JP5078034B2 - Communication device, P2P network construction method, program, and recording medium - Google Patents

Description

  The present invention forms a logical virtual network with an unstructured topology that does not depend on data arrangement on a physical IP network, and each node forwards it to an adjacent node, thereby delivering a search query to all nodes. The present invention relates to a communication device that performs such flooding search, a P2P network construction method, a program, and a recording medium.

  In recent years, a P2P (Peer to Peer / Personal to Personal) network in which terminals that are not clearly distinguished, such as a server and a client, connect equally and provide and use services has been attracting attention. This P2P network model is said to be highly scalable and fault-tolerant because data and load are distributed. Various applications using the P2P network model have been developed. A typical application is Gnutella software that publishes and shares files on many terminals.

  This Gnutella software logically configures a virtual network on a physical IP network with an unstructured topology that does not depend on data placement, and each node forwards a search query to an adjacent node and sends a search query to all nodes. By distributing, a flooding search such as searching for files held by all nodes is performed. Therefore, in Gnutella software, a large amount of messages are exchanged for search, and the increase in traffic due to that is a problem. Gnutella software configures a virtual network without considering the physical path of the IP network. For this reason, neighboring nodes on the virtual network are often physically located far away, which also causes an increase in traffic.

  Therefore, several methods for reducing the communication traffic of the physical network and determining an efficient virtual network topology have been proposed. Patent Document 1 discloses a technique for measuring a response time of a connection operation between peers and preferentially connecting a relatively short measurement time as a physical neighbor peer. However, this technique has a problem that the response time of the peer-to-peer connection operation varies greatly depending on the load state of the peer and the communication line, so that accurate determination cannot be made.

Patent Document 2 points out that measuring the distance between a large number of computers on a physical network increases the amount of communication for the measurement, and the distance is measured in a divided virtual space and is physically optimized. A technique for increasing the efficiency of the entire virtual space by arranging divided virtual spaces having a topology is disclosed. This technology proposes to reduce the amount of communication for measurement by limiting distance measurement to a representative computer. However, in order to obtain a high effect by this method, it is necessary to map the virtual space coordinates of the computer to a divided virtual space having many physically adjacent computers. However, this method is disclosed and suggested in Patent Document 2. Not. Furthermore, there is a problem that the elapsed time from the transmission of the distance measurement request message to the arrival of the reply message, that is, the round trip time, is the same as that of Patent Document 1. Patent Document 2 also presents a method using the current available bandwidth and the number of hops, but this method is not particularly excellent in terms of communication volume and effect.
JP 2005-252596 A JP 2006-33384 A

  The conventional P2P network construction method further has the following problems. When the virtual network configuration is configured in a form close to the physical network configuration, useless message transfer is suppressed and communication traffic can be reduced. However, the conventional method has a problem that, although the amount of communication for measuring the physical distance between the nodes is large, high-precision measurement is difficult, and the operation is complicated, so that the effective effect cannot be achieved. .

  Generally, when joining a virtual network, a node to be connected first is determined by manually inputting a known node address or inquiring a server. However, even if the server is inquired, it is necessary to enter the server address. Therefore, in order to participate in the virtual network, the user must always be aware of the existence of the virtual network. Physical network IP broadcasts are often used as a means to search for devices in the same subnetwork, but can be used in the present case where a virtual network is configured by preferentially linking to nodes in the subnetwork. Limitation and search automation can be performed simultaneously.

  When there are few gate nodes, it becomes a bottleneck for communication and performance is degraded. Further, when there are many gate nodes, the communication load increases due to communication between the gate nodes. Since the total communication amount greatly varies depending on the number of nodes, it is preferable to dynamically change the number of gate nodes in order to configure an efficient virtual network.

  In an IP network, a plurality of networks are connected by routers, and bringing a virtual network configuration closer to a physical network configuration connects a plurality of virtual network node groups with a small number of lines. In many cases, a virtual network such as a P2P network is composed of terminals, and the participation and withdrawal of nodes are intense. Therefore, there is a problem that when a gate node that connects a plurality of virtual network node groups leaves, the virtual network is easily divided.

  In order to keep a virtual network stable with respect to joining / leaving nodes, it is better to have more gate nodes. However, there is a problem that communication performance decreases when the number of external links increases proportionally.

  In view of the above problems, the present invention performs a search considering a physical network in a node search and preferentially links to a node in a subnetwork that is physically close to the physical network, thereby enabling communication traffic on the physical network. It is an object of the present invention to provide a communication device, a P2P network construction method, a program, and a recording medium that can easily construct and efficiently operate an efficient virtual network that reduces the amount of noise.

  The communication device according to the present invention is a communication device that forms a logical virtual network on a physical IP network, and is a first search means for searching for an internal virtual network node in an IP subnetwork to which the own node belongs. And a first search means for appropriately linking to at least one internal virtual network node to form a virtual network, and a second search means for searching for a virtual network gate node having a right to link to a node outside the IP subnetwork. Second configuration means for appropriately linking to at least one internal virtual network gate node to configure the virtual network, and detecting and counting the internal virtual network gate node in the IP subnetwork to which the own node belongs, The number of actual gate nodes in the subnetwork Whether or not to link to the external virtual network gate node outside the IP subnetwork to which the own node belongs based on the actual gate node number detecting means to be output and the actual gate node number detected by the real gate node number detecting means A determination means for determining, when the number of real gate nodes detected by the real gate node number detection means is less than the target gate node number, and is linked to an external virtual network gate node, and is equal to or greater than the target gate node number It is characterized in that it participates in a virtual network without linking to an external virtual network gate node.

  Further, the communication device according to the present invention includes a third search means for searching and discovering an internal virtual network node by broadcast of an IP network, and a fourth search means for searching and discovering a virtual network gate node by message distribution of the virtual network. It can be characterized by having.

  The communication apparatus according to the present invention may further include a target gate node number determination unit that sets a predetermined ratio to the number of internal virtual network nodes as a target gate node number.

  Further, the communication device according to the present invention has a fifth search means for searching for a gate node in an IP subnetwork to which the node belongs at irregular intervals, and when the other node searches for the gate node, Updating means for updating the time until the node search, and if the number of existing gate nodes is less than the target number of gate nodes, the gates in the IP sub-network are linked to the external virtual network gate nodes and become gate nodes. A virtual network that maintains the number of nodes can be configured.

  The communication apparatus according to the present invention also provides a notification means for notifying the internal virtual network gate node in the IP subnetwork of the number of internal virtual network gate nodes in the IP subnetwork to which the node belongs, and the number of internal virtual network gate nodes And adjusting means for adjusting the maximum number of links to the external virtual network gate node to form a virtual network in which the number of links with the external virtual network does not increase proportionally even when the number of internal virtual network gate nodes increases It can be characterized by.

  In addition, the P2P network construction method according to the present invention includes a first search step for searching for an internal virtual network node in an IP subnetwork to which the node belongs, and a virtual network by appropriately linking to at least one internal virtual network node. A first configuration step to configure, a second search step to search for a virtual network gate node having a right to link to a node outside the IP subnetwork, and a virtual network by appropriately linking to at least one internal virtual network gate node And detecting the number of internal virtual network gate nodes in the IP subnetwork to which the node belongs, and detecting the number of real gate nodes in the IP subnetwork. Process and number of real gate nodes A determination step for determining whether to link to an external virtual network gate node outside the IP subnetwork to which the node belongs, and when the number of existing gate nodes is less than the target number of gate nodes, It is characterized in that it is linked to a virtual network gate node and participates in a virtual network without linking to an external virtual network gate node when the number is equal to or more than the target gate node number.

  The program according to the present invention includes a process of searching for an internal virtual network node in an IP subnetwork to which the node belongs, a process of appropriately linking to at least one internal virtual network node to configure a virtual network, A process of searching for a virtual network gate node that has a right to link to a node outside the network, a process of appropriately linking to at least one internal virtual network gate node to form a virtual network, and an IP subnetwork to which the node belongs A process of detecting and counting a certain internal virtual network gate node and detecting the number of actual gate nodes in the IP subnetwork, and an external virtual network outside the IP subnetwork to which the own node belongs based on the number of actual gate nodes Get To determine whether or not to link to the host node, and when the number of existing gate nodes is less than the target number of gate nodes, link to the external virtual network gate node, and if the number is greater than the target number of gate nodes, the external It is characterized in that it participates in a virtual network without linking to a virtual network gate node.

  A recording medium according to the present invention is a computer-readable recording medium in which the program is recorded.

  ADVANTAGE OF THE INVENTION According to this invention, the virtual network with a smaller communication load than before can be comprised.

  In the virtual network according to the embodiment of the present invention, a terminal called a servant, such as a server and a client, whose distinction is not clear is linked to a plurality of servants to form a mesh topology, as in the conventional case. Here, it is assumed that an application shares a file distributed to servants. Searching and obtaining a file are performed in three steps: “send search request message”, “receive search result”, and “receive file”. . The search request source servant transmits a search request message including a keyword for searching the target file.

  The search request message is delivered to all servants by the bucket relay method. The servant that receives the search request message searches the file name, alias name, metafile information, etc. of the file that it has made public, and returns the file name and address information of the hit file. This search result reaches the search request source in the reverse route followed by the search request message. Then, the search request source servant receives the search result from each servant, selects the target file, directly connects to the servant holding the file, and receives the file.

  Since the topology is unstructured that does not consider the data arrangement for search, the file can be arranged freely in any servant. In addition, an unstructured mesh topology is unlikely to disrupt the communication path even if a servant leaves the virtual network, and can join the virtual network by linking to the found servant as appropriate so that it can join the virtual network. Strong. However, on the other hand, an increase in traffic due to flooding communication is regarded as a problem.

  A device located at a connection point of a network is generally called a node. In the following description, the term node is used instead of a servant.

  FIG. 1 shows an example of how the topology differs between a physical IP network, a conventional virtual network overlaid on the physical network, and the virtual network of this embodiment. The lower part of FIG. 1 shows six PCs A, B, C, D, E, and F in the subnetwork 1, two PCs K and L in the subnetwork 2, and G in the subnetwork 3. , H, I, and J, and a router 4 that connects the sub-network 3 to the IP network. PCs in the same subnetwork can perform one-hop communication, but two-hop communication to PCs in other subnetworks.

  An example when a virtual network is configured using the conventional method with the 12 PCs A to L, an example when a virtual network is configured using the method of the present embodiment, as shown in FIG. Shown in the middle row. While the conventional virtual network has a dense mesh topology, the virtual network of the present embodiment has a slightly sparse mesh topology. A conventional virtual network node is linked regardless of the position and distance of the node, but the virtual network node of this embodiment is preferentially connected to nodes in the same subnetwork, and only a limited number of gate nodes are connected to other nodes. This is for connection to a node of the subnetwork. In the present embodiment, a node connected to a node of another subnetwork is called a gate node. In the conventional and virtual networks of the present embodiment, the black circle node is a node linked to a node of another subnetwork.

  That is, in the conventional example, nine nodes A, C, D, F, G, H, I, K, and L are gate nodes, whereas in this embodiment, C, F, K, and G are used. These four nodes are gate nodes. Compared to the conventional virtual network in FIG. 1, it can be seen that the virtual network of this embodiment has fewer black circle nodes and fewer links between the black circle nodes. As described above, since communication within the sub-network does not pass through the router 4, the amount of packets passing through the router 4 can be suppressed and the number of hops in the physical network can be reduced by reducing the number of gate nodes in the method of this embodiment. Good virtual network communication is possible.

  FIG. 2 shows an example of the software structure of this embodiment. In FIG. 2, the lowermost layer is a physical network control layer 7 for performing TCP / IP (Transmission Control Protocol / Internet Protocol) and UDP / IP (User Datagram Protocol / Internet Protocol) communication in the OSI reference model. A physical layer, a data link layer, a network layer, and a transport layer are included. 2, the middle layer is a virtual network control layer 6 that performs construction and maintenance of virtual networks and message processing, and the top layer in FIG. 2 is a P2P application that exposes, searches, and acquires user interfaces and files. Layer 5. In the present embodiment, the virtual network layer 6 will be mainly described.

  FIG. 3 is a block diagram illustrating a schematic configuration example of a communication device expressed as a PC or a node in the present embodiment. The control unit 12 includes a computing unit such as a CPU, a RAM, and a ROM, and a memory, and is a central part that executes software. The storage unit 8 is an auxiliary storage device such as an HDD and stores programs and data. The input unit 9 includes a mouse, a keyboard, a touch panel, and the like, and accepts file search instructions and keyword inputs from the user. The display unit 10 includes a lamp and a liquid crystal display, and displays search results and file contents. The communication unit 11 includes a wired LAN device such as Ethernet (registered trademark) or a wireless LAN device such as IEEE802.11a / b / g, and performs TCP / IP and UDP / IP communication.

  In the control unit 12, modules of the virtual network control layer 6 are shown. The virtual network control layer 6 includes a virtual network management unit 13, a message processing unit 14, and a node link processing unit 15. The node link processing unit 15 has functions such as “internal node link”, “external node link”, and “link reception”. The “internal node link” and “external node link” of the node link processing unit 15 search and discover nodes inside and outside the subnetwork, and establish a TCP / IP communication connection (link) to a predetermined number of nodes. It is. “Internal node link” and “External node link” have a function of disconnecting a connection and trying a link to another node when the link destination node sends a link rejection message. . “Link acceptance” is a function for establishing a TCP / IP communication connection in response to a link request from another node. The “link acceptance” has a function of sending a link rejection message when the link request cannot be accepted.

  The message processing unit 14 has functions such as “request message”, “response message”, and “message transfer”. “Request message” is a function for generating and transmitting / receiving a request message. “Reply message” is a function for generating and transmitting / receiving a reply message. “Message transfer” is a function of transferring a message received from another node to another node. Request message flooding is performed by copying the received request message to all nodes except the node that sent the request message, which is linked to the node that received the request message. It is realized by doing. A unique message ID is assigned to the request message, and when a plurality of request messages are received, it can be determined whether or not the request messages are the same. A node that receives the same request message discards the request message without forwarding the received request message. The request message has a survival counter, and the node decrements the survival counter when copying and transferring the request message. A request message whose survival counter reaches 0 is discarded without being transferred. Then, the node that transferred the request message stores the request message management information in which the node that sent the request message is associated with the message ID as one record of the request message management table in the storage unit 8. Even if the request message is discarded without being transferred, if the node that sent the request message is different, the request message management information that associates the message ID with the node that sent the request message is stored in the storage unit. 8 records as one record of the request message management table.

  A response message to the request message also reaches the request message issuer by the message transfer of the node. The node that generated the response message in response to the request message refers to the request message management table in the storage unit 8 of the node, identifies the node that has transmitted the request message, and transmits the response message to the identified node. To do. The response message includes the message ID of the request message. The node that has received the response message refers to the request message management table in the storage unit 8 of the node, and if there is a record of the request message with the same message ID, the received response message is sent to the node that sent the request message. Forward. In addition, the node that transmits the response message sets a transfer completed flag indicating that the response message has been transmitted or transferred to the record having the same message ID in the request message management table of the storage unit 8 of the node. If a request message record with the same message ID does not exist in the request message management table of the storage unit 8 of the node, the received response message is discarded.

  The virtual network management unit 13 has functions such as “node link monitoring”, “gate node monitoring”, “subnetwork determination”, “gate node number detection”, and “internal node number detection”. "Node link monitoring" periodically checks whether the communication connection (link) between a node and another node linked to that node is maintained normally, and the other node (other node) leaves This is a function for issuing an instruction for linking to a new node to “node link processing” when the communication connection is broken due to a failure. “Gate node monitoring” is a process that irregularly checks how many gate nodes exist in the same sub-network as the node. This is a function to be performed. The “subnetwork determination” is a function for determining whether a node having a certain IP address is a node in the subnetwork using a subnetwork mask. “Detection of the number of gate nodes” and “detection of the number of internal nodes” are functions for checking the number of gate nodes and the number of internal nodes and addresses currently existing. There are two methods of searching: a search method using a request message in a virtual network and a search method using a broadcast of an IP network.

FIG. 10 shows an example of a message that flows on the virtual network in this embodiment. Message types are divided into request messages and response messages. The response message is an action result for the request message. Each message will be described below.
NODE_SERCH_INNER_ALL (internal all node IP request message) is a request message for collecting the IP addresses of all nodes in the subnetwork. NODE_SERCH_INNER_GATE (internal gate node IP request) is a request message for collecting the IP addresses of the gate nodes in the subnetwork. NODE_SERCH_OUTER_GATE (external gate node IP request) is a request message for collecting IP addresses of gate nodes outside the subnetwork. NODE_RESULT_ADDRESS (address response) is a response message for returning node address information in response to a NODE_SERCH request message. APPLI_SERCH_FILE (file search request) is a file search request message from the P2P application program. The node that has received the file search request searches the target storage device for a file that matches the search condition attached to the message, and creates a list of file names, file sizes, and the like. APPLI_RESULT_FILE (file search result response message) is a file search result response message from the P2P application program. The node that has received the file search request sends a list created together with the file search request to the source of the file search request as a response to the file search request. There are various contents in the actual message, but the explanation is omitted here.

  With reference to FIG. 4, the operation when a node newly joins the virtual network will be described. A node that intends to newly join the virtual network first searches for an internal node (step S101) and collects address information of the internal node (step S102). Thereby, the node which is going to newly join can acquire the IP address of the node which tries the link. There are two ways to obtain this. The first method uses a message of a virtual network. After linking to a known internal node, address information of the internal node is collected by an internal all-node IP request message. The second is a method of collecting address information of internal nodes by broadcasting an IP network.

  With reference to FIG. 8, each method for obtaining an IP address will be described. In the following description, it is assumed that the node M participates in the subnetwork N3 of the virtual network in the middle of FIG. First, the case of a method using a virtual network message will be described. The node M temporarily links to the node H according to the IP address set by the user. When the temporary link is established, an internal all node IP request message is transmitted, and an address reply message is waited for a predetermined time. The node H transfers the internal all node IP request message received from the node M to the node I and the node J, and returns an address response message to the node M.

  The node I transfers the internal all node IP request message received from the node H to the node G, and returns an address response message to the node H. Then, the internal all node IP request message received from the node J is discarded. The node J transfers the internal all node IP request message received from the node H to the node G, and returns an address response message to the node H. Node I forwards the address reply message received from node G to node H. The node H transfers the address response message received from the nodes I and J to the node M. The node M collecting the address information of the internal node disconnects the temporary link to the node H.

  Next, a case of a method of collecting address information of internal nodes using IP network broadcast will be described. The node M transmits a UDP packet requesting a reply of address information to the broadcast address and waits for a reply for a predetermined time. The UDP packet is delivered to the nodes G, H, I, and J in the subnetwork 3. Each node that receives the UDP packet transmits the UDP packet containing the address information to the node M by unicast. The node M receives the UDP packet containing the address information from each of the nodes G, H, I, and J, thereby acquiring the address information of the nodes G, H, I, and J, and collecting the address information of the internal nodes. To do.

  With reference to FIG. 9, an example of address information returned from the node G to the node M is shown. The address information in FIG. 9 is stored in the node G as an address information table. Here, the address information transmitted by the node G will be described as an example, but each node functioning as a virtual network node stores an address information table, and transmits the address information to the node M. The first column of the table is an IP address of a node that node G recognizes as a virtual network node. The second column is a link flag. The link flag is 0 if the node G is not linked to the node, 1 if it is linked, and 2 if it is linked. The third column is a gate node flag. The gate node flag is 1 if the node is a gate node, and 0 if it is not a gate node. The fourth column is a temporary link flag. 1 if the link is a temporary link, 0 if not. In the example of FIG. 9, the link with the node “192.168.300.4” is a temporary link. The first line of the table is the information of the own node, that is, the information of the node G.

  Returning to FIG. 4, the processing after collecting address information of internal nodes will be described. The number of gate nodes in the collected address information of the internal nodes is counted to determine the number of existing gate nodes, which is the number of gate nodes existing in the subnetwork (step S103). Subsequently, the number of existing gate nodes is compared with a predetermined target gate node number (step S104). If the number of existing gate nodes is larger than the predetermined target gate node number (step S104, NO), the process proceeds to step S111. If the number of existing gate nodes is smaller than the predetermined target gate node number (step S104, YES), the process proceeds to step S105. Subsequently, it is determined whether the number of existing gate nodes is 0 (step S105). When an internal gate node exists (step S105, NO), a temporary link is made to the internal gate node (step S107). If the internal gate node does not exist (step S105, YES), a temporary link is made to the external node (step S106). The external node to be temporarily linked is an IP address node manually input by a user or an IP address node obtained from a directory server. When the link is temporarily made to the gate node, the address information of the external gate node is collected by the external gate node IP request message (step S108).

  A sequence example of the external gate node IP request message will be described in the same manner as the internal all node IP request message with reference to FIG. The node M temporarily linked to the node G transmits an external gate node IP request message and waits for an address reply message for a predetermined time (step S109). The node G transfers the external gate node IP request message received from the node M to the nodes C and K and returns an address response message to the node M. The node C transfers the external gate node IP request message received from the node G to the node F and returns an address response message to the node G.

  Node C discards the external gate node IP request message received from node K. When the node F receives the external gate node IP request message from the node C, the node F returns an address reply message to the node C. When the node K receives the external gate node IP request message from the node G, the node K returns an address response message to the node G. Node C transfers the address reply message received from node F to node G. The node G transfers the address response message received from the nodes C and K to the node M.

  Returning to FIG. 4 again, the processing after collecting the address information of the external gate node will be described. When the address information of the external gate node is collected, it is linked to a predetermined number of gate nodes and the temporary link is disconnected (step S110). When the link to the external gate node is completed, the link information is linked to a predetermined number of internal nodes using the previously collected internal node address information (step S111). When the number of existing gate nodes reaches the target number of gate nodes, the link is made to a predetermined number of internal nodes without linking to external gate nodes.

  With reference to FIG. 5, a process when a node newly joins a virtual network will be described. The step surrounded by the dotted line in FIG. 5, that is, the step of counting internal nodes to determine the total number of internal nodes (step S204) and the step of multiplying the total number of internal nodes by a predetermined ratio to determine the target gate node number (step S205). ) Is the same as the process described in FIG. 4, and only the process within the dotted line will be described. After determining the number of existing gate nodes (step S203), the internal nodes are counted from the internal node address information to determine the total number of internal nodes (step S204). If this operation is performed simultaneously with the step of obtaining the number of existing gate nodes (step S203), it is efficient. Then, a target gate node number is obtained by multiplying the total number of internal nodes by a predetermined ratio (step S205). The target number of gate nodes is preferably about 4% of the total number of internal nodes, and a lower limit number of nodes such as at least two nodes is preferably provided.

  With reference to FIG. 6, a process when a normal node which is a node other than the gate node confirms the existence of the gate node and functions as a gate node if there is a shortage will be described. In FIG. 6, the part surrounded by a dotted line is the same as the process of FIG. 4, so the other part will be described. This process is premised on being executed at a time base interval of timer values, for example, at intervals of 1 second. First, it is checked whether another node has searched for a gate node (step S301). It can be checked by setting a flag when an internal all node IP request message and an internal gate node IP request message are received in the message processing. When this flag is set (S301, YES), a predetermined value is added to the gate node search start timer value (step S303), and the flag is cleared and the process ends. When the flag is not set (step S301, NO), the gate node search start timer value is decremented (step S302). Subsequently, it is checked whether the gate node search start timer value after decrementing in step S302 is 0 (step S304). If the gate node search start timer value does not become 0 (step S304, NO), the process ends without doing anything. When the gate node search start timer value becomes 0 (step S304, YES), the internal gate node is searched and the number of existing gate nodes is detected (step S305).

  Subsequently, techniques for searching for internal gate nodes and detecting the number of existing gate nodes will be described. First, address information of the internal gate node is collected by the internal gate node IP request message. A sequence example of the internal gate node IP request message will be described with reference to FIG. The node H transmits an internal gate node IP request message and waits for an address reply message for a predetermined time. Node I forwards the internal gate node IP request message received from node H to node G. Since node I is not a gate node, it does not return an address reply message to node M. Node J forwards the internal gate node IP request message received from node H to node G. Since node J is not a gate node, it does not return an address reply message to node M. Node G receives the internal gate node IP request message from node I. Since node G is a gate node, an address reply message is returned to node I. The node G does not forward the internal gate node IP request message to the external node, but discards the internal gate node IP request message received from the node J. Node I forwards the address reply message received from node G to node H.

  When the address information of the internal gate node is collected, the number of gate nodes is counted to obtain the number of existing gate nodes. If the number of existing gate nodes is smaller than a predetermined target gate node number, the process proceeds to a step of linking itself to an external node as a gate node. Finally, the gate node search start timer value, which is the interval of the next gate node search, is determined randomly so as not to overlap the timing of the search by other nodes and to avoid bias in search density (step S313).

  With reference to FIG. 7, a process when the gate node dynamically changes the number of links according to the number of other internal gate nodes will be described. The normal node flow diagram of FIG. 7 is a continuation of FIG. 6, and the normal node that has searched the internal gate node finally transmits the number of existing gate nodes to each internal gate node (step S401). A virtual network message that distributes the number of existing gate nodes may be created. However, since the number of internal gate nodes is not large, here, the number of existing gate nodes is sent by unicasting by directly connecting to the gate node via the IP network.

  The gate node receives the number of existing gate nodes (step S501), and determines the maximum number of links from the number of existing gate nodes to the external virtual network gate node (step S502). The current number of external links is compared with the maximum number of links (step S503). If the current number of external links is larger than the maximum number of links (step S503, YES), the number of links to the external virtual network gate node is reduced below the maximum number of links (step S504). When the current number of external links is equal to or less than the maximum number of links (step S503, NO), the number of external links is compared with a predetermined minimum number of links (step S505). If the current number of external links is less than the predetermined minimum number of links (step S505, YES), the number of links to the external virtual network gate node is increased beyond the minimum number of links (step S506). If the current number of external links is greater than or equal to the predetermined minimum number of links (step S505, NO), nothing is done.

  In the above description, the type of link is described using a link and a temporary link. However, the operation of the node link processing unit 6 using a link or a temporary link will be described with reference to FIG. In FIG. 11, a node that transmits a link request is described as a link source node, and a node that receives a link request is described as a link destination node.

  The node link function (including internal and external) of the node link processing unit 15 of the link source node sends a link request to the IP address of the link destination node and a predetermined port number via each layer of the physical network control layer 7. Alternatively, a temporary link request is transmitted (step S1101).

  Subsequently, the link reception function of the node link processing unit 15 of the link destination node receives the link request or the temporary link request transmitted from the link source node (step S1102). The link reception function of the link destination node determines whether the request transmitted from the link source node is a link request or a temporary link request (step S1103). If it is determined that the request is a temporary link request (YES in step S1103), the temporary link flag in the address information table is set to true, the link source node is registered (step S1105), and the process proceeds to step S1106. If the request transmitted from the link source node is a link request (step S1103, NO), refer to the address information table to obtain the number of nodes already linked, excluding the node with the temporary link flag set. Then, it is compared with a predetermined number (link number upper limit) (step S1104).

  As a result of the comparison in step S1104, if the number of already linked nodes is less than the upper limit of the number of links (NO in step S1104), the temporary link flag in the address information table is set to false and the link source node is registered ( The process proceeds to step S1105) and step S1106. Thereafter, the link reception function transmits a link request result indicating that the link request is permitted to the link source node via each layer of the physical network control layer 7 (step S1106).

  On the other hand, as a result of the comparison in step S1104, if the number of already linked nodes is larger than the upper limit of the number of links (step S1104, YES), the link reception function physically displays the link request result indicating that the link request is rejected. The data is transmitted to the link source node via each layer of the network control layer 7 (step S1107).

  The node link function (including internal and external) of the link source node receives the link request result transmitted from the link destination node (step S1108). The node link function (including internal and external) of the link source node confirms whether the received link request result indicates link permission or link rejection (step S1109).

  As a result of the confirmation in step S1109, if the link request result indicates link permission (step S1109, YES), the node link function (including internal and external) of the link source node registers the link destination node in the address information table. In step S1110, the link request process is terminated. At this time, if the link request is a temporary link request, the temporary link flag in the virtual network table is set to true.

  On the other hand, as a result of the confirmation in step S1109, if the link request result indicates link rejection (step S1109, NO), the link request process to the link destination node is terminated, and the node link processing function is different from the link destination. Start the process of requesting a link to the node.

  When the link destination node is registered in the address information table, the virtual network message can be exchanged by the message processing function of the virtual network control layer 6 in FIG. However, the temporary link state is designed so that only NODE_SERCH and NODE_RESULT messages of relatively small load can be exchanged. That is, the file cannot be searched in the temporary link state, but the connection is not refused by the link destination node, and there is an advantage that the node address can be reliably collected.

  According to the above embodiment, it is possible to configure a virtual network with a communication load smaller than that of the prior art. In addition, by using the IP broadcast in this embodiment in which a virtual network is configured by preferentially linking to nodes in the subnetwork, the search range can be limited and the search can be automated at the same time. And a virtual network that can be easily detached. In addition, since the total communication amount greatly varies depending on the number of nodes, the performance of the virtual network can be prevented from being lowered by dynamically changing the number of gate nodes. In addition, the virtual network can be prevented from being divided. Furthermore, the performance of the virtual network can be kept optimal by appropriately setting the number of gate nodes and the number of links to the outside according to the number of nodes in the sub-network.

It is a figure which shows the contrast at the time of constructing the IP network shown by the lower stage by the conventional virtual network construction method and the network construction method example in this embodiment. It is a figure which shows the example of the structure of the software in this embodiment. It is a block diagram which shows the example of schematic structure of the communication apparatus in this embodiment. It is a flowchart which shows an example when a node newly joins a virtual network in this embodiment. It is a flowchart which shows the example at the time of adding the process of calculating | requiring the number of gate nodes, when a node newly joins a virtual network in this embodiment. It is a flowchart which shows the example when a normal node confirms presence of a gate node in this embodiment, and functions as a gate node if there is a shortage. It is a flowchart which shows an example when a gate node updates the number of links dynamically according to the number of other internal gates in this embodiment. It is a flowchart which shows the example at the time of adding the process of calculating | requiring the number of gate nodes, when a node newly joins a virtual network in this embodiment. It is a figure which shows the example of address information which the node G returns in this embodiment. It is a figure which shows the example of the kind and content of a virtual network message in this embodiment. It is a flowchart which shows the operation example of the node link process part in this embodiment.

Explanation of symbols

1, 2, 3 Subnetwork 4 Router 5 P2P application layer 6 Virtual network control layer 7 Physical network control layer 8 Storage unit 9 Input unit 10 Display unit 11 Communication unit 12 Control unit 13 Virtual network management unit 14 Message processing unit 15 Node link Processing part

Claims (8)

A communication device that forms a logical virtual network on a physical IP network,
First search means for searching for an internal virtual network node in the IP subnetwork to which the node belongs;
First configuration means for configuring a virtual network by appropriately linking to at least one internal virtual network node;
A second search means for searching for a virtual network gate node having a right to link with a node outside the IP subnetwork;
Second configuration means for configuring a virtual network by appropriately linking to at least one internal virtual network gate node;
Real gate node number detection means for detecting and counting internal virtual network gate nodes in the IP subnetwork to which the own node belongs, and detecting the number of gate nodes existing in the IP subnetwork;
Determination means for determining whether to link to an external virtual network gate node outside the IP subnetwork to which the own node belongs based on the number of real gate nodes detected by the real gate node number detection means. And
When the actual gate node number detected by the real gate node number detection means is less than the target gate node number, the actual virtual node is linked to the external virtual network gate node. A communication apparatus that participates in a virtual network without linking. A third search means for searching for and discovering the internal virtual network node by broadcast of the IP network;
The communication device according to claim 1, further comprising: fourth search means for searching for and discovering the virtual network gate node by message delivery of the virtual network.   3. The communication apparatus according to claim 1, further comprising a target gate node number determining unit that sets a predetermined ratio to the number of internal virtual network nodes as a target gate node number. Fifth search means for searching for a gate node in the IP subnetwork to which the node belongs, at irregular intervals;
Updating means for updating a time until the own node searches for a gate node when another node searches for a gate node;
The virtual network is configured to maintain the number of gate nodes in the IP subnetwork by linking to an external virtual network gate node and becoming a gate node if the number of actual gate nodes is less than the target number of gate nodes. Item 4. The communication device according to any one of Items 1 to 3. Notification means for notifying the internal virtual network gate node in the IP subnetwork of the number of internal virtual network gate nodes in the IP subnetwork to which the node belongs;
Adjusting means for adjusting the maximum number of links to an external virtual network gate node according to the number of internal virtual network gate nodes,
5. The communication apparatus according to claim 1, wherein a virtual network is configured in which the number of links with an external virtual network does not increase proportionally even when the number of internal virtual network gate nodes increases. . A first search step of searching for an internal virtual network node in the IP subnetwork to which the node belongs;
A first configuration step of appropriately linking to at least one internal virtual network node to configure a virtual network;
A second search step of searching for a virtual network gate node that is entitled to link with a node outside the IP subnetwork;
A second configuration step of appropriately linking to at least one internal virtual network gate node to configure a virtual network;
Detecting and counting internal virtual network gate nodes in the IP subnetwork to which the node belongs, and detecting the number of actual gate nodes in the IP subnetwork; and
A determination step of determining whether to link to an external virtual network gate node outside the IP subnetwork to which the node belongs, based on the number of real gate nodes;
Linking to the external virtual network gate node when the number of existing gate nodes is less than the target number of gate nodes, and joining the virtual network without linking to the external virtual network gate node when the number is greater than the target number of gate nodes. A characteristic P2P network construction method. A process of searching for an internal virtual network node in the IP subnetwork to which the node belongs;
A process of appropriately linking to at least one internal virtual network node to configure a virtual network;
Searching for a virtual network gate node that is entitled to link to a node outside the IP subnetwork;
A process of appropriately linking to at least one internal virtual network gate node to configure a virtual network;
A process of detecting and counting internal virtual network gate nodes in the IP subnetwork to which the node belongs, and detecting the number of gate nodes existing in the IP subnetwork;
Determining whether to link to an external virtual network gate node outside the IP subnetwork to which the own node belongs based on the number of real gate nodes,
Linking to the external virtual network gate node when the number of actual gate nodes is less than the target number of gate nodes, and joining to the virtual network without linking to the external virtual network gate nodes when the number of target gate nodes is greater than or equal to the target number of gate nodes Program.   A computer-readable recording medium on which the program according to claim 7 is recorded.

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