JP5233295B2 - COMMUNICATION DEVICE, COMMUNICATION SYSTEM, AND COMMUNICATION METHOD - Google Patents

Description

  The present application relates to a communication device, a communication system, and a communication method, and more particularly, to a communication device, a communication system, and a communication method that transmit and receive data through a communication network having a plurality of communication paths.

  In recent years, in order to provide various communication services, a communication network for dividing data into a plurality of packets and transmitting the data has been used. Such communication services also include real-time communication services that require continuous data communication in real time, such as voice calls. In such a communication network, it is important to transmit data so that data being communicated is not lost between communication devices that transmit and receive data to and from each other. Therefore, in order to avoid data loss, various methods for ensuring communication quality are employed. For example, retransmission control is known as one of such methods. In the retransmission control, when there is a packet that could not be received by one communication apparatus, the packet is transmitted again from the other communication apparatus. By using retransmission control, even if a packet loss occurs during communication, a packet including the same content as the lost packet is transmitted again, so that the possibility of data loss during communication can be reduced. However, in retransmission control, the arrival order of packets may be reversed from the transmission order, or the transmission delay time may vary greatly. On the other hand, in the real-time communication service, if the packet transmission order and arrival order are reversed or the transmission delay time fluctuates, the communication device may not be able to accurately reproduce the data. Therefore, it is difficult to use retransmission control for real-time communication services to ensure communication quality.

  As another method, priority control is known. In the priority control, the priority for each packet is defined, and a relay node that transfers a packet in a communication network preferentially performs a transfer process for a packet having a higher priority. However, when the packet is congested or a failure occurs in the relay node, it is difficult to completely prevent the loss of the packet or the fluctuation of the transmission delay time.

  Therefore, one communication device transmits a plurality of packets including the same contents through a plurality of physically separated communication networks, and extracts only data considered to be normal from the packet received by the other communication device. A method has been developed (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 5-160813

  However, in order to use the method disclosed in Patent Document 1, a plurality of physically independent communication networks must be constructed. In order to construct a plurality of independent communication networks, it is necessary to prepare transmission lines, repeaters, etc. for each communication network, and the cost required for the construction and maintenance of the network becomes very high. In addition, when a failure occurs in a part of the constructed communication network, there is a possibility that fluctuation in transmission delay time and reversal of transmission order and arrival order cannot be prevented sufficiently.

  Accordingly, an object of the present application is to provide a communication system and a communication method in which fluctuations in transmission delay time during communication and inversion of data transmission order and arrival order hardly occur.

  According to one embodiment, a communication system is provided. The communication system includes a first communication device and a second communication device that transmit / receive data to / from each other, a communication network having a plurality of communication paths that connect the first communication device and the second communication device, and a plurality of communication networks A communication path evaluation unit that evaluates communication quality for at least one communication path, and a path that selects at least one communication path from a plurality of communication paths based on a communication quality evaluation result by the communication path evaluation unit. And a management unit. In the communication system, the first communication device transmits data to the second communication device via the selected at least one communication path.

  According to another embodiment, there is provided a communication device that transmits / receives data to / from another communication device via a communication network having a plurality of communication paths. The communication apparatus includes a communication path evaluation unit that evaluates communication quality for at least one communication path among the plurality of communication paths, and at least one of the plurality of communication paths based on a communication quality evaluation result by the communication path evaluation unit. A path management unit that selects one communication path, and a data transmission unit that transmits data to another communication device via the selected at least one communication path.

  According to still another embodiment, a communication path management device is provided. The communication path management apparatus evaluates communication quality for at least one communication path among a plurality of communication paths included in a communication network connecting the first communication apparatus and the second communication apparatus that mutually transmit and receive data. A path management unit that selects at least one communication path that connects the first communication apparatus and the second communication apparatus from a plurality of communication paths based on a communication quality evaluation result by the communication path evaluation unit. And have.

  According to yet another embodiment, there is provided a communication method for transmitting data via a communication network having a plurality of communication paths connecting a first communication device and a second communication device that transmit and receive data to and from each other. The According to the communication method, the communication quality is evaluated for at least one communication path among the plurality of communication paths, and at least one communication path is selected from the plurality of communication paths based on the evaluation result of the communication quality. Including transmitting data by the communication device to the second communication device via the selected at least one communication path.

  The communication system and the communication method disclosed in the present application are advantageous in that fluctuations in transmission delay time during communication and inversion of data transmission order and arrival order are unlikely to occur.

Hereinafter, a communication system according to an embodiment will be described with reference to the drawings.
In a communication system according to one embodiment, a plurality of communication devices that transmit and receive data to each other are connected by a communication network having a plurality of communication paths. The communication system evaluates the communication quality for at least one of the plurality of communication paths, and selects at least one communication path based on the evaluation result. Then, one communication device transmits a packet including the same data to each selected communication path. When the other communication device receives a plurality of packets including the same data, the other communication device selects the first received packet, acquires data from the packet, and discards the remaining packets.

  FIG. 1 is a schematic configuration diagram of a communication system 1 according to one embodiment. As shown in FIG. 1, the communication system 1 includes a server 2 and a client host 3. The server 2 and the client host 3 are connected via the communication network 4 and can communicate with each other. The communication network 4 includes a plurality of relay nodes 5-1, 5-2,. Each relay node is connected to one of the other relay nodes, or the server 2 or the client host 3 via a transmission line, and can transmit / receive data to / from the connected device. For example, the relay node 5-1 can transmit / receive data to / from the server 2 and the relay nodes 5-3 and 5-5. Note that the transmission line is not limited to a wired one, and may be one that transmits data wirelessly.

  The communication network 4 is an IP network used for communication according to a communication protocol such as TCP / IP. Each relay node is a device having a routing function, and is configured by, for example, a router or a switching hub. Further, IP addresses a to h are assigned to the relay nodes 5-1 to 5-8, respectively. When each relay node receives a packet transmitted from the server 2 or the client host 3, the relay node refers to destination information included in the packet and a routing table of the relay node itself, and determines a route for sending the packet.

  The server 2 and the client host 3 include a control circuit such as a CPU, a memory such as a ROM, a RAM, and a magnetic disk, a communication interface for communicating with other devices in accordance with a predetermined communication standard such as TCP / IP, and its peripherals It has a circuit. Further, the server 2 and the client host 3 may be connected to a video camera or a microphone and configured to acquire moving image data or audio data from these devices. The server 2 is installed by a service provider or a content provider, for example, and distributes real-time data such as moving image data and audio data according to a request from the client host 3. Alternatively, the server 2 may be a server that transmits data to other devices, such as a web server or an ftp server. On the other hand, the client host 3 is, for example, a PC or a line termination device installed in the home, and transmits a predetermined data acquisition request to the server 2. The client host 3 may also transmit real-time data such as moving image data or audio data to the server 2.

  FIG. 2 is a diagram showing a schematic configuration of the server 2 and the client host 3. The server 2 and the client host 3 are communication devices that transmit / receive data to / from each other. Each of the server 2 and the client host 3 includes a communication path evaluation unit 11, a path management unit 12, an application processing unit 13, a packet replication / selection unit 14, and an IP layer processing unit 15. Each of these units is a functional module implemented by the CPU of the server 2 and a program executed on the CPU. Alternatively, each unit described above may be implemented as firmware. The server 2 also includes a packet data transmission / reception unit 16 composed of a communication interface and its peripheral circuits, and a storage unit 17 composed of ROM, RAM, a magnetic recording medium, an access device thereof, and the like.

  As described above, the server 2 and the client host 3 have the same function and configuration with respect to data transmission / reception. Therefore, only the server 2 will be described in detail below.

  The communication path evaluation unit 11 evaluates the communication quality of the communication path from one communication apparatus (for example, the server 2) to the other communication apparatus (for example, the client host 3). For this purpose, the communication path evaluation unit 11 selects a communication path to be evaluated from communication paths registered in advance in the path information table stored in the storage unit 17. Then, the communication path evaluation unit 11 executes a traceroute command for each selected communication path in accordance with, for example, the Internet control notification protocol (hereinafter referred to as ICMP). Then, for each communication path, the communication path evaluation unit 11 transmits the transmission delay time from when the packet is transmitted from one communication apparatus to when it is received by the other communication apparatus, the fluctuation width of the transmission delay time, the packet loss rate, the packet Obtain route quality information such as the number of transfers. The communication path evaluation unit 11 may obtain path quality information based on other communication protocols or other methods. The communication path evaluation unit 11 associates the obtained information with each communication path and records the information in the path information table.

  In addition, the communication path evaluation unit 11 performs a failure occurrence status, the number of transmitted / received packets, the number of discarded packets, an error from a relay node existing on each communication path according to a simple network management protocol (hereinafter referred to as SNMP). Node quality information such as the number of received packets may be obtained. Furthermore, the communication path evaluation unit 11 may obtain node quality information in each relay node based on a communication protocol other than SNMP or another method. The communication path evaluation unit 11 associates the obtained information with each relay node and stores it in the storage unit 17 as a node information table.

  The communication path evaluation unit 11 measures the quality of each communication path periodically (for example, every 6 hours, every day, or every week), or when the network configuration is changed or when the network is maintained. Update table and node information table. The communication path evaluation unit 11 may evaluate the communication quality of all the communication paths at once, or may evaluate the communication quality in order for each part of the communication paths.

FIG. 3 shows an example of the route information table. The route information table 300 has one data set for each communication route. In FIG. 3, this data set is displayed as one row. Each data set includes a route identifier (hereinafter referred to as a route ID) 301 for identifying a communication route, route information 302 indicating the IP addresses of relay nodes included in the communication route in order of passage, and measurement for the communication route. The transmission delay time 303, the transmission delay time fluctuation range 304, the packet loss rate 305, and the path use status identification flag 306 are included. The variation width 304 of the transmission delay time is determined by transmitting a plurality of packets to the communication path to be evaluated at the time of path quality evaluation, measuring the transmission delay time for each packet, and measuring the minimum and maximum values of the transmission delay time. Measured as the difference in values. Further, the fluctuation range 304 may be measured as a difference in transmission delay time between the latest path quality evaluation and the previous path quality evaluation. Further, the fluctuation range 304 may be the standard deviation of the transmission delay time during the past several path quality evaluations. The packet loss rate 305 is a ratio of the number of unreceived packets to the number of transmitted packets. The route use status identification flag 306 indicates whether or not the corresponding communication route is used. For example, when the value is “1”, the corresponding communication route is used, and the value is “0”. Indicates that the corresponding communication path is not used.
For example, referring to the route information table 300, in the communication route with route ID # 0, server 2 → relay node 5-1 (IP address a) → relay node 5-3 (IP address c) → relay node 5-6. It is shown that packets are transferred in the order of (IP address f) → relay node 5-8 (IP address h) → client host 3. Also, the transmission delay time, transmission delay time fluctuation width, and packet loss rate of the communication path are 30 msec, 10 msec, and 1%, respectively, and the communication path is unused (path usage status identification flag = 0). I understand.

  FIG. 4 shows an example of the node information table. The node information table 400 has one data set for each relay node. In FIG. 4, this data set is displayed as one row. Each data set includes an IP address 401 of the relay node, failure occurrence information 402 indicating whether or not a failure has occurred, packet transmission / reception number 403 within a predetermined period, packet discard number 404 within a predetermined period, error packet within a predetermined period The reception number 405 is included. For example, when the value is “1”, the failure occurrence information indicates that a failure has occurred in the corresponding relay node. When the value is “0”, a failure has occurred in the corresponding relay node. It means not. In addition, the predetermined period can be, for example, the latest one minute, one hour, or one day at the time when the quality evaluation is performed for the target relay node.

  The communication path between the communication devices is manually set and written in the path information table, for example, at the time of initial setting, at the time of changing the network configuration, or at the time of network maintenance. Alternatively, the communication path evaluation unit 11 may automatically search for a communication path between communication apparatuses using a known routing protocol and add a new communication path to the path information table each time a new communication path is found.

  The route management unit 12 selects a communication route to be used based on the communication quality evaluation result of each communication route by the communication route evaluation unit 11. For this purpose, the route management unit 12 reads the route information table and the node information table from the storage unit 17. Then, the route management unit 12 refers to the route information table or the node information table, and selects the communication route that uses the communication route having a short transmission delay time and a small variation in the transmission delay time. Alternatively, the route management unit 12 may select a communication route that uses a communication route with a low probability of packet loss.

An example of a route selection procedure will be described with reference to the flowcharts of FIGS. In the following example, it is assumed that the data transmission source is the server 2 and the data transmission destination is the client host 3. First, as shown in FIG. 5, the communication path evaluation unit 11 refers to the path information table and extracts all communication paths connecting the server 2 and the client host 3 (step S101). Next, the communication path evaluation unit 11 evaluates the quality of each extracted communication path, and writes path quality information such as transmission delay time and packet loss rate indicating the evaluation result in the path information table (step S102). Further, the communication path evaluation unit 11 acquires node quality information such as a failure occurrence status from all the relay nodes included in any communication path, and writes it in the node information table (step S103). The acquisition of the route quality information of the communication route and the node quality information of the relay node is as described above.
Next, the route management unit 12 refers to the node information table and extracts a relay node in which a failure has occurred (step S104). If there is a faulty relay node, the path management unit 12 excludes the communication path including the faulty relay node from the extracted communication path (step S105).

  In step S104, when there is no faulty relay node or after step S105, the path management unit 12 refers to the node information table and indicates the ratio of the number of received error packets to the number of packet transmission / reception. A relay node having an error packet reception rate exceeding a predetermined threshold Th1 is extracted (step S106). The predetermined threshold Th1 is determined by the requested service and is set to a value such as 5%, for example. When there is a relay node with a high error packet reception rate, it is considered that other relay nodes that directly transmit packets to the relay node transmit many illegal packets. Alternatively, it is considered that many packet errors (or bit errors) occur in any communication path including a relay node with a high error packet reception rate. Therefore, if there is a relay node whose error packet reception rate exceeds a predetermined number, the path management unit 12 identifies the relay node that directly transmits the packet to the relay node (step S107). The route management unit 12 can specify the relay node by acquiring the routing table of the relay node from the relay node having an error packet reception rate exceeding a predetermined number by using SNMP. Then, the route management unit 12 excludes the communication route including the identified relay node from the extracted communication route (step S108).

  As shown in FIG. 6, in step S106, when there is no relay node whose error packet reception rate exceeds the predetermined threshold Th1, or after step S108, the path management unit 12 refers to the node information table, A relay node in which the discard packet rate indicating the ratio of the number of discarded packets to the number of normal packet transmission / reception exceeds a predetermined threshold Th2 is extracted (step S109). The normal packet transmission / reception number is a number obtained by subtracting the error packet reception number in the period from the packet transmission / reception number in the predetermined period. The predetermined threshold Th2 is determined by the requested service, and is set to a value such as 5%, for example. A relay node with a high discard packet rate is considered to have a high processing load on the relay node. Therefore, it is preferable to select a communication path that does not pass through such a relay node. Therefore, the path management unit 12 excludes communication paths including relay nodes whose discard packet rate exceeds the threshold value Th2 from the extracted communication paths (step S110).

  In step S109, when there is no relay node whose discard packet rate exceeds the predetermined threshold Th2, or after step S110, the path management unit 12 refers to the path information table and the fluctuation width of the transmission delay time is A communication path longer than the predetermined time Th3 is excluded (step S111). By excluding such communication paths, the possibility that the transmission order and arrival order of packets are reversed can be reduced. The predetermined time Th3 can be a time estimated that the packet transmission order and arrival order are not reversed, for example, a time corresponding to 50% of the transmission delay time of the communication path.

  Then, the path management unit 12 selects a predetermined number of communication paths as communication paths to be used in order from the shortest transmission delay time among the remaining communication paths that are not excluded (step S112). The predetermined number, that is, the number of communication paths to be used is appropriately set according to the communication service, and the minimum number is 1. Further, the higher the required communication quality, the larger the predetermined number. Finally, the route management unit 12 rewrites the value of the route use status identification flag in the route information table corresponding to the selected communication route to a value indicating that the communication route is used (step S113).

  Further, in the above steps S104 to 111, when all the communication routes extracted in step S101 are excluded, the route management unit 12 increases at least one of the threshold value Th1 or Th2 or sets a predetermined time Th3. You may enlarge and may perform the process of step S104-S111 again. Alternatively, the communication path evaluation unit 11 may search for a new communication path that is not listed in the path information table using, for example, various known routing protocols, and execute the processes of steps S102 to S113 described above. . Furthermore, the route management unit 12 may exclude relay nodes that must be routed (for example, the relay node 5-8 in the example of FIG. 1) from the processing of the above steps S107 and S109.

  Furthermore, the route management unit 12 may select a communication route to be used by using only some information described in the route information table or the node information table. For example, the path management unit 12 may select communication paths that use all communication paths that do not include a faulty relay node from among the communication paths extracted in step S101. Alternatively, the path management unit 12 may simply select a predetermined number of communication paths as communication paths to be used in order from the communication path extracted in step S101 described above, in order from the shortest transmission delay time. Furthermore, the route management unit 12 may use another selection criterion in addition to or instead of the above-described communication route selection criteria. For example, the path management unit 12 may select a predetermined number of communication paths in order from the lowest packet loss rate among the communication paths extracted in step S101 as the communication paths to be used.

  Further, when history information representing past evaluation results is also recorded for the quality information of each communication route, the route management unit 12 may select a communication route to be used with reference to the history information. For example, the route management unit 12 may exclude a communication route having a packet loss rate higher than that of the previous quality evaluation from the communication route to be used. Further, the route management unit 12 may select a communication route having a low packet loss rate at the time of several quality evaluations in the past (for example, less than 0.01%) as a preferentially used communication route. Or the path | route management part 12 may select as a communication path | route used preferentially in an order from the one with the lower average value of the transmission delay time at the past several quality evaluations.

  When there is a data transmission request from an application installed in the server 2, the application processing unit 13 sends the data to the packet duplication / selection unit 14. Conversely, when the server 2 receives data from the client host 3, the application processing unit 13 receives data included in the packet selected by the packet replication / selection unit 14 from the packet replication / selection unit 14. Then, the data is notified to the application installed in the server 2.

The packet duplication / selection unit 14 includes a duplication unit 141 and a selection unit 142. Among these, the replication unit 141 uses the data received from the application processing unit 13 by referring to the path usage status identification flag of the path information table stored in the storage unit 17 when the server 2 transmits data. Duplicate the number of communication paths that are in the state. Then, the duplication unit 141 gives a sequence number for identifying the contents of the data to each duplicated data. The duplicating unit 141 assigns the same sequence number to each duplicated data. That is, the same sequence number is assigned to data having the same content. On the other hand, different sequence numbers are assigned to data having different contents. In addition, the duplication unit 141 associates the route ID of each communication route in use with the duplicated data.
Then, the duplicating unit 141 sends each duplicated data and related information (sequence number, path identifier) to the IP layer processing unit 15.

  On the other hand, when the server 2 receives a packet through the communication network 4, the selection unit 142 of the packet duplication / selection unit 14 selects one packet from the duplicate received packets. Then, the selection unit 142 passes the data included in the selected packet to the application processing unit 13. For example, the selection unit 142 selects only the packet received earliest from among a plurality of packets including the same content data. For this purpose, when receiving the packet, the selection unit 142 refers to the sequence number included in the packet and compares the sequence number with the sequence number stored in the selection unit 142. When the sequence number included in the received packet does not match any of the sequence numbers stored in the selection unit 142, the selection unit 142 passes the data included in the packet to the application processing unit 13. Then, the selection unit 142 stores the sequence number included in the received packet to indicate that the packet has already been received.

  On the other hand, when the sequence number included in the received packet matches any of the sequence numbers stored in the selection unit 142, the selection unit 142 discards the packet. Note that the selection unit 142 deletes a sequence number that satisfies a predetermined condition for each stored sequence number in order to collate the sequence number included in the received packet in a short time. For example, when the selection unit 142 receives the same number of packets having the same sequence number as the number of used communication paths, the selection unit 142 deletes the sequence number. In addition, when a certain period of time elapses after receiving the first packet among the packets having data including the same contents, the selection unit 142 deletes the sequence number corresponding to the packet. The fixed period is, for example, a period equal to the longest transmission delay time measured for each communication path used, or a value obtained by adding a predetermined margin to the longest transmission delay time (for example, 10 msec) Or a value obtained by multiplying the longest transmission delay time by a coefficient such as 1.1). In order to determine the conditions for erasing the sequence number in this way, the server 2 acquires in advance information such as the transmission delay time of the communication path used for data transmission from the client host 3 that is the data transmission source. .

  Further, the selection unit 142 may select one packet from the duplicately received packets based on another selection criterion. For example, when the selection unit 142 receives a plurality of packets including the same data until the packet including the subsequent data arrives, the selection unit 142 selects the packet with the lowest error bit generation rate from those packets. Data may be acquired from the packet.

  When the server 2 transmits data, when receiving data to be transmitted from the packet duplication / selection unit 14, the IP layer processing unit 15 packetizes the data so that the data can be transmitted according to the IP protocol. Then, the IP layer processing unit 15 writes predetermined header information in the packet. When transmitting data according to IPv4, the IP layer processing unit 15 writes the route information corresponding to the route ID associated with the data in the source routing option area of each packet including the data. When transmitting data according to IPv6, the IP layer processing unit 15 writes the route information corresponding to the route ID associated with the data in the area of the routing header of each packet including the data. As described above, by writing the route information in the predetermined area of the header information of the packet, the server 2 can transmit the packet along the communication route indicated by the route information. Furthermore, the IP layer processing unit 15 writes the sequence number associated with the data to be transmitted, for example, at the beginning or end of the data area of the packet. The IP layer processing unit 15 sends the created packet to the communication network 3 via the packet data transmission / reception unit 16.

  On the other hand, when the server 2 receives a packet from the communication network 3 via the packet data transmission / reception unit 16, the IP layer processing unit 15 removes the header information from the packet according to the IP protocol, and the packet duplication / selection unit 14 Send to.

The data transmission procedure will be described below with reference to the flowchart shown in FIG. The following procedure will be described assuming that data is transmitted from the server 2 to the client host 3. However, the following procedure is similarly applied when data is transmitted from the client host 3 to the server 2.
First, when a data transmission request is notified to the application processing unit 13, the application processing unit 13 sends data to be transmitted to the packet duplication / selection unit 14 (step S201). When receiving the data from the application processing unit 13, the duplicating unit 141 of the packet duplicating / selecting unit 14 refers to the path information table and duplicates the data by the number of used communication paths determined by the path managing unit 12 (Step S1). S202). The communication path to be used is determined in advance according to the procedure shown in FIGS. 5 and 6, for example. Then, the duplication unit 141 attaches to each of the duplicated data a route ID corresponding to the communication route through which the data should pass and a sequence number indicating the identity of the data (step S203). Each duplicated data is passed to the IP layer processing unit 15.

  Next, the IP layer processing unit 15 acquires route information corresponding to the assigned route ID from the route information table for each piece of replicated data (step S204). Then, the IP layer processing unit 15 creates a packet for each duplicated data according to the IP protocol, writes path information in a predetermined area of the header information of the packet, and writes a sequence number in a predetermined position of the data area of the packet ( Step S205). Then, the IP layer processing unit 15 transmits each packet to the client host 3 via the packet data transmission / reception unit 16 (step S206).

The data reception procedure will be described with reference to the flowchart shown in FIG. The following procedure will be described assuming that the client host 3 receives data from the server 2. However, the following procedure is similarly applied when the server 2 receives data from the client host 3.
First, when the client host 3 receives a packet from the server 2 via the communication network 4, the IP layer processing unit 15 removes the header information from the received packet and passes the packet to the packet duplication / selection unit 14 ( Step S301). The selection unit 142 of the packet duplication / selection unit 14 checks whether or not the sequence number included in the received packet matches any of the sequence numbers stored in the packet replication / selection unit 14 (step S302). If the sequence number included in the received packet does not match any of the sequence numbers stored in the selection unit 142, the selection unit 142 sends the data included in the packet to the application processing unit 13 (step S303). ). Then, the selection unit 142 stores the sequence number included in the packet (step S304).

  On the other hand, in step S302, when the sequence number included in the received packet matches any of the sequence numbers stored in the selection unit 142, the selection unit 142 discards the packet (step S305).

  As described above, the communication system according to one embodiment evaluates the communication quality of at least one communication path among communication networks including a plurality of communication paths before transmitting data, and the evaluation result Based on the above, one or more optimum communication paths are selected. Then, one communication apparatus transmits a packet including data of the same content to each selected communication path. In addition, when the other communication device receives a plurality of packets including the same content data, the other communication device selects the earliest received packet, acquires the data, and discards the other packets. Therefore, it is possible to reduce the possibility of packet loss during communication, variation in transmission delay time, and reversal of packet transmission order and arrival order. Therefore, the communication system can be suitably used for real-time communication services such as a voice call service and a live video distribution service.

  The communication system according to one embodiment has been described above, but the present invention is not limited to the above embodiment. For example, the number of servers and client hosts included in the communication system is not limited to one each. And when communicating between servers or between client hosts, the path quality of the communication path is evaluated in the same manner as described above, and data is transmitted / received via the communication path selected based on the result. . In addition, one of a set of communication devices that transmit and receive data, for example, only a server may have the above-described configuration and functions, and the other communication device may be a known one. Furthermore, the number of relay nodes and the configuration of the communication network are not limited to the above embodiment.

In the above embodiment, the communication path evaluation unit and the path management unit included in the server and the client host are installed in a communication path management apparatus that is installed independently of the server and the client host and connected to the communication network. Also good.
FIG. 9 shows a configuration diagram of the communication system 10 when a communication path management device is installed independently from the server and the client host. In FIG. 9, the same reference numerals as those used in the above embodiment are assigned to the same functions as those in the above embodiment. In the communication system 10 shown in FIG. 9, the communication path management device 9 includes, for example, a control circuit such as a CPU, a memory such as a ROM, a RAM, and a magnetic disk, and other devices according to a predetermined communication standard such as TCP / IP. It has a communication interface for communication and its peripheral circuits. Then, according to the above-described procedure, the communication path evaluation unit 11 evaluates the communication path between the server 2 and the client host 3, and the path management unit 12 selects an optimal communication path. When there are a plurality of servers 2 and client hosts 3 connected to the communication network 4, an optimal communication path is selected as a communication device that transmits and receives data to and from any two of them. The communication path management apparatus 9 stores the selected path information in association with the addresses of the communication apparatuses for each combination of two communication apparatuses selected from the plurality of servers 2 and the client host 3. On the other hand, the server 2 and the client host 3 store the address of the communication path management device 9 in advance. Then, the server 2 or the client host 3 that intends to transmit data notifies the communication path management apparatus 9 of its own address and the address of the communication apparatus that is the communication partner, and inquires about an optimal communication path. Then, the communication path management device 9 returns the route information corresponding to the notified combination of communication devices to the server 2 or the client host 3 that has made the inquiry (the communication path management device 9 further communicates with the communication partner. The communication device may also be notified of the route information). Then, the server 2 or the client host 3 transmits data based on the route information notified from the communication route management device 9. Note that the communication path management device 9 and the server 2 or the client host 3 may be connected by a communication line installed independently of the communication network 4. Furthermore, any relay node included in the communication network may have the function of the communication path management device 9.

  Furthermore, as another embodiment, the communication path management device 9 may include the communication path evaluation unit 11, and the server 2 and the client host 3 may include the path management unit 12. In this case, the communication path management device 9 evaluates the communication path between the server 2 and the client host 3 by the communication path evaluation unit 11 and stores the path quality information and the node quality information as the evaluation results. On the other hand, the server 2 and the client host 3 acquire, from the communication path management device 9, path quality information and node quality information related to the communication path to the communication apparatus that is the communication partner in order to select a communication path to be used for communication. To do.

  As described above, those skilled in the art can make various modifications in accordance with the embodiment to be implemented within the scope of the present invention.

The following supplementary notes are further disclosed regarding the embodiment described above and its modifications.
(Appendix 1)
A first communication device (2) and a second communication device (3) that transmit and receive data to and from each other;
A communication network (4) having a plurality of communication paths connecting the first communication device (2) and the second communication device (3);
A communication path evaluation unit (11) for evaluating communication quality for at least one communication path among the plurality of communication paths;
A route management unit (12) that selects at least one communication route from the plurality of communication routes based on a communication quality evaluation result by the communication route evaluation unit;
The first communication device (2) is a communication system for transmitting data to the second communication device (3) via the selected at least one communication path.
(Appendix 2)
The path management unit (12) selects at least two communication paths among the plurality of communication paths, and the first communication device (2) determines the number of the selected communication paths for the data to be transmitted. The data replication unit (14) that replicates only, and the first communication device (2) transmits the replicated data to all the selected communication paths. Communications system.
(Appendix 3)
When the second communication device (3) receives the replicated data separately from at least two of the selected communication paths, the second communication device (3) received the first of the received replicated data. The communication system according to appendix 2, wherein data is selected and other data is discarded.
(Appendix 4)
The communication quality evaluation result includes a transmission delay time required for data transfer from the first communication device (2) to the second communication device (3), and the route management unit (12) The communication system according to appendix 1, wherein at least one communication path is selected in order from the shortest delay time.
(Appendix 5)
The communication network (4) includes a plurality of relay nodes (5-1,..., 5-8) that switch a data transmission path among the plurality of communication paths, and the communication path evaluation unit (11 ) Evaluates a communication state related to at least one of the plurality of relay nodes (5-1,..., 5-8), and uses node quality information representing the communication state as an evaluation result of the communication quality. The communication system according to appendix 1, wherein the path management unit (12) acquires and selects at least one communication path from the plurality of communication paths based on the node quality information.
(Appendix 6)
The node quality information includes failure information indicating whether a communication failure has occurred in any one of the plurality of relay nodes (5-1,..., 5-8), and the path The communication system according to appendix 1, wherein the management unit (12) refers to the failure information and selects at least one communication path that does not include a relay node in which a communication failure has occurred from the plurality of communication paths.
(Appendix 7)
The node quality information includes the number of illegal data received at any one of the plurality of relay nodes (5-1,..., 5-8), and the path management unit (12) When the number of receptions is greater than a predetermined number, among the plurality of relay nodes, at least one communication path that does not include a relay node that transmits data to a relay node having the number of receptions greater than the predetermined number is determined from the plurality of communication paths. The communication system according to attachment 1, wherein the communication system is selected.
(Appendix 8)
The evaluation result of the communication quality includes a fluctuation range of the transmission delay time, and the path management unit (12) selects at least one communication path having a fluctuation width of the transmission delay time of a predetermined time or less from the plurality of communication paths. The communication system according to attachment 1, wherein one is selected.
(Appendix 9)
A communication device (2) that transmits / receives data to / from another communication device (3) via a communication network having a plurality of communication paths,
A communication path evaluation unit (11) for evaluating communication quality for at least one communication path among the plurality of communication paths;
A route management unit (12) for selecting at least one communication route from the plurality of communication routes based on a communication quality evaluation result by the communication route evaluation unit (11);
A data transmission unit (16) for transmitting data to the other communication device (3) via the selected at least one communication path;
A communication device.
(Appendix 10)
Communication quality is set for at least one communication path among a plurality of communication paths included in the communication network (4) connecting the first communication apparatus (2) and the second communication apparatus (3) that transmit and receive data to and from each other. A communication path evaluation unit (11) to be evaluated;
At least one communication path connecting the first communication apparatus (2) and the second communication apparatus (3) from the plurality of communication paths based on the communication quality evaluation result by the communication path evaluation unit (11). A route management unit (12) for selecting
A communication path management device (9).
(Appendix 11)
A communication method for transmitting data via a communication network (4) having a plurality of communication paths connecting a first communication device (2) and a second communication device (3) that transmit and receive data to and from each other. ,
Evaluating communication quality for at least one of the plurality of communication paths;
Based on the evaluation result of the communication quality, select at least one communication path from the plurality of communication paths,
A communication method comprising transmitting data to the second communication device (3) by the first communication device (2) via the selected at least one communication path.
(Appendix 12)
The selection of the communication path selects at least two communication paths among the plurality of communication paths, and the transmission of the data duplicates the data to be transmitted by the number of the selected communication paths, 12. The communication method according to appendix 11, wherein the replicated data is transmitted to all selected communication paths.
(Appendix 13)
When the second communication device (3) receives the duplicated data separately from at least two of the selected communication paths, the first received data among the received duplicated data The communication method according to claim 12, further comprising: selecting and discarding other data.
(Appendix 14)
The evaluation result of the communication quality includes a transmission delay time required for data transfer from the first communication device (2) to the second communication device (3), and the selection of the communication path includes the transmission delay time. The communication method according to appendix 11, wherein at least one communication path is selected in order from the shortest.
(Appendix 15)
The communication network (4) includes a plurality of relay nodes (5-1,..., 5-8) that switch a path through which data is transmitted among the plurality of communication paths.
The communication quality is evaluated by evaluating a communication state related to at least one of the plurality of relay nodes (5-1,..., 5-8), and using the node quality information indicating the communication state as the communication quality. Obtained as an evaluation result of
The communication method according to appendix 11, wherein the communication path is selected by selecting at least one communication path from the plurality of communication paths based on the node quality information.
(Appendix 16)
The node quality information includes failure information indicating whether a communication failure has occurred in any one of the plurality of relay nodes (5-1, ..., 5-8), and the communication 12. The communication method according to appendix 11, wherein the route is selected by referring to the failure information and selecting at least one communication route not including a relay node in which a communication failure has occurred from the plurality of communication routes.
(Appendix 17)
The node quality information includes the number of illegal data received at any one of the plurality of relay nodes (5-1,..., 5-8). When the number is greater than a predetermined number, at least one communication path that does not include a relay node that transmits data to the relay node having the reception number greater than the predetermined number is selected from the plurality of communication paths. The communication method according to appendix 11.
(Appendix 18)
The communication quality evaluation result includes a fluctuation range of transmission delay time, and the communication path is selected by selecting at least one communication path having a transmission delay time fluctuation width of a predetermined time or less from the plurality of communication paths. The communication method according to appendix 11.

It is a schematic block diagram of the communication system by one Embodiment of this invention. It is a schematic block diagram of the server used by one Embodiment of this invention. It is a figure which shows an example of a path | route information table. It is a figure which shows an example of a node information table. It is a flowchart which shows an example of a route selection procedure. It is a flowchart which shows an example of a route selection procedure. It is a flowchart which shows an example of the procedure which transmits data. It is a flowchart which shows an example of the procedure which receives data. It is a schematic block diagram of the communication system by other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,10 Communication system 2 Server 3 Client host 4 Communication network 5-1, 5-2, ..., 5-8 Relay node 9 Communication path management apparatus 11 Communication path evaluation part 12 Path management part 13 Application processing part 14 Packet Replication / selection unit 141 Replication unit 142 Selection unit 15 IP layer processing unit 16 Packet data transmission / reception unit 17 Storage unit

Claims (3)

A first communication device and a second communication device that transmit and receive data to and from each other;
A communication network having a plurality of communication paths connecting the first communication apparatus and the second communication apparatus, and a plurality of relay nodes for switching a path through which data is transmitted among the plurality of communication paths;
A communication path evaluation unit that acquires node quality information including a ratio of error packets in the number of packet transmission / reception in any one of the plurality of relay nodes;
A path management unit that selects at least one communication path from the plurality of communication paths, and does not include a relay node that transmits data to a relay node in which the ratio of the plurality of relay nodes is higher than a predetermined threshold. ,
The first communication device is a communication system that transmits data to the second communication device via the selected at least one communication path. A communication device that transmits and receives data to and from other communication devices via a communication network having a plurality of communication paths and a plurality of relay nodes that switch among the plurality of communication paths. ,
A communication path evaluation unit that acquires node quality information including a ratio of error packets in the number of packet transmission / reception in any one of the plurality of relay nodes;
A path management unit that selects at least one communication path from the plurality of communication paths, not including a relay node that transmits data to a relay node in which the ratio of the plurality of relay nodes is higher than a predetermined threshold ;
A data transmission unit for transmitting data to the other communication device via the selected at least one communication path;
A communication device. A plurality of communication paths that connect a first communication apparatus and a second communication apparatus that transmit and receive data to each other, and a plurality of relay nodes that switch a path through which data is transmitted among the plurality of communication paths. A communication method for transmitting data via a communication network,
Obtaining node quality information including a ratio of error packets in a packet transmission / reception number in any one of the plurality of relay nodes;
Selecting at least one communication path from the plurality of communication paths, which does not include a relay node that transmits data to a relay node whose ratio among the plurality of relay nodes is higher than a predetermined threshold ;
A communication method including transmitting data to the second communication device via the selected at least one communication path by the first communication device.

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