WO2013065477A1

WO2013065477A1 - Communication system

Info

Publication number: WO2013065477A1
Application number: PCT/JP2012/076751
Authority: WO
Inventors: 水谷　昌彦
Original assignee: 株式会社日立製作所
Priority date: 2011-11-01
Filing date: 2012-10-17
Publication date: 2013-05-10
Also published as: JPWO2013065477A1; JP5784139B2

Abstract

Provided is a communication system that can lower the degradation of service qualities caused by the delays of data packets in packet communications. According to a communication system of the invention: the difference in transfer time between the communication path of a currently used channel and the communication path of a standby channel is measured in advance; it is arranged that under circumstances where no congestions have occurred, communication packets transmitted via the communication path of the currently used channel and communication packets transmitted via the communication path of the standby channel should reach a communication control apparatus on the receiving side nearly at the same time; a delay amount of a control packet transmitted via the communication path of the currently used channel is measured with reference to a control packet transmitted via the communication path of the standby channel; and when the measured delay amount exceeds a predetermined threshold value, the communication path of data packets is switched from the currently used channel to the standby channel.

Description

Communications system

The present invention relates to communication systems.

With the increase in communication capacity and diversification of services provided by communication, carrier service networks and enterprise infrastructures are required to have high reliability and communication quality. In such a communication infrastructure, in recent years, adoption of packet communication technology has been considered from the viewpoints of development cost and introduction of a high-performance communication device and reduction of operation cost.

However, in the connectionless communication method using packet communication technology, the time taken for a packet transmitted from a certain device to arrive at the destination device through the relay device is not constant, and depending on the line status and device load on the passing route. Frame discarding or a significant delay may occur, and the quality of goods may be lower than when a synchronous transmission method is used.

In order to avoid this, communication paths of the working system and the protection system are set between the transmitting device and the destination device, and a control packet for checking connectivity is periodically transmitted to the communication path of the working system, Ethernet technology, which determines that the current communication path is faulty and switches the data communication path to the backup path when the reception interval exceeds a predetermined interval (for example, 3.5 times the transmission interval). Based on Ethernet network linear protection switching technology is known (see, for example, Non-Patent Document 1).

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

However, in this case, when the control packet received immediately before is already delayed, path switching is determined by the time difference from the delayed control packet, so the timing at which the control packet should be actually received is However, even if there is a considerable delay, if the elapsed time from the reception time of the immediately preceding control packet is less than the allowable time, path switching will not be performed. When a plurality of control packets are delayed little by little, the delay time is accumulated, and the amount of delay from the timing at which the control packets should actually be received becomes larger.

In the case of communication data such as voice communication in which the amount of data to be transmitted per unit time is not very large, the influence of missing data packets or delay on the quality of service is not so great. However, with the increase in communication capacity, the amount of data to be transmitted per unit time has increased, and the amount of data stored in one data packet has also increased. The impact on the

In particular, in video streaming that handles a large amount of data and streaming of music content that requires rhythmic continuity, the degradation of the nature of service due to missing data packets or delays is particularly noticeable to users, so the impact on services is particularly large.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to suppress deterioration in quality of service caused by delay of data packet in packet communication low.

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-mentioned problems. For example, when congestion occurs in the communication path of the current system, the communication path of the data packet is prepared in advance. A communication system for switching to a reserved communication path,
A first communication control device,
And 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 is
The data transmission unit for transmitting the data packet including the user data to the second communication control device via either the working system or the spare system communication path, and the communication route in advance for each of the working system and the spare system. A control packet transmission unit that transmits the same control packet to the second communication control apparatus at a predetermined timing;
And a path switching instruction unit instructing the data transmission unit to switch the communication path of the data bucket from the current system to the standby system when receiving a path switching request from the second communication control device.
The second communication control device is
A time difference measurement unit for measuring a time difference from the reception time of the control packet received via the communication path of the protection system to the reception time of the same control packet received via the communication path of the active system, and the time difference measurement unit And 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 more than a predetermined first threshold.

According to the communication system of the present invention, it is possible to suppress the deterioration of the quality of service caused by the delay of data packets in packet communication.
Problems, configurations, and effects other than those described above will be apparent from the description of the embodiments below.

It is a system configuration figure showing an example of composition of communication system 10 concerning one embodiment of the present invention. FIG. 2 is a block diagram showing an example of a detailed functional configuration of a communication control device 20. It is a figure which shows an example of the data structure of the transmission path | route table 220 stored in transmission path | 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. FIG. 6 is a view showing an example of the data structure of a measurement result report packet 41. It is a figure which shows an example of the data structure of the control packet for switching determination. FIG. 6 is a diagram showing an example of a data structure of a user data packet 43. FIG. 6 is a view showing an example of the data structure of a switching request packet 44. FIG. 8 is a view showing an example of the data structure of a switching response packet 45. FIG. 6 is a view showing an example of the data structure of a switching completion notification packet 46. It is a figure which shows an example of the data structure of the switchback request packet 47. As shown in FIG. 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. As shown in FIG. It is a flowchart which shows an example of measurement operation | movement of the transmission time difference of the communication path of an active system and a protection system. It is a flowchart which shows an example of 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 switching operation | movement of the communication control apparatus 20 of a transmission side. It is a flowchart which shows an example of the switchback operation | movement of the communication control apparatus 20 of the receiving side. It is a flowchart which shows an example of the switchback operation | movement of the communication control apparatus 20 of the transmission side. FIG. 3 is a block diagram showing an example of a detailed functional configuration of a relay device 30. It is a figure which shows an example of the data structure of the transmission destination table 340 stored in transmission destination DB34. FIG. 6 is a diagram showing an example of a data structure of a warning packet 50. 5 is a flowchart showing an example of the operation of the relay device 30. It is a flowchart which shows an example of 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 showing an example of the 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. Further, each communication control device 20 is connected to another communication control device 20 via the 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 an accumulation switching system.

The management device 11 presets communication paths of the working system and the protection system for each of the two communication control devices 20 in the communication system 10 for each of the transmission and reception communication paths, and necessary information (for example, communication) A VLAN ID for identifying a path, a transfer destination of a data packet, etc.) is set in each of the communication control unit 20 and the relay unit 30.

In the example illustrated in FIG. 1, among the plurality of communication control devices 20 included in the communication system 10, data packets of the communication control device 20-1 and the communication control device 20-2 are transmitted via the relay devices 30. A state in which the communication path of the active system (solid arrow) and the communication path of the backup system (dashed arrow) are set in advance in the direction of transmission from -1 to the communication control device 20-2.

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

FIG. 2 is a block diagram showing an example of a detailed functional configuration of the communication control device 20. As shown in FIG. 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 sending unit 25, a route type DB 26, a time difference measurement unit 27, a threshold DB 28, and a route switching request unit 29. .

For example, a transmission path table 220 as shown in FIG. 3 is stored in the transmission path DB 22. In the transmission path table 220, a path indicating the type of communication path to which the user data packet including the data is to be sent, in association with the service ID 221 identifying each service provided by the data transmitted and received by the communication device 14. A type 222 and a service level 223 indicating the degree of delay time allowed for the service are stored. "W" described in the column of the service level 223 represents that it is a communication path of the working system, and "P" represents that it is a communication path of the protection system.

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

Here, the service includes, for example, high-quality video streaming, low-quality video streaming, voice communication, and best-effort data communication. Also, for example, in services such as high-quality video streaming, the amount of data per unit time is large, and the communication device 14 on the receiving side can not store data for a very long time, so the allowable delay time is Short, for example, the service level is 1.

Also, in services such as low-quality video streaming, the amount of data per unit time is not so large, and the communication device 14 on the receiving side can store data for a relatively long time, so an allowable delay time can be obtained. Can be longer than high quality video streaming. However, if it is too long, the video will be cut off, so it will be shorter than the service like voice call, for example, the service level will be 2.

Further, in a service such as voice communication, although the amount of data per unit time is small, it is necessary to suppress the delay to such an extent that a conversation can be established, so the service level is 3, for example. Also, in a service such as best effort data communication, the restriction on delay is even smaller than the other services described above, and the service level is 4, for example.

In the delay DB 24, for example, a delay table 240 as shown in FIG. 4 is stored. In the delay table 240, a reference VLAN ID 242 for identifying a communication path of a backup system that has transmitted a control packet serving as a calculation reference of the delay amount in association with the VLANID 241 for identifying each active communication path; A delay amount 243 indicating a time difference until reception of the same control packet via the communication path of the current system is stored based on the reception time of the control packet received via the communication path.

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

Further, for example, in the delay amount 243 of the second line of the delay table 240 in FIG. 4, the control packet received through the communication path of the active system of VLANID 241 of “V003” is of the standby system of reference VLAN ID 242 of “V004”. It indicates that the communication control apparatus 20 on the receiving side has arrived 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 type of communication route is stored in the route type table 260 in association with the VLAN ID 261 that identifies each communication route. The path type table 260 illustrated in FIG. 5 is provided in the path type DB 26 for each of the other communication control devices 20 of the transmission destination of the communication packet.

In the threshold DB 28, for example, a switching threshold table 280 as shown in FIG. 6 and a switching back threshold table 285 as shown in FIG. 7 are stored. In the switching threshold table 280, the time difference corresponds to the switching threshold 281 in correspondence with the switching threshold 281 indicating the threshold of the time difference for switching the communication path of the data packet including data for providing service to the standby system. When the above occurs, 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 communication control device 20 on the receiving side receives the same control packet via the working communication path from the reception time when the specific control packet described later is received via the spare system communication path. Point to the time difference up to The switching threshold in each service level is determined in advance based on the allowable range of the 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.

Also, in the switchback threshold table 285, the threshold of the time difference for switching back from the spare system to the active system after switching the communication path of the data packet including the data for providing the service from the active system to the standby system. The service level 287 of the service for switching back from the spare system to the active system is stored in association with the switching back threshold 286 indicating that the time difference is less than the switching back threshold 286.

It should be noted that the backbone network 12 is normally designed to continue using the active communication path, and if there is no problem with the quality of service, it may be preferable to continue using the active system as much as possible from the viewpoint of operation as well. There are many. Therefore, the communication path is switched from the backup system to the active system at a stage where the difference in delay time between the active system and the backup system is reduced.

However, if the reversion threshold is too long, the possibility of switching again immediately after reversion is increased, and wasteful traffic generated in the backbone network 12 accompanying switching and reversion 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 transmission unit 25 creates two control packets 40 for delay measurement having a data structure as shown in FIG. 8 at a predetermined timing (for example, a timing instructed by the management apparatus 11). The control packet 40 includes a header 400 and a payload 401, and the payload 401 includes a message ID 402, a VLAN ID 403, a sequence number 404, and a transmission time 405.

The control packet transmitter 25 stores information indicating that the control packet 40 is the control packet 40 for delay measurement in the message ID 402 in the two control packets 40 created, and the same numerical value is stored in the sequence number 404. Store. Then, the control packet transmission unit 25 stores the identification information of the communication path of the current system in the VLAN ID 403 of one control packet 40 with reference to the path type DB 26, and the communication path of the backup system in the VLAN ID 403 of the other control packet 40. Stores identification information of

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

The control packet transmission unit 25 repeats the process of transmitting the control packet 40 for delay measurement with the same sequence number to both the active and standby communication paths at predetermined time intervals (for example, every 100 milliseconds) a plurality of times. . Then, the control packet transmitter 25 receives the measurement result report packet 41 as shown in FIG. 9 from the communication control apparatus 20 of 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, and 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 packet for measurement result report. The VLAN ID 413 stores identification information of the communication path of the current system for which the delay time is to be measured. The VLAN ID 414 stores identification information of the communication path of the backup system, which is the measurement standard of the delay time. In the measurement result 415, the communication control device 20 of the transmission source of the measurement result report packet 41 uses the communication path of the working system from the reception time when the control packet 40 for delay measurement is received via the communication path of the protection system. A time difference until reception of the control packet 40 for delay measurement having the same sequence number 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 sets the VLAN ID 414 included in the measurement result report packet 41 as the reference VLAN ID 242 as the measurement result report packet. The measurement result 415 contained in 41 is stored in the delay table 240 in the delay DB 24 as the delay amount 243.

The control packet 40 for delay measurement and the measurement result report packet 41 are, for example, ITU-T Y.3. It can be configured based on the format of Vendor Specific Message (VSM) frame or Automatic Protection Switching (APS) frame defined in 1731.

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

The control packet transmitter 25 stores information indicating that the control packet 42 is the control packet 42 for switching determination in the message ID 422 in the two control packets 42 created, and the same numerical value is stored in the sequence number 424. The service ID, path type, and service level information 426 is stored in the service information 425 for the path type set in the transmission path table 220. The service information 425 may be included in at least one of the two control packets 42 created.

Then, the control packet transmission unit 25 stores the identification information of the communication path of the current system in the VLANID 423 of one control packet 42 with reference to the path type DB 26, and the communication path of the backup system in the VLANID 423 of the other control packet 42. Stores identification information of

The control packet 42 is, for example, ITU-T Y.3. It can be configured based on the format of a Continuity Check Message (CCM) frame defined in 1731.

Next, the control packet transmitter 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. Extract

When the extracted delay amount is a positive value (that is, when the delay of the active communication path is larger than that of the backup communication path), the control packet transmitter 25 transmits the control packet 42 at a timing. The control packet 42 having the identification information of the communication path of the active system in the VLAN ID 423 is transmitted to the communication control device 20 via the communication path of the active system at the timing earlier than the extracted delay amount by time. At the timing when the packet 42 is to be transmitted, the control packet 42 having the identification information of the communication path of the protection system in the VLAN ID 423 is transmitted to the communication control device 20 via the communication path of the protection system.

On the other hand, when the extracted delay amount is a negative value (ie, when the delay of the active communication path is smaller than that of the standby communication path), the control packet transmitter 25 transmits the control packet 42. A control packet 42 having identification information of the communication path of the active system in the VLAN ID 423 is transmitted to the communication control device 20 via the communication path of the active system at a timing after the extracted delay amount time than the power timing. At the timing when the control packet 42 is to be transmitted, the control packet 42 having the identification information of the communication path of the protection system in the VLAN ID 423 is transmitted to the communication control device 20 via the communication path of the protection system.

As a result, when the control packet 42 for switching determination having the same sequence number transmitted through each of the active communication path and the backup communication path is not congested in any of the communication paths. Is received by the communication control apparatus 20 on the receiving side at almost the same timing. In order to precisely match the reception timing in the communication control apparatus 20 on the receiving side when congestion does not occur, the measurement of the difference in transmission time between the communication path of the active system and the communication path of the standby system It is preferable to be performed at a time zone where there is a low possibility that congestion has occurred (for example, midnight, light, etc.).

The control packet transmitter 25 transmits the control packet 42 for switching determination having the same sequence number whose transmission timing has been 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 to select the communication control device 20 to which the communication device 14 serving as the destination of the user data is connected. The transmission route table 220 is identified. Then, the data transmitting / receiving unit 21 refers to the identified transmission route table 220 to identify 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 identifies VLANID corresponding to the specified route type as identification information of a communication route to which user data is to be transmitted.

In the case where the provision of the service is ended, the data transmitting / receiving unit 21 starts providing the service by the user data in order to delete the route type associated with the service ID of the service from the transmission route table 220. In the transmission path table 220, the data transmitting / receiving unit 21 associates the service type of the service with the path type indicating the active system.

Then, the data transmitting / receiving 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, a DA 432 indicating the address of the communication control apparatus 20 of the destination of the user data packet 43, an SA 433 indicating the address of the communication control apparatus 20 of the transmission source of the user data packet 43, and the user data packet 43 are transmitted. The VLAN ID 434 of the communication path, the sequence number 435 for uniquely identifying the user data packet 43, and the service ID 436 of the service provided by the data contained in the user data packet 43 are stored.

Then, when the path type of the communication path to which the created user data packet 43 is to be transmitted is the active system, the data transmission / reception unit 21 refers to the delay table 240 of the delay DB 24 to identify the active communication path. Extract the delay amount associated with the information.

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

On the other hand, when the extracted delay amount is a negative value, the data transmitting / receiving unit 21 uses the current measurement system at a timing after the extracted delay amount for a time portion of the extracted measurement result report packet 41 than the transmission timing. It transmits to the communication control apparatus 20 via the following communication path.

Further, when the data transmission / reception unit 21 is instructed by the path switching instruction unit 23 to start double transmission together with the service ID, the communication of both the active system and the backup system includes the user data packet including the corresponding service ID in the header. It transmits to another communication control apparatus 20 via a path.

Then, when it is instructed from the path switching instructing unit 23 to finish double transmission together with the service ID and VLAN ID, the data transmitting / receiving unit 21 is a user data packet including the corresponding service ID in the header and Among the user data packets transmitted through both communication paths, transmission of user data packets through the communication path corresponding to the designated VLAN ID is stopped.

When the time difference measurement unit 27 receives the control packet 40 for delay measurement shown in FIG. 8 from the other communication control device 20 opposed thereto via the communication paths of the working system and the protection system, the time difference measurement unit 27 From the transmission time of the control packet 40 for delay measurement through the communication path, measurement of the time difference of the transmission time of the control packet 40 for delay measurement through the communication path of the working system is started. At this time, the time difference measurement unit 27 sets the 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 measurement unit 27 calculates, as a measurement result, an average of time differences measured for a predetermined number (for example, 100) of control packet sets for delay measurement. Then, the time difference measurement unit 27 creates a measurement result report packet 41 (see FIG. 9) including the calculated measurement result, and controls the communication of the transmission source of the control packet 40 for delay measurement of the created measurement result report packet 41. It transmits to the apparatus 20, for example via the communication path of a backup system.

Further, when the time difference measurement unit 27 receives the control packet 42 for switching determination shown in FIG. 10 via the communication paths of the active system and the backup system, the time difference measurement unit 27 performs switching determination via the communication path of the backup system. The time difference from the reception time at which the control packet 42 for control is received to the reception of the control packet 42 for switching determination via the communication path of the working system is measured. Then, the time difference measurement unit 27 transmits the measurement result to the path 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 measurement unit 27, the path switching request unit 29 refers to the switching threshold table 280 in the threshold DB 28, and the time difference indicated by the measurement result is stored in the switching threshold table 280 at least. It is determined whether or not any switching threshold value or more is reached.

If it is equal to or higher than at least one of the switching thresholds, the path switching request unit 29 extracts the service level associated with the largest switching threshold among the corresponding switching thresholds from the switching threshold table 280. Then, the route switching request unit 29 further extracts the service level associated with the currently used route type in the service information received from the time difference measuring unit 27 from the extracted service levels.

If the service information received from the time difference measurement unit 27 includes the service level associated with the route type of the active system, it means that the user data packet of the service level passes through the communication route of the active system. Means that it has been sent. If the service information received from the time difference measurement unit 27 does not include the service level associated with the currently used route type, the user data packet of the service level is transmitted via the backup communication route. It means being done.

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 device 20 of the transmission source of the control packet 42 for switching determination. For example, it transmits via the communication path of a backup system. Here, as shown in FIG. 12, for example, the switching request packet 44 includes a header 440 and a payload 441, and the payload 441 has 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, for example, a switching response packet 45 as shown in FIG. 13 from the communication control device 20 of the transmission destination of the switching request packet 44. For example, as shown in FIG. 13, the switching response packet 45 includes a header 450 and a payload 451, and the payload 451 has a message ID 452 indicating that the packet is a switching response packet, and a service to be switched. And the service ID 453 of the

When the switching response packet 45 is received, the path switching request unit 29 sets 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 to the active and standby systems. Through each communication path of The route switching request unit 29 is the user data packet 43 including the specified service ID in the header, and the communication routes of the active system and the spare system for the user data packet 43 including the same sequence number in the header. It is determined whether the payloads 431 of the user data packets 43 received via the address match.

If the data of the set of user data packets 43 having the same sequence number received through the communication paths of the active system and the spare system continuously matches a predetermined number (for example, 100 packets) or more, the path switching request unit The packet 29 creates, for example, a switching completion notification packet 46 as shown in FIG. 14 and transmits the created switching completion notification packet 46 to the communication control apparatus 20 of 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 target of switching. And the service ID 463 of the service to be stored.

Further, when the path switching request unit 29 receives the measurement result of the time difference from the time difference measurement unit 27, the path switching request unit 29 refers to the switching back threshold table 285 in the threshold DB 28 and stores the time difference indicated by the measurement result in the switching back threshold table 285 It is determined whether it is less than at least one of the reversion thresholds that have been made.

If it is less than at least one of the reversion thresholds, the path switching request unit 29 extracts the service level associated with the largest reversion threshold among the corresponding reversion thresholds from the reversion threshold table 285. Do. Then, the route switching request unit 29 further extracts the service level associated with the route type of the spare system 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, for example, a switchback request packet 47 as shown in FIG. 15, and creates the switchback request packet 47 as the communication control device 20 of the transmission source of the control packet 42 for switching determination. , For example, via a spare communication path. Here, as shown in FIG. 15, for example, the failback request packet 47 includes a header 470 and a payload 471, and the payload 471 has a message ID 472 indicating that the packet is a failback request packet, and The service level 473 extracted with reference to the return threshold table 285 is stored.

Next, after transmitting the switchback request packet 47, the path switch request unit 29 receives a switchback response packet 48 as shown in FIG. 16, for example, from the communication control device 20 of the transmission destination of the switchback request packet 47. For example, as shown in FIG. 16, the failback response packet 48 includes a header 480 and a payload 481, and the payload 481 includes a message ID 482 indicating that the packet is a failback response packet, and a target of failback. And the service ID 483 of the service to be stored.

When the switch back response packet 48 is received, the path switch request unit 29 uses the user data packet 43 (see FIG. 11) including the service ID specified by the service ID 483 of the switch back response packet 48 in the header. It receives via each communication path of the spare system. Then, the path switching request unit 29 is a user data packet 43 including the specified service ID in the header, and for the user data packet 43 having the same sequence number, through the respective communication paths of the active system and the spare system. It is determined whether the data of the received user data packet 43 match.

If the data of the set of user data packets 43 having the same sequence number received through the communication paths of the active system and the spare system continuously matches a predetermined number (for example, 100 packets) or more, the path switching request unit The packet 29 creates, for example, a switchback completion notification packet 49 as shown in FIG. 17 and transmits the created switchback completion notification packet 49 to the communication control apparatus 20 of the transmission source of the user data packet 43.

For example, as illustrated in FIG. 17, the failback completion notification packet 49 includes a header 490 and a payload 491, and the payload 491 includes a message ID 492 indicating that the packet is a failback completion notification packet, and a failback. And the service ID 493 of the service to be a target of.

The switching request packet 44, the switching response packet 45, the switching completion notifying packet 46, the switching back request packet 47, the switching back response packet 48, and the switching back completion notification packet 49 are, for example, ITU-T Y.3. It can be configured based on the format of Vendor Specific Message (VSM) frame or Automatic Protection Switching (APS) frame defined in 1731.

Returning to FIG. 2, the description will be continued. When the switching request packet 44 shown in FIG. 12 is received, the path switching instruction unit 23 refers to the transmission path table 220 in the transmission path DB 22 and copes with the service level included in the received switching request packet 44. It extracts the service ID which is attached and which is associated with the route type of the current system.

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

Then, the path switching instructing unit 23 instructs the data transmitting / receiving unit 21 to start double transmission together with the extracted service ID. Then, the path switching instructing unit 23 transmits the switching response packet 45 (see FIG. 13) including the service ID to the communication control device 20 of the transmission source of the switching request packet 44 via, for example, the communication path of the protection system.

Then, when the switching completion notification packet 46 shown in FIG. 14 is received, the path switching instructing unit 23 instructs the data transmitting / receiving unit 21 to finish double transmission together with the service ID included in the switching completion notification packet 46. . Then, the path switching instruction unit 23 refers to the transmission path table 220 and rewrites the path type associated with the service ID into information indicating a communication path of the protection system.

When the switchback 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 the service included in the received switchback request packet 47. The service ID that is associated with the level and that is associated with the spare route type is extracted.

Then, the path switching instructing unit 23 instructs the data transmitting / receiving unit 21 to start double transmission together with the extracted service ID. Then, the path switching instructing unit 23 transmits the switchback response packet 48 (see FIG. 16) including the service ID to the communication control device 20 of the transmission source of the switchback request packet 47 via, for example, the communication path of the protection system. Do.

Then, when the switchback completion notification packet 49 shown in FIG. 17 is received, the path switching instructing unit 23 sends the data transmission / reception unit 21 the dual transmission end together with the service ID included in the switchback completion notification packet 49. To direct. Then, the path switching instruction unit 23 refers to the transmission path table 220, and rewrites the path type associated with the service ID into information indicating the currently used communication path.

Next, the operation of the communication system 10 will be described using a flowchart. FIG. 18 is a flow chart showing an example of the measurement operation of the transmission time difference between the communication paths of the working system and the protection system. The communication control device 20 starts the operation shown in the flowchart in accordance with an instruction from the management device 11 in a time zone in which the possibility of occurrence of congestion such as midnight or light is low. In this flowchart, the communication control device 20-1 on the transmission side and the communication control device 20-2 on the reception side in the system configuration of FIG. 1 will be described as an operation subject.

First, the control packet transmitter 25 of the communication control device 20-1 creates the control packet 40 for measuring the delay time shown in FIG. 8 and communicates the created control packet 40 with the communication path of the active system and the backup system. It transmits to the communication control device 20-2 via each of the paths (S100).

Next, the time difference measurement unit 27 of the communication control device 20-2 receives the control packet 40 through the communication paths of the working system and the protection system, and for delay measurement received through the communication path of the protection 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 through the communication path of the working system is measured (S101).

Then, the time difference measurement unit 27 creates the measurement result report packet 41 (see FIG. 9) including the measurement result, and sends the created measurement result report packet 41 to the communication control device 20-1 via, for example, the communication path of the spare system. And transmit (S102). The control packet transmission unit 25 of the communication control device 20-1 delays the information of the VLAN ID 414 and the measurement result 415 contained in the measurement result report packet 41 in correspondence with the VLAN ID 413 contained 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 is transmitted to each of the communication paths of the active system and the spare system at predetermined time intervals (for example, every 100 milliseconds) (S104).

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

First, when the time difference measurement unit 27 receives the control packet 42 for switching determination shown in FIG. 10 via the communication paths of the active system and the backup system, the time difference measurement unit 27 performs switching determination via the communication path of the backup system. The reception time difference until reception of the control packet 42 for switching determination via the communication path of the active system from the reception time at which the control packet 42 for E4 is received is measured (S200). Then, the time difference measurement unit 27 transmits the measurement result to the path 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 table 280 in the threshold DB 28, and the switching threshold indicated by the measurement result received from the time difference measuring unit 27 is the switching threshold with the largest value (4000 mm in the example of FIG. 6). It is judged whether it is more than switching threshold 4 which is second) (S201).

If the time difference is equal to or greater than the switching threshold 4 (S201: Yes), the path switching request unit 29 extracts 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 currently used route type in the service information received from the time difference measurement unit 27 among the extracted service levels 1 to 4 (ie, the active communication route Further extract the service level of the service).

Next, the route switching request unit 29 creates the switching request packet 44 (see FIG. 12) including the extracted service level, and sends the created switching request packet 44 to the communication control device 20-1, for example, It transmits via (S202). When 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 measurement unit 27 performs step S200 again. Execute the process shown in.

Next, when the switch response packet 45 (see FIG. 13) is received from the communication control device 20-1 (S209: Yes), the path switch request unit 29 continues to be specified by the service ID 453 of the switch response packet 45. 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 for the user data packet 43 having the same sequence number, through the respective communication paths of the active system and the spare system. It is determined whether the data of the received user data packet 43 match (S210).

When the data of the set of user data packets 43 having the same sequence number received through the communication paths of the active system and the spare 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 route switching request unit 29 transmits the created switching completion notification packet 46 to the communication control device 20-1 via, for example, the communication route of the protection system (S211), and the time difference measuring unit 27 indicates again to step S200. Execute the process.

On the other hand, data of a set of user data packets 43 having the same sequence number received via respective communication paths of the active system and the spare system may be compared by a predetermined number (for example, 1000 packets) or more. If the packets do not continuously match for more than 100 packets (S210: No), the path switching request unit 29 notifies the communication control device 20-1 of an error (S212), and the time difference measurement unit 27 repeats step S200 again. 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 the time difference indicated by the measurement result received from the time difference measurement unit 27 However, it is determined whether or not the switching threshold value 3 (100 milliseconds in the example of FIG. 6), which is the next largest, is not less than (S203).

If 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 currently used route type in the service information received from the time difference measurement unit 27 among the extracted service levels (ie, provided via the currently used communication route). Further extract the service level of the service.

Then, the route switching request unit 29 creates the switching request packet 44 (see FIG. 12) including the extracted service level, and sends the created switching request packet 44 to the communication control device 20-1 via, for example, the communication route of the spare system. And transmit (S204), and execute the processing shown in step S209. 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 execute path switching, so the time difference measurement unit 27 performs step S200 again. 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 the time difference indicated by the measurement result received from the time difference measurement unit 27 However, it is determined whether or not the switching threshold value 2 (30 milliseconds in the example of FIG. 6), which is the next largest, is not less than (S205).

If 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 currently used route type in the service information received from the time difference measurement unit 27 among the extracted service levels (ie, provided via the currently used communication route). Further extract the service level of the service.

Then, the route switching request unit 29 creates the switching request packet 44 (see FIG. 12) including the extracted service level, and sends the created switching request packet 44 to the communication control device 20-1 via, for example, the communication route of the spare system. And transmits (S206), and executes the processing shown in step S209. 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 execute path switching, so the time difference measurement unit 27 performs step S200 again. 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 the time difference indicated by the measurement result received from the time difference measurement unit 27 However, it is determined whether or not the switching threshold value 1 (10 milliseconds in the example of FIG. 6) which is the smallest value or more. When the time difference is less than the switching threshold 1 (S207: No), it is not necessary to execute the switching of the path, so the time difference measurement unit 27 executes the process shown in step S200 again.

If 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, if the extracted service level 1 is associated with the currently used route type in the service information received from the time difference measurement unit 27 (ie, provided via the currently used communication route), the route switching request unit 29 If so, the 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 device 20-1 via, for example, the communication path of the protection system (S208), and executes the processing shown in step S209. When the service level 1 is not the service level of the service being provided via the active communication path, it is not necessary to execute path switching, so the time difference measuring unit 27 repeats the process shown in step S200. Run.

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

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

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

Next, the route switching instructing unit 23 instructs the data transmitting / receiving unit 21 to start double transmission together with the service ID (S 304), and determines whether the switching completion notification packet 46 shown in FIG. S305). When not receiving the switching completion notifying packet 46 but receiving an error notification, the path switching instructing unit 23 notifies the administrator of the communication control apparatus 20, the management apparatus 11 or the like of an error indicating a failure in switching.

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 finish double transmission together with the service ID included in the received switching completion notification packet 46 (S305: 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 into information indicating the communication path of the protection system (S307), The process shown in step S300 is executed again.

FIG. 21 is a flowchart showing an example of the switching back operation of the communication control device 20 on the receiving side. In this flowchart, the communication control device 20-2 on the receiving side in the system configuration of FIG. 1 will be described as an operation subject.

First, when the time difference measurement unit 27 receives the control packet 42 for switching determination shown in FIG. 10 via the communication paths of the active system and the backup system, the time difference measurement unit 27 performs switching determination via the communication path of the backup system. The reception time difference until reception of the control packet 42 for switching determination via the communication path of the active system from the reception time at which the control packet 42 for E4 is received is measured (S400). Then, the time difference measurement unit 27 transmits the measurement result to the path 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 back threshold table 285 in the threshold DB 28, and the switching back threshold 1 in which the time difference indicated by the measurement result received from the time difference measuring unit 27 is the smallest value is the switching back threshold. It is determined whether it is less than 5 milliseconds (in the example of FIG. 7) (S401).

If the time difference is less than the switchback threshold 1 (S401: Yes), the path switch request unit 29 extracts the service levels 1 to 4 associated with the switchback threshold 1 from the switchback threshold table 285. Then, the route switching request unit 29 is associated with the route type of the spare system in the service information received from the time difference measuring unit 27 among the extracted service levels 1 to 4 (that is, the communication route of the spare system is Further extract the service level of the service).

Then, the path switching request unit 29 creates the failback request packet 47 (see FIG. 15) including the extracted service level, and sends the created failback request packet 47 to the communication control device 20-1, for example, the communication route of the spare system. (S402). When there is no service level of the service being provided via the communication path of the spare system among the service levels 1 to 4, there is no need to execute path switching back, so the time difference measurement unit 27 performs step again. The process shown in S400 is performed.

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 by the service ID 483 of the switchback response packet 48. The user data packet 43 (see FIG. 11) including the specified service ID in the header is received through the communication paths of the active system and the spare system. Then, the path switching request unit 29 is a user data packet 43 including the specified service ID in the header, and for the user data packet 43 having the same sequence number, through the respective communication paths of the active system and the spare system. It is determined whether the data of the received user data packet 43 match (S410).

When the data of the set of user data packets 43 having the same sequence number received through the communication paths of the active system and the standby system continuously match a predetermined number (for example, 100 packets) or more (S410: Yes) The path switching request unit 29 creates the failback 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 device 20-1 via, for example, the communication path of the backup system (S411), and the time difference measurement unit 27 returns to step S400 again. Execute the indicated process.

On the other hand, data of a set of user data packets 43 having the same sequence number received via respective communication paths of the active system and the spare system may be compared by a predetermined number (for example, 1000 packets) or more. If the packets do not continuously match for more than 100 packets (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 the switchback threshold 1 or more (S401: No), the path switch 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 the time difference to be indicated is less than the next smaller return threshold value 2 (15 milliseconds in the example of FIG. 7) (S403).

If the time difference is less than the switchback threshold 2 (S403: Yes), the path switch 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 route type of the spare system in the service information received from the time difference measurement unit 27 among the extracted service levels (ie, provided via the communication route of the spare system). Further extract the service level of the service.

Then, the path switching request unit 29 creates the failback request packet 47 (see FIG. 15) including the extracted service level, and sends the created failback request packet 47 to the communication control device 20-1, for example, the communication route of the spare system. (S404), and the process shown in step S409 is executed. If there is no service level of the service being provided through the communication path of the spare system among the service levels 2 to 4, it is not necessary to execute path switching back, so the time difference measurement unit 27 performs step again. The process shown in S400 is performed.

In step S403, when the time difference is the switchback threshold 2 or more (S403: 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 It is determined whether the time difference indicated by is less than the next smaller return threshold value 3 (50 milliseconds in the example of FIG. 7) (S405).

If 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 route type of the spare system in the service information received from the time difference measurement unit 27 among the extracted service levels (ie, provided via the communication route of the spare system). Further extract the service level of the service.

Then, the path switching request unit 29 creates the failback request packet 47 (see FIG. 15) including the extracted service level, and sends the created failback request packet 47 to the communication control device 20-1, for example, the communication route of the spare system. (S406), and the process shown in step S409 is executed. When there is no service level of the service being provided through the communication path of the spare system in

service levels

3 and 4, it is not necessary to execute path switching back, so the time difference measurement unit 27 performs step again. The process shown in S400 is performed.

In step S405, when the time difference is the switchback threshold 3 or more (S405: No), the path switch 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 the indicated time difference is less than the largest return threshold 4 (S407). When the time difference is equal to or more than the switching back threshold 4 (S407: No), since it is not necessary to execute the switching back of the path, the time difference measurement unit 27 executes the processing shown in step S400 again.

If 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, if the extracted service level 4 is associated with the route type of the spare system in the service information received from the time difference measurement unit 27 (ie, provided via the communication route of the spare system), the route switching request unit 29 Medium), create a failback request packet 47 (see FIG. 15) including the service level.

Then, the path switching request unit 29 transmits the created switchback request packet 47 to the communication control device 20-1, for example, via the communication path of the protection system (S408), and executes the processing shown in step S409. If the service at service level 4 is not being provided via the spare communication path, it is not necessary to execute path switching back, so the time difference measurement unit 27 executes the process shown in step S400 again. .

FIG. 22 is a flowchart showing an example of the switching back 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 operation subject in the system configuration of FIG.

First, when the path switching instruction unit 23 receives the switchback request packet 47 shown in FIG. 15 (S500: Yes), the path switch instructing unit 23 refers to the transmission path table 220 in the transmission path DB 22 and receives the switchback request packet. Extract the service ID of the service that is associated with the service level 47 and that is associated with the spare route type (that is, of the service being provided via the spare communication route) (S501).

Next, the path switching instructing unit 23 extracts one service ID having the highest service level (the lowest value of the service level) among the extracted service IDs (S 502), and performs failback including the extracted service ID. The response packet 48 (see FIG. 16) is transmitted to the communication control device 20-2, for example, via the communication path of the protection system (S503).

Next, the route switching instructing unit 23 instructs the data transmitting / receiving unit 21 to start double transmission together with the service ID (S 504), and determines whether or not the switchback completion notification packet 49 shown in FIG. 17 has been received. (S505). When not receiving the switchback completion notification packet 49 but receiving an error notification, the path switching instruction unit 23 notifies the administrator of the communication control apparatus 20, the management apparatus 11, and the like of an error indicating failure in switching back.

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 finish double transmission together with the service ID included in the received switchback completion notification packet 49. To do (S506). 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 into information indicating the currently used communication path (S507), The process shown in step S500 is executed again.

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

As apparent from the above description, according to the communication system 10 of the present embodiment, it is possible to suppress the deterioration of the quality of service caused by the delay of data packets in packet communication.

Further, the communication control device 20 in the embodiment described above measures the transmission time difference between the communication path of the working system and the protection system with the opposing communication control device 20, and the communication on the receiving side based on the measurement result. In the control system 20, the transmission timing is adjusted so that communication packets transmitted through the communication paths of the active system and the standby system arrive almost simultaneously, so that there is a low possibility of occurrence of congestion. It is possible to accurately detect an increase in transmission delay (occurrence of congestion) of the communication path of the working system based on the reception timing of the control packet for switching determination received through the communication path.

In addition, the communication control unit 20 in the above-described embodiment can also arrive at the communication control unit 20 on the receiving side substantially simultaneously, taking into consideration the transmission delay of each of the communication paths of the working system and the protection system. Even if switching of the communication path is executed between the active system and the spare system, the delay of the user data packet 43 before and after the switching can be prevented from increasing.

In addition, since the communication control device 20 in the above-described embodiment can set the threshold for switching or switching back the communication route for each service level, switching of the communication route is prioritized from services with a small amount of delay tolerance. It can be implemented and can enhance the stability of the service.

Further, when switching the communication path, the communication control device 20 in the above embodiment transmits the same user data packet 43 to both the active system and the standby system, and the user data packet of the predetermined number or more in the communication path of the switching destination. When the signal 43 can be continuously received normally, the switching of the communication path is completed, so that it is possible to prevent the loss of data due to the switching of the communication path.

In addition, since the communication control device 20 in the above-described embodiment switches the communication path back to the active system if the transmission delay of the active system becomes smaller after switching the communication path to the standby system, the current-use system has higher reliability. The time to use the communication path of the system can be longer. In addition, since it is possible to reduce the number of packets to be sent to the communication path of the protection system, it is possible to provide a margin for the communication band of the communication path of the protection system, and to detect an increase in transmission delay of the active system. The delay of the reference control packet 42 can be reduced, and an increase in the transmission delay of the working system can be detected more accurately.

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 of FIG. In the present embodiment, the relay device 30 included in the communication path of the active system predicts the occurrence of congestion and issues a warning, and based on the warning, the communication control device 20-2 on the receiving side is the communication control device on the transmitting side. The point of transmitting the switching request packet 44 to 20-1 is different from the first embodiment.

FIG. 23 is a block diagram showing an example of a detailed functional configuration of the relay device 30. As shown in FIG. 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.

In the transmission destination DB 34, for example, a transmission destination table 340 as shown in FIG. 24 is stored. The transmission destination table 340 stores a VLAN ID 341 identifying each communication path, and an address 342 of the communication control apparatus 20 serving as the termination of the communication path.

The packet receiving unit 31 receives a communication packet such as the 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 transmitter 33 relays the communication packet stored in the transmission buffer 32 to the relay destination designated for each communication path stored in the header.

The warning transmission unit 35 monitors the data amount of data stored in the transmission buffer 32, and when the data amount becomes equal to or more than a predetermined ratio (for example, 80%) of the capacity of the transmission buffer 32, The identification information of the communication path stored in the header of each stored user data packet 43, that is, the VLAN ID is extracted.

Then, the warning transmission unit 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 apparatus. .

The warning packet 50 is, for example, ITU-T Y.3. It can be configured based on the format of Vendor Specific Message (VSM) frame or Automatic Protection Switching (APS) 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 the data amount is equal to or more than the warning threshold (S600). If the amount of data in the transmission buffer 32 becomes equal to or greater than the warning threshold (S600: Yes), the warning transmission unit 35 uses the VLAN ID stored in the header of each user data packet 43 stored in the transmission buffer 32. Extract (S601).

Next, the warning transmission unit 35 creates the 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 VLANID from the transmission destination DB 34, and transmits the generated warning packet 50 to the extracted address (S602). Then, the warning transmission unit 35 stands by for a predetermined time (for example, several seconds) until the path switching is completed (S603), and executes the processing shown in step S600 again.

FIG. 27 is a flowchart showing an example of the switching operation of the communication control device 20 on the receiving side in the second embodiment. Note that, in FIG. 27, the processes given the same reference numerals as those in FIG. 19 are the same as the processes in FIG.

First, the time difference measurement unit 27 determines whether 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 measurement unit 27 extracts the service levels 1 to 4 associated with the switching threshold 4 from the switching threshold table 280. Then, among the extracted service levels 1 to 4, the route switching request unit 29 is associated with the currently used route type in the service information received from the time difference measurement unit 27 immediately before that (that is, Further extract the service level of the service (provided through the communication path).

Then, the route switching request unit 29 creates the switching request packet 44 (see FIG. 12) including the extracted service level, and sends the created switching request packet 44 to the communication control device 20-1 via, for example, the communication route of the spare system. It transmits (S202), and performs the process shown to step S209.

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

The fact that the amount of data in the transmission buffer of the relay device 30 increases means that data transmission waiting occurs for some reason, such as a line failure or a high processing load of the relay device 30 on the communication path. It is shown that. Then, when the free space of the transmission buffer decreases due to the increase of data waiting for transmission, discarding of data and further transmission waiting in the relay apparatus 30 upstream thereof occur, which increases the possibility of occurrence of congestion.

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

The present invention is not limited to the above-described embodiments, and includes various modifications. In the embodiment described above, the difference between the transmission times of the communication paths of the working system and the protection system is measured in advance, and in a situation where congestion does not occur, communication transmitted via the communication paths of the working system and the protection system. The packets arrive at the receiving side communication control apparatus 20 almost simultaneously, and the control packet transmitted via the working communication path is based on the control packet transmitted via the spare communication path. Although the delay amount is measured and communication path switching is performed when the measured delay amount exceeds a predetermined threshold value, the present invention is not limited to this.

For example, the arrival interval of the control packet transmitted through the communication path of the active system is statistically processed to determine the occurrence of congestion of the communication path of the active system, and when it is determined that congestion has occurred, the communication path is reserved. You may switch to the system.

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

The average value (point of dispersion zero) obtained here is the arrival time interval predicted by the receiver, and there is some difference in the communication path when the predicted value and the actual frame arrival interval are separated by 3σ or more (see FIG. It is determined that congestion occurs and the communication path is switched from the active system to the spare system.

(2) When transmission intervals of control packets transmitted at fixed intervals are set in the communication control device 20 on the receiving side, similarly to the above, for a fixed period via the communication path of the active system For the reception time of the received control packet, the average value and the variance of the arrival time interval are calculated. This is statistical data for examining changes in the arrival interval. If the error between the average value of this statistical data and the arrival interval set in advance deviates by more than 3σ (may be σ or 2σ depending on the setting), there is a problem in the communication path (occurrence of congestion) judge.

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

(3) When the reception time of the control packet transmitted at a constant interval is set in the communication control device 20 on the reception side, the set arrival time and the actual time as in the second half in the case of (2) above. The statistical processing is performed on the difference from the arrival time of (a), and in the case of (A) or (B), it is possible to determine the occurrence of an abnormality.

In the above-described embodiment, the communication control device 20 receives the control packet transmitted through the communication path of the protection system, and then receives the control packet transmitted through the communication path of the active system. If the time difference between the two exceeds the predetermined threshold, priority is given to a service with a high demand for delay time, but the present invention is not limited to this, and a priority is given to a service with low demand for delay time. It may be switched to a spare system.

Even if it is a user data packet of a service with a loose demand for delay time, switching the communication route to the backup system makes it possible to make room for the communication bandwidth of the active system, and eliminate congestion on the active system communication route. Can. Further, the communication path of the protection system may have lower reliability than the communication path of the active system because it has the property of a backup of the active system.

Therefore, by eliminating the congestion of the communication path of the active system while leaving the service with a strict request for delay time in the active system, the congestion of the communication path can be resolved while maintaining the quality of the service high.

Further, in the above-described embodiment, when switching back the communication path from the active system to the standby system after switching the communication path from the active system to the active system, the communication control apparatus 20 gives priority to the service with strict requirements for delay time and switches it to the active system. Although it was made to return, this invention is not limited to this. For example, a service with a low demand for delay time may be switched back to the active system in preference.

For example, when a failure occurs intermittently in the current system, after switching back the communication path from the protection system to the current system, it is switched to the protection system again due to the increase of the delay amount. In such a case, the delay amount of the active system increases until the delay amount of the communication path of the active system exceeds the switching threshold. Therefore, the quality of the service with severe requirements for delay time is degraded by giving priority to the service with a low demand for delay time and switching back to the active system until the failure occurring in the active system is completely eliminated. Can be reduced.

In addition, the above-described embodiments are described in detail in order to explain the present invention in an easy-to-understand manner, and the present invention is not necessarily limited to those having all the described components. Also, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Moreover, it is possible to add, delete, and replace other configurations for part of the configurations of the respective embodiments.

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

Further, control lines and information lines indicate what is considered to be necessary for the description, and not all control lines and information lines in the product are necessarily shown. In practice, almost all configurations may be considered to be mutually connected.

DESCRIPTION OF SYMBOLS 10 ... Communication system, 11 ... Management apparatus, 12 ... Basic network, 13 ... Access network, 14 ... Communication apparatus, 20 ... Communication control apparatus, 21 ... Data transmission / reception part 22, transmission route DB, 23: route switching instruction unit, 24: delay DB, 25: control packet transmission unit, 26: route type DB, 27: time difference measurement unit, 28: threshold DB, 29: route switching request unit, 30: relay device, 31: packet reception unit, 32: transmission buffer, 33: packet transmission unit, 34: Transmission destination DB, 35: Warning transmission unit, 40: Control packet, 41: Measurement result report packet, 42: Control packet, 43: User data packet, 44: Switching 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

A communication system for switching a communication path of data packets to a communication path of a backup system prepared in advance when congestion occurs in the communication path of the active system,
A first communication control device,
And 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 is
The data transmission unit for transmitting the data packet including the user data to the second communication control device via either the working system or the spare system communication path, and the communication route in advance for each of the working system and the spare system. A control packet transmission unit that transmits the same control packet to the second communication control apparatus at a predetermined timing;
And a path switching instruction unit instructing the data transmission unit to switch the communication path of the data bucket from the current system to the standby system when receiving a path switching request from the second communication control device.
The second communication control device is
A time difference measurement unit that measures a time difference between the reception time of the control packet received via the communication path of the protection system and the reception time of the same control packet received via the communication path of the active system;
And a path switching request unit for transmitting a path switching request to the first communication control device when the time difference measured by the time difference measuring unit is equal to or greater than a predetermined first threshold. Communications system.
The communication system according to claim 1, wherein
The time difference measurement unit
When congestion does not occur in any of the active and standby communication paths, the difference between the reception times of control packets received from the first communication control device via the respective communication paths is measured and measured. Notifying the first communication control device of the result;
The control packet transmission unit
The measurement result of the difference in the reception time is received from the second communication control apparatus, and the control packet via the communication path of the current system arrives at the second communication control apparatus earlier than the difference in the reception time. , And sends the same control packet to the communication path of the current system after a time equivalent to the difference in the reception time has elapsed since the control packet was sent to the communication path of the protection system.
When the difference in the reception time indicates that the control packet via the communication path of the current system arrives later in the second communication control device, the control packet is sent out to the communication path of the current system before the reception A communication system characterized in that the same control packet is sent out to a communication path of a spare system after a time corresponding to a time difference has elapsed.
The communication system according to claim 2, wherein
The data transmission unit
When the data packet is sent to the communication path of the current system when the difference in the reception time indicates that the control packet via the communication path of the current system arrives earlier in the second communication control apparatus The data packet is sent after a time corresponding to the difference in the reception time has elapsed from the timing when the packet should be sent, and when the data packet is sent out to the communication path of the spare system, the data packet is sent at the timing when it should be sent. Send out data packets,
When the data packet is sent to the communication path of the current system when the difference in the reception time indicates that the control packet via the communication path of the current system arrives later in the second communication control device When transmitting the data packet at the timing to transmit the packet and transmitting the data packet to the communication path of the spare system, the data packet is transmitted after the time equivalent to the difference of the reception time has elapsed from the timing to transmit the data packet. A communication system characterized by transmitting data packets.
The communication system according to any one of claims 1 to 3, wherein
The second communication control device is
And a threshold storage unit storing the first threshold indicating a delay time allowed for the service in association with a service level indicating a degree of shortness of the allowed delay time;
The route switching request unit
At least one of the time differences stored in the threshold storage unit from the time when the control packet is received through the communication path of the protection system to the time when the same control packet is received through the communication path of the working system. If the threshold is exceeded, the service level stored in the threshold storage unit in association with the threshold is included in the path switching request and transmitted to the first communication control device.
The route switching instruction unit
A data packet communication path including data for providing a service corresponding to the service level included in the path switching request received from the second communication control device from the communication path of the active system to the communication path of the backup system A communication system comprising: instructing the data transmission unit to switch.
The communication system according to any one of claims 1 to 4, wherein
The data transmission unit
When path switching is instructed from the path switching instruction unit, the same data packet is transmitted to both the active and standby communication paths until the path switching completion notification is received from the second communication control unit. Send out
The route switching request unit
After transmitting the path switching request to the first communication control device, the same data packet as the data packet received through the communication path of the active system is continuously continued by a predetermined number or more through the communication path of the standby system. And a path switching completion notification is transmitted to the first communication control apparatus when the communication is successfully received.
The communication system according to any one of claims 1 to 5, wherein
The route switching request unit
When the time difference measured by the time difference measurement unit becomes less than a second threshold shorter than the first threshold after transmitting the route switching request, the route return back to the first communication control device Send a request,
The route switching instruction unit
A communication system characterized by instructing the data transmission unit to switch back the communication path of the data bucket from the backup system to the active system when receiving a path switchback request from the second communication control apparatus.
The communication system according to any one of claims 1 to 6, wherein
It further comprises one or more relay devices provided on the working communication path,
Each of the relay devices is
When the amount of data in the transmission buffer for storing communication packets to be transmitted becomes equal to or greater than a predetermined threshold value, warning information indicating that congestion is likely to occur is transmitted to the second communication control device. Have a warning transmitter to
The route switching request unit
A communication system characterized by transmitting the route switching request to the first communication control device when the warning information is received from the relay device.