JP5784139B2 - Communications system - Google Patents

Description

  The present invention relates to a communication system.

  With the increase in communication capacity and the diversification of services provided by communication, carrier service networks and corporate infrastructure are required to have high reliability and communication quality. In such a communication infrastructure, in recent years, adoption of packet communication technology is being studied from the viewpoint of development cost and introduction of a high-performance communication device, reduction of operation cost, and the like.

  However, in the connectionless communication method using the packet communication technology, the time until a packet transmitted from a certain device arrives at the destination device via the relay device is not constant, and it depends on the line condition on the passage route and the device load. There is a possibility that a frame is discarded or a significant delay occurs, and there is a case where the quality of product is lower than the case where the synchronous transmission method is used.

  In order to avoid this, a communication path for the active system and the standby system is set between the transmission apparatus and the destination apparatus, and a control packet for confirming connectivity is periodically transmitted to the communication path of the active system, Ethernet (registered trademark) technology that determines that a failure occurs in the active communication path and switches the data communication path to the standby system when the reception interval exceeds a predetermined interval (for example, 3.5 times the transmission interval). An Ethernet network linear protection switching technique based on this is known (for example, see Non-Patent Document 1).

ITU-T Recommendation G.8031 / Y.1342

  By the way, in the technique of Non-Patent Document 1, when a control packet for confirming connectivity is received, a time difference between the reception time and the reception time of the control packet received immediately before the control packet is determined in advance. Compared to the time (for example, 3.5 times the transmission interval), if the time difference is greater than or equal to the allowable time, the path switching from the active system to the standby system is executed. Route switching is not performed.

  However, in this case, if the control packet received immediately before has already been delayed, the path switching is determined based on the time difference from the delayed control packet, so the timing at which the control packet should actually be received If the elapsed time from the reception time of the immediately preceding control packet is less than the allowable time, the path switching is not executed even if it is considerably delayed. If a plurality of control packets are delayed little by little, the delay time accumulates, and the amount of delay from the timing at which the control packet should actually be received further increases.

  In the case of communication data such as a voice call in which the amount of data transmitted per unit time is not so large, the effect of the missing or delayed data packet on the quality of service is not so great. However, due to the increase in communication capacity, the amount of data transmitted per unit time has increased, and the amount of data stored in one data packet has also increased. The impact on the world is growing.

  In particular, in video streaming that handles a large amount of data and streaming of music content that requires continuity of rhythm, the deterioration of the service essence due to missing or delayed data packets is easy for the user to understand, so the influence on the service is particularly large.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to suppress degradation of service quality due to a delay of a data packet in packet communication.

In order to solve the above problems, for example, the configuration described in the claims is adopted.
The present application includes a plurality of means for solving the above-described problems. For example, when congestion occurs in the active communication path, a data packet communication path is prepared in advance. A communication system for switching to a standby communication path,
A first communication control device;
A second communication control device connected to the first communication control device via the communication paths of the active system and the standby system,
The first communication control device includes:
A data transmission unit for transmitting a data packet including user data to the second communication control device via either the active or standby communication path and the active and standby communication paths in advance. A control packet transmitter for transmitting the same control packet to the second communication control device at a determined timing;
A path switching instruction unit that instructs the data transmission unit to switch the communication path of the data bucket from the active system to the standby system when a path switching request is received from the second communication control device;
The second communication control device includes:
A time difference measuring unit for measuring a time difference from a reception time of the control packet received via the standby communication path to a reception time of the same control packet received via the active communication path, and the time difference measuring unit A path switching request unit configured to transmit a path switching request to the first communication control device when the measured time difference is equal to or greater than a predetermined first threshold value;

According to the communication system of the present invention, it is possible to suppress degradation of service quality due to a delay of a data packet in packet communication.
Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

1 is a system configuration diagram illustrating an example of a configuration of a communication system 10 according to an embodiment of the present invention. 3 is a block diagram illustrating an example of a detailed functional configuration of a communication control device 20. FIG. It is a figure which shows an example of the data structure of the transmission route table 220 stored in transmission route DB22. It is a figure which shows an example of the data structure of the delay table 240 stored in delay DB24. It is a figure which shows an example of the data structure of the route classification table 260 stored in route classification DB26. It is a figure which shows an example of the data structure of the switching threshold value table 280 stored in threshold value DB28. It is a figure which shows an example of the data structure of the switchback threshold value table 285 stored in threshold value DB28. It is a figure which shows an example of the data structure of the control packet 40 for delay measurement. 6 is a diagram illustrating an example of a data structure of a measurement result report packet 41. FIG. It is a figure which shows an example of the data structure of the control packet 42 for switching determination. 4 is a diagram illustrating an example of a data structure of a user data packet 43. FIG. 6 is a diagram illustrating an example of a data structure of a switching request packet 44. FIG. 6 is a diagram illustrating an example of a data structure of a switching response packet 45. FIG. 6 is a diagram illustrating an example of a data structure of a switch completion notification packet 46. FIG. It is a figure which shows an example of the data structure of the switchback request packet 47. It is a figure which shows an example of the data structure of the switchback response packet. It is a figure which shows an example of the data structure of the switchback completion notification packet 49. It is a flowchart which shows an example of the measurement operation | movement of the transmission time difference of the active system and a backup system communication path. It is a flowchart which shows an example of the switching operation | movement of the communication control apparatus 20 of the receiving side in 1st Embodiment. It is a flowchart which shows an example of the switching operation | movement of the communication control apparatus 20 of a transmission side. It is a flowchart which shows an example of the switch-back operation | movement of the communication control apparatus 20 of the receiving side. It is a flowchart which shows an example of the switch-back operation | movement of the communication control apparatus 20 of a transmission side. 3 is a block diagram illustrating an example of a detailed functional configuration of a relay device 30. FIG. It is a figure which shows an example of the data structure of the transmission destination table 340 stored in transmission destination DB34. 4 is a diagram illustrating an example of a data structure of a warning packet 50. FIG. 5 is a flowchart illustrating an example of the operation of the relay device 30. It is a flowchart which shows an example of the switching operation | movement of the communication control apparatus 20 of the receiving side in 2nd Embodiment.

  First, a first embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a system configuration diagram illustrating an example of a configuration of a communication system 10 according to an embodiment of the present invention. The communication system 10 includes a plurality of communication control devices 20. Each communication control device 20 is connected to a communication device 14 such as a user terminal or a server via an access network 13. Each communication control device 20 is connected to another communication control device 20 via a backbone network 12 having a plurality of relay devices 30. In the present embodiment, the backbone network 12 is a packet switching network, but may be a frame switching network or the like as long as it is a storage switching system.

  For each of the two communication control devices 20 in the communication system 10, the management device 11 presets the active and standby communication paths for each of the transmission and reception communication paths, and sets necessary information (for example, communication The VLAN ID for identifying the route, the transfer destination of the data packet, etc.) are set in the communication control device 20 and the relay device 30, respectively.

  In the example illustrated in FIG. 1, among the plurality of communication control devices 20 included in the communication system 10, data packets are transmitted via the relay devices 30 for the communication control device 20-1 and the communication control device 20-2. -1 schematically shows that the active communication path (solid arrow) and the standby communication path (broken arrow) are set in advance in the direction transmitted from -1 to the communication control apparatus 20-2.

  In the following, taking the system configuration of FIG. 1 as an example, when the communication control device 20-2 on the receiving side detects an increase in the delay of the data packet transmitted via the active communication path, communication control on the transmitting side is performed. A process in which the device 20-1 switches the data packet transmission path from the active system to the standby system will be described.

  FIG. 2 is a block diagram illustrating an example of a detailed functional configuration of the communication control device 20. The communication control device 20 includes a data transmission / reception unit 21, a transmission route DB 22, a route switching instruction unit 23, a delay DB 24, a control packet transmission unit 25, a route type DB 26, a time difference measurement unit 27, a threshold value DB 28, and a route switching request unit 29. .

  For example, a transmission route table 220 as shown in FIG. 3 is stored in the transmission route DB 22. In the transmission route table 220, a route indicating the type of communication route to which a user data packet including the data is to be sent in association with the service ID 221 for identifying each service provided by the data transmitted / received by the communication device 14 The type 222 and the service level 223 indicating the degree of short delay time allowed in the service are stored. “W” described in the column of the service level 223 indicates that it is an active communication path, and “P” indicates that it is a standby communication path.

  In the transmission route table 220 illustrated in FIG. 3, information on the service ID 221 and the service level 223 is set in advance, and when a data packet including data for actually providing the corresponding service is transmitted, the data The type of the communication path through which the packet is transmitted is stored in the path type 222. Also, the transmission path table 220 illustrated in FIG. 3 is provided in the transmission path DB 22 for each other communication control apparatus 20 to which the communication packet is transmitted.

  Here, the service includes, for example, high-quality video streaming, low-quality video streaming, voice call, and best-effort data communication. In addition, for example, in a service such as high-quality video streaming, the amount of data per unit time is large, and the long-term data cannot be stored in the communication device 14 on the receiving side. For example, the service level is 1, for example.

  In addition, in a service such as low-quality video streaming, the amount of data per unit time is not so large, and a relatively long time can be stored in the communication device 14 on the receiving side. Can take longer than high-quality video streaming. However, since the video is interrupted if it is too long, it is shorter than a service such as a voice call. For example, the service level is 2.

  In a service such as a voice call, the amount of data per unit time is small, but it is necessary to suppress the delay to such an extent that a conversation can be established. Further, in a service such as best-effort data communication, there are even fewer restrictions on delay compared to the other services described above, and the service level is, for example, 4.

  For example, a delay table 240 as shown in FIG. 4 is stored in the delay DB 24. The delay table 240 includes a reference VLAN ID 242 that identifies a standby communication path that transmits a control packet serving as a delay amount calculation reference in association with the VLAN ID 241 that identifies each active communication path, and the standby system. A delay amount 243 indicating a time difference until the same control packet is received via the working communication path is stored with reference to the reception time of the control packet received via the communication path.

  For example, the delay amount 243 in the first row of the delay table 240 in FIG. 4 indicates that the control packet received via the active communication path with the VLAN ID 241 “V001” indicates the standby communication path with the reference VLAN ID 242 “V002”. It shows that the communication control device 20 on the receiving side has been reached with a delay of 2 milliseconds with reference to the reception time of the control packet received via the network.

  Further, for example, the delay amount 243 in the second row of the delay table 240 in FIG. 4 indicates that the control packet received via the active communication path with the VLAN ID 241 “V003” is the standby packet with the reference VLAN ID 242 “V004”. This shows that the communication control device 20 on the receiving side has been reached one millisecond earlier with reference to the reception time of the control packet received via the communication path.

  In the route type DB 26, for example, a route type table 260 as shown in FIG. 5 is stored. The route type table 260 stores the type of the communication route in association with the VLAN ID 261 for identifying each communication route. Note that the route type table 260 illustrated in FIG. 5 is provided in the route type DB 26 for each other communication control device 20 to which the communication packet is transmitted.

  The threshold DB 28 stores a switching threshold table 280 as shown in FIG. 6, for example, and a switchback threshold table 285 as shown in FIG. 7, for example. In the switching threshold table 280, the communication path of the data packet including the data for providing the service is associated with the switching threshold 281 indicating the threshold of the time difference for switching from the active system to the standby system. In this case, the service level 282 of the service for switching from the active system to the standby system is stored.

  This time difference means that the reception side communication control device 20 receives the same control packet via the working communication path from the reception time when a specific control packet, which will be described later, is received via the standby communication path. The time difference until. The switching threshold value at each service level is determined in advance based on an allowable range of delay time required for each service included in each service level, and is set in each communication control device 20 by the management device 11, for example.

  The switchback threshold table 285 includes a time difference threshold for switching the communication path of a data packet including data for providing a service from the active system to the standby system and then switching back from the standby system to the active system. The service level 287 of the service for switching back from the standby system to the active system when the time difference is less than the switchback threshold 286 is stored.

  Note that the backbone network 12 is normally designed to continue to use the working communication path, and if there is no problem in service quality, it may be preferable to continue to use the working system as much as possible in terms of operation. Many. Therefore, the communication path is switched back from the standby system to the active system when the difference between the delay times of the active system and the standby system is reduced.

  However, if the switchback threshold is set too long, the possibility of switching again immediately after switching back increases, and unnecessary traffic generated in the backbone network 12 due to switching or switchback increases. The switchback threshold is preferably sufficiently shorter than the switching threshold (for example, about half of the switching threshold).

  Returning to FIG. 2, the description will be continued. The control packet transmitter 25 creates two control packets 40 for delay measurement having a data structure as shown in FIG. 8, for example, at a predetermined timing (for example, a timing instructed from the management apparatus 11). The control packet 40 includes a header 400 and a payload 401. The payload 401 includes a message ID 402, a VLAN ID 403, a sequence number 404, and a transmission time 405.

  In the created two control packets 40, the control packet transmitter 25 stores information indicating that the control packet 40 is a delay measurement control packet 40 in the message ID 402, and assigns the same numerical value to the sequence number 404. Store. Then, the control packet transmission unit 25 refers to the route type DB 26, stores the identification information of the active communication route in the VLAN ID 403 of one control packet 40, and the standby communication route in the VLAN ID 403 of the other control packet 40. The identification information of is stored.

  Then, the control packet transmitter 25 sets the current time to the transmission time 405 of one control packet 40 and transmits it to the communication control device 20 via the active communication path, and the transmission time 405 of the other control packet 40. Is set to the current time and transmitted to the communication control apparatus 20 via the standby communication path. In addition, if the time at the time of transmission of each control packet 40 is set to each transmission time 405, the time information set to the transmission time 405 of two control packets 40 may not be the same value. .

  The control packet transmitter 25 repeats the process of sending the delay measurement control packet 40 with the same sequence number to both the active and standby communication paths a plurality of times at predetermined time intervals (for example, every 100 milliseconds). . Then, the control packet transmitter 25 receives the measurement result report packet 41 as shown in FIG. 9 from the communication control device 20 that is the transmission destination of the control packet 40 for delay measurement. The measurement result report packet 41 includes a header 410 and a payload 411. The payload 411 includes a message ID 412, a VLAN ID 413, a VLAN ID 414, and a measurement result 415.

  The message ID 412 stores information indicating that the measurement result report packet 41 is a measurement result report packet. The VLANID 413 stores identification information of the active communication path that is a delay time measurement target. The VLAN ID 414 stores identification information of a standby communication path that is a measurement standard for delay time. The measurement result 415 includes the current communication path from the reception time when the communication control apparatus 20 that has transmitted the measurement result report packet 41 receives the delay measurement control packet 40 via the standby communication path. The time difference until the control packet 40 for delay measurement having the same sequence number is received is stored.

  When the measurement result report packet 41 is received, the control packet transmission unit 25 sets the VLAN ID 413 included in the measurement result report packet 41 as the VLAN ID 241 and the VLAN ID 414 included in the measurement result report packet 41 as the reference VLAN ID 242. 41 is stored in the delay table 240 in the delay DB 24 as the delay amount 243.

  The delay measurement control packet 40 and the measurement result report packet 41 are, for example, ITU-TY. It can be configured based on the format of a VSM (Vendor Specific Message) frame or an APS (Automatic Protection Switching) frame defined in 1731.

  Next, the control packet transmitter 25 creates two control packets 42 for data structure switching determination as shown in FIG. 10, for example. The control packet 42 includes a header 420 and a payload 421. The payload 421 includes a message ID 422, a VLAN ID 423, a sequence number 424, and service information 425.

  In the generated two control packets 42, the control packet transmitter 25 stores information indicating that the control packet 42 is a switching determination control packet 42 in the message ID 422, and the sequence number 424 has the same numerical value. The service information 425 stores service ID, route type, and service level information 426 for values for which the route type is set in the transmission route table 220. Note that the service information 425 only needs to be included in at least one of the two created control packets 42.

  Then, the control packet transmission unit 25 refers to the route type DB 26, stores the identification information of the active communication route in the VLANID 423 of one control packet 42, and the standby communication route in the VLANID 423 of the other control packet 42. The identification information of is stored.

  The control packet 42 is, for example, ITU-T Y. A CCM (Continuity Check Message) frame format defined in 1731 can be used as a base.

  Next, the control packet transmitting unit 25 refers to the delay table 240 of the delay DB 24 based on the identification information of the active communication path set in the VLAN ID 423, and the delay amount associated with the active VLAN ID. To extract.

  When the extracted delay amount is a positive value (that is, when the delay of the working communication path is larger than that of the standby communication path), the control packet transmitting unit 25 should transmit the control packet 42 The control packet 42 having the identification information of the active communication path in the VLAN ID 423 is transmitted to the communication control apparatus 20 via the active communication path at a timing before the extracted delay amount. At the timing when the packet 42 should be transmitted, the control packet 42 having the identification information of the standby communication path in the VLAN ID 423 is transmitted to the communication control apparatus 20 via the standby communication path.

  On the other hand, when the extracted delay amount is a negative value (that is, when the delay of the working communication path is smaller than that of the standby communication path), the control packet transmitting unit 25 transmits the control packet 42. The control packet 42 having the identification information of the active communication path in the VLAN ID 423 is transmitted to the communication control apparatus 20 via the active communication path at a timing after the extracted delay amount. At a timing when the control packet 42 is to be transmitted, the control packet 42 having the identification information of the standby communication path in the VLAN ID 423 is transmitted to the communication control apparatus 20 via the standby communication path.

  As a result, the switching determination control packet 42 having the same sequence number transmitted through each of the active communication path and the standby communication path has no congestion in any communication path. Are received by the communication control device 20 on the receiving side at substantially the same timing. In order to accurately match the reception timing in the communication controller 20 on the receiving side when congestion does not occur, the difference in transmission time between the active communication path and the standby communication path is measured by the backbone network 12. It is preferable to be executed in a time zone (for example, late at night or tomorrow) where there is a low possibility that congestion is occurring.

  The control packet transmitter 25 transmits the switching determination control packet 42 having the same sequence number whose transmission timing is adjusted every predetermined time (for example, every 100 milliseconds).

  When the data transmission / reception unit 21 receives user data from the communication device 14 via the access network 13, the data transmission / reception unit 21 refers to the transmission path DB 22 and connects the communication device 14 that is the destination of the user data to the communication control device 20. The transmission route table 220 is specified. Then, the data transmission / reception unit 21 refers to the identified transmission route table 220 and identifies the route type associated with the service ID of the service provided by the user data. Then, the data transmitting / receiving unit 21 refers to the route type table 260 in the route type DB 26 and specifies the VLAN ID corresponding to the specified route type as identification information of the communication route to which user data is to be transmitted.

  When the service provision ends, the data transmission / reception unit 21 deletes the route type associated with the service ID of the service from the transmission route table 220, and therefore starts providing the service using the user data. In the transmission route table 220, the data transmitting / receiving unit 21 associates the service ID of the service with the route type indicating the active system.

  Then, the data transmission / reception unit 21 creates a user data packet 43 as shown in FIG. 11, for example. The user data packet 43 includes a header 430 and a payload 431, and the payload 431 stores user data. In the header 430, the DA 432 indicating the address of the communication control device 20 that is the destination of the user data packet 43, the SA 433 indicating the address of the communication control device 20 that is the transmission source of the user data packet 43, and the user data packet 43 are transmitted. A VLAN ID 434 of the communication path, a sequence number 435 for uniquely identifying the user data packet 43, and a service ID 436 of a service provided by data included in the user data packet 43 are stored.

  Then, when the route type of the communication path to which the created user data packet 43 is to be transmitted is the working system, the data transmitting / receiving unit 21 refers to the delay table 240 of the delay DB 24 and identifies the working communication path. The delay amount associated with the information is extracted.

  When the extracted delay amount is a positive value, the data transmitting / receiving unit 21 transmits the created measurement result report packet 41 at the timing before the timing to transmit the time of the extracted delay amount. It transmits to the communication control apparatus 20 via a path | route.

  On the other hand, when the extracted delay amount is a negative value, the data transmitting / receiving unit 21 transmits the created measurement result report packet 41 at the timing after the extracted delay amount by a time after the timing to transmit. To the communication control apparatus 20 via the communication path.

  In addition, when the data transmission / reception unit 21 is instructed to start double transmission together with the service ID from the path switching instruction unit 23, the data transmission / reception unit 21 transmits the user data packet including the corresponding service ID in the header to both the active and standby systems. It transmits to the other communication control apparatus 20 via a path | route.

  When the dual switching end is instructed together with the service ID and VLAN ID from the path switching instruction unit 23, the data transmission / reception unit 21 is a user data packet including the corresponding service ID in the header, and the active system and the standby system Of the user data packets that have been transmitted through both communication paths, the transmission of the user data packet through the communication path corresponding to the instructed VLAN ID is stopped.

  When the time difference measuring unit 27 receives the control packet 40 for delay measurement shown in FIG. 8 from the other communication control device 20 facing each other through the communication paths of the active system and the standby system, the time difference measuring unit 27 From the transmission time of the delay measurement control packet 40 via the communication path, measurement of the time difference of the transmission time of the delay measurement control packet 40 via the active communication path is started. At this time, the time difference measuring unit 27 sets a time obtained by subtracting the transmission time 405 in the control packet 40 from the reception time of the control packet 40 for delay measurement as the transmission time of the communication path.

  Then, the time difference measuring unit 27 calculates an average of time differences measured for a set of a predetermined number (for example, 100) of delay control packets 40 as a measurement result. Then, the time difference measuring unit 27 creates a measurement result report packet 41 (see FIG. 9) including the calculated measurement result, and uses the created measurement result report packet 41 as the communication control of the transmission source of the control packet 40 for delay measurement. For example, the data is transmitted to the apparatus 20 via a standby communication path.

  In addition, when the time difference measuring unit 27 receives the control packet 42 for switching determination shown in FIG. 10 via the communication paths of the active system and the standby system, the time difference measuring unit 27 determines the switching via the communication path of the standby system. The time difference from the reception time at which the control packet 42 is received until the control packet 42 for switching determination is received through the active communication path is measured. Then, the time difference measurement unit 27 transmits the measurement result to the route switching request unit 29 together with the service information included in the control packet 42 for switching determination.

  When the path switching request unit 29 receives the measurement result of the time difference from the time difference measuring unit 27, the path switching request unit 29 refers to the switching threshold table 280 in the threshold DB 28, and at least the time difference indicated by the measurement result is stored in the switching threshold table 280. It is determined whether or not any switching threshold is exceeded.

  When it is at least one of the switching thresholds or more, the path switching request unit 29 extracts the service level associated with the maximum switching threshold among the corresponding switching thresholds from the switching threshold table 280. Then, the route switching request unit 29 further extracts a service level associated with the active route type in the service information received from the time difference measuring unit 27 from the extracted service levels.

  The service information received from the time difference measuring unit 27 includes the service level associated with the active route type. This means that the user data packet of that service level is transmitted via the active communication route. Means that it has been sent. If the service information received from the time difference measuring unit 27 does not include a service level associated with the active route type, a user data packet of that service level is transmitted via the standby communication route. It means that

  Next, the path switching request unit 29 creates a switching request packet 44 as shown in FIG. 12, for example, and sends the created switching request packet 44 to the communication control apparatus 20 that is the transmission source of the control packet 42 for switching determination. For example, transmission is performed via a standby communication path. Here, for example, as shown in FIG. 12, the switching request packet 44 includes a header 440 and a payload 441. The payload 441 includes a message ID 442 indicating that the packet is a switching request packet, and a switching threshold table. The service level 443 extracted with reference to 280 is stored.

  Next, after transmitting the switching request packet 44, the path switching request unit 29 receives a switching response packet 45 as shown in FIG. 13 from the communication control apparatus 20 that is the transmission destination of the switching request packet 44, for example. For example, as shown in FIG. 13, the switching response packet 45 includes a header 450 and a payload 451. The payload 451 includes a message ID 452 indicating that the packet is a switching response packet, and a service to be switched. Of the service ID 453 is stored.

  When the switching response packet 45 is received, the path switching request unit 29 receives the user data packet 43 (see FIG. 11) including the service ID specified by the service ID 453 of the switching response packet 45 in the header, as the active system and the standby system. Are received via respective communication paths. Then, the path switching request unit 29 is a user data packet 43 that includes the specified service ID in the header, and the user data packet 43 that includes the same sequence number in the header. It is determined whether or not the payload 431 of the user data packet 43 received via the ID matches.

  When the data of a set of user data packets 43 having the same sequence number received via the communication paths of the active system and the standby system are continuously matched by a predetermined number (for example, 100 packets), a path switching request unit 29 creates a switching completion notification packet 46 as shown in FIG. 14, for example, and transmits the created switching completion notification packet 46 to the communication control device 20 that is the transmission source of the user data packet 43.

  For example, as shown in FIG. 14, the switching completion notification packet 46 includes a header 460 and a payload 461. The payload 461 includes a message ID 462 indicating that the packet is a switching completion notification packet, and a switching target. The service ID 463 of the service to be stored is stored.

  When the path switching request unit 29 receives the time difference measurement result from the time difference measurement unit 27, the path switching request unit 29 refers to the switchback threshold value table 285 in the threshold value DB 28 and stores the time difference indicated by the measurement result in the switchback threshold value table 285. It is determined whether or not it is less than at least one of the switchback thresholds.

  If it is less than at least one of the switchback thresholds, the path switching request unit 29 extracts the service level associated with the maximum switchback threshold among the switchback thresholds from the switchback threshold table 285. To do. Then, the route switching request unit 29 further extracts a service level associated with the standby route type in the service information received from the time difference measuring unit 27 from the extracted service levels.

  Next, the path switching request unit 29 creates a switchback request packet 47 as shown in FIG. 15, for example, and uses the created switchback request packet 47 as a communication control device 20 that is a transmission source of the control packet 42 for switching determination. For example, via a standby communication path. Here, for example, as shown in FIG. 15, the return request packet 47 includes a header 470 and a payload 471. The payload 471 includes a message ID 472 indicating that the packet is a return request packet, and a return ID. The service level 473 extracted with reference to the return threshold table 285 is stored.

  Next, after transmitting the switch-back request packet 47, the path switching request unit 29 receives a switch-back response packet 48 as shown in FIG. 16, for example, from the destination communication control apparatus 20 of the switch-back request packet 47. For example, as shown in FIG. 16, the return response packet 48 includes a header 480 and a payload 481. The payload 481 includes a message ID 482 indicating that the packet is a return response packet, and an object to be returned. The service ID 483 of the service to be stored is stored.

  When the switchback response packet 48 is received, the path switching request unit 29 receives the user data packet 43 (see FIG. 11) including the service ID specified by the service ID 483 of the switchback response packet 48 in the header, Receive via each communication path of the backup system. Then, the path switching request unit 29 is a user data packet 43 including the specified service ID in the header, and the user data packet 43 having the same sequence number is transmitted through the communication paths of the active system and the standby system. It is then determined whether the data of the received user data packet 43 matches.

  When the data of a set of user data packets 43 having the same sequence number received via the communication paths of the active system and the standby system are continuously matched by a predetermined number (for example, 100 packets), a path switching request unit 29 creates a fail-back completion notification packet 49 as shown in FIG. 17, for example, and sends the created fail-back completion notification packet 49 to the communication control device 20 that is the transmission source of the user data packet 43.

  For example, as shown in FIG. 17, the switchback completion notification packet 49 includes a header 490 and a payload 491. The payload 491 includes a message ID 492 indicating that the packet is a switchback completion notification packet, and a switchback. The service ID 493 of the service that is the target of the service is stored.

  Note that the switch request packet 44, the switch response packet 45, the switch completion notification packet 46, the switchback request packet 47, the switchback response packet 48, and the switchback completion notification packet 49 are, for example, ITU-T Y. It can be configured based on the format of a VSM (Vendor Specific Message) frame or an APS (Automatic Protection Switching) frame defined in 1731.

  Returning to FIG. 2, the description will be continued. When receiving the switching request packet 44 illustrated in FIG. 12, the path switching instruction unit 23 refers to the transmission path table 220 in the transmission path DB 22 and corresponds to the service level included in the received switching request packet 44. A service ID associated with the active route type is extracted.

  If there are a plurality of corresponding service IDs, the service ID with the highest associated service level (the lowest service level value) is extracted. If a plurality of service IDs are still extracted, the service ID of the service with the highest priority is extracted from the service IDs according to a predetermined priority for each service.

  Then, the path switching instruction unit 23 instructs the data transmission / reception unit 21 to start double transmission together with the extracted service ID. Then, the path switching instruction unit 23 transmits a switching response packet 45 (see FIG. 13) including the service ID to the communication control device 20 that is the transmission source of the switching request packet 44 via, for example, a standby communication path.

  When the switching completion notification packet 46 illustrated in FIG. 14 is received, the path switching instruction unit 23 instructs the data transmission / reception unit 21 to terminate the double transmission together with the service ID included in the switching completion notification packet 46. . Then, the route switching instruction unit 23 refers to the transmission route table 220 and rewrites the route type associated with the service ID into information indicating the standby communication route.

  In addition, when the switch-back request packet 47 shown in FIG. 15 is received, the path switching instruction unit 23 refers to the transmission path table 220 in the transmission path DB 22, and includes the service included in the received switch-back request packet 47. A service ID that is associated with a level and that is associated with a backup route type is extracted.

  If there are a plurality of corresponding service IDs, the service ID with the highest associated service level (the lowest service level value) is extracted. If a plurality of service IDs are still extracted, the service ID of the service with the highest priority is extracted from the service IDs according to a predetermined priority for each service.

  Then, the path switching instruction unit 23 instructs the data transmission / reception unit 21 to start double transmission together with the extracted service ID. Then, the path switching instruction unit 23 transmits a switchback response packet 48 (see FIG. 16) including the service ID to the communication control device 20 that is the transmission source of the switchback request packet 47 via, for example, a standby communication path. To do.

  When the switching completion notification packet 49 shown in FIG. 17 is received, the path switching instruction unit 23 notifies the data transmission / reception unit 21 of the end of the double transmission together with the service ID included in the switching completion notification packet 49. Instruct. Then, the route switching instruction unit 23 refers to the transmission route table 220 and rewrites the route type associated with the service ID into information indicating the active communication route.

  Next, the operation of the communication system 10 will be described using a flowchart. FIG. 18 is a flowchart showing an example of an operation for measuring the transmission time difference between the active and standby communication paths. The communication control device 20 starts the operation shown in this flowchart in response to an instruction from the management device 11 in a time zone where there is a low possibility that congestion such as midnight or light is occurring. In this flowchart, the transmission side communication control device 20-1 and the reception side communication control device 20-2 in the system configuration of FIG.

  First, the control packet transmission unit 25 of the communication control apparatus 20-1 creates the control packet 40 for delay time measurement shown in FIG. 8, and uses the created control packet 40 as the active communication path and the standby communication. It transmits to the communication control apparatus 20-2 via each of the paths (S100).

  Next, the time difference measuring unit 27 of the communication control apparatus 20-2 receives the control packet 40 via the communication paths of the active system and the standby system, and uses the delay measurement received via the communication path of the standby system. From the transmission time of the control packet 40, the time difference of the transmission time of the control packet 40 for delay measurement received via the working communication path is measured (S101).

  Then, the time difference measuring unit 27 creates a measurement result report packet 41 (see FIG. 9) including the measurement results, and sends the created measurement result report packet 41 to the communication control device 20-1 via, for example, a standby communication path. (S102). The control packet transmission unit 25 of the communication control apparatus 20-1 associates the VLAN ID 413 and the measurement result 415 information included in the measurement result report packet 41 with the delay DB 24 in association with the VLAN ID 413 included in the received measurement result report packet 41. (S103).

  Then, the control packet transmitter 25 of the communication control device 20-1 creates two control packets 42 for switching determination shown in FIG. 10, and based on the delay amount stored in the delay table 240 in the delay DB 24. The transmission timing is adjusted, and the control packet 42 created in each of the active and standby communication paths is transmitted at predetermined time intervals (for example, every 100 milliseconds) (S104).

  FIG. 19 is a flowchart illustrating an example of a switching operation of the communication control device 20 on the receiving side in the first embodiment. In this flowchart, the receiving side communication control apparatus 20-2 will be described as an operating subject in the system configuration of FIG.

  First, when the time difference measuring unit 27 receives the control packet 42 for switching determination shown in FIG. 10 via the communication paths of the active system and the standby system, the time difference measuring unit 27 performs the switching determination via the communication path of the standby system. The reception time difference from the reception time at which the control packet 42 for reception is received until the control packet 42 for switching determination is received through the active communication path is measured (S200). Then, the time difference measurement unit 27 transmits the measurement result to the route switching request unit 29 together with the service information included in the control packet 42 for switching determination.

  Next, the path switching request unit 29 refers to the switching threshold value table 280 in the threshold value DB 28, and the switching threshold value (4000 mm in the example of FIG. 6) indicates that the time difference indicated by the measurement result received from the time difference measuring unit 27 is the largest. It is determined whether or not the switching threshold is 4 or more (seconds) (S201).

  When the time difference is equal to or greater than the switching threshold 4 (S201: Yes), the path switching request unit 29 extracts the service levels 1 to 4 associated with the switching threshold 4 from the switching threshold table 280. Then, the route switching request unit 29 is associated with the active route type in the service information received from the time difference measuring unit 27 from the extracted service levels 1 to 4 (that is, the active communication route is changed). The service level of the service (provided via the service) is further extracted.

  Next, the path switching request unit 29 creates a switching request packet 44 (see FIG. 12) including the extracted service level, and sends the created switching request packet 44 to the communication control apparatus 20-1, for example, a standby communication path. (S202). Note that if there is no service level of the service being provided through the active communication path among the service levels 1 to 4, there is no need to execute path switching, so the time difference measuring unit 27 again performs step S200. Execute the process shown in.

  Next, when the switching response packet 45 (see FIG. 13) is received from the communication control device 20-1 (S209: Yes), the path switching request unit 29 continues to be specified by the service ID 453 of the switching response packet 45. A user data packet 43 (see FIG. 11) including the service ID in the header is received via the communication paths of the active system and the standby system. Then, the path switching request unit 29 is a user data packet 43 including the specified service ID in the header, and the user data packet 43 having the same sequence number is transmitted through the communication paths of the active system and the standby system. Then, it is determined whether the data of the received user data packet 43 is identical (S210).

  When the data of the set of user data packets 43 having the same sequence number received via the communication paths of the active system and the standby system continuously match a predetermined number (for example, 100 packets) or more (S210: Yes) The path switching request unit 29 creates the switching completion notification packet 46 shown in FIG. Then, the path switching request unit 29 transmits the created switching completion notification packet 46 to the communication control apparatus 20-1 via, for example, the standby communication path (S211), and the time difference measuring unit 27 again shows in step S200. Execute the process.

  On the other hand, even if the data of a set of user data packets 43 having the same sequence number received via the communication paths of the active system and the standby system are compared with a predetermined number (for example, 1000 packets), a predetermined number (for example, (100 packets) If they do not match continuously (S210: No), the path switching request unit 29 notifies the communication control device 20-1 of an error (S212), and the time difference measuring unit 27 again performs step S200. Execute the process shown in.

  In step S201, when the time difference is less than the switching threshold 4 (S201: No), the path switching request unit 29 refers to the switching threshold table 280 in the threshold DB 28 and indicates the time difference indicated by the measurement result received from the time difference measuring unit 27. However, it is determined whether or not it is equal to or greater than the next largest switching threshold 3 (100 milliseconds in the example of FIG. 6) (S203).

  When the time difference is equal to or greater than the switching threshold 3 (S203: Yes), the path switching request unit 29 extracts the service level associated with the switching threshold 3 from the switching threshold table 280. Then, the route switching request unit 29 is associated with the active route type in the service information received from the time difference measuring unit 27 from the extracted service levels (ie, provided via the active communication route). Further extract the service level of the service.

  Then, the path switching request unit 29 creates a switching request packet 44 (see FIG. 12) including the extracted service level, and sends the created switching request packet 44 to the communication control apparatus 20-1 via, for example, a standby communication path. (S204), and the process shown in step S209 is executed. Note that if there is no service level of the service being provided through the active communication path among the service levels 1 to 3, it is not necessary to perform path switching, so the time difference measuring unit 27 again performs step S200. Execute the process shown in.

  In step S203, when the time difference is less than the switching threshold 3 (S203: No), the path switching request unit 29 refers to the switching threshold table 280 in the threshold DB 28 and indicates the time difference indicated by the measurement result received from the time difference measuring unit 27. However, it is determined whether or not it is equal to or greater than the next largest switching threshold 2 (30 milliseconds in the example of FIG. 6) (S205).

  When the time difference is equal to or greater than the switching threshold 2 (S205: Yes), the path switching request unit 29 extracts the service level associated with the switching threshold 2 from the switching threshold table 280. Then, the route switching request unit 29 is associated with the active route type in the service information received from the time difference measuring unit 27 from the extracted service levels (ie, provided via the active communication route). Further extract the service level of the service.

  Then, the path switching request unit 29 creates a switching request packet 44 (see FIG. 12) including the extracted service level, and sends the created switching request packet 44 to the communication control apparatus 20-1 via, for example, a standby communication path. (S206), and the process shown in step S209 is executed. Note that if there is no service level of the service being provided through the active communication path in the service levels 1 and 2, there is no need to perform path switching, so the time difference measuring unit 27 again performs step S200. Execute the process shown in.

  In step S205, when the time difference is less than the switching threshold 2 (S205: No), the path switching request unit 29 refers to the switching threshold table 280 in the threshold DB 28 and indicates the time difference indicated by the measurement result received from the time difference measuring unit 27. However, it is determined whether or not it is greater than or equal to the smallest switching threshold 1 (10 milliseconds in the example of FIG. 6) (S207). When the time difference is less than the switching threshold value 1 (S207: No), it is not necessary to execute the path switching, and therefore the time difference measurement unit 27 executes the process shown in step S200 again.

  When the time difference is equal to or greater than the switching threshold 1 (S207: Yes), the path switching request unit 29 extracts the service level 1 associated with the switching threshold 1 from the switching threshold table 280. Then, the route switching request unit 29 provides the extracted service level 1 if it is associated with the active route type in the service information received from the time difference measuring unit 27 (that is, provided via the active communication route). If so, a switch request packet 44 (see FIG. 12) including the service level is created.

  Then, the path switching request unit 29 transmits the created switching request packet 44 to the communication control apparatus 20-1 via, for example, a standby communication path (S208), and executes the process shown in step S209. Note that when the service level 1 is not the service level of the service being provided through the active communication path, there is no need to perform path switching, so the time difference measurement unit 27 performs the process shown in step S200 again. Run.

  FIG. 20 is a flowchart illustrating an example of the switching operation of the communication control device 20 on the transmission side. In this flowchart, the transmission-side communication control device 20-1 in the system configuration of FIG.

  First, when receiving the switching request packet 44 illustrated in FIG. 12 (S300: Yes), the path switching instruction unit 23 refers to the transmission path table 220 in the transmission path DB 22 and determines the received switching request packet 44. A service ID that is associated with the included service level and that is associated with the active route type (that is, the service being provided via the active communication route) is extracted (S301). ).

  Next, the path switching instruction unit 23 extracts one service ID having the highest service level (the lowest service level value) among the extracted service IDs (S302), and a switching response including the extracted service ID. The packet 45 (see FIG. 13) is transmitted to the communication control apparatus 20-2 via, for example, a standby communication path (S303).

  Next, the path switching instruction unit 23 instructs the data transmission / reception unit 21 to start double transmission together with the service ID (S304), and determines whether or not the switching completion notification packet 46 shown in FIG. 14 has been received (S304). S305). When an error notification is received instead of the switching completion notification packet 46, the path switching instruction unit 23 notifies the administrator of the communication control device 20, the management device 11, and the like of an error indicating a switching failure.

  When the switching completion notification packet 46 is received (S305: Yes), the path switching instruction unit 23 instructs the data transmission / reception unit 21 to terminate the double transmission together with the service ID included in the received switching completion notification packet 46 ( S306). Then, the path switching instruction unit 23 refers to the transmission path table 220 in the transmission path DB 22, and rewrites the path type associated with the service ID to information indicating the standby communication path (S307), The process shown in step S300 is executed again.

  FIG. 21 is a flowchart illustrating an example of the switching operation of the communication control device 20 on the receiving side. In this flowchart, the reception side communication control device 20-2 in the system configuration of FIG.

  First, when the time difference measuring unit 27 receives the control packet 42 for switching determination shown in FIG. 10 via the communication paths of the active system and the standby system, the time difference measuring unit 27 performs the switching determination via the communication path of the standby system. The reception time difference from the reception time at which the control packet 42 for reception is received until the control packet 42 for switching determination is received through the active communication path is measured (S400). Then, the time difference measurement unit 27 transmits the measurement result to the route switching request unit 29 together with the service information included in the control packet 42 for switching determination.

  Next, the path switching request unit 29 refers to the switchback threshold value table 285 in the threshold value DB 28, and the switchback threshold value 1 is the switchback threshold value 1 in which the time difference indicated by the measurement result received from the time difference measurement unit 27 is the smallest value. It is determined whether it is less than (5 milliseconds in the example of FIG. 7) (S401).

  When the time difference is less than the switchback threshold value 1 (S401: Yes), the path switching request unit 29 extracts the service levels 1 to 4 associated with the switchback threshold value 1 from the switchback threshold value table 285. Then, the route switching request unit 29 is associated with the standby route type in the service information received from the time difference measuring unit 27 from the extracted service levels 1 to 4 (that is, the standby communication route is changed). The service level of the service (provided via the service) is further extracted.

  Then, the path switching request unit 29 creates a switchback request packet 47 (see FIG. 15) including the extracted service level, and sends the created switchback request packet 47 to the communication control device 20-1, for example, a standby communication path. (S402). If the service level of the service being provided through the standby communication path does not exist in the service levels 1 to 4, there is no need to perform path switchback, so the time difference measuring unit 27 performs the step again. The process shown in S400 is executed.

  Next, when the switchback response packet 48 (see FIG. 16) is received from the communication control device 20-1 (S409: Yes), the path switching request unit 29 continues to specify the service ID 483 of the switchback response packet 48. The user data packet 43 (see FIG. 11) including the service ID in the header is received via the communication paths of the active system and the standby system. Then, the path switching request unit 29 is a user data packet 43 including the specified service ID in the header, and the user data packet 43 having the same sequence number is transmitted through the communication paths of the active system and the standby system. Then, it is determined whether or not the data of the received user data packet 43 matches (S410).

  When data of a set of user data packets 43 having the same sequence number received via the communication paths of the active system and the standby system continuously match a predetermined number (for example, 100 packets) (S410: Yes) The route switching request unit 29 creates the switchback completion notification packet 49 shown in FIG. Then, the path switching request unit 29 transmits the created switchback completion notification packet 49 to the communication control apparatus 20-1 via, for example, the standby communication path (S411), and the time difference measurement unit 27 returns to step S400 again. Perform the indicated process.

  On the other hand, even if the data of a set of user data packets 43 having the same sequence number received via the communication paths of the active system and the standby system are compared with a predetermined number (for example, 1000 packets), a predetermined number (for example, (100 packets) If there is no continuous match (S410: No), the path switching request unit 29 notifies the communication control device 20-1 of an error (S412), and the time difference measurement unit 27 again performs step S400. Execute the process shown in.

  In step S401, when the time difference is greater than or equal to the switchback threshold value 1 (S401: No), the path switching request unit 29 refers to the switchback threshold value table 285 in the threshold value DB 28, and the measurement result received from the time difference measurement unit 27 is It is determined whether or not the indicated time difference is less than the next smallest return threshold value 2 (15 milliseconds in the example of FIG. 7) (S403).

  When the time difference is less than the switchback threshold 2 (S403: Yes), the path switching request unit 29 extracts the service level associated with the switchback threshold 2 from the switchback threshold table 285. Then, the route switching request unit 29 is associated with the standby route type in the service information received from the time difference measuring unit 27 from the extracted service levels (that is, provided via the standby communication route). Further extract the service level of the service.

  Then, the path switching request unit 29 creates a switchback request packet 47 (see FIG. 15) including the extracted service level, and sends the created switchback request packet 47 to the communication control device 20-1, for example, a standby communication path. (S404), and the process shown in step S409 is executed. If the service level of the service being provided through the standby communication path does not exist in the service levels 2 to 4, there is no need to perform path switching back, so the time difference measuring unit 27 performs the step again. The process shown in S400 is executed.

  In step S403, when the time difference is equal to or greater than the switchback threshold value 2 (S403: No), the path switching request unit 29 refers to the switchback threshold value table 285 in the threshold value DB 28 and receives the measurement result received from the time difference measurement unit 27. It is determined whether or not the time difference indicated by is less than the next smallest return threshold value 3 (50 milliseconds in the example of FIG. 7) (S405).

  When the time difference is less than the switchback threshold 3 (S405: Yes), the path switching request unit 29 extracts the service level associated with the switchback threshold 3 from the switchback threshold table 285. Then, the route switching request unit 29 is associated with the standby route type in the service information received from the time difference measuring unit 27 from the extracted service levels (that is, provided via the standby communication route). Further extract the service level of the service.

  Then, the path switching request unit 29 creates a switchback request packet 47 (see FIG. 15) including the extracted service level, and sends the created switchback request packet 47 to the communication control device 20-1, for example, a standby communication path. (S406), and the process shown in step S409 is executed. Note that if there is no service level of the service being provided through the standby communication path in the service levels 3 and 4, there is no need to perform path switching back, so the time difference measuring unit 27 performs the step again. The process shown in S400 is executed.

  In step S405, when the time difference is greater than or equal to the switchback threshold 3 (S405: No), the path switching request unit 29 refers to the switchback threshold table 285 in the threshold DB 28, and the measurement result received from the time difference measurement unit 27 is It is determined whether or not the time difference shown is less than the largest return threshold 4 (S407). If the time difference is greater than or equal to the switchback threshold value 4 (S407: No), it is not necessary to execute the switchback of the route, so the time difference measuring unit 27 executes the process shown in step S400 again.

  When the time difference is less than the switchback threshold 4 (S407: Yes), the path switching request unit 29 extracts the service level 4 associated with the switchback threshold 4 from the switchback threshold table 285. Then, the path switching request unit 29 provides the extracted service level 4 if the service level 4 is associated with the standby path type in the service information received from the time difference measuring section 27 (that is, provided via the standby communication path). If so, a failback request packet 47 (see FIG. 15) including the service level is created.

  Then, the path switching request unit 29 transmits the created switchback request packet 47 to the communication control apparatus 20-1 via, for example, a standby communication path (S408), and executes the process shown in step S409. When the service level 4 service is not being provided via the standby communication path, it is not necessary to switch back the path, and therefore the time difference measurement unit 27 executes the process shown in step S400 again. .

  FIG. 22 is a flowchart illustrating an example of a switchback operation of the communication control device 20 on the transmission side. In this flowchart, the communication control device 20-1 on the transmission side will be described as an operating subject in the system configuration of FIG.

  First, the path switching instruction unit 23 refers to the transmission path table 220 in the transmission path DB 22 when receiving the switching request packet 47 shown in FIG. 15 (S500: Yes). 47, the service ID associated with the service level included in 47 and associated with the standby path type (that is, the service being provided via the standby communication path) is extracted. (S501).

  Next, the path switching instruction unit 23 extracts one service ID having the highest service level (the lowest service level numerical value) among the extracted service IDs (S502), and performs switching back including the extracted service ID. The response packet 48 (see FIG. 16) is transmitted to the communication control apparatus 20-2 through, for example, a standby communication path (S503).

  Next, the path switching instruction unit 23 instructs the data transmission / reception unit 21 to start double transmission together with the service ID (S504), and determines whether or not the switchback completion notification packet 49 shown in FIG. 17 has been received. (S505). When an error notification is received instead of the switchback completion notification packet 49, the path switching instruction unit 23 notifies the administrator of the communication control device 20, the management device 11, etc. of an error indicating a switchback failure.

  When the switchback completion notification packet 49 is received (S505: Yes), the path switching instruction unit 23 instructs the data transmission / reception unit 21 to end the double transmission together with the service ID included in the received switchback completion notification packet 49. (S506). Then, the route switching instruction unit 23 refers to the transmission route table 220 in the transmission route DB 22, and rewrites the route type associated with the service ID to information indicating the active communication route (S507), The process shown in step S500 is executed again.

  The first embodiment of the present invention has been described above.

  As is clear from the above description, according to the communication system 10 of the present embodiment, it is possible to suppress degradation of service quality due to the delay of data packets in packet communication.

  In addition, the communication control device 20 in the above-described embodiment measures the transmission time difference between the active and standby communication paths with the communication control device 20 facing the communication control device 20, and the communication on the receiving side is based on the measurement result. In the control device 20, the transmission timing is adjusted so that the communication packets transmitted through the communication paths of the active system and the standby system arrive almost simultaneously, so that the standby system is less likely to have congestion. With reference to the reception timing of the switching determination control packet 42 received via the communication path, it is possible to accurately detect an increase in transmission delay (occurrence of congestion) on the active communication path.

  In addition, the communication control device 20 in the above-described embodiment also allows the user data packet 43 to arrive at the reception-side communication control device 20 almost simultaneously in consideration of the transmission delay of each of the active and standby communication paths. Therefore, even when the communication path is switched between the active system and the standby system, an increase in the delay of the user data packet 43 before and after the switching can be prevented.

  In addition, since the communication control device 20 in the above-described embodiment can set the threshold for switching or switching back the communication path for each service level, the communication path is switched in preference to a service with a small allowable amount of delay. It can be executed and the stability of the service can be improved.

  Further, the communication control device 20 in the above-described embodiment transmits the same user data packet 43 to both the active system and the standby system when switching the communication path, and a predetermined number or more user data packets are transmitted in the switching destination communication path. When 43 is successfully received continuously, the switching of the communication path is completed, so that data loss due to the switching of the communication path can be prevented.

  In addition, since the communication control apparatus 20 in the above-described embodiment switches the communication path to the standby system and then the transmission delay of the active system becomes small, the communication path is switched back to the active system again. It is possible to take a longer time to use the communication path of the system. This also reduces the number of packets that flow through the standby communication path, so that the communication band of the standby communication path can be given a margin, and an increase in the transmission delay of the active system can be detected. The delay of the reference standby control packet 42 can be reduced, and an increase in the transmission delay of the active system can be detected with higher accuracy.

  Next, a second embodiment of the present invention will be described with reference to the drawings.

  The system configuration of this embodiment is the same as that shown in FIG. In this embodiment, the relay device 30 included in the active communication path predicts the occurrence of congestion and issues a warning, and based on the warning, the reception-side communication control device 20-2 sends the transmission-side communication control device. The point which transmits the switch request packet 44 to 20-1 differs from 1st Embodiment.

  FIG. 23 is a block diagram illustrating an example of a detailed functional configuration of the relay device 30. The relay device 30 includes a packet reception unit 31, a transmission buffer 32, a packet transmission unit 33, a transmission destination DB 34, and a warning transmission unit 35.

  For example, a transmission destination table 340 as shown in FIG. 24 is stored in the transmission destination DB 34. The transmission destination table 340 stores a VLAN ID 341 that identifies each communication path, and an address 342 of the communication control device 20 that is the end of the communication path.

  The packet receiving unit 31 receives a communication packet such as a user data packet 43 from the communication control device 20 or another relay device 30 and stores the received communication packet in the transmission buffer 32. The packet transmission unit 33 relays the communication packet stored in the transmission buffer 32 to a relay destination designated for each communication path stored in the header.

  The warning transmitter 35 monitors the amount of data stored in the transmission buffer 32, and when the amount of data exceeds a predetermined ratio (for example, 80%) of the capacity of the transmission buffer 32, the warning transmission unit 35 The identification information of the communication path stored in the header of each stored user data packet 43, that is, VLANID is extracted.

  Then, the warning transmitter 35 creates a warning packet 50 as shown in FIG. 25, for example. The warning packet 50 includes a header 500 and a payload 501, and the payload 501 stores a message ID 502 indicating that the packet is a warning packet and a VLAN ID 503 of a communication path including the own device. .

  The warning packet 50 is, for example, ITU-T Y. It can be configured based on the format of a VSM (Vendor Specific Message) frame or an APS (Automatic Protection Switching) frame defined in 1731.

  Then, the warning transmission unit 35 extracts the address of the communication control device 20 corresponding to the extracted VLANID from the transmission destination DB 34, and transmits the generated warning packet 50 to the extracted address.

  FIG. 26 is a flowchart illustrating an example of the operation of the relay device 30.

  First, the warning transmission unit 35 monitors the data amount of data stored in the transmission buffer 32, and determines whether or not the data amount is equal to or greater than a warning threshold (S600). When the data amount in the transmission buffer 32 is equal to or greater than the warning threshold (S600: Yes), the warning transmission unit 35 uses the VLANID stored in the header of each user data packet 43 stored in the transmission buffer 32. Extract (S601).

  Next, the warning transmitter 35 creates a warning packet 50 shown in FIG. Then, the warning transmission unit 35 extracts the address of the communication control device 20 corresponding to the extracted VLAN ID from the transmission destination DB 34, and transmits the generated warning packet 50 to the extracted address (S602). Then, the warning transmission unit 35 waits for a predetermined time (for example, several seconds) until the path switching is completed (S603), and again executes the process shown in step S600.

  FIG. 27 is a flowchart illustrating an example of a switching operation of the communication control device 20 on the receiving side in the second embodiment. Except for the points described below, in FIG. 27, the processes denoted by the same reference numerals as those in FIG. 19 are the same as the processes in FIG.

  First, the time difference measuring unit 27 determines whether or not the warning packet 50 has been received (S220). When the warning packet 50 has not been received (S220: No), the time difference measurement unit 27 executes the process shown in step S200.

  On the other hand, when the warning packet 50 is received (S220: Yes), the time difference measuring unit 27 extracts the service levels 1 to 4 associated with the switching threshold 4 from the switching threshold table 280. The route switching request unit 29 is associated with the active route type in the service information received from the time difference measuring unit 27 immediately before the extracted service levels 1 to 4 (that is, the active service type The service level of the service (provided via the communication path) is further extracted.

  Then, the path switching request unit 29 creates a switching request packet 44 (see FIG. 12) including the extracted service level, and sends the created switching request packet 44 to the communication control apparatus 20-1 via, for example, a standby communication path. (S202), and the process shown in step S209 is executed.

  The second embodiment of the present invention has been described above.

  An increase in the amount of data in the transmission buffer of the relay device 30 means that there is a wait for data transmission for some reason, such as a line failure or a high processing load on the relay device 30 on the communication path. It is shown that. When the free space in the transmission buffer decreases due to an increase in the data waiting for transmission, there is a higher possibility that congestion will occur due to data discarding and further transmission waiting in the upstream relay device 30.

  Therefore, the relay device 30 according to the present embodiment transmits a warning indicating that congestion may occur to the communication control device 20 when the amount of data in the transmission buffer exceeds a predetermined threshold, and performs communication control. The device 20 is prompted to switch the route. Thereby, before the congestion occurs, path switching can be executed, and the quality of service can be stably kept high.

  In addition, this invention is not limited to each above-described embodiment, Various modifications are included. In the above-described embodiment, a difference in transmission time between the active and standby communication paths is measured in advance, and in a situation where congestion does not occur, communication transmitted via the respective communication paths of the active and standby systems The packet arrives at the receiving side communication control device 20 almost simultaneously, and the control packet transmitted through the active communication path is used as a reference with respect to the control packet transmitted through the standby communication path. Although the delay amount is measured and the communication path is switched when the measured delay amount exceeds a predetermined threshold, the present invention is not limited to this.

  For example, statistical processing is performed on the arrival interval of control packets transmitted via the working communication path to determine the occurrence of congestion on the working communication path, and when it is determined that congestion has occurred, the communication path is reserved. You may make it switch to a system.

  For example, (1) when the transmission interval of the control packet transmitted at a constant interval is not set in the communication control device 20 on the receiving side, first, the control received through the active communication path for a certain period For the packet reception time, the average value and variance of the arrival time intervals are calculated. By using a normal distribution model using the average value and the variance, an error range of arrival time intervals falling within 3σ (may be σ or 2σ depending on the setting) is determined.

  The average value (zero dispersion point) obtained here is the arrival time interval predicted by the receiving apparatus. When the predicted value and the actual frame arrival interval are separated by 3σ or more, there is some change in the communication path ( And the communication path is switched from the active system to the standby system.

  Further, (2) when the transmission interval of control packets transmitted at regular intervals is set in the communication control device 20 on the receiving side, as in the above, during a certain period via the active communication path With respect to the reception time of the received control packet, the average value and variance of the arrival time intervals are calculated. This is statistical data for examining fluctuations in the arrival interval. When an error between the average value of the statistical data and a preset arrival interval deviates by 3σ (may be σ or 2σ depending on the setting), a problem occurs in the communication path (congestion occurs). judge.

  As for the change in the reception interval, it is determined whether or not the communication state is normal as in the case of (1) above. Also, the time at which the next control packet should be received can be calculated from the predicted arrival interval (a constant value) and the time at which the control packet was actually received. By statistically processing the difference between the predicted arrival time and the time when the control packet is actually received, the average value and variance of the difference can be calculated. At this time, when (A) the difference exceeds a certain threshold value, (B) when the observed variation in the difference exceeds the variance 3σ (or σ or 2σ), it is determined as an abnormal state.

  Further, (3) when the reception time of the control packet transmitted at regular intervals is set in the communication control device 20 on the receiving side, the set arrival time and the actual time as in the latter half of the case of (2) above. Statistical processing is performed on the difference between the arrival time and the occurrence of abnormality in each case (A) or (B).

  In the above-described embodiment, the communication control device 20 receives a control packet transmitted via the standby communication path and then receives a control packet transmitted via the active communication path. However, the present invention is not limited to this, and priority is given to services with less demand on delay times. You may make it switch to a backup system.

  Even if the user data packet is a service with a low demand for delay time, switching the communication path to the standby system will allow the active communication band to be freed up, eliminating congestion on the active communication path. Can do. In addition, since the standby communication path has a property as a backup for the active system, the reliability may be lower than that of the active communication path.

  Therefore, by eliminating congestion on the working communication path while leaving a service with a demand for delay time in the working system, congestion on the communication path can be solved while keeping the quality of the service high.

  In the above-described embodiment, the communication control device 20 switches the communication path from the active system to the standby system and then switches back to the active system, giving priority to the service that requires strict delay time, and switching to the active system. However, the present invention is not limited to this. For example, priority may be given to a service with a low request for delay time to switch back to the active system.

  For example, when a failure occurs intermittently in the active system, the communication path is switched from the standby system to the active system, and then switched to the standby system again due to an increase in the delay amount. In such a case, the delay amount of the working system increases until the delay amount of the working communication path exceeds the switching threshold. Therefore, until the fault that occurred in the active system is completely resolved, the service that is demanding the delay time is prioritized and switched back to the active system in order to reduce the quality of the service that is demanding the delay time. Can be suppressed.

  Further, each of the above-described embodiments has been described in detail for easy understanding of the present invention, and the present invention is not necessarily limited to the one having all the constituent elements described. In addition, a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of a certain embodiment. In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  Each of the above-described configurations, functions, processing units, processing means, and the like may be realized by hardware by designing a part or all of them with, for example, an integrated circuit. Each of the above-described configurations, functions, and the like may be realized by software by the processor interpreting and executing a program that realizes each function. Information such as programs, tables, and files for realizing each function can be stored in a recording device such as a memory, a hard disk, an SSD (Solid State Drive), or a recording medium such as an IC card, an SD card, or a DVD.

  Further, the control lines and information lines indicate what is considered necessary for the explanation, and not all the control lines and information lines on the product are necessarily shown. Actually, it may be considered that almost all the components are connected to each other.

DESCRIPTION OF SYMBOLS 10 ... Communication system, 11 ... Management apparatus, 12 ... Core network, 13 ... Access network, 14 ... Communication apparatus, 20 ... Communication control apparatus, 21 ... Data transmission / reception part , 22 ... transmission path DB, 23 ... path switching instruction section, 24 ... delay DB, 25 ... control packet transmission section, 26 ... path type DB, 27 ... time difference measurement section, 28 ... Threshold DB, 29 ... Route switching request unit, 30 ... Relay device, 31 ... Packet reception unit, 32 ... Transmission buffer, 33 ... Packet transmission unit, 34 ... Destination DB, 35 ... warning transmitter, 40 ... control packet, 41 ... measurement result report packet, 42 ... control packet, 43 ... user data packet, 44 ... switch request packet 45... Switching response packet 46. Replacement completion notification packet, 47 ... changeback request packet, 48 ... changeback response packet, 49 ... changeback completion notice packet, 50 ... warning packet

Claims (7)

A communication system for switching a data packet communication path to a standby communication path prepared in advance when congestion occurs in the active communication path,
A first communication control device;
A second communication control device connected to the first communication control device via respective communication paths of an active system and a standby system,
The first communication control device includes:
A plurality of units that perform communication between the second communication control unit and a data transmission unit that transmits a data packet including user data to the second communication control unit via either the active or standby communication path A first table storing a plurality of service levels indicating communication quality required for each of the services;
The control packet including the service level having the same sequence number and stored in the first table is transmitted to the second communication control at a predetermined timing via the communication paths of the active system and the standby system. A control packet transmitter for transmitting to the device;
A path switching instruction unit that instructs the data transmission unit to switch the communication path of the data packet from the working system to the standby system when a path switching request is received from the second communication control device;
The second communication control device includes:
From the reception time of the control packet received via the communication path of the standby system, a time difference measuring unit for measuring a time difference until the time of receiving the control packet having the same sequence number received via the communication path of the working system,
A second table for storing a plurality of correspondence relationships between the service level and a time threshold;
One or a plurality of time threshold values of the second table smaller than the time difference measured by the time difference measuring unit are extracted, and stored in the second table corresponding to the extracted time threshold values. A path switching request unit that extracts a service level and transmits a path switching request to the first communication control device for the communication of the extracted service level;
A communication system comprising: The communication system according to claim 1,
The time difference measurement unit is configured to determine a reception time of a control packet received from the first communication control device via each communication path when congestion has not occurred in any of the active and standby communication paths. Measuring the difference, notifying the first communication control device of the measurement result,
The control packet transmitter is
Receiving the measurement result of the reception time difference from the second communication control device;
When the reception time difference indicates that the control packet passing through the working communication path arrives at the second communication control apparatus earlier, the control packet is sent to the standby communication path and then the reception is performed. After the time corresponding to the time difference has elapsed, the same control packet is sent to the active communication path,
When the difference in the reception time indicates that the control packet passing through the working communication path arrives at the second communication control apparatus later, the control packet is sent to the working communication path and then received. A communication system, wherein the same control packet is sent to a standby communication path after a time corresponding to a time difference has elapsed. A communication system according to claim 2,
The data transmitter is
When the difference in the reception time indicates that the control packet passing through the working communication path arrives at the second communication control apparatus earlier, data is sent when the data packet is sent to the working communication path. The data packet is transmitted after a time corresponding to the difference in the reception time has elapsed from the timing at which the packet should be transmitted, and when the data packet is transmitted to the standby communication path, the data packet is transmitted at the timing at which the data packet should be transmitted. Send data packets,
When the difference in the reception time indicates that the control packet passing through the active communication path is later than the second communication control apparatus, the data packet is transmitted when the data packet is transmitted to the active communication path. The data packet is transmitted at the timing at which the packet is to be transmitted, and when the data packet is transmitted to the standby communication path, the time corresponding to the difference in the reception time from the timing at which the data packet should be transmitted A communication system characterized by transmitting a data packet. The communication system according to any one of claims 1 to 3,
The packet switching instruction unit of the first communication control device includes a data packet communication including data for providing a service corresponding to a service level included in the route switching request received from the second communication control device. A communication system characterized by instructing the data transmission unit to switch a path from an active communication path to a standby communication path. The communication system according to any one of claims 1 to 4,
When the data transmission unit is instructed to switch the route from the route switching instruction unit, both the active and standby communication routes are received until the route switching completion notification is received from the second communication control device. Send the same data packet to
The path switching request unit transmits a path switching request to the first communication control device, and then transmits the same data packet as the data packet received via the active communication path via the standby communication path. A communication system, wherein a route switching completion notification is transmitted to the first communication control device when a predetermined number or more can be continuously received. The communication system according to any one of claims 1 to 5,
The route switching request unit, after transmitting the route switching request, when the time difference measured by the time difference measuring unit is less than a threshold set shorter than the time threshold of the second table, A route return request is transmitted to the first communication control device;
The path switching instructing unit instructs the data transmitting unit to switch the communication path of the data packet from the standby system to the active system when a path switchback request is received from the second communication control device. A communication system characterized by the above. The communication system according to any one of claims 1 to 6,
It further comprises one or more relay devices provided on the active communication path,
Each of the relay devices provides warning information indicating that congestion is likely to occur when the amount of data in the transmission buffer for storing communication packets to be transmitted is equal to or greater than a predetermined threshold. A warning transmission unit for transmitting to the communication control device 2;
The path switching request unit, when receiving the warning information from the relay apparatus, transmits the path switching request to the first communication control apparatus.

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