JP2011029781A - Communication system and packet transfer method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a communication system that allows the setting of a transfer path optimizing the efficiency of the whole system. <P>SOLUTION: The communication system is configured as follows. The correspondence between communication terminals 1 and repeaters 3 connected to the communication terminals 1 is dispersedly held by the repeaters 3 as databases on the basis of identifiers of the communication terminals and identifiers of the repeaters. A management device 8 holds path information received from the repeaters 3. When receiving a packet, the repeater 3 transfers the packet to the repeater holding the database of the destination communication terminal on the basis of the identifier of the destination communication terminal and the identifiers of the other repeaters 3. When holding the database of the destination communication terminal of the received packet, the repeater notifies the management device 8 of the destination repeater connected to the destination communication terminal, the transmission-source repeater, and the destination communication terminal. The management device 8 calculates an optimal transfer path from the transmission-source repeater to the destination repeater where the efficiency index value becomes optimal on the basis of the path information so as to notify the transmission-source repeater of the optimal transfer path. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a communication system using an overlay network and a packet transfer method in the communication system.

  A scalable hash table (DHT) method described in Non-Patent Document 1, for example, is a method for performing inter-node communication using an overlay network and data distributed arrangement in a scalable manner. In an overlay network that employs the DHT method, a fixed-length identifier is assigned to both the nodes constituting the network and the data arranged therein using a hash function. Each data is managed by the node having the closest identifier value so that the data is distributed.

  On the other hand, a node that manages the above data is selected based on the difference in identifier values, and a logical communication path is set for the selected node, enabling data management and search to be performed in a scalable manner. Network can be constructed. Patent Document 1 below discloses a method of performing communication by selecting a packet transfer path by an autonomous distributed operation between nodes on an overlay network using this.

JP 2008-219644 A

Ion Stoica et al., “Chord: A Scalable Peer-to-Peer Lookup Service for Internet Applications”, Proc. ACM SIGCOMM, 2001

  However, according to the above-described conventional technology, identifiers are assigned to user terminals that perform communication and nodes constituting the network, and data (ID information) that associates these identifiers is distributed and managed by the DHT. At the time of packet transfer, by searching for this data, the node to which the destination terminal is connected is found and transferred. At this time, the packet transfer path to reach the destination node is determined based only on the identifier, but the node identifier is assigned regardless of the physical network configuration. Therefore, there has been a problem that the most efficient route cannot always be selected while reflecting the physical network configuration between nodes. Also, with this conventional method, it is difficult to optimize the efficiency of the entire system.

  The present invention has been made in view of the above, and an object of the present invention is to provide a communication system and a packet transfer method capable of setting a transfer route that optimizes the efficiency of the entire system when using an overlay network. To do.

  In order to solve the above-described problems and achieve the object, the present invention includes a plurality of relay devices and a communication terminal connected to the relay device, and the relay device routes the relay device directly transferable. A communication system for holding a packet held as information and transferring a received packet based on the path information, comprising: a management device connected to the relay device; and correspondence with the relay device connected to the communication terminal And assigning to the relay device based on the identifier of the communication terminal and the identifier of the relay device, the relay device holds the correspondence assigned to the own device as a distributed database, the relay device The route information held is transmitted to the management device, and the management device holds the route information received from the relay device as route management information for each relay device. When the relay device receives a packet addressed to another communication terminal from the communication terminal, the relay device is based on an identifier of the destination communication terminal that is the communication terminal that is the destination of the packet and an identifier of the other relay device. , Obtaining the relay device holding the distributed database of the destination communication terminal, transferring the received packet with the identifier of its own device added to the obtained relay device, and when the relay device receives the packet, When a distributed database of the destination communication terminal of the packet is held, a relay device connected to the destination communication terminal is obtained as a destination relay device based on the held distributed database, and the relay device of the transmission source of the packet The source relay device, the destination relay device, and the destination communication terminal are notified to the management device, and the management device is based on the route management information. And calculating a transfer route from the transmission source relay device to the destination relay device with an optimal efficiency index value indicating high transfer efficiency as an optimal transfer route, and determining the optimal transfer route and the destination communication terminal as optimal route information. To the transmission source relay device, and when the relay device receives the optimum route information, the relay device holds the optimum route information and sends the optimum route to the next relay device of the own device on the optimum transfer route. Information is notified, and when a packet addressed to the destination communication terminal is received, the packet is forwarded to the next relay device of the own device on the optimum transfer route.

  According to the present invention, a database that is a correspondence between a communication terminal and a relay device connected to the communication terminal is held by each relay device as a distributed database, and the management device receives route information from each relay device. A relay device that acquires and holds the distributed database related to the communication terminal that is the destination of the packet, a transmission source relay device that connects to the communication terminal that is the source of the packet, and a destination relay device that connects to the destination communication terminal To the management device, the management device obtains a predetermined index value indicating the transfer efficiency based on the route management information, and optimally transfers the route from the transmission source relay device to the destination relay device with the optimal index value. Since it is obtained as a route and the transfer route is notified to the transmission source relay device, it is possible to set a transfer route that optimizes the efficiency of the entire system. To.

FIG. 1 is a diagram showing a configuration example of a communication system according to the present invention. FIG. 2 is a diagram illustrating a configuration example of a database representing a relationship between a communication terminal and a relay device to which the terminal is connected. FIG. 3 is a diagram illustrating an example in which databases are distributed and arranged in relay apparatuses. FIG. 4 is a diagram illustrating an example of a transfer procedure when a communication terminal transmits a packet. FIG. 5 is a diagram illustrating an example of an arrangement in consideration of the configuration of the subnetwork. FIG. 6 is a diagram illustrating a configuration example when a management apparatus is installed. FIG. 7 is a diagram illustrating an example of IP addresses of a communication terminal, a relay device, a management device, and a subnetwork. FIG. 8 is a diagram illustrating an example of a path management table constructed by the management apparatus. FIG. 9 is a diagram illustrating an example of the configuration of the network configuration table. FIG. 10 is a diagram illustrating an example of the classification table. FIG. 11 is a diagram illustrating an example of a transfer procedure when an optimal transfer path is selected. FIG. 12 is a flowchart illustrating an example of a procedure for the management apparatus to obtain a transfer path between relay apparatuses.

  Embodiments of a communication system and a packet transfer method according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment.
FIG. 1 is a diagram showing a configuration example of a communication system according to the present invention. As shown in FIG. 1, the communication system of this embodiment includes communication terminals 1a to 1c (1a, 1b, 1c), relay devices 3a to 3f (3a, 3b, 3c, 3d, 3e, 3f), The relay apparatuses 3 a to 3 f constitute a network 2. The relay devices 3a to 3f are connected to the relay devices 3a to 3f that are directly connected by the communication line 4, respectively. In FIG. 1, for the sake of simplification, only the communication line 4 connecting the relay device 3c and the relay device 3e is provided with a reference numeral, and the arrow lines connecting the other relay apparatuses and between the relay apparatus and the communication terminal are provided with reference numerals. Although not shown, the other arrow lines in FIG. The communication terminals 1a to 1c are connected to the network 2, and communicate with the communication terminals 1a to 1c other than the own terminal via the relay devices 3a to 3f in the network 2.

  It is assumed that a unique identifier is assigned to each of the communication terminals 1a to 1c and the relay devices 3a to 3f. Further, the relay devices 3a to 3f constitute an overlay network, and manage the route information about the relay devices 3a to 3f other than the own device capable of direct transfer. Based on the transfer. In FIG. 1, it is assumed that transfer is possible only in the direction indicated by the arrow in the figure. For example, the relay device 3a holds the identifiers and IP (Internet Protocol) addresses of the relay devices 3b and 3d as route information, and can be directly transferred to two devices 3a to 3b and 3a to 3d. On the other hand, since the relay devices 3b and 3d do not have the route information to 3a, the transfer from 3b to 3a and 3d to 3a in the opposite direction to the above cannot be performed.

  Further, it is assumed that the relay devices 3a to 3f hold the route information for the communication terminals 1a to 1c to which the relay devices 3a to 3f are directly connected, and the communication terminals 1a to 1c have the route information to the relay devices 3a to 3f to which they are directly connected. Suppose you hold it.

  FIG. 2 is a diagram illustrating a configuration example of a database (ID information) representing a relationship between the communication terminal 1 and the relay apparatuses 3a to 3f to which the terminal is connected in the communication system according to the present embodiment. As shown in FIG. 2, the database includes relay devices 3a to 3f (3a, 3e, 3d,...) Connected to the identifiers (1a, 1b, 2c,...) Of the communication terminals 1a to 1c and the communication terminals 1a to 1c. Information of the relay devices 3a to 3f to which the communication terminals 1a to 1c are directly connected are shown.

  By referring to this database, the identifiers of the relay devices 3a to 3f to which the communication terminals 1a to 1c are connected can be searched using the identifiers of the communication terminals 1a to 1c as search keys. For example, in the example of FIG. 2, by searching for the identifier (1b) of the communication terminal 1b using the search key, the relay device connected to the communication terminal 1b as shown in the second entry from the top is the relay device 3e (identifier 3e).

  In the present embodiment, the database shown in FIG. 2 is distributed and arranged in the relay apparatuses 3a to 3f. FIG. 3 is a diagram showing an example in which the database shown in FIG. 2 is distributed and arranged in the relay apparatuses 3a to 3f. Here, for each entry in the database, the hash value of the identifier of the communication terminal 1a to 1c, which is the search key, is obtained, and the entry is placed in the relay devices 3a to 3f where the obtained hash value and the hash value of the identifier are closest. I decided to. The relay apparatuses 3a to 3f hold a distributed database that is distributed and arranged in itself.

  The example of FIG. 3 shows an example in which distributed databases 5a, 5b, and 5c, which are databases distributed in this way, are arranged in the relay devices 3b, 3c, and 3f, respectively. Specifically, for example, the relay device 3b holds a distributed database 5a including entries relating to the communication terminal 1a, the relay device 3c holds a distributed database 5b including entries related to the communication terminal 1c, and the relay device 3f is connected to the communication terminal 1b. The distributed database 5c including entries related to is held. In FIG. 3, for the sake of simplification, the “identifier of the communication terminal” in FIG. 2 is shown as “communication terminal”, and the “identifier of the relay device to which the communication terminal is connected” is shown as “relay device”. .

  Next, a packet transfer procedure according to the present embodiment will be described. FIG. 4 is a diagram illustrating an example of a transfer procedure when the communication terminal 1a transmits a packet to the communication terminal 1b. First, the communication terminal 1a sends a packet addressed to the communication terminal 1b to the relay device 3a to which the communication terminal 1a is directly connected (step S11). This packet includes the identifier of the destination communication terminal 1b.

  Since the relay device 3a does not have an entry for the communication terminal 1b that is the destination of the packet in the distributed database 5a held by the relay device 3a, the relay device 3a maintains a distributed database that includes an entry related to the communication terminal 1b based on the hash value of the identifier of the communication terminal 1b. It recognizes that the relay device to perform is the relay device 3f, and transfers the received packet to the relay device 3f (step S12). Specifically, the relay device 3a obtains a hash value of the identifier of the communication terminal 1b, and obtains a relay device whose identifier is closest to the obtained hash value, thereby maintaining a distributed database including an entry related to the communication terminal 1b. Ask for equipment. Each relay device adds its own identifier to the packet when transferring the packet.

  Since the relay device 3f to which the packet has been transferred holds an entry relating to the communication terminal 1b that is the destination of the packet in the distributed database 5c, the communication terminal 1b is searched by using the identifier of the communication terminal 1b as a search key. Recognizing that it is connected to the relay device 3e, the packet is transferred to the relay device 3e (step S13).

  The relay device 3e to which the packet is transferred from the relay device 3f transfers the packet to the communication terminal 1b connected to the relay device 3e based on the route information held by itself (step S14). With the above procedure, packet transmission from the communication terminal 1a to the communication terminal 1b is completed.

  FIG. 5 is a diagram illustrating an example of an arrangement in which the configuration of the sub-network is considered in the communication system illustrated in FIG. The relay device and communication devices 1a to 1c shown in FIG. 1 are arranged separately in sub-networks 7a to 7c, and the router 6 is connected to the sub-networks 7a to 7c. The procedure of steps S21 to S24 in the figure is the same as the procedure of steps S11 to 14 described above.

  FIG. 6 is a diagram illustrating a configuration example of a communication system in a case where a management device 8 that controls the whole is installed in the arrangement illustrated in FIG. The management device 8 is installed in an independent subnetwork 7d different from the subnetworks 7a to 7c, and can communicate with the relay devices 3a to 3e by connecting to the router 6 via the subnetwork 7d.

  FIG. 7 is a diagram illustrating an example of IP addresses of the communication terminals 1a to 1c, the relay devices 3a to 3e, the management device 8, and the sub networks 7a to 7d. For example, as shown in FIG. 7, it is assumed that IP addresses are assigned to the respective devices and sub-networks 7a to 7d. Each of the relay apparatuses 3a to 3f notifies the management apparatus 8 of the identifier of the own apparatus, the IP address of the own apparatus, and path information (identifier of another relay apparatus that can be transferred from the own apparatus).

  The management device 8 constructs a route management table based on the relay device identifiers, IP addresses, and identifiers of other relay devices that can be transferred from the relay devices 3a to 3f. FIG. 8 is a diagram illustrating an example of a path management table constructed by the management apparatus 8. As illustrated in FIG. 8, the route management table is a table that stores a notified identifier, an IP address, and a transferable relay device for each relay device.

  In addition, the management device 8 acquires a transfer route table managed by the router 6 through communication with the router 6 and constructs a network configuration table including an IP address for each interface. FIG. 9 is a diagram illustrating an example of the configuration of the network configuration table. As described above, the network configuration table includes the identifier of the interface (corresponding to the subnetwork) and the IP address, and indicates the network configuration known by the router 6.

  Based on the route management table illustrated in FIG. 8 and the network configuration table illustrated in FIG. 9, the management device 8 constructs a classification table that is a table in which the relay devices 3 a to 3 f managed by itself are classified for each subnetwork. To do. FIG. 10 is a diagram illustrating an example of the classification table. The management device 8 refers to the route management table to obtain the IP addresses of the relay devices 3a to 3f, and collates the obtained IP address with the IP address of the network configuration table, thereby the relay devices 3a to 3f and the subnetwork 7a to The correspondence with 7d is obtained, and the relay apparatuses 3a to 3f are classified for each sub-network. As shown in FIG. 10, the classification table is a table including the IP address (network address) of the subnetwork and the identifiers of the relay devices 3a to 3f belonging to the subnetwork.

  FIG. 11 is a diagram illustrating an example of a transfer procedure when an optimal transfer path is selected. 11 is based on the same configuration as that shown in FIG. First, transfer is performed in the same procedure as in step S11 and step S12 described with reference to FIG. 4, and the packet transmitted from the communication terminal 1a is transferred to the relay device 3f (step S11, step S12). Here, the relay device 3f holds the distributed database 5c including entries relating to the destination communication terminal 1b of the transferred packet as shown in FIGS. Therefore, the relay device 3f can obtain a destination relay device (in this case, the relay device 3e) that is a relay device connected to the communication terminal 1b.

  The relay device 3f that manages the distributed database of the packet destination communication terminal 1b includes a transmission source relay device (in this case, the relay device 3a), a destination relay device (in this case, the relay device 3e), and a notification source relay device (in this case). Notifies the management device 8 of the relay device 3f) and the destination communication terminal 1b (step S31). Here, the transmission source relay device indicates a relay device that has directly received a packet from the communication terminal 1b that has transmitted the packet, that is, a packet transfer source relay device.

  Based on the classification table illustrated in FIG. 10, the management device 8 determines that the transmission source relay device (relay device 3 a) notified from the relay device 3 f corresponds to the network address of the sub-network 7 a. It is recognized that the device 3a) belongs to the subnetwork 7a, and similarly that the destination relay device (relay device 3e) belongs to the subnetwork 7b. Further, the management device 8 obtains a transfer route from the transmission source relay device to the destination relay device, which is completed by the recognized relay device in the sub-networks 7a and 7b, based on the classification table and the route management table. Here, when the transfer route to the relay device 3d held by the relay device 3a and the transfer route to the relay device 3e held by the relay device 3d are combined and transferred in the order of 3a → 3d → 3e, the sub-networks 7a and 7b Since it can be completed by the relay device, this route is obtained, and the obtained route is notified to the transmission source relay device (relay device 3a) as a transfer route of the packet addressed to the communication terminal 1b (step S32).

  When the relay device 3a receives the notification transmitted in step S32, the relay device 3a stores the transfer path included in the notification as the transfer route of the packet addressed to the communication terminal 1b, and subsequent packets addressed to the communication terminal 1b pass through the relay device 3d. Then, the data is transferred to the relay device 3e (step S33). The transfer from the relay device 3e to the communication terminal 1b is the same as step S14 in FIG. 4 (step S14). In this way, packet transmission from the communication terminal 1a to the communication terminal 1b is completed.

  FIG. 12 is a flowchart illustrating an example of a procedure for the management apparatus 8 to obtain a transfer path between relay apparatuses. As described above, when a relay apparatus holding a distributed database including an entry related to a destination communication terminal receives a packet, the relay apparatus (relay apparatus 3f in the example of FIG. 11) transmits the source relay apparatus and the destination relay. The device, the notification source relay device, the destination communication terminal of the packet, and the management device 8 are notified. In this way, when the management device 8 receives notifications from the relay device that holds the database including entries relating to the destination communication terminal, the source relay device, the destination relay device, the notification source relay device, and the destination communication terminal, The management device 8 starts processing for obtaining a transfer route.

  First, the management apparatus 8 searches for a transfer path that can be directly transferred from the transmission source relay apparatus to the destination relay apparatus based on the path management table, and determines whether there is a transfer path (step S1). If it is determined that there is no transfer path that can be directly transferred (No in step S1), based on the network configuration table and the IP addresses of the source relay device and the destination relay device, the subnetwork (subnet) to which both relay devices belong Is obtained (step S2).

  Next, based on the route management table, the management device 8 determines a route from the subnetwork to which the transmission source relay device belongs (hereinafter referred to as the transmission source subnetwork) to the subnetwork to which the destination relay device belongs (hereinafter referred to as the destination subnetwork). It searches and it is judged whether there exists a path | route (step S3). That is, it is transferred whether there is a relay device that can be directly transferred from the relay device that belongs to the destination subnetwork and belongs to the transmission source subnetwork. For example, when the transmission source relay device is the relay device 3a and the destination relay device is the relay device 3e as shown in FIG. 11, the relay device 3a belonging to the transmission source network directly transfers to the relay device 3d belonging to the destination network. Since this is possible, there is a route in step S3.

  When it is determined in step S3 that there is a route from the transmission source subnetwork to the destination subnetwork (Yes in step S3), the management device 8 determines whether or not the searched route starts from the transmission source relay device. Is determined (step S4). For example, in the case of FIG. 11 described above, it is determined that the route is a route starting from the relay device 3a that is the transmission source device.

  If it is determined in step S4 that the route does not start from the transmission source relay device (No in step S4), the start point of the route determined to be step S3 based on the route management table and the network configuration table For the relay device, a transfer route (link) that is completed within the source subnetwork is searched from the source relay device, and it is determined whether there is a transfer route (step S5). For example, when the transmission source device is the relay device 3e, there is a transfer path from the relay device 3d in the transmission source subnetwork as shown in FIG. Will do.

  If it is determined in step S5 that there is a transfer route that is completed within the transmission source subnetwork from the transmission source relay device (Yes in step S5), it is determined in step S3 that there is a route based on the route management table and the network configuration table. For the relay device that is the end point of the route, a search is made for a transfer route that is completed within the destination subnetwork to the destination relay device, and it is determined whether there is a transfer route (step S6).

  If it is determined in step S6 that there is a transfer path that is completed within the destination subnetwork to the destination relay device (Yes in step S6), the transmission from the source relay device to the destination relay device obtained in the previous processing is performed. The transfer path is notified to the transmission source relay apparatus together with the identifier of the destination communication terminal of the packet as the optimum transfer path (step S7), and the process is terminated.

  On the other hand, when it is determined in step S1 that there is a transfer path that can be directly transferred (Yes in step S1), the process proceeds to step S7, the transfer path is notified to the transmission source relay apparatus (step S7), and the process ends. If it is determined in step S3 that there is no route from the transmission source subnetwork to the destination subnetwork (No in step S3), the process is terminated as it is because there is no optimal transfer route. Even if it is determined in step S5 that there is no transfer route that is completed within the transmission source subnetwork from the transmission source relay device (No in step S5), the processing is terminated as it is because there is no optimal transfer route, and in step S6. Even when it is determined that there is no transfer path to be completed in the destination subnetwork to the destination relay device (No in step S6), the process is ended as it is because there is no optimal transfer path.

  If it is determined in step S4 that the route searched in step S3 starts from the transmission source relay device (Yes in step S4), the process proceeds to step S6.

  Through the above processing, the management device 8 can obtain an optimum transfer route taking into consideration the network configuration, and transmits the optimum transfer route to the transmission source relay device. Then, the transmission source relay apparatus transfers the packet to the next relay apparatus based on the notified transfer path, and at this time, the optimal transfer path is included in the packet and notified. Note that the optimum transfer path may be notified separately from the packet. Then, the relay device to which the packet has been transferred sequentially transfers based on the optimum transfer route, and notifies the optimum transfer route at that time.

  For example, in the example of FIG. 5, the packet addressed to the communication terminal 1b transmitted from the communication terminal 1a is transmitted via the relay device 3a, the relay device 3d, the relay device 3f, and the relay device 3e. When the management device 8 obtains an optimal transfer path, the packet is transmitted via the relay device 3a, the relay device 3d, and the relay device 3e. Thereby, compared with the case where the management apparatus 8 is not used, it is possible to reduce the number of relay apparatuses and sub-networks that are passed through. If it is determined in the processing described with reference to FIG. 12 that there is no optimal transfer route, the transfer is performed according to the route information held by each relay device, as in the case where the management device 8 is not provided. The transfer is performed by a normal procedure (for example, the procedure described in FIG. 5).

  In addition, when the relay devices 3a to 3e periodically transmit a survival confirmation packet to the management device 8 and the management device 8 cannot confirm the survival, the routes held by the relay devices respectively If the transfer is performed according to the normal procedure of performing transfer according to the information, it is possible to avoid the stop of the network function when a failure occurs in the management device 8.

  In the present embodiment, the information for constructing the network configuration table is acquired from the router 6. However, the present invention is not limited to this, and the network configuration is set by other methods such as setting in the management device 8 in advance. A table may be constructed and held.

  In the present embodiment, the management device 8 acquires the IP address of the subnetwork as a network configuration from the router 6 and selects a simple route in the source network and the destination network as the optimum route. Not limited to this, for example, a predetermined index value indicating transfer efficiency is determined, information necessary for obtaining the index value is collected, and based on the index value calculated using the collected information A transfer path may be selected.

  For example, in the examples shown in FIGS. 11 and 12, it can be considered that both the number of sub-networks that are routed as index values and the number of relay devices that are routed correspond to the index values. When the optimum transfer route is obtained in accordance with the processing procedure of FIG. 12, the number of routed sub-networks is minimum (the minimum value is 2 when the transmission source network and the destination network are different, and the transmission source network and the destination network are the same). The minimum value is 1), and the transfer route with the smallest number of relay devices passing through is selected. In addition to this, for example, when the network is not divided into sub-networks, the number of relay devices that pass from the transmission source relay device to the destination relay device is used as an index value, and the transfer path that minimizes the index value is selected. For example, the optimum transfer route may be obtained by other methods.

  As described above, in this embodiment, the management apparatus 8 is provided, and each relay apparatus notifies the management apparatus 8 of information on the identifier, IP address of the apparatus, and the relay apparatus that can be directly transferred from the apparatus. 8 holds the information as a route management table, and the management device 8 acquires network configuration information from the router 6 and holds it as a network configuration table. In addition, each relay device holds a database that is a correspondence between the communication terminal and the relay device connected to the communication terminal as a distributed database.

  Then, the relay device that holds the distributed database related to the communication terminal that is the destination of the packet notifies the management device 8 of the transmission source relay device and the destination relay device of the packet. Based on the configuration table, the route from the source relay device to the destination relay device, which is completed in the source network and the destination network, is obtained as an optimum transfer route, and the transfer route is notified to the source relay device. Therefore, when an overlay network is used, a transfer route that optimizes the efficiency of the entire system can be set.

  As described above, the communication system and the packet transfer method according to the present invention are useful for a communication system employing an overlay network, and are particularly suitable for a communication system including a subnetwork.

1a to 1c Communication terminal 2 Network 3a to 3f Relay device 4 Communication line 5a to 5c Distributed database 6 Router 7a to 7d Subnetwork 8 Management device

Claims (6)

A communication system comprising a plurality of relay devices and a communication terminal connected to the relay device, the relay device holding the relay device directly transferable by the relay device as route information, and transferring a packet received based on the route information Because
A management device connected to the relay device;
With
The correspondence with the relay device connected to the communication terminal is assigned to the relay device for each communication terminal based on the identifier of the communication terminal and the identifier of the relay device,
The relay device holds the correspondence assigned to the own device as a distributed database,
The relay device transmits the stored route information to the management device,
The management device holds the route information received from the relay device as route management information for each relay device,
When the relay device receives a packet addressed to another communication terminal from the communication terminal, the relay device is based on an identifier of the destination communication terminal that is the communication terminal that is the destination of the packet and an identifier of the other relay device. The relay device holding the distributed database of the destination communication terminal is obtained, and the received packet is forwarded by adding the identifier of the own device to the obtained relay device,
When the relay device holds a distributed database of the destination communication terminal of the packet when the packet is received, the relay device connects the relay device connected to the destination communication terminal based on the held distributed database. As a device, and notifies the management device of the source relay device, the destination relay device and the destination communication terminal that are the relay device of the source of the packet,
The management device calculates, as the optimum transfer route, a transfer route from the transmission source relay device to the destination relay device, for which an efficiency index value indicating high transfer efficiency is optimal based on the route management information, and Notifying the transmission source relay device of the transfer route and the destination communication terminal as optimum route information,
When receiving the optimum route information, the relay device holds the optimum route information, notifies the next route device of its own device on the optimum transfer route, and notifies the destination communication. When a packet addressed to the terminal is received, the packet is transferred to the next relay device of the own device on the optimum transfer path.
A communication system characterized by the above. The number of relay devices that pass through the efficiency index value,
The management device calculates, as the optimum transfer route, a transfer route from the transmission source relay device to the destination relay device that minimizes the number of the relay devices that pass through.
The communication system according to claim 1. The relay device and the communication device are divided into two or more sub-networks, and the management device belongs to a sub-network that does not include the relay device and the communication device,
A router connecting the sub-networks,
Further comprising
The management device acquires address information of the subnetwork to which the router is connected from the router as network configuration information, and further calculates the optimum transfer path based on the network configuration information.
The communication system according to claim 1. The efficiency index value is defined as the number of relay devices to be routed and the number of subnetworks to be routed.
The management device calculates, as the optimum transfer route, a transfer route from the transmission source relay device to the destination relay device that minimizes the number of routed sub-networks and minimizes the number of routed relay devices. ,
The communication system according to claim 1. The relay device periodically transmits a survival confirmation packet to the management device, and when there is no normal response to the survival confirmation packet from the management device, the relay device receives it based on path information held by the own device Perform packet forwarding,
The communication system according to any one of claims 1 to 4. It is composed of a plurality of relay devices, a communication terminal connected to the relay device, and a management device connected to the relay device. The relay device that can be directly transferred by the relay device is held as route information, and the route information is A packet transfer method in a communication system for transferring a packet received based on
The correspondence with the relay device connected to the communication terminal is assigned to the relay device for each communication terminal based on the identifier of the communication terminal and the identifier of the relay device,
A distributed database holding step in which the relay device holds the correspondence assigned to the own device as a distributed database;
A route information transmission step in which the relay device transmits route information held by the relay device to the management device;
A route management information holding step in which the management device holds the route information received from the relay device as route management information for each relay device;
When the relay device receives a packet addressed to another communication terminal from the communication terminal, based on the identifier of the destination communication terminal that is the communication terminal that is the destination of the packet and the identifier of the other relay device A packet transfer step of obtaining the relay device holding a distributed database of the destination communication terminal, and forwarding the received packet with the identifier of the own device added to the obtained relay device;
When the relay apparatus holds a distributed database of the destination communication terminal of the packet when the packet is received, the relay apparatus connects the relay apparatus connected to the destination communication terminal based on the held distributed database. A relay device notifying step for notifying the management device of the source relay device, the destination relay device, and the destination communication terminal, which are the relay devices that are the source of the packets,
The management device calculates, as the optimum transfer route, a transfer route from the transmission source relay device to the destination relay device, for which an efficiency index value indicating high transfer efficiency is optimal based on the route management information, and An optimal route information notification step of notifying the transmission source relay device of the transfer route and the destination communication terminal as optimal route information;
When receiving the optimum route information, the relay device holds the optimum route information, notifies the next route device of its own device on the optimum transfer route, and notifies the destination communication. When receiving a packet addressed to the terminal, an optimal transfer path transfer step of transferring the packet to the next relay apparatus of the own apparatus on the optimal transfer path;
A packet transfer method comprising:

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