node devices 2 is stored is constructed.

[0077] The control unit 35 performs overall control of the connection destination introduction server 3 by executing a program stored in the storage unit 36 or the like by the CPU, and when there is a request for participation of node devices that have not participated. The above-mentioned authentication, 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 specified) The hash value hashed with the hash function) is stored in the database. After that, if there is an inquiry about the connection destination of the node device due to a reception failure in the node device, etc., The digital certificate digest is used as a session key (this eliminates the need for authentication).

In addition, when the above authentication is valid, the control unit 35 determines the location information and hierarchy level information of a plurality of upstream node devices that are connection destination candidates for the node device that has requested participation. (In other words, information indicating how many layers the upstream node device is in) and the location information and layer level information of the remote node device (that is, how many layers the remote node device is in) Information) is transmitted through the communication unit 37. In the node device that has received the location information, the physical proximity on the network 10 of a plurality of upstream node devices that are connection destination candidates is compared, and the upstream node device that is present at the closest location is selected. As a result, a connection request is made to the upstream node device and a 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 server 3. . On the other hand, the control unit 35 stores topology information about the node device in the database.

[0079] [5. Operation of tree-type content distribution system]

Next, the operation of the tree-type content distribution system S when the missing data packet is complemented will be described with reference to FIG. 7 to FIG.

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, and FIG. 8 is a flowchart showing details of the packet supplement processing in FIG. FIGS. 9 and 10 are flowcharts showing processing in the control unit 21 of the node device 2 that has received the supplement request information. FIG. 11 shows the control unit 11 of the broadcast station device 1 that has received the supplement request information. It is a flowchart which shows the process in.

[0081] The process shown in Fig. 7 is a request for participation to the non-participating node device connection destination introduction server 3, and the location information and hierarchy level information of a plurality of upstream node devices that are connection destination candidates. This is started 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 The data packet related to the content data that has also been transmitted by the upstream node device power is received through the communication unit 29a (step S1), and the received data packet is the complementary data transmitted from the other node device 2 according to the supplement request information. Whether it is a packet For example, it is determined by referring to the packet type information described in the payload portion of the packet (step S2).

[0082] Then, if the received data packet is not a complementary data packet (step S2: N), the control unit 21 uses 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).

[0083] Then, when the received data packet is not a packet that has been received before (for example, when the received data packet and the data packet having the same packet number are not stored in the buffer memory 23). (Step S3: N), the control unit 21 inserts the received data packet into the buffer memory 23 and writes it (Step S4).

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

Here, the complement mode is a state in which the complement processing of the data packet is enabled. For example, the user operates the input unit 29b to input the content purchase instruction (for example, press the purchase button). ), The complement mode is set by the control unit 21.

[0086] If the mode of the device that is currently set is not the complementary mode (step S5: N), the control unit 21 transmits the data packet (upstream) stored in the notch memory 23. Considering the case where the stream is interrupted due to the withdrawal of the located node equipment, etc., the data packet received in the past for a certain period of time so as not to be affected by this is read and transmitted to the downstream node equipment 2 through the communication unit 29a. (Transfer) (Step S6).

[0087] Next, the control unit 21 reads a predetermined amount of data packets stored in the storage area of the buffer memory 23 indicated by the playback pointer, uses the decryption key obtained in advance from the IC card 29e. Then, the data is decrypted by the decryption accelerator 24 and output to the decoder unit 25 (step S7). A predetermined amount of data packets output to the decoder unit 25 are reproduced, and 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.

[0088] In step S8, the control unit 21 determines whether or not to stop receiving the content data. To do. 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 the reception of the content data is stopped (step S8: Y), for example, when the distribution (broadcasting) of the content unit (for example, one movie or one song) is completed, or input from the user If there is an instruction to stop receiving content data via part 29b, the processing ends.

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

[0090] In step S9, the control unit 21 determines whether or not the currently set mode (state) force of the device is the complementary mode described above, and if it is the complementary mode (step S9: Y). The received complementary data packet is inserted into the complementary buffer in the buffer memory 23 (a buffer different from that for the normal data packet) 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 not in complement mode, the data packet for complementation is not necessary, and the packet is discarded.

[0091] If the received data packet is a packet that has been received before in step S3 (step S3: Y), the control unit 21 discards the duplicated data packet. (Step S11), return to Step S1.

[0092] In addition, in the above step S5, when the mode of the device that is currently set! Is the complementary mode (step S5: N), the control unit 21 detects that the data packet is missing (missing). If the data packet received this time is not a data packet to be received next to the previously received data packet, the missing data is listed in the missing packet list of the content data. Describe the packet number of the packet (that is, register the missing data packet in the missing packet list) (step S12). The check for missing data packets is performed by, for example, the packet number (in the payload portion) of the received data packet and the sequence counter (the packet of the next data packet to be received) held by the node device 2. This is done by comparing with the counter indicated by the number. Next, the control unit 21 determines whether or not a packet number of a predetermined number (eg, 10) or more of data packets is described (registered) in the missing packet list (step S 13). If packet numbers of more than a few data packets are not described (step S13: N), the process proceeds to step S6, and if more than a predetermined number of data packet packet numbers are described (that is, a predetermined number or more) (Step S14: Y), the packet complementing process of step S14 is performed.

In the packet complementing process, as shown in FIG. 8, first, the control unit 21 adjusts a preset threshold j8 of the probability (step S111). More specifically, the control unit 21 refers to the hierarchical level information of the remote node device acquired from the connection destination introduction server 3, compares its own node device 2 and the hierarchy with the hierarchy of the remote node device, and If the level of the remote node device is lower (downstream) than the level of its own node device 2, adjust the threshold value | 8 to temporarily lower (upstream is easier to select). Note that the threshold value) 8 is maintained as it is when the hierarchy of the remote node device is not lower (downstream) than the own node device 2 hierarchy.

[0095] Next, the control unit 21 acquires the random value R generated by the random number generator (step S112), and determines whether or not the random value R is greater than or equal to the threshold value β (step S112). SI 13), if the random value R is greater than or equal to the threshold β (step S113: Y), the upstream node device is selected, and the complementary request information including the missing packet list is sent to the upstream node device through the communication unit 29a. (Step S114), and the process returns to the process in FIG. On the other hand, if the random value R is not greater than or equal to the threshold j8 (step S 113: N), the far node device is selected and the complementary request information including the missing packet list is transmitted to the far node device through the communication unit 29a. (Step SI 15), the processing returns to FIG.

[0096] 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 Therefore, the data is stored in a complementary nother in the nother memory 23. Then, when the complement completion information (from the processing of steps S 25, S 45, and S 53 described later) received from the other node device 2 or the broadcasting station device 1 is received, the control unit 12 Multiple data packets stored in 23 (normal data packets) and complementary data packets ( The data packet stored in the complementary buffer) is extracted (used) to restore the complete content data, and as a recording means, this is recorded on the HD in the storage unit 22 as another recording medium (for example, To purchase 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 processing shown in FIG. 9 is processing in the control unit 21 of the sword device 2 that is directly connected to the broadcasting station device 1.

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

[0099] 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 of the above-described information through the communication unit 29a. Transmit (reply) to the source node device 2 (step S22). Then, the control unit 21 deletes the packet number corresponding to the data packet related to the reply from the missing packet list to update the missing packet list (step S23), and proceeds 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 lost packet list. If the packet number of the data packet is not described in the missing packet list (step S 24: N), all the missing data packets have been transmitted. Complement completion information is transmitted to the node device 2 that is the transmission source of the supplement request information through the communication unit 29a. Transmit (step S25), and the process ends.

[0101] On the other hand, when the packet number of the data packet is still described in the updated missing packet list (step S24: Y), the control unit 21 has been set in advance as in step S111. Adjust the probability threshold j8 (step S26), then obtain the random value R generated by the random number generator (step S27), and determine whether the random value R is greater than or equal to the threshold j8. (Step S28). If the random value R is greater than or equal to the threshold j8 (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 The supplement request information including the list is transmitted (transferred) to the upstream node device through the communication unit 29a (step S29), and the process is terminated. On the other hand, if the random value R is not greater than or equal to the threshold j8 (step S28: N), the remote node device is selected and the missing packet list (if updated, the updated missing packet list) is included. The request information is transmitted to the remote node device through the communication unit 29a (step S30), 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 the supplement request information including the missing packet list (or updated missing packet list if updated) to the broadcasting station device 1 through the communication unit 29a. The process ends.

Next, the processing shown in FIG. 11 is started in the broadcast station apparatus 1 that has received the supplement request information, and the control unit 11 performs master processing based on the packet number and content ID described in the missing packet list. A complementary data packet is acquired from the content data (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). Further, the completion completion information of the data packet is transmitted to the node device 2 that is the transmission source of the above complement request information (step S53), and the processing is terminated. [0106] In the process shown in Fig. 7 in the above embodiment, a data packet drop check is performed during distribution of content data related to one unit of content, and a predetermined number or more of data packets are lost. In this case, content data related to one unit of content is received to the end (in other words, buffering is completed). In such a case, 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).

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

[0110] 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 thus a duplicate description is omitted. Further, when the supplement 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.

[0111] 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 complementary request information (step S65), and stores it in the buffer memory. The complete content data is restored using a plurality of data packets stored in the noffer memory 23 and the complementary data packets (complementary packets). This is recorded on the HD in the storage unit 22 as another recording medium (for example, for the purchase of content data) (step S66). [0112] If there is no missing data packet in step S62 (step S62: Y), the complete content data is restored using a plurality of data packets stored in the noffer memory 23 as a recording means. Then, this is recorded on the HD in the storage unit 22 as another recording medium (for example, for the purchase of content data).

[0113] 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 the purchase of the content data is completed. Is notified to the user (for example, by display or audio output) (step S68), and the process is terminated. As a result, even if 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 when, for example, the user gives a reproduction instruction via the input unit 29b. The video data is displayed on the display unit 27 via the video processing unit 26, and the audio data is received from the speaker 29 via the audio processing unit 28. It will be output as a sound wave.

[0115] As described above, according to the above-described embodiment, the node device in which the supplement request information transmitted from the node device that supplements the missing data packet includes the data packet indicated in the node. Since the data is transferred until it reaches 2, the data packet can be complemented more efficiently. However, 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 data packet can be complemented more efficiently in a wide range while suppressing the burden on the node device 1 and the upstream node device 2.

[0116] Note that in the above embodiment, the node device 2 that is the source of the supplement request information has changed the upstream node device to which it is connected and raised the layer level (for example, from the fourth layer to the second layer) In this case, for example, if complementary request information is transmitted to a remote node device that also recognizes the initial power, the remote node device may be in a lower layer than itself, and therefore, the transfer of the complementary request information may loop. (See Figure 3). The operation of the node device 2 for avoiding this will be described. [0117] Fig. 13 shows an operation 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, when the node device 2r that is the source of the supplement request information increases the hierarchical level, the node device 2r of the supplement request information Instead, referral request information (including its own location information and hierarchy level information) is transmitted, and the remote node device 2w that has received the referral request information forwards the referral request information to its own upstream node device 2k. However, the upstream node device 2k compares its own layer with the layer of the source node device 2r and is not the same layer, so the introduction request information is transferred to the upstream upstream node device 2e. However, since the upstream node device 2e is the same layer by comparing its own layer and the layer of the source node device 2r, its location information and layer level are compared with the source node device 2r. Send introduction response information including information It has become so. As a result, even when the node device 2r that is the transmission source of the complement request information changes the upstream node device to be connected and raises the hierarchical level, the node device 2 that is the source of the transmission is 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.

[0119] In the above embodiment, as an example of the first node device, any node positioned on the communication path from itself to the broadcasting station device 1 as the upstream node device to which it is directly connected. It can also be used as an upstream node device!

[0120] Further, the present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope.

[0121] In addition, the entire disclosure of the Japanese patent application (No. 2005-138041), including the specification, claims, drawings, and abstract filed on May 11, 2005, refers to all of them. So it is incorporated here.

Claims

The scope of the claims

[1] 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 node device included,

A packet receiving means for receiving the plurality of data packets that have been distributed; a missing packet presence / absence judging means for judging whether or not there is a missing data packet based on the received data packet;

When the missing packet presence / absence determining means 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 to

Complementary packet receiving means for receiving the data packet returned from the node device power in response to the complementary request information;

A node device comprising:

[2] In 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 located on a communication path other than the communication path. Any one of the second node devices other than the node device located downstream of the node device is selected with a preset probability, and the complement request information is transmitted to the selected node device. A node device.

[3] In the node device according to claim 2,

The probability that the first node device is selected is set to be higher than the probability that the second node device is selected.

[4] In the node device according to claim 2 or 3,

The second node device is a node device in a hierarchy higher than or equal to itself.

[5] In the node device according to claim 2,

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. A node device.

[6] In the node device according to claim 1,

Storage means for temporarily storing the received data packet;

Of the plurality of data packets forming a content unit, when a missing data packet is supplemented by the supplement request information, the plurality of data packets stored in the storage means and the supplement packet are used to complete the data packet. Recording means for recovering and recording content data to other recording media,

A node device further comprising:

[7] A node device comprising complementary request information receiving means for receiving the complementary request information transmitted from the node device according to claim 1,

A packet presence / absence determining means for determining whether or not it has the data packet indicated by the received complement request information;

When the packet presence / absence determining means determines that the data packet is included, the data packet return means for returning the data packet to the node device that has transmitted the complement request information;

A node device comprising:

[8] In the node device according to claim 7,

When it is determined by the packet presence / absence determining means that the data packet is not included, a complementary request transfer for transferring the complementary request information to a node device other than the node device located downstream of itself. A node device further comprising means.

[9] A node device comprising complementary request information receiving means for receiving the complementary request information transmitted from the node device according to claim 1,

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 has power; A data packet return means for returning the data packet determined to be present by the packet presence / absence determination means to the node device that transmitted the complement request information;

The packet identification information corresponding to the data packet related to the reply is deleted from the missing packet list to update the missing packet list, and the packet identification information is not yet in the updated missing packet list. Packet identification information presence / absence judging means for judging whether or not it is described,

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. A complementary request transfer means for transferring the complementary request information including:

A node device comprising:

[10] In 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, and a self-location request that is located on a communication route other than the communication route. A node device other than the node device located downstream of the node device is selected with a preset probability, and the complementary request information is transferred to the selected node device. A node device.

[11] The node device according to claim 10,

[12] In the node device according to claim 10,

[13] The node device according to claim 10,

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 different from a communication route from itself to the distribution source device of the data packet. A node device located above.

[14] A program that causes a computer to function as the node device according to claim 1.

[15] A program that causes a computer to function as the node device according to claim 7.

[16] Provided with a plurality of node devices, 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 relayed by the node device from upstream to downstream In the distribution system that is being distributed,

The node device of 1

When the missing packet presence / absence determining means determines that there is the missing data packet, a complement indicating a request for complementing the missing data packet is issued to a node device other than the node device located downstream of itself. A complementary request sending means for sending request information;

Complement packet receiving means for receiving the data packet returned from the other node device power 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 supplement request information is included;

When the packet presence / absence determining means determines that the data packet is included, the data packet returning means for returning the data packet to the one node device;

A distribution system comprising:

[17] In the distribution system according to claim 16, The other node device is:

When it is determined by the packet presence / absence determining means that the data packet is not included, a complementary request transfer for transferring the complementary request information to a node device other than the node device located downstream of itself. A distribution system further comprising means.

[18] 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 of complementing data packets,

Receiving the plurality of continuous data packets distributed to the one node device !,

A step of determining whether or not there is a missing data packet based on the received data packet in the one node device;

If it is determined in the one node device that the missing data packet exists, a request for complementing the missing data packet is sent to a node device other than the node device located downstream of the one node device. Transmitting the complementary request information indicating the following: in the other node device, receiving the complementary request information transmitted from the one node device;

Determining whether the other node device has the missing data packet indicated by the received supplement request information;

A step of returning the data packet to the one node device when it is determined that the other node device has the data packet; and And receiving the data packet returned from the other node device.

A method of complementing a data packet comprising:

[19] In the data packet complementing method according to claim 18,

If it is determined that the other node device has the data packet, the node device other than the node device located downstream of the other node device A method for complementing a data packet, further comprising a step of transferring the complement request information.