JP2013201698A - Communication control apparatus, communication control method, and computer program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce deterioration in communication quality in a system that performs multicast distribution.SOLUTION: In a network including a first relay apparatus on an upstream, a second relay apparatus on a downstream, and a plurality of terminal devices, a communication apparatus controls whether the first relay apparatus or the second relay apparatus performs a copy processing for copying data addressed to a multicast address required by the plurality of terminal devices for addressing a partial terminal device of the plurality of terminal devices to relay the data, based on a communication state in the network.

Description

  The present invention relates to a technique for multicast distribution.

  In recent years, the amount of multicast traffic flowing on a network has increased with the enhancement of content and quality improvement in video distribution services. Therefore, there is concern about further consumption of network bandwidth. As a technique for multicast distribution in a network, efficiency is improved by snooping (see, for example, Patent Document 1).

FIG. 9 is a diagram illustrating an outline of a system that performs multicast distribution by snooping. The system shown in FIG. 9 includes a video server 91, a first relay device 92, a second relay device 93, and a plurality of communication devices 94 (94-1 to 94-3). The plurality of communication devices 94 are connected to one VLAN (Virtual Local Area Network).
The video server 91 multicasts video data to a plurality of communication devices 94 via a network. Hereinafter, data distributed by multicast is referred to as multicast data. The first relay device 92 is arranged on the upstream side (video server 91 side) of the second relay device 93 and receives multicast data from the video server 91 via the network. The first relay device 92 transfers the multicast data to the second relay device 93 arranged on the downstream side (communication device 94 side).

  The second relay device 93 stores the port to which the communication device 94 requesting multicast data is connected. When the second relay device 93 receives the multicast data from the first relay device 92, the second relay device 93 determines the port to which the communication device 94 requesting the multicast data is connected (hereinafter referred to as “transfer destination port”), and transfers it. Multicast data is copied according to the number of destination ports. Then, the second relay device 93 transfers the copied multicast data from each transfer destination port to the communication device 94.

JP 2008-153766 A

  In general, a device arranged on the downstream side like the second relay device 93 is often inferior in performance to a device arranged on the upstream side like the first relay device 92. For this reason, when multicast data is copied in the second relay device 93, there is a possibility that the communication performance is deteriorated due to insufficient device performance.

  In view of the above circumstances, an object of the present invention is to provide a technique for reducing a decrease in communication quality in a system that performs multicast distribution.

  One aspect of the present invention is a communication control device connected to a network including a first relay device on the upstream side, a second relay device on the downstream side, and a plurality of terminal devices, and requested by the plurality of terminal devices. Which of the first relay device and the second relay device performs a copy process for copying and relaying data addressed to a multicast address to some of the terminal devices among the plurality of terminal devices, It is a communication control apparatus provided with the control part controlled based on the state of communication in the said network.

  One aspect of the present invention is the communication control device described above, further including a determination unit that determines whether the state in the second relay device is a state that causes a decrease in communication quality, and the control unit includes: When it is determined that the state in the second relay device is a state that causes a reduction in communication quality, the first relay device is caused to execute a part of the copy processing that has been performed by the second relay device until then. .

  One aspect of the present invention is a communication control method in a network including a first relay device on the upstream side, a second relay device on the downstream side, and a plurality of terminal devices, and is requested by the plurality of terminal devices. Which of the first relay device and the second relay device performs copy processing for copying and relaying data destined for a multicast address to a part of the plurality of terminal devices, in the network It is a communication control method which has a control step which controls based on the state of communication.

  One aspect of the present invention is requested by a plurality of terminal devices for a computer connected to a network including a first relay device on the upstream side, a second relay device on the downstream side, and a plurality of terminal devices. Which of the first relay device and the second relay device performs copy processing for copying and relaying data destined for a multicast address to a part of the plurality of terminal devices, in the network It is a computer program for performing the control step controlled based on the state of communication.

  According to the present invention, it is possible to reduce a decrease in communication quality in a system that performs multicast distribution.

It is a system configuration figure showing the system configuration of video distribution system 1 of a first embodiment of the present invention. 2 is a schematic block diagram illustrating a functional configuration of a relay device 102 of the video distribution system 1. FIG. It is a figure showing the specific example of a multicast information table. 6 is a flowchart showing a flow of processing relating to transition processing in the relay apparatus 102; 10 is a flowchart illustrating a processing flow of a transfer destination relay apparatus. It is a system configuration figure showing the system configuration of video distribution system 1a in a second embodiment. It is a schematic block diagram showing the function structure of the management apparatus 104 of the video delivery system 1a. It is a figure showing the specific example of the multicast information table for management. It is a figure which shows the outline of the system which performs multicast delivery by snooping.

[First embodiment]
FIG. 1 is a system configuration diagram showing a system configuration of a video distribution system 1 according to the first embodiment of the present invention. First, an outline of the video distribution system 1 will be described.
The video distribution system 1 includes a video server 101, a plurality of relay devices 102 (102-1, 102-2), and a plurality of communication devices 103 (103-1 to 103-3). The plurality of communication devices 103 are connected to one VLAN.

  The video server 101 multicasts video data to a plurality of communication devices 103 via a network. The relay device 102-1 (corresponding to the first relay device or the second relay device of the present invention and the communication control device) is arranged on the upstream side (video server 101 side) of the relay device 102-2. Multicast data is received from the video server 101 via the network. The relay device 102-1 transfers the multicast data to the relay device 102-2 arranged on the downstream side (communication device 103 side). When the relay device 102-2 (corresponding to the first relay device or the second relay device of the present invention and the communication control device) receives the multicast data from the relay device 102-1, it becomes the destination of the multicast data. Multicast data is transferred to the communication apparatus 103.

  In the video distribution system 1, the copy point is controlled for each combination of the multicast address and the distribution destination communication device 103 according to the communication state in the system. A copy point refers to a device that performs a copy process of data that occurs when one multicast data is converted into a plurality of data (multicast data or unicast data). Conventionally, all the multicast data copy processing is performed by a communication device (for example, the second relay device 93 in FIG. 9) located at the branch point of the communication path. However, in the video distribution system 1, the device (relay device 102-2) located at the branch point of the communication path and the device (relay device 102-1) located upstream from the branch point of the communication path are shared. Perform copy processing. That is, the video distribution system 1 distributes copy points. Therefore, it is possible to prevent the copy processing from concentrating on a specific relay apparatus 102, and to reduce a decrease in communication quality due to insufficient performance of the apparatus.

<Details>
Hereinafter, details of one embodiment of the present invention will be described. FIG. 2 is a schematic block diagram illustrating a functional configuration of the relay apparatus 102 of the video distribution system 1. The relay device 102 includes a CPU (Central Processing Unit), a memory, an auxiliary storage device, and the like connected by a bus, and executes a relay program. The relay device 102 executes the relay program, thereby causing the communication unit 201, the relay unit 202, the copy unit 203, the state determination unit 204, the state information storage unit 205, the transition determination unit 206, the multicast information storage unit 207, and the transition unit 208. It functions as a device provided with. All or some of the functions of the relay apparatus 102 may be realized using hardware such as an application specific integrated circuit (ASIC), a programmable logic device (PLD), or a field programmable gate array (FPGA). The relay program may be recorded on a computer-readable recording medium. The computer-readable recording medium is, for example, a portable medium such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, or a storage device such as a hard disk built in the computer system. The relay program may be transmitted via a telecommunication line.

The communication unit 201 has a function as a network interface, and transmits and receives data to and from a transmission path such as a network.
The relay unit 202 relays data received from a device arranged on the upstream side to a downstream device. Further, the relay unit 202 relays data received from a device arranged on the downstream side to the upstream device.
Further, when receiving the multicast data, the relay unit 202 determines whether to perform the copy process based on the multicast information table stored in the multicast information storage unit 207 and the multicast address of the received multicast data. . If it is determined that the copy process is to be performed, the copy unit 203 is instructed to execute the copy process. Thereafter, the relay unit 202 relays the data generated by the copy process to the downstream apparatus.

The copy unit 203 copies one multicast data to a plurality of data (multicast data or unicast data) according to an instruction received from the relay unit 202.
The state determination unit 204 determines the communication state on the communication path in which the relay device 102 is installed and the state of the own device (relay device 102). The communication state determined by the state determination unit 204 is, for example, a packet loss rate, a communication amount per unit time, a total multicast data amount, and the like. The total multicast data amount represents the total number of combinations of the communication device 103 receiving data addressed to the multicast address and the multicast address. For example, when the communication device 103-1 receives data addressed to two multicast addresses and the communication device 103-2 also receives data addressed to the same two multicast addresses, the total multicast data amount is “4”. It becomes. The state of the own device is, for example, a CPU load factor, a memory usage, and the like.

The state information storage unit 205 is configured using a storage device such as a magnetic hard disk device or a semiconductor storage device. The state information storage unit 205 stores state information (corresponding to the communication state of the present invention). The state information is information representing the determination result of the state determination unit 204.
The transition determination unit 206 stores a transition condition for the state information in advance. The transition condition is a condition for determining whether or not the communication quality is deteriorated. When the transition condition is not satisfied, the transition condition is set so that the communication quality does not deteriorate (even if it occurs, it remains within the allowable range).

  The transition determination unit 206 determines whether or not to perform transition processing based on whether or not the state information (the determination result of the state determination unit 204) stored in the state information storage unit 205 satisfies the transition condition. Hereinafter, a specific example of the migration determination process will be described. For example, the transition determination unit 206 may determine that the transition process is performed when a state where the packet loss rate is equal to or higher than a predetermined value continues for a predetermined time. For example, the transition determination unit 206 may determine to perform the transition process when a state where the communication amount per unit time is equal to or greater than a predetermined value continues for a predetermined time. For example, the migration determination unit 206 may determine to perform the migration process when the total multicast data amount exceeds a predetermined value. For example, the transition determination unit 206 may determine that the transition process is to be performed when a state where the CPU load factor is equal to or greater than a predetermined value continues for a predetermined time. For example, the migration determination unit 206 may determine that the migration process is to be performed when a state where the memory usage is equal to or greater than a predetermined value continues for a predetermined time. Further, the migration determination unit 206 may determine to perform the migration process when a plurality of conditions among the above-described conditions are satisfied.

The multicast information storage unit 207 is configured using a storage device such as a magnetic hard disk device or a semiconductor storage device. The multicast information storage unit 207 stores a multicast information table. The multicast information table is information indicating multicast data that is subject to copy processing of the own device among multicast data in the network to which the own device is connected.
When the migration determination unit 206 determines that the migration process is to be performed, the migration unit 208 executes the migration process with another relay apparatus 102.

  FIG. 3 is a diagram illustrating a specific example of the multicast information table. The multicast information table includes a multicast address, a distribution flag, and a copy point flag that may be requested for each identification information (for example, MAC address) of the communication device 103 that is a request source of multicast data in the network to which the device is connected. Are associated with the record 31. The distribution flag indicates whether or not the communication device 103 indicated by the identification information is requesting data addressed to the multicast address of the record 31. For example, “1” indicates that it is requested, and “0” indicates that it is not requested. The copy point flag indicates whether or not the own device performs a copy process performed when transmitting the multicast data indicated by the multicast address of the record 31 to the communication device 103 indicated by the identification information. For example, “1” indicates that the own device performs copy processing, and “0” indicates that the own device does not perform copy processing.

  When receiving the multicast data, the relay unit 202 refers to the record 31 corresponding to the address (multicast address) of the received multicast data, and searches for the record 31 whose copy point flag is “1”. When there is no record 31 with the copy point flag “1”, the relay unit 202 transfers multicast data to the downstream side without instructing the copy unit 203 to perform copy processing.

  On the other hand, when there is a record 31 whose copy point flag is “1”, the relay unit 202 instructs the copy unit 203 to perform a copy process based on the retrieved record 31. For example, the relay unit 202 instructs the copy unit 203 to generate data addressed to the communication device 103 corresponding to the MAC address of the retrieved record 31. The copy unit 203 executes a copy process in accordance with an instruction from the relay unit 202, and generates data to be transmitted to the MAC address of the retrieved record 31. At this time, when a plurality of records 31 are retrieved, the copy unit 203 executes a copy process according to the number of retrieved records 31.

  FIG. 4 is a flowchart showing a flow of processing relating to the migration processing in the relay apparatus 102. The state determination unit 204 performs state determination when the timing for state determination arrives (step S101—YES, step S102). The state determination unit 204 records the determination result in the state information storage unit 205. In addition, the transition determination unit 206 performs transition determination when the timing for performing transition determination arrives (step S103—YES, step S104). When the transition determination unit 206 determines not to execute the transition process (step S105—NO), the relay device 102 returns to the process of step S101.

  When the migration determination unit 206 determines that the migration process is to be performed (YES in step S105), the migration unit 208 requests the other relay apparatus 102 to migrate the copy process (step S106). If the requested relay device 102 does not accept the migration (NO in step S107), the migration unit 208 determines whether or not there is another relay device 102 (for example, a relay device 102 that has not been requested within a predetermined time). judge. If there is another relay device 102 (YES in step S108), the processing after step S106 is performed on the relay device 102. When there is no other relay apparatus 102 (step S108-NO), the transfer unit 208 determines not to execute the transfer process (step S109). And the relay apparatus 102 returns to the process of step S101.

  In the process of step S107, if the requested relay apparatus 102 has approved the transfer (step S107-YES), the transfer unit 208 performs a transfer process with the relay apparatus 102 that has approved the transfer (step S110). Specifically, it is as follows. First, the migration unit 208 selects the record 31 to be migrated from the multicast information table. For example, the migration unit 208 selects the record 31 with the shortest time after the copy point flag becomes “1” as the target of the migration process. The migration unit 208 notifies the migration destination relay apparatus 102 of the MAC address and multicast address of the selected record 31. Then, the migration unit 208 updates the multicast information table (step S111). Specifically, the migration unit 208 changes the value of the copy point flag of the record 31 that has been subject to migration processing to “0”.

  FIG. 5 is a flowchart showing a flow of processing of the transfer destination relay apparatus 102. When the migration determination unit 206 receives a migration request from another relay device 102 (YES in step S201), the migration determination unit 206 executes a migration acceptance determination process (step S202). The transition acceptance determination process is determined based on whether or not the transition acceptance condition is satisfied. The transfer acceptance condition may be the same as or different from the transfer condition. For example, the predetermined value in the transition acceptance condition may be set higher than the predetermined value in the transition condition. For example, the predetermined time in the transition acceptance condition may be set longer than the predetermined time in the transition condition. In addition, the transition determination unit 206 may estimate the communication state after the transition is made and the state of the own device, and may determine the transition acceptance condition based on the estimation result.

When the transfer acceptance condition is not satisfied (step S203—NO), the transfer unit 208 notifies the transfer-source relay device 102 of transfer rejection (step S204). On the other hand, when the migration acceptance condition is satisfied (step S203—YES), the migration unit 208 notifies the migration relay device 102 of the migration acceptance (step S205). Thereafter, the transfer unit 208 performs transfer processing with the transfer source relay device 102 (step S206). Specifically, it is as follows. First, the transfer unit 208 is notified of the record 31 to be transferred from the transfer source relay device 102. The migration unit 208 searches the multicast information table of its own device for the record 31 corresponding to the notified MAC address and multicast address of the record 31. Then, the migration unit 208 updates the retrieved record 31 (step S207). Specifically, the migration unit 208 changes the value of the copy point flag of the record 31 that has been subject to migration processing to “1”.
In the video distribution system 1 configured as described above, it is possible to reduce a decrease in communication quality when performing multicast distribution. Specifically, it is as follows.

  In the video distribution system 1, the transition conditions are set so that the communication quality does not deteriorate in each relay device 102 (even if it occurs, it remains within the allowable range). When the transfer condition is satisfied, that is, when there is a possibility that the communication quality is deteriorated (exceeding the allowable range), part or all of the copy processing is transferred to another relay apparatus 102. Then, the copy process is shared so that any relay apparatus 102 does not satisfy the migration condition. For this reason, it is possible to reduce the deterioration of communication quality due to the burden of copy processing in multicast communication.

<Modification>
In the video distribution system 1, the data distributed by multicast need not be limited to video data.
The system configuration shown in FIG. 1 is only an example. The system configuration of the video distribution system 1 is not limited to the configuration shown in FIG. For example, a plurality of relay devices 102 may be connected downstream of the relay device 102.
If the transfer destination relay device 102 does not satisfy the transfer conditions even if all of the copy processing is performed with only one device, the transfer processing is not performed by a plurality of relay devices 102 but is transferred to the transfer destination relay device 102. All copy processing may be executed only by the above.

  If the migration condition is not satisfied in the migration source relay apparatus 102 after the copy process is migrated, the migration unit 208 of the migration source relay apparatus 102 performs the copy process on the migration destination relay apparatus 102. You may notify that transfer is canceled. In this case, the migration unit 208 of the migration destination relay device 102 may perform a process of returning the copy process that has undergone migration from the migration source relay device 102 to the migration source relay device 102. Specifically, a process of returning the value of the copy point flag of the record 31 that is the transfer target recorded in each relay apparatus 102 before the transfer is performed.

[Second Embodiment]
FIG. 6 is a system configuration diagram showing a system configuration of the video distribution system 1a in the second embodiment. The video distribution system 1a is different from the video distribution system 1 (first embodiment) in that it further includes a management device 104 (corresponding to the communication control device of the present invention), and other configurations are the same.

  FIG. 7 is a schematic block diagram showing a functional configuration of the management apparatus 104 of the video distribution system 1a. The management device 104 includes a CPU, a memory, an auxiliary storage device, and the like connected by a bus, and executes a management program. The management device 104 functions as a device including a communication unit 401, a status information collection unit 402, a status information storage unit 403, a migration determination unit 404, and a multicast information storage unit 405 by executing a management program. All or some of the functions of the management device 104 may be realized using hardware such as an ASIC, PLD, or FPGA. The management program may be recorded on a computer-readable recording medium. The computer-readable recording medium is, for example, a portable medium such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, or a storage device such as a hard disk built in the computer system. The relay program may be transmitted via a telecommunication line.

The communication unit 401 has a function as a network interface, and transmits and receives data to and from a transmission path such as a network.
The status information collection unit 402 collects status information from each relay device 102. For example, the status information collection unit 402 may collect the status information of each relay device 102 by receiving the status information transmitted by the status determination unit 204 of each relay device 102. The status information collection unit 402 records the collected status information in the status information storage unit 403.

The state information storage unit 403 is configured using a storage device such as a magnetic hard disk device or a semiconductor storage device. The status information storage unit 403 stores the status information of each relay apparatus 102 collected by the status information storage unit 403.
The transition determination unit 404 stores a transition condition for the state information in advance. The transition determination unit 404 determines whether or not to perform transition processing based on whether or not the state information of each relay apparatus 102 stored in the state information storage unit 403 satisfies the transition condition. When the migration determination unit 404 determines to perform migration processing, the migration determination unit 404 determines the relay device 102 that is the migration destination. Then, the migration determination unit 404 instructs the migration source relay device 102 and the migration destination relay device 102 to execute the migration process.

  The multicast information storage unit 405 is configured using a storage device such as a magnetic hard disk device or a semiconductor storage device. The multicast information storage unit 405 stores a management multicast information table. The management multicast information table is information indicating the multicast data to be copied by each relay apparatus 102 among the multicast data in the network to which the own apparatus is connected.

  FIG. 8 is a diagram illustrating a specific example of the management multicast information table. The management multicast information table is different from the multicast information table in that it has a copy point ID instead of a copy point flag, and the other configurations are the same. The copy point ID is information representing the relay apparatus 102 that performs the copy process corresponding to the record.

  Hereinafter, a specific example of the migration determination process performed by the migration determination unit 404 will be described. For example, when the transition determination unit 404 determines that a transition condition is satisfied for a certain relay apparatus 102, the transition determination unit 404 determines whether there is a relay apparatus 102 that can be a transition destination. At this time, the migration determination unit 404 performs a migration acceptance determination process for each relay device 102 other than the relay device 102 (migration source) that satisfies the migration condition, for example. If it is determined that a certain relay device 102 can be migrated, the migration determination unit 404 selects the relay device 102 as a migration destination. Thereafter, the migration determination unit 404 selects the record 32 to be migrated and instructs the migration source relay device 102 to execute the migration process. For example, the migration determination unit 404 selects the record 32 having the shortest time after the copy point ID becomes the ID of the migration source relay device 102 as the migration process target.

  When the transfer unit 208 of each relay apparatus 102 receives a transfer instruction from the management apparatus 104, the transfer unit 208 performs a transfer process according to the received transfer instruction. When the migration process is completed, the migration unit 208 notifies the management apparatus 104 that the migration process has been completed. Upon receiving notification of completion from both the transfer source relay device 102 and the transfer destination relay device 102, the transfer determination unit 404 of the management device 104 updates the multicast information table. Specifically, the copy point ID of the record 32 to be transferred is changed from the ID of the transfer source relay device 102 to the ID of the transfer destination relay device 102.

Also in the video distribution system 1a of the second embodiment configured as described above, it is possible to obtain the same effects as the video distribution system 1 of the first embodiment.
In the video distribution system 1a of the second embodiment, the management device 104 determines the transfer source relay device 102 and the transfer destination relay device 102. Therefore, unlike the video distribution system 1 of the first embodiment, it is possible to reduce communication between the relay apparatuses 102 that occurs when determining the migration destination.

<Modification>
The video distribution system 1a of the second embodiment may be modified and configured in the same manner as the first embodiment.
The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1, 1a ... Video delivery system, 102-1, 102-2 ... Relay apparatus, 103-1 to 103-3 ... Communication apparatus, 104 ... Management apparatus, 201 ... Communication part, 202 ... Relay part, 203 ... Copy part, 204 ... state determination unit, 205 ... state information storage unit, 206 ... transition determination unit, 207 ... multicast information storage unit, 208 ... transition unit, 401 ... communication unit, 402 ... state information collection unit, 403 ... state information storage unit, 404 ... migration determination unit, 405 ... multicast information storage unit

Claims (4)

A communication control device connected to a network including a first relay device on the upstream side, a second relay device on the downstream side, and a plurality of terminal devices,
Copy processing for copying and relaying data addressed to a multicast address requested by the plurality of terminal devices to some terminal devices among the plurality of terminal devices, the first relay device and the second relay device A communication control device comprising a control unit that controls which one of the above is performed based on the state of communication in the network. A determination unit for determining whether or not the state in the second relay device is a state that causes a decrease in communication quality;
When it is determined that the state in the second relay device is a state that causes a decrease in communication quality, the control unit performs a part of the copy processing that has been performed by the second relay device up to the first time. The communication control apparatus according to claim 1, which is executed by one relay apparatus. A communication control method in a network including an upstream first relay device, a downstream second relay device, and a plurality of terminal devices,
Copy processing for copying and relaying data addressed to a multicast address requested by the plurality of terminal devices to some terminal devices among the plurality of terminal devices, the first relay device and the second relay device The communication control method which has a control step which controls which is performed based on the state of communication in the said network. For a computer connected to a network including a first relay device on the upstream side, a second relay device on the downstream side, and a plurality of terminal devices,
Copy processing for copying and relaying data addressed to a multicast address requested by the plurality of terminal devices to some terminal devices among the plurality of terminal devices, the first relay device and the second relay device A computer program for executing a control step for controlling which one of the above is performed based on the state of communication in the network.

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