JP4770804B2 - Overlay network type communication system, overlay network type node device and program - Google Patents

Description

  The present invention relates to a technique for a plurality of node devices to communicate with each other on an overlay network constructed by participation of a plurality of node devices, and in particular, to determine the logical position of each node device on the overlay network. The present invention relates to a technique in which each node device determines a node ID to be represented.

  In order to share information such as contents (for example, audiovisual contents) among a plurality of node devices (for example, a plurality of personal computers), an overlay network is logically constructed by the participation of the plurality of node devices, and Thus, a technology that enables the plurality of node devices to communicate with each other has already been put into practical use.

  An example of such a communication system is disclosed in Patent Document 1 as a peer-to-peer type content distribution system. In this overlay network type communication system, a plurality of logical positions on the overlay network are assigned to a plurality of node devices, respectively. For example, a distributed hash table (DHT) is used in order to distribute and store a plurality of logical positions respectively assigned to a plurality of node devices on the overlay network.

Data for identifying a logical position of each node device on the overlay network is generally referred to as a node ID. For example, when the above-described DHT is used, a predetermined hash function is applied to information unique to each node device, and a value obtained as a result is adopted as the node ID.
JP 2006-197400 A

  In general, before each node device participates in the overlay network, information unique to each node device (eg, IP address, MAC address assigned to each node device, serial number of each node device, participation in the overlay network) The node ID of the own node device is determined in accordance with a predetermined rule (for example, a hash function common to a plurality of node devices is applied to the specific information) based on the date and time when Designed.

  The node ID should be determined so as to be unique to each node device. However, when each node device determines the node ID according to the predetermined rule, the properties such as the hash function (the two results may be the same even if two separate values are given to the same hash function) Therefore, although the probability is very low, the same node ID may be assigned to a plurality of node devices.

  When a plurality of node devices participate in the overlay network with the same node ID assigned to the node devices, a disclosure is made so that a node device can make new contents visible to other node devices. Even if a message (publish message) is distributed to another node device, it is not known which of the plurality of node devices to which the same node ID is assigned the published message.

  As described above, when the destination of the public message for new content is unknown, even if another node device tries to find the content on the overlay network, correct routing is not performed on the overlay network. If correct routing is not performed, each node device cannot reach the content holder that holds the target content even though the target content exists on the overlay network, and finds the target content. I can't.

  On the other hand, when there is a possibility that the same node ID may be assigned to a plurality of node devices, if a management server common to the plurality of node devices is installed in the overlay network and the node ID is managed by the management server It is easy to prevent the same node ID from being assigned to a plurality of node devices. However, when such a management server is installed, new costs and maintenance are required. Therefore, it is desirable to omit such a management server as much as possible.

  Against the background described above, the present invention provides the same node ID to a plurality of node devices without requiring the intervention of a management server that manages the node ID representing the logical position of the node device on the overlay network. An object of the present invention is to provide a technique for determining the node ID of the own node device so that it is not assigned.

  The following aspects are obtained by the present invention. Each aspect is divided into sections, each section is given a number, and is described in a form that cites other section numbers as necessary. This is to facilitate understanding of some of the technical features that the present invention can employ and combinations thereof, and the technical features that can be employed by the present invention and combinations thereof are limited to the following embodiments. Should not be interpreted. That is, it should be construed that it is not impeded to appropriately extract and employ the technical features described in the present specification as technical features of the present invention although they are not described in the following embodiments.

  Further, describing each section in the form of quoting the numbers of the other sections does not necessarily prevent the technical features described in each section from being separated from the technical features described in the other sections. It should not be construed as meaning, but it should be construed that the technical features described in each section can be appropriately made independent depending on the nature.

(1) An overlay network communication system in which an overlay network is constructed by participation of a plurality of node devices, and the plurality of node devices communicate with each other on the overlay network,
Each node device
Prior to joining the overlay network, when the own node apparatus joins the overlay network according to a predetermined rule based on predetermined information, the own node apparatus is located on the overlay network. Node ID determination means for determining a node ID for uniquely identifying the position;
When the own node device is a participation request node device that requests to participate in the overlay network from now on, the relationship between the node ID of the other node device and the communication information necessary for communication with the node device is acquired. In order to store the relationship in the storage means, the node device represents a request that the node device wants to participate in the overlay network and includes participation request information including the determined node ID in any of the plurality of node devices. Participation request information transmitting means for transmitting
When receiving the participation request information, other node devices having a node ID close to the node ID included in the received participation request information among node IDs of other node devices stored in the storage unit Transfer means for transferring the participation request information to
The node ID of the own node device is closer to the node ID included in the received participation request information than the node IDs of the other node devices stored in the storage means. Therefore, when there is no transfer destination of the transfer means, participation request reply information transmitting means for transmitting participation request reply information corresponding to the participation request information to the participation request node device;
Node ID change necessity determination means for determining whether or not to change the node ID of the own node device based on the received participation request reply information;
A node ID changing unit that changes the node ID of the own node device when the node ID change necessity determining unit determines to change the node ID of the own node device;
An overlay network type communication system comprising: retransmission means for resending the participation request information including the changed node ID to any one of the plurality of node devices when the node ID of the own node device is changed.

  Prior to joining the overlay network, each node device constituting this overlay network type communication system determines the node ID of its own node device according to a predetermined rule based on predetermined information.

  Each node device transmits participation request information to one of a plurality of node devices when the node device is a participation request node device that requests to join the overlay network. When each node device receives participation request information from another node device in a state where the node device is neither a participation request node device nor a final transfer destination described below, each node device is stored in the storage means of the own node device. Among the node IDs of the other node devices, the participation request information is sent to the other node devices having a node ID logically close to the node ID (node ID of the participation request node device) included in the received participation request information. Forward.

  Each node device configuring the overlay network type communication system according to this section, when its own node device is not a participation request node device, but receives participation request information from another node device in a state where it is a final transfer destination. The participation request reply information corresponding to the participation request information is transmitted to the participation request node device.

  Each node device constituting the overlay network type communication system according to this section determines whether or not to change the node ID of its own node device based on the received participation request reply information. The node ID of the node device is changed. Then, when the node ID of the own node device is changed, each node device retransmits the participation request information including the changed node ID to any one of the plurality of node devices.

  Therefore, according to the overlay network type communication system according to this section, the situation where the same node ID is assigned to a plurality of node devices is prevented without making the management server indispensable.

(2) An overlay network type communication method in which an overlay network is constructed by participation of a plurality of node devices, and the plurality of node devices communicate with each other on the overlay network,
Prior to joining the overlay network, when each node device joins the overlay network according to a predetermined rule based on predetermined information, each node device is positioned on the overlay network. A node ID determining step for determining a node ID for uniquely identifying the position;
When the own node device is a participation request node device that requests to participate in the overlay network from now on, the relationship between the node ID of the other node device and the communication information necessary for communication with the node device is acquired. In order to store the relationship in the storage means, the node device represents a request that the node device wants to participate in the overlay network and includes participation request information including the determined node ID in any of the plurality of node devices. A participation request information sending step for sending
When receiving the participation request information, other node devices having a node ID close to the node ID included in the received participation request information among node IDs of other node devices stored in the storage unit Transferring the participation request information to:
The node ID of the own node device is closer to the node ID included in the received participation request information than the node IDs of the other node devices stored in the storage means. Therefore, when there is no transfer destination of the transfer means, a participation request reply information transmission step of transmitting participation request reply information corresponding to the participation request information to the participation request node device;
A node ID change necessity determination step for determining whether to change the node ID of the own node device based on the received participation request reply information;
A node ID changing step of changing the node ID of the own node device when it is determined that the node ID of the own node device is changed by the node ID change necessity determining step;
And a retransmission step of resending the participation request information including the changed node ID to any one of the plurality of node devices when the node ID of the own node device is changed.

  This overlay network type communication method is executed as an operation method of the overlay network type communication system according to the item (1). Since the operation method is described in the above section (1), the overlay network type communication method will be briefly described below.

  When this overlay network type communication method is executed, each node device determines the node ID of its own node device according to a predetermined rule based on predetermined information prior to joining the overlay network.

  Further, each node device transmits participation request information to one of a plurality of node devices when the node device is a participation request node device.

  Further, each node device is stored in the storage means of its own node device when it receives participation request information from another node device in a state where the own node device is neither a participation request node device nor a final transfer destination described later. The participation request information is transferred to another node device having a node ID logically close to the node ID of the participation request node device among the node IDs of the other node devices.

  Furthermore, each node device returns a participation request corresponding to the participation request information when the local node device is not a participation request node device but receives participation request information from another node device in a state where it is a final transfer destination. The information is transmitted to the participation request node device.

  Further, each node device determines whether or not to change the node ID of the own node device based on the received participation request reply information, and when it is determined to change the node ID of the own node device, Change the node ID.

  Further, when the node ID of the own node device is changed, each node device retransmits participation request information including the changed node ID to any one of the plurality of node devices.

  Therefore, according to the overlay network type communication method according to the present section, a situation in which the same node ID is assigned to a plurality of node devices is prevented without making it necessary to install a management server.

(3) An overlay network type node device that constructs an overlay network by participating together with other node devices and communicates with other node devices on the overlay network,
Prior to joining the overlay network, when the own node apparatus joins the overlay network according to a predetermined rule based on predetermined information, the own node apparatus is located on the overlay network. Node ID determination means for determining a node ID for uniquely identifying the position;
When the own node device is a participation request node device that requests to participate in the overlay network from now on, the relationship between the node ID of the other node device and the communication information necessary for communication with the node device is acquired. In order to store the relationship in the storage means, the node device represents a request that the node device wants to participate in the overlay network and includes participation request information including the determined node ID in any of the plurality of node devices. Participation request information transmitting means for transmitting
When receiving the participation request information, other node devices having a node ID close to the node ID included in the received participation request information among node IDs of other node devices stored in the storage unit Transfer means for transferring the participation request information to
The node ID of the own node device is closer to the node ID included in the received participation request information than the node IDs of the other node devices stored in the storage means. Therefore, when there is no transfer destination of the transfer means, participation request reply information transmitting means for transmitting participation request reply information corresponding to the participation request information to the participation request node device;
Node ID change necessity determination means for determining whether or not to change the node ID of the own node device based on the received participation request reply information;
A node ID changing unit that changes the node ID of the own node device when the node ID change necessity determining unit determines to change the node ID of the own node device;
An overlay network type node device comprising: retransmission means for resending the participation request information including the changed node ID to any of the plurality of node devices when the node ID of the own node device is changed.

  This overlay network type node device corresponds to each of a plurality of node devices constituting the overlay network type communication system according to the item (1). Since the configuration and operation of each node device have been described in the above section (1), redundant description is omitted here.

(4) The participation request reply information transmitting unit includes the participation request reply information corresponding to the participation request information, which includes a node ID of the own node device when the transfer unit has no transfer destination. Means for transmitting to the requesting node device;
The node ID change necessity determination means includes means for determining that the node ID of the own node device is changed when the node ID included in the received participation request reply information matches the node ID of the own node device (3 The overlay network type node device according to the item).

(5) The participation request reply information transmitting unit determines whether or not the node ID of the participation request node device included in the participation request information matches the node ID of the own node device when there is no transfer destination of the transfer unit. Means for transmitting the participation request reply information including the node ID change instruction information for instructing the change of the node ID to the participation request node device when it is determined that they match,
The node ID change necessity determining means includes means for determining that the node ID of the own node apparatus is changed when the node ID change instruction information is included in the received participation request reply information. The described overlay network type node device.

(6) The predetermined node information and / or the rule used for determining the original node ID without referring to the original node ID determined by the node ID determining unit. The overlay network type node according to any one of (3) to (5), further including an acquisition unit that acquires a new node ID different from the original node ID using information and / or rules different from apparatus.

(7) The acquisition means includes means for acquiring the new node ID by additionally or alternatively using information different from the information used for determining the original node ID. The overlay network type node device according to item (6).

(8) The node ID changing means includes an acquiring means for acquiring a new node ID different from the original node ID by referring to the original node ID determined by the node ID determining means (3 The overlay network type node device according to any one of items (5) to (5).

(9) The overlay network type node device according to (8), wherein the acquisition unit includes a unit that acquires the new node ID by performing a predetermined calculation on the original node ID. .

(10) storage means for storing the node ID used when participating in the overlay network even after the power of the own node device is shut down;
When attempting to join the overlay network, the node ID is read from the storage means, and the read node ID is set as an initial value of the node ID used by the own node device to join the overlay network from now on. Including setting means to
The overlay request according to any one of (3) to (9), wherein the participation request information transmitting unit transmits the participation request information including the node ID set by the setting unit to any of the plurality of node devices. Network type node equipment.

  According to this overlay network type node device, after its own power is turned on, the node device uses the same node ID as that used when the node device joined the overlay network during the previous power-on. To join the overlay network.

  Therefore, according to this overlay network type node device, the self node device logically appears on the overlay network when it joins the overlay network during the previous power-on after its power is turned on. It is logically arranged at the same position as the arranged position.

  Therefore, according to this overlay network type node device, in order for the own node device to search for information such as specific contents, there is a possibility that routing is performed on the overlay network through the same route at the previous participation and at the current participation. And the search and transfer of information does not stagnate.

(11) The node ID determination unit determines the node ID according to the predetermined rule based on the predetermined information when the node ID is not stored in the storage unit. Overlay network type node device.

(12) When the participation request node apparatus receives the participation request information in a state where the own node apparatus is not the participation request node apparatus, the participation request node apparatus acquires a relationship between a node ID of another node apparatus and the communication information. Participation request information corresponding process execution means for executing processing corresponding to the participation request information for the participation request node apparatus in order to allow the storage means of the participation request node apparatus to store the relationship. The overlay network type node device according to any one of (3) to (11).

  According to this node device, when the participation request information is received in a state where the own node device is not a participation request node device, a process corresponding to the participation request information is executed for the participation request node device, thereby It is supported that the participation request node device creates the routing table described above.

  As a result, when the participation request node device transmits participation request information to another node device, in response thereto, information necessary for creating a routing table is received from the other node device. That is, the participation request node device transmits participation request information to another node device in order to create a routing table.

(13) A program executed by a computer to operate the overlay network type node device according to any one of (3) to (12).

  If this program is executed by a computer, the same operation and effect can be realized according to basically the same principle as that of the overlay network type node device according to any one of the above items (3) to (12).

  The program according to this section can be interpreted so as to include not only a combination of instructions executed by a computer to fulfill its function, but also files and data processed in accordance with each instruction.

  In addition, this program may achieve its intended purpose by being executed by a computer alone, or may be intended to achieve its intended purpose by being executed by a computer together with other programs. it can. In the latter case, the program according to this section can be mainly composed of data.

(14) A recording medium on which the program according to item (13) is recorded so as to be readable by a computer.

  When the program recorded on this recording medium is executed by a computer, the same operation effect is realized according to basically the same principle as the overlay network type node device according to any one of the above items (3) to (12). Can be done.

  This recording medium can adopt various formats, for example, a magnetic recording medium such as a flexible disk, an optical recording medium such as a CD and a CD-ROM, a magneto-optical recording medium such as an MO, and an unremovable storage such as a ROM. Any of these may be adopted.

  Hereinafter, one of more specific embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, when the present invention is applied to an information communication system S that makes it possible to perform peer-to-peer communication while sharing information such as content among a plurality of node devices by configuring an overlay network using DHT. It is an example.

[Overall outline]
FIG. 1 systematically shows the connection configuration of the information communication system S. In this information communication system S, each node device selectively performs various processes according to the type of role that changes over time. Schematically, each node device (represented by white circles in FIG. 1) performs the following processing.

1. Calculation of Node ID Prior to participating in the overlay network, the own node device is determined according to a predetermined hash function based on predetermined information (eg, IP address, MAC address, serial number, etc. of the own node device). Calculate the node ID of the device.

2. 2. Creation of routing table 2-1. Sending a Join (JOIN) Message to a Contact Node The local node device creates a routing table for the local node device when the local node device is a participation request node device (hereinafter also referred to as “participation request node”). For this purpose, the participation message (which is an example of the above-mentioned “participation request information”) is sent to a contact node device (hereinafter also referred to as “contact node”) that is one of a plurality of node devices. Send.

  The participation request node transmits a participation message to the contact node. The join message also has the purpose of confirming whether the contact node is actually in the same overlay network, depending on whether the transmission is successful. That is, the participation message also has a function as a presence confirmation message.

  The contact node reads the node IDs of other node devices corresponding to the area designation information (information for designating the level of the routing table) included in the participation message from the routing table stored in the contact node. This contact node further confirms its existence to request that the corresponding other node device returns information to the participation request node regarding whether or not the node device actually exists in the same overlay network. The message is transmitted to the corresponding other node device.

2-2. Transfer of Participation Message When the local node apparatus receives a participation message from another node apparatus in a state where the local node apparatus is neither a participation request node nor a final transfer destination node (root node) of the participation message, the local node apparatus Among the node IDs of the other node devices stored in the node ID, the participation message is transferred to another node device having a node ID logically close to the node ID of the participation request node (belonging to the same ID space area).

  The local node device that is not the participation request node exists to request the transfer destination of the participation message to return information about whether or not the transfer destination actually exists in the same overlay network to the participation request node. A confirmation message is transmitted to the transfer destination together with the participation message described above.

  The own node device that is not the participation request node, from the routing table stored by itself, the node ID of another node device corresponding to the area designation information (information for designating the level of the routing table) included in the participation message Is read. This own node device further exists to request the corresponding other node device to return information regarding whether or not the node device actually exists in the same overlay network to the participation request node. A confirmation message is transmitted to the corresponding other node device.

2-3. Reception of response message The participation request node receives the response message transmitted from each other node device in response to the reception of the participation message and the presence confirmation message, and creates a routing table using the received response message. .

3. Transmission of a transfer completion message to the participation request node The own node device sends a participation message from another node device in a state where the own node device is not the participation request node but is the final transfer destination node (root node) of the participation message. When received, a transfer completion message (which is an example of the above-mentioned “participation request reply information”) including the node ID of the own node device and indicating that the transfer of the participation message is completed is transmitted to the participation request node. To do.

4). Selective change of node ID The participation request node receives the transfer completion message, and when the node ID of the final transfer destination node (root node) matches the node ID of the own node device, the node ID of the participation request node To change.

5. Retransmission of participation message When the node ID of the node is changed, the participation request node retransmits the participation message including the changed node ID to the contact node.

[System configuration]
Next, a physical configuration and a logical configuration of the information communication system will be described with reference to FIG.
In FIG. 1, the overlay network 9 as a logical entity is systematically shown in the upper frame denoted by reference numeral 100, while the physical existence is present in the lower frame denoted by reference numeral 101 in FIG. 1. The network (for example, the Internet, LAN, WAN) 8 is systematically shown.

  As shown in the lower frame 101, an IX (Internet eXchange) 3, an ISP (Internet Service Provider) 4, a DSL (Digital Subscriber Line) line provider is used to construct a physical network (real-world network) 8. Apparatus 5, apparatus 6 for FTTH (Fiber To The Home) line operators, communication line (for example, telephone line, optical cable, etc.) 7, etc. are used.

  The information communication system S is configured to include a plurality of node devices 1a, 1b, 1c,..., 1x, 1y, 1z,. Thus, a peer-to-peer network system is realized.

  Each node device 1a, 1b, 1c,..., 1x, 1y, 1z,... Has a serial number unique to each node device 1 as information (device ID) indicating the identity of each node device 1. And an IP (Internet Protocol) address. The serial number and IP address of each node device 1 are set so as not to overlap among the plurality of node devices 1.

  Hereinafter, for convenience of explanation, the node device 1a, 1b, 1c,..., 1x, 1y, 1z,.

[Create DHT]
Next, an algorithm for calculating a node ID using a distributed hash table DHT (Distributed Hash Table) will be described. In the information communication system S, in order for the two node devices 1 to exchange information with each other, each must know the IP address of the other party. For example, in order to share the same content with each other, each node device 1 participating in the network 8 may know the IP addresses of all the node devices 1 participating in the network 8.

  However, when the number of node devices 1 connected to the network 8 becomes an enormous number, such as tens of thousands, hundreds of thousands, it is realistic that each node device 1 remembers the IP addresses of all the node devices 1. Absent. Specifically, for example, every time the power of one of the node devices 1 is turned on or off, the IP address of any one of the node devices 1 must be updated in all the other node devices 1. As a result, processing in each node device 1 becomes frequent, and system operation becomes difficult.

  In order to avoid such an inconvenience, one node device 1 is made to remember only the IP addresses of the minimum necessary number of node devices 1 among all the node devices 1 participating in the network 8. As for the node device 1 that does not remember the IP address, a system that uses the information transfer between the node devices 1 to be delivered to the own node device 1 has already been put into practical use.

  An example of such a system is an overlay network 9, and this overlay network 9 is constructed as shown in the upper frame 100 of FIG. 1 by an algorithm using DHT. The overlay network 9 means a network composed of virtual links formed using the existing network 8.

  This embodiment is based on an overlay network 9 constructed by an algorithm using DHT. The node device 1 logically arranged on the overlay network 9 is referred to as a node device 1 participating in the information communication system S, that is, a node device 1 participating in the overlay network 9.

  Since the node device (participation request node) 1 that has not yet participated participates in the information communication system S, the participation request node is another arbitrary node device 1 (contact) that has already participated in the information communication system S. It is necessary to send a participation message to the node. The participation message indicates a request that the participation request node wants to participate in the overlay network 9, and is created to include information for specifying the participation request node.

Each node device 1 participating in the information communication system S is given a node ID (identification information) as a unique number for each node device 1. The number of bits of that number is set to a number that can accommodate the maximum number of node devices 1 to be operated. For example, if a 128-bit number is used, 2 ¹²⁸ = 340 × 10 ³⁶ node devices can be operated.

  More specifically, the node ID of each node device 1 is a hash common to a plurality of node devices 1 with respect to a value unique to each node device 1 such as the IP address (or serial number) of each node device 1. A hash value obtained by applying a function (hash algorithm). Since the hash function is publicly known, detailed description thereof is omitted. By using the hash value, a plurality of node devices 1 are distributed in the same node ID logical space without being distributed. Thus, the node ID obtained for each node device 1 by the common hash function has a very low probability of being converted to the same hash value if the IP address (or manufacturing number) is different.

  In addition, in this embodiment, a value obtained by converting the IP address (global IP address) of each node device 1 by a hash function common to the plurality of node devices 1 is defined as the node ID of each node device 1. The

[Create routing table]
Next, an example of a method for creating a routing table using DHT will be described with reference to FIG. FIG. 2 shows an example of how a routing table is created using DHT.

  Since the plurality of node IDs respectively assigned to the plurality of node devices 1 are generated by a common hash function, the plurality of node devices 1 are the same as shown in FIGS. 2 (A) to 2 (C). The ring-shaped ID spaces are scattered and exist without much bias. In the figure, black circles indicate logical positions of the respective node devices 1.

  In the example shown in FIG. 2, the number representing each node ID is composed of 8 bits (4 digits in quaternary display), and the number representing the ID increases counterclockwise in the ring-shaped ID space. To do.

  In order to create the routing table, first, as shown in FIG. 2A, the ID space is equally divided into a plurality of areas. In practice, the ID space is generally divided into about 16 areas, but here, for simplicity of explanation, the ID space is divided into four and the node ID is expressed in quaternary numbers. And a bit length of 8 bits.

  A specific example of a method for creating a routing table will be described by taking a node device 1 as an example, that is, a node device 1N whose node ID is “1023” as an example.

<Level 1 routing>
First, the ID space is equally divided into four areas. Each area is represented by a numeric string “0XXX”, “1XXX”, “2XXX”, “3XXX” (X is an integer from 0 to 3, the same shall apply hereinafter) in which the maximum number of digits is expressed in quaternary numbers. Is done. Since the node ID of the node device 1N is “1023”, the node device 1N exists in the area “1XXX” in the lower left in FIG.

  Furthermore, the node device 1N appropriately selects another node device 1 existing in each area other than the area where the node device 1N exists (that is, the area of “1XXX”), and the selected node device 1 Are registered in the level 1 table.

  FIG. 3A shows an example of a level 1 table. In the table, since the second column indicates the node device 1N itself, it is not necessary to register the IP address.

<Level 2 routing>
Next, as shown in FIG. 2B, among the four areas divided by the level 1 routing described above, the area where the node device 1N exists is further divided into four subareas “10XX”, “11XX”, “ Divided into 12XX and 13XX.

  Further, similarly to the above, the node device 1N appropriately selects the node device 1 existing in each sub-area other than the sub-area where the node device 1N exists, and sets the IP address of the selected node device 1 in the level 2 table. sign up.

  FIG. 3B shows an example of a level 2 table. Since the first column indicates the node device 1N itself, it is not necessary to register the IP address.

<Level 3 routing>
Further, as shown in FIG. 2C, among the four subareas divided by the level 2 routing described above, the subareas in which the user exists are further divided into four subareas “100X”, “101X”, “102X”. ”And“ 103X ”.

  Further, similarly to the above, the node device 1N appropriately selects the node device 1 existing in each sub-area other than the sub-area in which the node device 1N exists, and sets the IP address of the selected node device 1 to the level 3 table. Register with.

  FIG. 3C shows an example of a level 3 table. Since the third column indicates the node device 1N itself, it is not necessary to register the IP address, and the second and fourth columns are blank because there is no node device in each subarea. Become.

<Level 4 routing>
Since the node ID of the node device 1N is “1023”, the fourth column indicates the node device 1N itself in the level 4 table, as shown in FIG. Need not be registered, and the first to third columns are blank because there is no node device in each sub-area.

  In this way, routing tables from level 1 to level 4 are created as shown in FIG. When the routing table is created up to level 4, all node IDs expressed in 8 bits can be covered. As the level goes up, white space will stand out in the table.

  Each node device 1 creates and owns a routing table using the method described above. In this way, each node device 1 creates a routing table that stores the IP addresses of the other node devices 1.

  In the present embodiment, each node device 1 has an IP address as node information, a node ID as identification information, and a logical position (DHT level and column position) at which the node ID is assigned to the node ID space. Are defined in association with each other).

  Here, a node device having a node ID close to the node ID of its own node device 1N is a root node to be described later (a node device whose node ID is “1000” in FIGS. 2C and 3D). Assume that

  As shown in FIG. 3D, the number of levels is determined according to the number of digits of the node ID, and the attention digit (at each level of the routing table) according to the number of decimal numbers used to express the node ID. For example, in the case of level 1, the number of digits that can appear in the first digit and in the case of level 2 the second digit) is determined.

  For example, when the node ID is expressed by a 16-digit hexadecimal number, the node ID has 64 bits, the number of levels is 16, and the number of (English) numbers that can appear in the attention digit is 16. ("0" to "f"). In the subsequent description of the routing table, the part representing the number appearing in the attention digit of each level is also simply referred to as “column”.

[Node device configuration]
Next, the configuration and function of each node device 1 will be described with reference to FIG. Since the configuration of each of the plurality of node devices 1 is common to each other, only one node device 1 will be representatively described. FIG. 4 schematically shows an example of the configuration of the representative node device 1.

  As illustrated in FIG. 4, the node device 1 includes a control unit 11 and a storage unit 12. The control unit 1 includes a computer including a CPU having a calculation function, a working RAM, a ROM that stores various data and programs, and the like. The storage unit 12 includes an HD for storing and storing (stores) content data, index information, the DHT, the program, and the like. However, among the plurality of node devices 1, there is also a node device 1 that does not store content data. The storage unit 12 constitutes an example of the “storage unit”.

  The node device 1 further decodes the encoded video data (video information), audio data (sound information), etc. included in the content memory and the buffer memory 13 for temporarily storing the received content data, etc. And a decoder unit 14 for decoding and the like. The node device 1 further performs a predetermined drawing process on the decoded video data or the like and outputs it as a video signal, and a CRT that displays a video based on the video signal output from the video processing unit 15 And a display unit 16 such as a liquid crystal display.

  The node device 1 further converts the decoded audio data into an analog audio signal by D (Digital) / A (Analog) conversion, amplifies the signal by an amplifier, and outputs the signal, and the audio processing unit The speaker 18 which outputs the audio signal output from 17 as a sound wave is provided.

  The node device 1 further receives a command from the user and performs an instruction signal in accordance with the instruction from the communication unit 20 for performing communication control of information with the other node device 1 through the network 8. An input unit (for example, a keyboard, a mouse, an operation panel, etc.) 21 is provided.

  As shown in FIG. 4, the control unit 11, the storage unit 12, the buffer memory 13, the decoder unit 14, and the communication unit 20 are connected to each other via a bus 22.

  In the node device 1, the CPU in the control unit 11 executes various programs stored in the storage unit 12 and the like, whereby the entire node device 1 is controlled in an integrated manner. Further, content data registration processing or the like is performed in response to an instruction signal from the input unit 21.

  The role played by the node device 1 varies depending on the type of program to be executed. Specifically, the node device 1 functions as a node device that transmits (transfers) information or functions as a node device that receives information.

[Outline of information communication system]
An outline of the information communication system S will be described with reference to FIGS. FIG. 5 is a schematic diagram for explaining a flow of a plurality of messages transmitted / received between a plurality of node devices 1 in order for a participation request node to participate in the information communication system S (overlay network 9). FIG. 6 is a schematic diagram for explaining the flow of these messages in more detail than FIG.

  However, FIG. 5 shows a state in which the node ID of the participation request node is changed according to the present embodiment because of a collision of node IDs, whereas FIG. 6 omits the state. Has been. That is, FIG. 6 shows an example in which it is not necessary to change the node ID of the participation request node (an example in which no node ID collision occurs) for convenience of explanation.

  Prior to joining the overlay network 9, the node device 1 (participation request node) that requests participation in the overlay network 9 is based on predetermined information (for example, the IP address, MAC address, serial number, etc. of the participation request node). The node ID of the participation request node is calculated according to a predetermined hash function.

  Next, the participation request node, as shown in FIG. 5, for the purpose of creating a routing table in any node device (contact node) with which the node first communicates and already knows the IP address. In addition, a participation (JOIN) message (indicated by a solid line with “JOIN” in FIG. 5) is transmitted to the contact node.

  Subsequently, as shown in FIG. 5, the participation request node receives a response message (indicated by a broken line in FIG. 5) from the contact node, and uses the received response message to send a routing table for the participation request node. Create The response message includes a combination of the source node ID and the IP address, and the combination is transferred to the destination.

  When a plurality of node devices 1 receive a participation message from another node device in a role that is neither a participation request node nor a final transfer destination node (root node) of the participation message, as shown in FIG. Of the node IDs of the other node devices stored in the node device, the participation message is transferred to the other node device having the node ID logically closest to the node ID of the participation request node (“JOIN” in FIG. 5). "Transfer".)

  Subsequently, as shown in FIG. 5, the participation request node receives a response message (indicated by a broken line in FIG. 5) from another node device, and uses the received response message for the participation request node. Create a routing table.

  When the own node device is not the participation request node but plays the role of the final transfer destination node (root node) of the join message, when the own node device receives the join message from another node device, FIG. As shown in FIG. 4, a transfer completion message including the node ID of the own node device and indicating that the transfer of the participation message is completed is transmitted to the participation request node.

  The participation request node receives the transfer completion message, and when the node ID of the final transfer destination node (root node) of the participation message matches (collision) with the node ID of the participation request node, the participation request node Change the ID. When the node ID is changed, the routing table created so far is deleted.

  When the participation request node changes the node ID of the node, the participation request node retransmits the participation message including the changed node ID to the contact node. The participation request node performs the above-described trial until the node ID of the final transfer destination node does not match (collision) with the node ID of the participation request node. As a result, participation of the participation request node in the overlay network 9 is completed.

  Therefore, according to this embodiment, it is reliably prevented that the same node ID is assigned to a plurality of node devices 1 redundantly. Therefore, according to the present embodiment, there is a low probability that the transfer or transmission of information (including various messages and various content data) using the routing table will be stagnant due to duplication of node IDs. Avoided.

  The elements of the present embodiment that are important for understanding the present invention have been schematically described above with reference to FIG. 5. Hereinafter, the entire embodiment will be described in detail with reference to FIG. 6.

  As described above, when one node device participates in the overlay network 9, the information communication system S receives a response message from another node device, so that information on the node device that transmitted the response message ( A routing table is created based on the IP address and node ID).

  Hereinafter, for convenience of explanation, a participation request node that requests participation in the overlay network 9 is represented as “node Z”, and any node device that already knows the IP address with which the node Z first communicates (Contact node) is expressed as “Node B”.

  The routing table is also simply referred to as “table”. The storage of node information and identification information of other node devices in the own node device is also referred to as “registration” in the own node device.

  FIG. 6 is a schematic diagram illustrating a flow of a plurality of messages transmitted and received between a plurality of node devices 1 in order for the participation request node to create a routing table. FIGS. 7A to 7C show examples of routing tables stored in the nodes B, E, and G participating in the information communication system S prior to the participation of the node Z, respectively. . FIG. 8 is an example of a routing table created by the node Z receiving response messages from the nodes B, E, and G.

  As shown in FIG. 6, when a node Z (participation request node) attempts to participate in the overlay network 9, it transmits a participation message to the node B that is a contact node (arrow 101). Then, the node Z confirms that the node B exists from the fact that the transmission of the participation message to the node B is successful (arrow 102).

  Next, the node B (contact node) sequentially transmits an existence confirmation message to the nodes A, E, and C registered in the level 1 as shown in FIG. 7A (arrows 103, 105, and 107). ). Node A then sends a response message to node Z (arrow 104), node E sends a response message to node Z (arrow 106), and node C sends a response message to node Z (arrow 108).

  In each of FIGS. 7A to 7C, a ▲ mark is attached to the left of any one of a plurality of levels. This means that an existence confirmation message is transmitted to another node device registered at a certain level.

  In each of FIGS. 7A to 7C, one of the plurality of node devices is surrounded by a square frame. This is because the own node device is surrounded by a square frame. This means that the join message is transferred to another node device. The transfer destination of the participation message is a node ID that is close to the node ID of the node Z (participation request node) (belongs to the same ID space area) among a plurality of other node devices registered at the level marked with ▲. It is what has.

  Node Z (participation request node) uses the response messages from node A, node B, node C, and node E, so that the IP addresses of node A, node B, node C, and node E in the table of FIG. Therefore, the node Z can store the IP address and the corresponding node ID in association with each other.

  In addition, in this embodiment, as clearly shown in FIG. 6, the node device 1 (hereinafter referred to as the participation message transferred from the node device that has received the participation message from the participation request node or is not the participation request node). The node information of a plurality of other node devices stored in the routing table of “the node device 1 that relays the participation message” is the one that is currently participating in the overlay network 9 among these other node devices. However, the message is directly returned to the participation request node without going through the node device 1 that relays the participation message.

  On the other hand, for example, the node device 1 that relays the participation message uses the node information of all other node devices stored in the routing table of the node device 1, and the other node devices actually participate in the overlay network 9. It is possible to implement the present invention in a manner of returning to the participation request node regardless of whether or not it is.

  Node B (contact node) forwards the join message to node E in the hope that it will eventually reach the root node of node Z (arrow 109). At this time, the node B adds area designation information indicating that the transmission destination of the presence confirmation message is the next level 2 to the participation message.

  Next, as shown in FIG. 7B, the node E sequentially transmits an existence confirmation message to the node G, the node D, and the node F registered in the next level 2 (arrows 110, 112, and 114). . Then, node G transmits a response message to node Z (participation request node) (arrow 111), node D transmits a response message to node Z (arrow 113), and node F transmits a response message to node Z. (Arrow 115).

  At this time, the node Z (participation request node) uses the response messages from the node D, the node F, and the node G, so that the IP addresses and node IDs of the node D, the node F, and the node G in the table of FIG. Can be stored. Node E then forwards the join message to node G in the hope that it will eventually reach the root node of node Z (arrow 116). At this time, the node E adds area designation information indicating that the transmission destination of the existence confirmation message is the next level 3 to the participation message.

  Next, as shown in FIG. 7C, the node G transmits a presence confirmation message to the node H registered at the next level 3 (arrow 117). Node H then sends a response message to node Z (arrow 118).

  The node ID of the node Z, which is the participation request node, is “1013”. As shown in FIG. 7C, among the plurality of node devices stored in the routing table of the node G, the node ID “ The node ID closest to the area “1013” is “1023”, which is the node ID of the node G. This means that there is no node device to which the join message is to be transferred next, and at the same time, node G is the root node for node Z. That is, the node G is the final transfer destination node of the participation message issued from the node Z. At this time, the node Z (participation request node) can store the IP address and node ID of the node H in the table of FIG. 8 by using the transfer completion message from the node H. In this case, since the node ID of the node Z that is the participation request node is “1013” and the node ID of the node H included in the transfer completion message from the node H is “1023”, the node that is the participation request node Z determines that his node ID has not collided, and the participation process to the information communication system S is thereby completed.

  Through the processing described above, the node Z (participation request node) can create the routing table shown in FIG. The table of the node Z is created based on response messages received from a plurality of existing node devices 1.

  Therefore, according to the present embodiment, information (various messages and various contents using the routing table) is stored in the routing table because other node devices that actually have withdrawn from the overlay network 9 are stored. The situation that the probability that the transfer or transmission of data (including data) will be stagnated is reduced. Therefore, according to this embodiment, the communication efficiency of the information communication system S is improved as a whole.

  Here, assuming that the node ID of the node Z that is the participation request node is “1023”, the node ID of the node H included in the transfer completion message from the node H is “1023”. The node ID of a certain node Z is fixed to the node ID of the node H. In this case, the node Z changes its own node ID, and again transmits a participation message to the node B that is the contact node.

[Operation of Information Communication System]
Next, the operation of each node device 1 in the information communication system S of the present embodiment will be described with reference to FIGS. The following processing is performed by each node device 1.

1. Participation Process When the own node apparatus 1 is a participation request node, the process for the own node apparatus 1 to participate in the overlay network 9 in the information communication system S (see FIG. 9)

2. Creation Processing When the local node device 1 is a participation request node, processing for the local node device 1 to create a routing table (step S4 in FIGS. 6 to 8 and FIG. 9).

3. Transfer processing When the local node device 1 is not a participation request node, the participation message is transferred to another node device 1, and when the local node device 1 is the final transfer destination node of the participation message, a transfer completion message is transmitted. Process for sending to the join request node

  However, the creation process among the above three processes has already been described in detail with reference to FIGS. 6 to 8 and is not an indispensable process for understanding the present invention. Briefly described.

  When the control unit 11 of the node Z recognizes that the power of the node device 1 is turned on by the input unit 11 or the like, it initializes various settings of the node Z and participates conceptually shown in the flowchart of FIG. Start the processing program. The participation processing program is stored in the storage unit 12 in a nonvolatile manner and is executed by the CPU of the control unit 11. However, prior to the execution of this participation processing program, it is assumed that the node Z holds in advance the IP address of the contact node (the node B described above) that should communicate first in order to participate in the overlay network 9.

  When the participation processing program is started, first, in step S1, the node ID of the participation request node is calculated. In FIG. 10, the details of step S1 are conceptually represented by a flowchart as a node ID calculation routine.

  In this node ID calculation routine, first, in step S101, the previous node ID, that is, the node ID calculated by executing this node ID calculation routine during the previous power-on of this participation request node is stored as the previous node ID. It is determined whether or not it is stored in the non-volatile memory of the unit 12.

  This time, assuming that the previous node ID is not stored in the storage unit 12, the determination in step S101 is NO, and the process proceeds to step S102. In step S102, reference information to be referred to in order to calculate a node ID unique to the participation request node using a hash function common to the plurality of node devices 1 is fetched from the storage unit 12. The reference information is, for example, at least one of an IP address, a MAC address, and a serial number (for example, CPU_ID) of the participation request node.

  Next, in step S103, by applying a hash function to the fetched reference information, the node ID of the participation request node is calculated as the current node ID. This completes one execution of this node ID calculation routine.

  On the other hand, this time, assuming that the previous node ID is stored in the storage unit 12, the determination in step S101 is YES, and the process proceeds to step S104. In step S104, the previous node ID is read from the storage unit 12. Subsequently, in step S105, the read previous node ID is set as the current node ID as it is. This completes one execution of this node ID calculation routine.

  In any case, a participation message to be transmitted from the participation request node to the contact node is then created in step S2 shown in FIG. Specifically, this participation message is created so as to include the current node ID assigned to the participation request node.

  Subsequently, in step S <b> 3, the created participation message is transmitted to the contact node whose communication information is stored in advance in the nonvolatile memory of the storage unit 12. Thereafter, in step S4, a response message is received from the contact node. The response message includes the node ID and IP address of the contact node.

  In step S4, the routing table of the participation request node is created using the received response message as described above. Specifically, waiting until a response message or transfer complete message is received, the node ID in the corresponding message is stored in the appropriate location in the DHT routing table, thereby creating the routing table. .

  Thereafter, in step S5, it is determined whether or not the participation request node has received a transfer completion message during execution of step S4. This time, assuming that the transfer completion message has not yet been received, the determination in step S5 is NO, and in step S10, it is determined whether or not the power of the participation request node has been turned off.

  This time, assuming that the power of the participation request node remains on, the determination in step S10 is NO, and the process returns to step S4. Normally, steps S4, S5, and S10 are repeatedly executed while the participation request node is powered on, whereby the participation request node sequentially receives response messages from a plurality of other node devices, and the received plurality of response messages. As shown in FIG. 8, a routing table for the participation request node (node Z) is created.

  On the other hand, this time, assuming that the participation request node is powered off, the determination in step S10 is YES, and the execution of this participation processing program is terminated.

  As described above, the case where the participation request node has not yet received the transfer completion message has been described. However, if it has been received, the determination in step S5 is YES, and in step S6, the final transfer is started from the received transfer completion message. The node ID of the previous node (root node) is extracted. Thereafter, in step S7, it is determined whether or not the extracted node ID matches the current node ID of the participation request node.

  If it is assumed that the node ID of the final transfer destination node does not match the node ID of the participation request node this time, the determination in step S7 is NO and the process proceeds to step S9. At this point, participation of the participation request node in the DHT system is completed. In step S <b> 9, the current node ID is stored in the nonvolatile memory in the storage unit 12.

  Thereafter, in step S20, it is determined whether or not there is a user operation. If there is an operation, the determination in step S20 is YES, and after the necessary processing is executed in step S21, the process proceeds to step S22. If there is no operation, the determination in step S20 is performed. NO is determined, and the process immediately proceeds to step S22.

  In step S22, it is determined whether a message has been received. If a message is received, the determination in step S22 is YES, and in step S23, the necessary message reception process is performed, and then the process proceeds to step S24. If no message is received, step S22 is performed. The determination in S22 is NO, and the process immediately proceeds to step S24. In step S24, it is determined whether or not the power is turned off. If the power is turned off, the determination in step S24 is YES, and the execution of this participation process program ends. If the power is not turned off, the determination in step S24 is NO, and the step Return to S20.

  The case where the node ID of the final transfer destination node does not match the node ID of the participation request node has been described above. However, when the node ID matches, the determination in step S7 becomes YES, and a new node is added for the participation request node in step S11. Reference information to be referred to in order to calculate the ID using the same hash function is fetched from the storage unit 12. This reference information is different from the reference information (see step S102 shown in FIG. 10) referred to for calculating the previous node ID of the participation request node.

  For example, when the combination of the IP address, MAC address, and manufacturing number of the participation request node is used to calculate the previous node ID, information different from the information is used to calculate the current node ID. For example, computer time information (for example, current time) of the participation request node is additionally used.

  In this example, the reference information captured in step S13 is a combination of the IP address, MAC address, and serial number of the participation request node and computer time information.

  In addition, in order to change the node ID, an addition (an example of calculation) is added to the value of the previous reference information with respect to “1” (an example of a setting value), or the value of the previous node ID is further changed. The same hash function or another hash function may be applied.

  Thereafter, in step S12, the current node ID is calculated as a node ID different from the previous node ID by applying the same function as the hash function to the reference information acquired in step S11. Subsequently, in step S13, the routing table created so far is deleted in the storage unit 12. Thereafter, the process returns to step S2 to create a new participation message and transmit the participation message to the contact node. The new participation message is created so as to include the current node ID calculated in step S12.

  FIG. 11 conceptually shows in a flowchart a message processing program executed by the CPU of the control unit 11 in order to perform the above-described transfer processing. The flowchart in FIG. 11 is a detailed flowchart for step S23 shown in FIG.

  This message processing program is executed in response to each node device 1 receiving a message from another node device 1 after completion of participation in the overlay network.

  When this message processing program is executed, first, in step S201, it is determined whether or not the own node device 1 has received a participation message from another node device 1. This time, assuming that the node device 1 has not yet received the participation message, the determination in step S201 is NO, and in step S202, it is determined whether or not the received message is a presence confirmation message. Assuming that it is a presence confirmation message this time, the determination in step S202 is YES, and in step S203, a response message is created, and the created response message is transmitted to the participation request node. This completes the execution of this message processing program and proceeds to step S24 shown in FIG.

  On the other hand, this time, assuming that the received message is not an existence confirmation message, the determination in step S202 is NO, and processing corresponding to the type of the received message is executed in step S204. This completes the execution of this message processing program and proceeds to step S24 shown in FIG.

  On the other hand, this time, assuming that the own node device 1 has received the participation message, the determination in step S201 becomes YES, and in step S205, the participation request is obtained by extracting necessary information from the received participation message. The node ID of the node is specified.

  Thereafter, in step S206, an existence confirmation message is created, and the created existence confirmation message is transmitted to the participation request node. The existence confirmation message includes the node ID and the IP address of the node that sends it.

  Subsequently, in step S207, the node ID of the identified participation request node is collated with the routing table (see FIG. 8) stored in the node device 1, so that the node device 1 transmits a participation message. Next, it is determined whether or not there is another node device to be transferred, that is, whether or not the own node device 1 is a root node for the participation request node.

  This time, assuming that there is another node device to which the node device 1 should transfer the join message next time, the determination in step S207 is NO, and then a response message is created and created in step S208. A response message is sent to the join request node.

  Subsequently, in step S209, the transfer destination of the participation message is determined by collating the node ID of the participation request node with the routing table (see FIG. 8) stored in the own node device 1. Subsequently, in step S210, the participation message is transferred from the node device 1 to the determined transfer destination. Thus, the execution of this message processing program is completed, and then the process proceeds to step S24 shown in FIG.

  The case where there is another node device to which the node device 1 should transfer the join message next has been described above. If there is no node device, the determination in step S207 is YES, and the process proceeds to step S211. In step S211, a transfer completion message is created. Specifically, this transfer completion message is created to indicate that the transfer of the participation message has been completed, and to include the node ID and IP address of the participation request node.

  Thereafter, in step S212, the created transfer completion message is transmitted to the participation request node. This is the end of the execution of this message processing program, and then the process proceeds to step S24 shown in FIG.

  In addition, in this embodiment, in order to change the node ID after the node ID of the participation request node is once calculated, the original node ID is changed without referring to the original node ID. A new node ID different from the original node ID is acquired using information different from the information used for determination.

  According to an example of this technique, a new node can be created by using additional or alternative information (eg, computer time information) different from the information used to determine the original node ID. An ID is acquired.

  Other techniques can be employed to change the node ID. For example, it is possible to adopt a method of acquiring a new node ID different from the original node ID by referring to the original node ID. According to an example of this technique, a new node is obtained by performing a predetermined operation (for example, adding, subtracting, multiplying, or dividing a certain value) with respect to the original node ID. An ID is acquired.

  As is clear from the above description, in the present embodiment, for convenience of explanation, the storage unit 12 constitutes an example of the “storage unit” in the item (1) for each node device 1, and the control unit 11 Of these, the part that executes step S1 in FIG. 9 constitutes an example of “node ID determining means” in the same term, and the part that executes steps S2 and S3 in FIG. It can be considered to constitute an example of “transmitting means”.

  Furthermore, in the present embodiment, for convenience of explanation, for each node device 1, a part of the control unit 11 that executes steps S201 to S210 in FIG. 11 constitutes an example of the “transfer means” in the section (1). Then, it can be considered that the part of the control unit 11 that executes steps S207, S211 and S212 in FIG. 11 constitutes an example of the “participation request reply information transmitting means” in the same section.

  Further, in the present embodiment, for convenience of explanation, for each node device 1, the part of the control unit 11 that executes step S7 in FIG. 9 is the “node ID change necessity determination means” in the above item (1). The part that executes S12 in FIG. 9 of the control unit 11 constitutes an example of “node ID changing means” in the same section, and the part that executes step S2 in FIG. It can be considered that it constitutes an example of the “retransmission means” in the section.

  Further, in the present embodiment, for convenience of explanation, for each node device 1, a part of the control unit 11 that executes step S12 in FIG. 9 constitutes an example of “acquiring means” in the above section (4). It is possible to think that

  Furthermore, in the present embodiment, for convenience of explanation, in each node device 1, the storage unit 12 and the part that executes step S9 in FIG. It can be considered that an example of “storing means” is configured, and a part of the control unit 11 that executes steps 101, S104, and S105 in FIG. 11 constitutes an example of “setting means” in the same section. .

  Further, in the present embodiment, for convenience of explanation, for each node device 1, a part of the control unit 11 that executes steps S101 to S103 in FIG. 11 is an example of the “node ID determination means” in the above item (9). It is possible to think that it constitutes.

  Further, in the present embodiment, for the convenience of explanation, for each node device 1, the part that executes the part that returns a response message to the participation request node in step S4 in FIG. It can be considered that it constitutes an example of the “participation request information handling processing execution means” in the section).

  Further, in the present embodiment, for convenience of explanation, for each node device 1, the participation processing program shown in FIG. 9 and the message processing program shown in FIG. It can be considered that it constitutes an example.

  In addition, in this embodiment, in the participation request node, it is determined whether or not the node ID of the node ID and the node ID of the root node (node having no message transfer destination) match each other. In this case, the node ID is changed (recalculated).

  On the other hand, in the root node, it is determined whether or not the node ID and the node ID of the participation request node match each other. If it is determined that the node IDs match, node ID change instruction information for instructing the node ID change. The participation request reply information including the message ID is transferred to the participation request node, while the participation request node implements the present invention in such a manner that its own node ID is changed in response to the node ID change instruction information. Is possible.

  In order to realize this aspect, the above-described embodiment may be changed as follows, for example. That is, when the determination in step S207 in FIG. 11 is YES, it is determined whether or not the node ID of the root node and the node ID of the participation request node match each other. The transfer completion message including the instructed node ID change instruction information is created, and when it is determined that they do not match, the transfer completion message including the node ID change unnecessary information indicating that the node ID does not need to be changed is created. That's fine. Furthermore, step S6 in FIG. 9 may be deleted, and step S7 may be changed to a step of determining whether or not node ID change instruction information is included in the transfer completion message received by the participation request node. In that step, if it is determined that the node ID change instruction information is included in the transfer completion message, the process proceeds to step S11. On the other hand, if it is determined that it is not included, the process proceeds to step S9.

  As described above, some of the embodiments of the present invention have been described in detail with reference to the drawings. However, these are merely examples, and the knowledge described by those skilled in the art including the aspects described in the above [Disclosure of the Invention] section. The present invention can be implemented in other forms based on various modifications and improvements.

1 is a system diagram conceptually showing a physical configuration and a logical configuration of a network in an information communication system according to an embodiment of the present invention. 2A, 2B, and 2C are diagrams for explaining an example of how an ID space and a routing table are created by DHT in the information communication system shown in FIG. 3A shows an example of a level 1 routing table, FIG. 3B shows an example of a level 2 routing table, and FIG. 3C shows a level 3 routing table. FIG. 3D illustrates an example of a routing table, and FIG. 3D illustrates an example of a completed routing table. FIG. 2 is a block diagram conceptually illustrating an example of a schematic hardware configuration of each node device illustrated in FIG. 1. FIG. 2 is a diagram for describing a participation process performed for a certain node device to participate in an overlay network in the information communication system illustrated in FIG. 1. It is a figure for demonstrating an example of the method of producing a routing table in the information communication system shown in FIG. FIGS. 7A, 7B, and 7C are diagrams showing examples of routing tables stored in a plurality of node devices that are not participation request nodes in the information communication system shown in FIG. FIG. 3 is a diagram illustrating an example of a routing table created by a node Z that is a participation request node in the information communication system illustrated in FIG. 1. 2 is a flowchart conceptually showing a participation process program executed by a computer of each node device shown in FIG. 1. 10 is a flowchart conceptually showing details of step S1 in FIG. 9 as a node ID calculation routine. 2 is a flowchart conceptually showing a message processing program executed by a computer of each node device shown in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Node apparatus 8 Network 9 Overlay network 11 Control part 12 Memory | storage part 13 Buffer memory 14 Decoder part 15 Image | video processing part 16 Display part 17 Audio | voice processing part 18 Speaker 20 Communication part 21 Input part 22 Bus S Information communication system

Claims (13)

An overlay network type communication system in which an overlay network is constructed by participation of a plurality of node devices, and the plurality of node devices communicate with each other on the overlay network,
Each node device
Prior to joining the overlay network, when the own node apparatus joins the overlay network according to a predetermined rule based on predetermined information, the own node apparatus is located on the overlay network. Node ID determination means for determining a node ID for uniquely identifying the position;
When the own node device is a participation request node device that requests to participate in the overlay network from now on, the relationship between the node ID of the other node device and the communication information necessary for communication with the node device is acquired. In order to store the relationship in the storage means, the node device represents a request that the node device wants to participate in the overlay network and includes participation request information including the determined node ID in any of the plurality of node devices. Participation request information transmitting means for transmitting
When receiving the participation request information, other node devices having a node ID close to the node ID included in the received participation request information among node IDs of other node devices stored in the storage unit Transfer means for transferring the participation request information to
The node ID of the own node device is closer to the node ID included in the received participation request information than the node IDs of the other node devices stored in the storage means. Therefore, when there is no transfer destination of the transfer means, participation request reply information transmitting means for transmitting participation request reply information corresponding to the participation request information to the participation request node device;
Node ID change necessity determination means for determining whether or not to change the node ID of the own node device based on the received participation request reply information;
A node ID changing unit that changes the node ID of the own node device when the node ID change necessity determining unit determines to change the node ID of the own node device;
An overlay network type communication system comprising: retransmission means for resending the participation request information including the changed node ID to any one of the plurality of node devices when the node ID of the own node device is changed. An overlay network type communication method in which an overlay network is constructed by participation of a plurality of node devices, and the plurality of node devices communicate with each other on the overlay network,
Prior to joining the overlay network, when each node device joins the overlay network according to a predetermined rule based on predetermined information, each node device is positioned on the overlay network. A node ID determining step for determining a node ID for uniquely identifying the position;
When the own node device is a participation request node device that requests to participate in the overlay network from now on, the relationship between the node ID of the other node device and the communication information necessary for communication with the node device is acquired. In order to store the relationship in the storage means, the node device represents a request that the node device wants to participate in the overlay network and includes participation request information including the determined node ID in any of the plurality of node devices. A participation request information sending step for sending
When receiving the participation request information, other node devices having a node ID close to the node ID included in the received participation request information among node IDs of other node devices stored in the storage unit Transferring the participation request information to:
The node ID of the own node device is closer to the node ID included in the received participation request information than the node IDs of the other node devices stored in the storage means. Therefore, when there is no transfer destination of the transfer means, a participation request reply information transmission step of transmitting participation request reply information corresponding to the participation request information to the participation request node device;
A node ID change necessity determination step for determining whether to change the node ID of the own node device based on the received participation request reply information;
A node ID changing step of changing the node ID of the own node device when it is determined that the node ID of the own node device is changed by the node ID change necessity determining step;
And a retransmission step of resending the participation request information including the changed node ID to any one of the plurality of node devices when the node ID of the own node device is changed. An overlay network type node device that constructs an overlay network by participating together with other node devices and communicates with other node devices on the overlay network,
Prior to joining the overlay network, when the own node apparatus joins the overlay network according to a predetermined rule based on predetermined information, the own node apparatus is located on the overlay network. Node ID determination means for determining a node ID for uniquely identifying the position;
When the own node device is a participation request node device that requests to participate in the overlay network from now on, the relationship between the node ID of the other node device and the communication information necessary for communication with the node device is acquired. In order to store the relationship in the storage means, the node device represents a request that the node device wants to participate in the overlay network and includes participation request information including the determined node ID in any of the plurality of node devices. Participation request information transmitting means for transmitting
When receiving the participation request information, other node devices having a node ID close to the node ID included in the received participation request information among node IDs of other node devices stored in the storage unit Transfer means for transferring the participation request information to
The node ID of the own node device is closer to the node ID included in the received participation request information than the node IDs of the other node devices stored in the storage means. Therefore, when there is no transfer destination of the transfer means, participation request reply information transmitting means for transmitting participation request reply information corresponding to the participation request information to the participation request node device;
Node ID change necessity determination means for determining whether or not to change the node ID of the own node device based on the received participation request reply information;
A node ID changing unit that changes the node ID of the own node device when the node ID change necessity determining unit determines to change the node ID of the own node device;
An overlay network type node device comprising: retransmission means for resending the participation request information including the changed node ID to any of the plurality of node devices when the node ID of the own node device is changed. The participation request reply information transmitting means includes the node ID of its own node apparatus and the participation request reply information corresponding to the participation request information when the transfer destination of the transfer means does not exist. Including means for transmitting to
The node ID change necessity determining means includes means for determining that the node ID of the own node device is changed when the node ID included in the received participation request reply information matches the node ID of the own node device. 4. The overlay network type node device according to 3. The participation request reply information transmission unit determines whether or not the node ID of the participation request node device included in the participation request information matches the node ID of the own node device when the transfer destination of the transfer unit does not exist And means for transmitting the participation request reply information including the node ID change instruction information for instructing the change of the node ID to the participation request node device when it is determined that they match.
The node ID change necessity determination means includes means for determining to change the node ID of the own node apparatus when the node ID change instruction information is included in the received participation request reply information. Overlay network type node equipment.   The node ID changing unit is different from the predetermined information and / or the rule used to determine the original node ID without referring to the original node ID determined by the node ID determining unit. 6. The overlay network type node device according to claim 3, further comprising an obtaining unit that obtains a new node ID different from the original node ID using information and / or rules.   The acquisition means includes means for acquiring the new node ID by additionally or alternatively using information different from the information used for determining the original node ID. 6. The overlay network type node device according to 6.   6. The node ID changing means includes acquisition means for acquiring a new node ID different from the original node ID by referring to the original node ID determined by the node ID determining means. The overlay network type node device according to any one of the above.   9. The overlay network type node device according to claim 8, wherein the acquisition means includes means for acquiring the new node ID by performing a predetermined operation on the original node ID. A storage means for storing the node ID used when participating in the overlay network even after the power of the node device is shut off;
When attempting to join the overlay network, the node ID is read from the storage means, and the read node ID is set as an initial value of the node ID used by the own node device to join the overlay network from now on. Including setting means to
The overlay network type node according to any one of claims 3 to 9, wherein the participation request information transmitting unit transmits the participation request information including the node ID set by the setting unit to any of the plurality of node devices. apparatus.   11. The overlay network type node according to claim 10, wherein the node ID determination unit determines a node ID according to the predetermined rule based on the predetermined information when a node ID is not stored in the storage unit. apparatus.   When the local node device receives the participation request information in a state where it is not the participation request node device, the participation request node device acquires the relationship between the node ID of the other node device and the communication information, and determines the relationship. A participation request information corresponding process executing means for executing a process corresponding to the participation request information with respect to the participation request node apparatus, in order to enable the storage means of the participation request node apparatus to be stored. The overlay network type node device according to any one of 3 to 11.   A program executed by a computer to operate the overlay network type node device according to any one of claims 3 to 12.

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