WO2011121705A1

WO2011121705A1 - Communication apparatus, communication system and path switching method

Info

Publication number: WO2011121705A1
Application number: PCT/JP2010/055586
Authority: WO
Inventors: 佐藤　浩司
Original assignee: 三菱電機株式会社
Priority date: 2010-03-29
Filing date: 2010-03-29
Publication date: 2011-10-06
Also published as: TW201218685A

Abstract

A communication apparatus (1), which has a currently used system of communication path and a reserve system of communication path both established to communicate with an opposed communication apparatus, comprises a switching control unit (13) that, when having selected, as a selected path, one of the communication paths and using the selected path to perform a data transmission, determines, based on a traffic flow amount, whether the selected path exhibits a heavy traffic and that, when having determined that the selected path exhibits a heavy traffic, selects some of transport data as to-be-switched data and then switches the transmission path of the to-be-switched data to the communication path other than the selected path.

Description

Communication apparatus, communication system, and path switching method

The present invention relates to a communication apparatus in which two paths of a point-to-point active system and a standby system are set in advance with a communication partner apparatus, and a path switching method in the communication apparatus.

Protection that makes the end-to-end connection between two devices redundant and automatically switches to a backup path when a failure occurs as a technology to prevent communication interruption when a failure occurs in the communication path when communicating between the two devices There is a switching technology. For example, ITU-T (International Telecommunication Union Telecommunication Standardization Sector) Recommendation G. In the linear protection switching technique defined in 8031, two paths of an active system and a standby system between two devices corresponding to Ethernet (registered trademark) are set in advance, and the standby system path is automatically set when a failure occurs in the active system path. Switch to. By using such a linear protection switching technique, it is possible to continue the communication by switching the path even when a failure occurs in the communication between the two devices.

As a conventional technique for performing linear protection switching, for example, Patent Document 1 below discloses a path protection method capable of improving switching efficiency. In this method, when there is a plurality of traffic to be switched when a failure is detected at a certain location, the order of switching to the standby system can be specified and controlled for each traffic.

JP 2007-181010 A

However, the ITU-T recommendation G. In the linear protection switching technique defined in 8031, a VLAN (Virtual Local Area Network) set as a switching target is switched to a backup path when triggered by a failure detection or switching operation instruction. Therefore, even if the active route is congested and frame loss actually occurs, it is not possible to switch to the backup route until a failure is detected even for high priority traffic. Even in the case of occurrence, there was a problem that temporary communication interruption due to failure occurred. There is also a problem that frame loss due to congestion cannot be prevented.

In the method described in Patent Document 1, a plurality of VLANs are grouped and a switching order is set for each group, so that when a failure is detected, switching is performed in the set switching order, and priority is given. The VLAN group to be switched can be completed in a short time. However, even in the method described in Patent Document 1, the trigger for switching is failure detection. Therefore, ITU-T Recommendation G. Similar to the linear protection switching technique defined in 8031, there is a problem that a temporary communication interruption occurs due to a failure, and that a frame loss due to congestion cannot be prevented.

The present invention has been made in view of the above, and obtains a communication device, a communication system, and a route switching method capable of reducing congestion of a route in use without interruption of communication of high-priority traffic. For the purpose.

In order to solve the above-described problems and achieve the object, the present invention provides a communication device in which a plurality of communication paths are set with a facing communication device, and one of the communication paths is set. When the selected route is used and data transmission is performed using the selected route, the congestion determining unit that determines whether the selected route is congested and the congestion determining unit are configured so that the selected route is congested. Switching control means for selecting a part of the transmission data as switching target data and switching the transmission path of the switching target data to a communication path other than the selection path when it is determined that To do.

The communication device, the communication system, and the route switching method according to the present invention have an effect that congestion of a route in use can be reduced without communication interruption of high priority traffic.

FIG. 1 is a diagram illustrating a configuration example of a communication system according to the first embodiment. FIG. 2 is a diagram illustrating a functional configuration example of the communication apparatus according to the first embodiment. FIG. 3 is a diagram illustrating an example of usage route information. FIG. 4 is a diagram illustrating a configuration example of an Ethernet (registered trademark) frame. FIG. 5 is a diagram illustrating a configuration example of C-TAG TCI. FIG. 6 is a diagram illustrating a configuration example of S-TAG TCI and B-TAG TCI. FIG. 7 is a diagram illustrating a configuration example of the I-TAG TCI. FIG. 8 is a diagram illustrating an example of an active route and a standby route for each traffic. FIG. 9 is a flowchart illustrating an example of a route switching processing procedure according to the first embodiment. FIG. 10 is a diagram illustrating an example of use route information when a threshold is set for each priority. FIG. 11 is a diagram illustrating a configuration example of an APS protocol message (APS message) format. FIG. 12 is a diagram showing information included in the data format of the APS protocol. FIG. 13 is a sequence diagram illustrating an example of a route switching procedure when an APS message is used. FIG. 14 is a diagram illustrating a configuration example of an APS message storing priority information. FIG. 15 is a diagram illustrating another configuration example of an APS message storing priority information. FIG. 16 is a diagram illustrating a sequence example in the case of switching during congestion.

Hereinafter, embodiments of a communication device, a communication system, and a path switching method according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration example of a first embodiment of a communication system according to the present invention. As shown in FIG. 1, the communication system of this embodiment is an ITU-T G. The communication device 1 and the communication device 2 having a linear protection switching function defined in 8031, and

communication paths

3 and 4 are provided. The

communication paths

3 and 4 are communication paths set for communication between the communication apparatus 1 and the communication apparatus 2, and the communication path 3 is set as an active path and the communication path 4 is set as a backup path.

The communication flow from the communication device 1 to the communication device 2 is transferred using either the communication route 3 or the communication route 4. When the communication apparatus 1 and the communication apparatus 2 are directly adjacent to each other, the communication path 3 and the communication path 4 are each a single link. In the present embodiment, are the communication paths 3 and 4 a single link? It doesn't matter. It is assumed that a plurality of VLANs are set between the communication device 1 and the communication device 2.

Note that this embodiment is based on a communication system in which the transfer source side determines the transfer route, assuming that the transfer route does not matter whether or not the transfer route is the same route. Therefore, the communication device 1 that is the transfer source device has only to determine the transfer destination route, and the transfer destination communication device 2 does not obtain information on which route of the

communication routes

3 and 4 is transmitted in advance. However, a predetermined reception process is performed on the traffic input through one of the

communication paths

3 and 4. When communication in the direction from the communication device 2 to the communication device 1 is performed, the transfer destination communication device 2 has the same configuration as that of the communication device 1 according to the present embodiment, and the communication device 2 has the communication device 1 described below. What is necessary is just to perform operation | movement.

FIG. 2 is a diagram illustrating a functional configuration example of the communication device 1 according to the present embodiment. As shown in FIG. 2, the communication device 1 includes a communication interface 11, a transfer processing unit 12, a switching control unit 13, a failure monitoring unit 14, a traffic flow measurement unit 15, and a communication interface 16. The

The communication device 1 of the present embodiment is an ITU-T G. By implementing the linear protection switching function defined in 8031, switching when there is a failure when switching the route when there is a failure, and congestion when switching the route when it is determined that the destination route is congested even if no failure has occurred Perform both time-path switching.

The communication interface 11 includes ports 21-1 to 21-5, performs predetermined reception processing on the traffic input from the ports 21-1 to 21-5, and outputs the processed traffic to the transfer processing unit 12. To do. It is assumed that the communication interface 11 supports a link speed such as 10 Mbps / 100 Mbps / 1 Gbps used in Ethernet (registered trademark), and can measure a flow rate of traffic received by each port and detect a failure.

The communication interface 16 includes ports 22-1 to 22-5, performs predetermined transmission processing on the traffic output from the transfer processing unit 12, and sends the processed traffic from the ports 22-1 to 22-5. Output. The communication interface 16 is assumed to be compatible with a link speed such as 10 Mbps / 100 Mbps / 1 Gbps used in Ethernet (registered trademark), and can measure the flow rate of traffic transmitted by each port and detect a failure. In FIG. 2, each of the communication interface 11 and the communication interface 16 includes five ports. However, the number of ports is not limited to this, and the number of ports included in the communication interface 11 and the communication interface 16 is not limited thereto. But you can.

Here, the communication interface 11 is described as an input-side communication interface, and the communication interface 16 is described as an output-side communication interface. However, both the communication interface 11 and the communication interface 16 are both input-side and output-side communication. It may have a function as an interface.

The transfer processing unit 12 uses, as a transfer rule, the correspondence with the transfer destination port (any one of the ports 22-1 to 22-5) for each received VLAN identifier (or for each VLAN identifier and priority). Hold and perform transfer processing based on transfer rules.

The switching control unit 13 uses a VLAN identifier of a VLAN to be switched at the time of congestion and information for identifying whether to transfer traffic corresponding to the VLAN identifier using an active route or a standby route. The information is retained, the used route information is updated based on the failure information and the traffic flow information, and the transfer processing unit 12 is instructed to rewrite the transfer rule based on the used route information.

The traffic flow measurement unit 15 collects the traffic flow measurement results of the ports 22-1 to 22-5 of the communication interface 16, monitors whether the traffic flow exceeds the threshold, and the traffic flow exceeds the threshold. When a port is detected, the switch control unit 13 is notified of the port number and traffic flow rate with a predetermined threshold value. Note that the traffic flow measurement unit 15 obtains and holds threshold values corresponding to the ports 22-1 to 22-5 from the switching control unit 13 in advance.

The failure monitoring unit 14 detects the failure occurrence and recovery of each port 22-1 to 22-5 of the communication interface 16, and transmits the detected event (failure detection or recovery) to the switching control unit 13. It should be noted that detection of failure occurrence and recovery may be performed for each port or for each VLAN. As a method for detecting failure occurrence and recovery, an ETH-CC (ETHernet (registered trademark) Continuity Check) function defined by ITU-T recommendation Y.1731, or other methods may be used.

Next, the switching operation at the time of congestion in this embodiment will be described. FIG. 3 is a diagram illustrating an example of usage route information held by the switching control unit 13. As shown in FIG. 3, the usage path information includes, for each VLAN identifier, the working system port number (abbreviated as working system in the figure), threshold, highest priority, and standby system port number (in the figure, the standby system). A selection system (currently selected system: information on whether the active system path is selected as the transfer path or the backup system path is selected as the transfer path). Note that FIG. 3 is an example, and information similar to that shown in FIG. 3 may be stored as long as similar information is stored.

The active system port number indicates the identification number of the port to which the VLAN traffic is transferred (any one of the ports 22-1 to 22-5). For example, it is assumed that ports 22-1, 22-2,..., 22-5 correspond to port numbers # 1, # 2,. The transfer destination port corresponds to the transfer route, and the active port number indicates the port number when transferring to the active route. Similarly, the standby port number indicates the port number when forwarding to the standby path.

In the present embodiment, the switching control unit 13 switches the traffic path for each VLAN identifier and priority based on the VLAN identifier and priority information of the Ethernet (registered trademark) frame as switching during congestion. Suppose you want to switch between In other words, in the present embodiment, even when traffic with the same VLAN identifier has different priorities, the traffic is identified for each priority and the path is switched for each priority. For example, priority A traffic and priority B traffic (A ≠ B) with the same VLAN identifier are identified, and priority A traffic and priority B traffic are transferred to different transfer paths. Sometimes.

The threshold shown in FIG. 3 is a threshold for the traffic flow measurement unit 15 to determine whether or not it is congested, and is set for each VLAN. This threshold value may be set in any way. For example, a method of setting a small threshold value for a VLAN that performs communication of an application with a severe delay requirement may be considered. The switching control unit 13 obtains a minimum threshold value for each port based on the use route information, and notifies the traffic flow rate measurement unit 15 of the threshold value as a threshold value for each port.

The highest priority shown in FIG. 3 is the highest priority to be switched when the traffic flow exceeds the VLAN threshold. Based on the port number and traffic flow notified from the traffic flow measurement unit 15, the switching control unit 13 determines a VLAN whose traffic flow exceeds the threshold, and the traffic of the VLAN has a priority lower than the highest priority. The traffic transfer route is switched to a communication route other than the selected system. For the VLAN traffic whose traffic flow rate exceeds the threshold, the transfer route of the traffic with the priority exceeding the highest priority is left as the selection system. Generally, high priority traffic has severe demands for communication interruption. In the present embodiment, by switching the transfer route of traffic below a certain priority (highest priority) to a communication route other than the selection system, it is possible to reduce the congestion of the selection system while preventing communication interruption of high priority traffic. Can be resolved. Here, it is assumed that the higher the priority value, the higher the priority.

Here, the traffic flow measurement unit 15 notifies the switching control unit 13 of the port number and the traffic flow when the traffic flow exceeds the threshold for each port. Not limited to. For example, the traffic flow measurement unit 15 may not have a threshold value, and periodically notify the switching control unit 13 of the port number and the traffic flow rate.

In this embodiment, for example, priority information (PCP: Priority Code Point) in a VLAN tag stored in an Ethernet (registered trademark) frame is used to determine the priority of traffic. 4 to 7 are diagrams showing examples of priority information used for determining the priority of traffic.

FIG. 4 is a diagram illustrating a configuration example of an Ethernet (registered trademark) frame. The Ethernet (registered trademark) frame includes information of DA (Destination Address) / SA (Source Address), Type indicating the type of frame, and TCI (Tag Control Information). When Type is “81-00”, C-TAG TCI (Customer VLAN Tag Control Information) is used as TCI. When Type is “88-a8”, S-TAG TCI (Service VLAN Tag Control Information) or TCI is used. B-TAG TCI (Backbone VLAN Tag Control Information) is used. When Type is “88-e7”, I-TAG TCI (Backbone Service Instance VLAN Tag Control Information) is used as TCI.

FIG. 5 is a diagram showing a configuration example of C-TAG TCI. As shown in FIG. 5, C-TAG TCI includes PCP, CFI (Canonical Format Indicator), and VID (VLAN Identifier). In the case of a frame including C-TAG TCI, the priority of each traffic is determined using this PCP as priority information.

FIG. 6 is a diagram showing a configuration example of S-TAG TCI and B-TAG TCI. As shown in FIG. 6, the S-TAG TCI and the B-TAG TCI include PCP, DEI (Drop Eligible Indicator), and VID. In the case of a frame including S-TAG TCI or B-TAG TCI, the priority of each traffic is determined using this PCP as priority information.

FIG. 7 is a diagram showing a configuration example of I-TAG TCI. As shown in FIG. 7, I-TAG TCI includes I-PCP, I-DEI, UCA (Use Customer Address), I-SID (Backbone Service Instance Identifier), and C-DA (Encapsulated Customer Destination Address). ) And C-SA (Encapsulated Customer Source Address). In the case of a frame including I-TAG TCI, the priority of each traffic is determined using this IPCP as priority information. Note that the priority information described above is an example, and the present invention is not limited to this, and other information may be used as the priority information.

FIG. 8 is a diagram illustrating an example of the active route and the standby route of each traffic based on the used route information illustrated in FIG. The traffic 31 in FIG. 8 indicates traffic with the VLAN identifier # 5, the traffic 32 indicates traffic with the VLAN identifier # 7, and the traffic 33 indicates traffic with the VLAN identifier # 10. Further, the solid line in FIG. 8 indicates the active system, and the dotted line indicates the standby system.

As shown in FIG. 8, for example, the communication device 1 transfers the traffic 31 that is the traffic with the VLAN identifier # 5 to the port # 2 when the active route is selected, and selects the standby route. If so, transfer to port # 4. In the example of FIG. 3, since the selected system with the VLAN identifier # 5 is the active system, the traffic 31 is transferred to the port # 2.

For VLANs in which the selection system is not congested (traffic flow rate does not exceed the threshold), all priority traffic is transferred to the ports corresponding to the selection system.

Therefore, the transfer processing unit 12 only needs to maintain the correspondence between the VLAN identifier and the transfer destination port as a transfer rule for a VLAN that is not congested in the selection system, but congestion occurs in the selection system. For the existing VLAN, information on the transfer destination port is held for each priority information. The transfer processing unit 12 rewrites the transfer rule based on an instruction from the switching control unit 13.

FIG. 9 is a flowchart illustrating an example of a route switching processing procedure according to the present embodiment. First, the switching control unit 13 determines whether or not a failure detection notification has been received from the failure monitoring unit 14 (step S1). When a failure detection notification is received from the failure monitoring unit 14 (Yes in step S1), a VLAN that uses a port in which a failure is detected based on the use path information (uses that port as a standby system or an active system) is used. It discriminate | determines (step S2). For example, when the use route information illustrated in FIG. 3 is held and a failure is detected at port # 2, it is determined that the VLANs using the port are VLAN # 5 and VLAN # 7. .

Next, the switching control unit 13 determines whether or not there is an unprocessed VLAN (the following steps S4 to S7 are not performed) among the determined VLANs (step S3), and there is no unprocessed VLAN. If so (No at step S3), the process returns to step S1. If there is an unprocessed VLAN (Yes in step S3), for the unprocessed VLAN (or any one of the unprocessed VLANs), the failure notified in step S1 corresponds to that VLAN. It is determined whether or not the failure corresponds to the backup transfer path (step S4).

If it is determined in step S4 that the failure corresponds to the backup transfer path of the standby system (Yes in step S4), the switching control unit 13 updates the use path information with the selected system of the VLAN as the active system (step S5). The transfer processing unit 12 is instructed to rewrite the transfer rule with the transfer destination of the VLAN as the port corresponding to the working path, and the transfer processing unit 12 rewrites the transfer rule based on the instruction (step S7), and step S3. Return to.

If it is determined in step S4 that the failure does not correspond to the transfer path of the backup system (No in step S4), the switching control unit 13 updates the use path information with the selected system of the VLAN as the backup system, and the VLAN The transfer processing unit 12 is instructed to rewrite the transfer rule with the transfer destination as the port corresponding to the backup route, and the transfer processing unit 12 rewrites the transfer rule based on the instruction (step S7), and returns to step S3.

The above processing at the time of failure occurrence (steps S1 to S7) is the same as the conventional one. Same as 8031. In the case of failure recovery, ITU-T Recommendation G. The same operation as 8031 is performed.

On the other hand, if it is determined in step S1 that a failure detection notification has not been received from the failure monitoring unit 14 (No in step S1), the switching control unit 13 determines that the traffic flow rate and port that exceeded the threshold from the traffic flow measurement unit 15 It is determined whether or not a number has been notified (whether or not an overthreshold has been detected) (step S9), and if the traffic flow and port number that have exceeded the threshold have not been notified (No in step S9), the process returns to step S1. .

If it is determined in step S9 that the traffic flow exceeding the threshold and the port number have been notified (Yes in step S9), the switching control unit 13 determines the threshold based on the notified traffic flow, port number, and usage route information. VLANs that exceed are determined (step S10).

The switching control unit 13 determines whether or not there is an unprocessed VLAN (the following steps S12 to S14 are not performed) among the VLANs determined in step S10 (step S11). If not (No at Step S11), the process returns to Step S1. When there is an unprocessed VLAN (step S11, Yes), the switching control unit 13 determines the unprocessed VLAN (or one of the unprocessed VLANs when there are a plurality of unprocessed VLANs) based on the use route information. It is determined whether or not the port corresponding to the VLAN selection system exceeds the threshold (step S12). For example, it is assumed that the usage route information shown in FIG. 3 is held, and that traffic flow of 80% of the physical bandwidth is measured at port # 2. In this case, the active port # 2 is used as a selection system and VLAN # 5 is set with a threshold of 60%, and the active port # 2 is used as a selection system and a threshold of 80% is set. For VLAN # 7, it is determined that the port corresponding to the VLAN selection system exceeds the threshold.

If it is determined in step S12 that the port corresponding to the VLAN selection system does not exceed the threshold value (No in step S12), the process returns to step S11. If it is determined in step S12 that the port corresponding to the VLAN selection system has exceeded the threshold (Yes in step S12), the highest priority of the VLAN is acquired based on the use route information, and the maximum priority or lower is obtained. A transfer rule for transferring the traffic to the non-selection system is generated (step S13). Then, the transfer processing unit 12 is instructed to update the transfer rule to the generated transfer rule, and the transfer processing unit 12 updates the transfer rule based on the instruction (step S14).

For example, if the use route information shown in FIG. 3 is held, and if traffic flow of 80% of the physical bandwidth is measured at port # 2, it is determined in step S13 that the threshold is exceeded in VLAN # 5. In step S14, a transfer rule is generated so that traffic having a priority of 6 or lower corresponding to VLAN # 5 is transferred to port # 4, which is a standby system.

As described above, in the present embodiment, for a VLAN in which the traffic flow rate exceeds the threshold value in the selected system, traffic having a priority or lower is switched to a non-selected system path. Therefore, it is possible to keep the traffic flow of the selected system low without adversely affecting the high priority traffic such as a communication interruption due to switching.

Note that when the above switching at the time of congestion is performed, monitoring of the traffic flow is continued, the congestion of the ports 22-1 to 22-5 that has exceeded the threshold is eliminated, and the traffic flow is reduced to a predetermined value or less. In such a case, it may be possible to return to a state before switching at the time of congestion (transmission of traffic of all priorities through the route that was the selection system before switching at the time of congestion).

In the present embodiment, the switching control unit 13 is also provided with a function of a congestion determination unit that determines whether the route of the selected system is congested. However, the congestion determination unit is separated from the switching control unit 13. You may make it prepare. In this case, the congestion determination unit performs the processing from step S1 to step S12 based on the usage route information, and the switching control unit 13 performs the processing of steps S13 and S14 based on the usage route information.

Also, here, it is assumed that the higher the priority, the severer the request for communication disconnection, and the traffic below a certain priority for a VLAN whose traffic flow exceeds the threshold in the selected system is switched to a non-selected system path. However, for example, there is a case where there is severe traffic demand for communication interruption even in low priority communication. In order to cope with such a case, a threshold value may be set for each priority level to determine whether to perform switching.

FIG. 10 is a diagram illustrating an example of use route information when a threshold is set for each priority. When setting a threshold value for each priority, for example, as shown in FIG. 10, the active system port number, threshold value, standby system port number, and selection system information are stored for each VLAN and priority level. In step S10, the combination of the VLAN exceeding the threshold and the priority is determined. Then, the following steps S11 to S14 are performed for each combination of VLAN and priority.

Note that the method of determining switching using the highest priority illustrated in FIG. 3 can also be considered as an example of a method of determining whether to perform switching for each priority. For example, as the usage route information in the format shown in FIG. 10, VLANs and entries with a priority lower than the highest priority are stored, and the same value that does not depend on the priority is set as the threshold. It is possible to perform the same operation as when using.

In this embodiment, when the selection system is congested, the traffic is distributed to the selection system and the non-selection path using the priority. However, the present invention is not limited to this. Traffic may be distributed using criteria.

In the present embodiment, when the selection system is congested, the route is switched based on the priority of traffic. However, when a failure occurs, the route can be switched using the priority. For example, in the case where the usage route information shown in FIG. 3 is retained, if a failure occurs in the active route, the traffic exceeding the highest priority is discarded without transferring the traffic data below the highest priority without transferring it. Is switched to the backup path and transferred. Specifically, in step S6 of FIG. 9, when the selected system is set as the backup system, the traffic exceeding the highest priority is switched to the backup path, and the traffic data below the highest priority is transferred so as to be discarded. Generate rules. By doing so, a route having a low communication capacity can be used as the standby communication route. When both the above-described switching at the time of mixing and path switching using the priority at the time of failure occurrence are performed, the highest priority corresponding to each may be set separately.

In this embodiment, whether or not the selection system is congested is determined based on the traffic flow rate for each port. However, when the occurrence of congestion can be detected by another means such as detection of a delay time. Alternatively, it may be determined whether or not it is crowded by other means.

In this embodiment, the case where a plurality of VLANs are set has been described as an example. However, if two communication paths of the active system and the standby system are set, no VLAN is set. The switching method at the time of congestion of the present embodiment can also be applied to a communication system. In this case, since the VLAN tag value cannot be used as the priority information, the traffic whose path is switched to the non-selected system is selected using other priority information.

In addition, when two or more routes are set in advance, the switching method at the time of congestion of this embodiment may be applied. In this case, although there are a plurality of routes other than the selected system, one of them may be used as a forwarding route for traffic with the highest priority or lower, and two or more routes may be used for traffic with the highest priority or lower. It may be used as a transfer path.

As described above, in the present embodiment, the switching control unit 13 holds the use route information storing the threshold for the traffic flow of the selected system for each VLAN and the priority for switching to the non-selected system when the threshold is exceeded. Then, the path switching is instructed based on the used path information and the traffic flow rate for each port, and the transfer processing unit 12 performs the transfer on the switched path according to the path switching instruction. For this reason, it is possible to reduce the congestion of the selected route (route in use) without disconnecting high-priority traffic.

Embodiment 2. FIG.
Next, a route switching method according to the second embodiment of the present embodiment will be described. The configuration of the communication system of the present embodiment is the same as that of the first embodiment. Further, the configuration of the communication apparatus 1 of the present embodiment is the same as that of the first embodiment. Components having the same functions as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and description thereof is omitted.

In Embodiment 1, the method of switching the one-way communication path from the communication device 1 to the communication device 2 has been described. In the present embodiment, when bidirectional communication is performed between the communication device 1 and the communication device 2 and between the communication device 2 and the communication device 1, the same route (however, the direction is opposite) is used in both directions. Will be described. In the present embodiment, the communication device 2 has the same configuration as the communication device 1. In the case of setting a route for each direction in bidirectional communication, the communication device 1 and the communication device 2 may perform the operation of the first embodiment.

When the same route is used in both directions, when the communication device 1 switches the route, it is necessary to notify the communication device 2 of the VLAN and the priority of which the route has been switched. Then, the communication device 2 sets a route for transferring data to the communication device 1 based on the notification. Any method may be used as this notification method. Here, for example, ITU-T G. The following description will be given by taking as an example the case of using the APS (Automatic Protection Switching) protocol defined in 8031.

FIG. 11 is a diagram illustrating a configuration example of an APS protocol message (APS message) format. FIG. 12 is a diagram showing information included in the data format of the APS protocol. As shown in FIG. 11, the data used by the APS protocol includes Request / State, Protection Type indicating the type of protection, Requested Signal, and Bridged Signal.

FIG. 12 is a diagram showing the value and meaning of each item in the format of the APS message shown in FIG. FIG. 13 is a sequence diagram illustrating an example of a route switching procedure when an APS message is used. FIG. 13 shows a switching procedure when a failure occurs, and this procedure is the same as the conventional linear protection switching technique.

NR in FIG. 13 indicates an APS message in which NR (No Request) is set in Request / State, and SF indicates an APS message in which SF (Signal Fail) is set in Request / State. R / b is an abbreviation for Request / Bridged Signal.

FIG. 13 shows an example in which two communication devices, WEST and EAST, are performing bidirectional communication. WEST and EAST have the same configuration as that of communication apparatus 1 shown in the first embodiment. However, in the first embodiment, the path switching at the time of transmission is controlled, but in this embodiment, since the same path is used in both directions, the transmission path is changed. Then, the reception path is changed as well. In the present embodiment, the communication interface 16 has a transmission / reception function, and the switching control unit 13 also controls switching of the reception path (from which port of the communication interface 16 is received), and reception is performed on the selected path. Generate a transfer rule to

SEL in FIG. 13 shows the state of the selector for switching the reception path between the active system and the standby system, the white part shows the state of receiving from the active system, and the filled part is received from the standby system It shows the state. BRG indicates the state of the bridge that switches the transmission path between the active system and the standby system, the white part indicates the state of transmission to the active system, and the filled part transmits to the standby system Indicates the state. Further, SEL and BRG shown on the left side indicate the WEST state, and SEL and BRG shown on the right side indicate the EAST state. Here, it is assumed that the switching control unit 13 performs APS protocol processing. That is, the switching control unit 13 performs processing (switching processing and the like) according to the APS protocol when the switching control unit 13 generates an APS message and receives the APS message. The generated APS message is transmitted via the transfer processing unit 12 and the communication interface, and is received by the switching control unit 13 via the transfer processing unit 12 and the communication interface.

In the initial state of FIG. 13, it is assumed that the working communication path is used in both the west-to-east direction and the east-to-west direction. WEST and EAST each periodically transmit an APS message (APS periodic transmission) to the counterpart device (steps S21 and S22). In the case where no failure has occurred and the working communication path is used, the EST and the EAST are NR (r / b = null) indicating that nothing is transmitted / received in the backup system as a periodic APS message. Send a message. The NR (r / b = null) message is an APS message in which NR is set in Request / State and Request and Bridged Signal are set as Null Signal.

Next, it is assumed that a communication disconnection in one direction (from WEST to EAST) occurs in the active communication path. When detecting the communication disconnection, the EAST switches its own route (transmission / reception route) to the standby system and transmits an APS message (step S23). This APS message is transmitted as an SF (r / b = normal) message indicating that Signal Fail (communication disconnection) is detected and transmitted / received in the standby system (step S24). The SF (r / b = normal) message is an APS message in which SF is set in Request / State, and Request and Bridged Signal are set as Normal Traffic Signal.

WEST transmits an NR (r / b = null) message as a regular transmission until it is notified even after EAST detects a one-way communication disconnection (step S25). When the WEST receives the SF (r / b = normal) message, the WEST switches the transmission / reception route of its own station to the standby system (step S26). Then, the EST is an NR (r / b = normal) message indicating that transmission / reception is performed in the standby system in response to a request from the opposite device (EAST) although it is a No Request (the communication is not detected by the own station). Is transmitted (step S27).

WEST transmits an NR (r / b = normal) message in the subsequent APS periodic transmission (step S29). In addition, the EAST transmits an SF (r / b = normal) message as APS regular transmission (steps S28 and S30).

Note that, for the Protection Type in the APS message used in the above process, a value according to the switching method set in the communication system is set. Since the present embodiment is premised on two-way communication (communication that requires a route agreement with the opposite device), the value corresponding to the two-way communication is set in Protection Type. Further, since the path switching is performed for each VLAN, the above steps S21 to S30 are performed for each VLAN.

Next, route switching at the time of congestion according to the present embodiment will be described. In this embodiment, since communication is bidirectional, when the communication device 1 on the transmission side selects a route for each traffic based on the priority information at the time of congestion as described in the first embodiment, the opposite device also receives traffic. Each time the transmission path is switched so that the same path (direction is reversed) is obtained. Therefore, in the present embodiment, the switching control unit 13 of the communication device 1 notifies priority information used as a reference for switching to the opposite device to the opposite route. Here, the case where the communication apparatus 1 communicates with the communication apparatus 2 as illustrated in FIG. 1 will be described as an example.

In this embodiment, priority information is stored in an APS message and transmitted. FIG. 14 is a diagram illustrating a configuration example of an APS message storing priority information. In the APS message shown in FIG. 14, a part of the Reserved area of the APS message shown in FIG. 11 is used as the priority information area. In FIG. 14, it is assumed that PCP (or I-PCP) included in the VLAN tag is used as priority information as exemplified in the first embodiment, and a new area for storing PCP is defined. Then, the PCP value corresponding to the highest priority described in the first embodiment is stored in this area. The priority information stored in the APS message is not limited to PCP, and any information may be used as long as the priority information is agreed in advance with the opposite device. The Request / State of the APS message that stores the priority information may be defined by using a value indicating that switching at the time of congestion is being performed, or an existing value such as SF may be used. Good. r / s may be used even if a corresponding value is defined during switching at the time of congestion. For example, Normal Traffic Signal may be used.

Since the APS message is sent for each VLAN, the communication device 1 on the APS message transmission side stores the highest priority corresponding to the VLAN and transmits the APS message. When the communication device 1 on the transmission side performs switching at the time of congestion (both the standby system and the active system are used), the PCP is stored in the APS message and transmitted, and the standby system or the active system is transmitted as in the past. When transmission is performed only through one of the routes of the system, PCP is not stored in the APS message. Thereby, the communication apparatus 2 can obtain information on whether or not the opposite communication apparatus 1 is performing transmission by switching at the time of congestion and the highest priority. Note that the communication device 1 separately notifies whether or not switching is performed during congestion (uses both the standby system and the active system), and always stores the PCP in the APS message. Also good.

When the communication device 2 recognizes that the opposite communication device 1 is performing transmission by switching at the time of congestion, congestion has occurred in the route of the selection system for transmission (route used for transmission) at that time. And the same processing as that in step S13 and step S14 described in the first embodiment is performed. At this time, the highest priority to be referred to is the PCP notified by the APS message. In step S14, the transfer rule is updated, and the communication device 2 transmits traffic of each priority through a transmission route opposite to the transmission route from the communication device 1. When the communication device 2 detects congestion, the operation similar to that of the communication device 1 is performed, and the communication device 1 performs the same operation as that of the communication device 2 described above.

FIG. 15 is a diagram showing another configuration example of an APS message storing priority information. In FIG. 14, the PCP corresponding to the highest priority is stored in the APS message, but in the example of FIG. 15, the priority (switching target priority) corresponding to the traffic to be switched (transmitted in the non-selection system) is set to APS. Store in message. As illustrated in FIG. 10 of the first embodiment, when a threshold value is set for each priority level, when switching is performed at the time of congestion, for example, the priority level transmitted in a non-selected system is communicated in the format of FIG. The device 2 can be notified.

In addition, although the example which stores and notifies priority information in an APS message was demonstrated here, priority information may be notified not only by this method but by what kind of method.

FIG. 16 is a diagram illustrating an example of a sequence in the case of switching during congestion. In FIG. 16, WEST and EAST are communication apparatuses similar to the communication apparatus 1. Here, during the congestion switching, a value indicating that the APS message Request / State is being switched is used (in the following description, this value is referred to as CON). In FIG. 16, the SEL and BRG fill portions are periods during which communication using both the standby system and the active system is performed.

WEST and EAST perform APS regular transmission as in the example of FIG. 13 (steps S21 and S22). Therefore, when the EAST detects the congestion due to the traffic flow rate of a certain port exceeding the threshold value, the VLAN using that port as the selection system (set as a switching target VLAN) according to the procedure described in the first embodiment. Is switched to a non-selection route (step S31).

Then, the EAST transmits an APS message (CON (priority)) indicating that the switching at the time of congestion storing the highest priority is being performed for each switching target VLAN (step S32). Step S25 is similar to the example of FIG. When receiving the APS message indicating that switching at the time of congestion is being performed, the WEST switching control unit 13 performs switching so that traffic below the highest priority is transmitted in a non-selected system based on the highest priority (step S33). ). In this case, the WEST switching control unit 13 performs path switching based on an instruction from the EAST. Therefore, WEST also has a function as instruction switching control means for switching a route based on an instruction including the highest priority notified from EAST when EAST detects congestion.

Steps S27 and S29 are the same as in the example of FIG. Note that, here, NR (r / b = normal) is transmitted even when switching is performed by the notification during switching of the opposite device during congestion, but by notification during switching of the opposite device during congestion. A value indicating that the switching is performed may be separately determined and an APS message storing the value may be transmitted. In addition, the EAST transmits CON (priority) as APS regular transmission (steps S34 and S35).

Note that when the congestion is resolved and the transmission is switched to the transmission of only the normal standby system or the active system only, the EAST notifies the fact using the APS message.

As described above, in this embodiment, when performing bidirectional communication, when switching during congestion is performed as in Embodiment 1, the switching control unit 13 stores the highest priority in the APS message. I sent it. Then, the opposite device switches the transmission path based on the highest priority stored in the received APS message. Therefore, even when the round-trip transfer paths are the same, congestion of the working path can be reduced without interruption of traffic with high priority traffic.

As described above, the communication apparatus, the communication system, and the path switching method according to the present invention provide a communication apparatus in which two paths of a point-to-point active system and a standby system are set in advance with a communication partner apparatus. It is useful and is particularly suitable for communication devices that transfer traffic of various priorities.

DESCRIPTION OF

SYMBOLS

1, 2

Communication apparatus

3, 4 Communication path 11, 16 Communication interface 12 Transfer processing part 13 Switching control part 14 Fault monitoring part 15 Traffic flow measurement part

Claims

A communication device that sets a plurality of communication paths with a facing communication device,
One of the communication paths is a selected path, and when data transmission is performed using the selected path, a congestion determination unit that determines whether the selected path is congested;
When the congestion determination unit determines that the selected route is congested, a part of transmission data is selected as switching target data, and the transmission route of the switching target data is a communication route other than the selected route. Switching control means for switching to,
A communication apparatus comprising:
Failure detection means for detecting a failure in the communication path;
Further comprising
The switching control means switches the transmission path of transmission data to the communication path other than the selected path when the fault detecting means detects a fault on the selected path.
The communication apparatus according to claim 1.
The switching control means selects the switching target data based on a priority included in transmission data.
The communication apparatus according to claim 1 or 2, wherein
The switching control means holds a predetermined highest priority and selects transmission data corresponding to a priority equal to or lower than the highest priority as the switching target data.
The communication apparatus according to claim 3.
The congestion determination unit determines that the selected route is congested when the traffic flow of the selected route exceeds a predetermined threshold.
The communication apparatus according to claim 4.
The congestion determination means holds a traffic flow rate threshold for each predetermined priority, and when the traffic flow of the selected route exceeds the threshold corresponding to the priority of transmission data, the transmission data is switched to Select as target data,
The communication apparatus according to claim 3.
Assume that multiple communication paths are set for each VLAN.
The congestion determination means determines whether the selected route is congested for each VLAN,
The switching control means switches the transmission path for each VLAN.
The communication apparatus according to claim 1 or 2, wherein
Assume that multiple communication paths are set for each VLAN.
The congestion determination means determines whether the selected route is congested for each VLAN,
The switching control means switches the transmission path for each VLAN.
The communication apparatus according to claim 3.
The switching control means holds a highest priority predetermined for each VLAN, and selects transmission data corresponding to a priority equal to or lower than the highest priority as the switching target data.
The communication apparatus according to claim 8.
The congestion determination unit holds a predetermined threshold of traffic flow for each VLAN, and determines that the selected route is congested when the traffic flow of the selected route exceeds a predetermined threshold for each VLAN. To
The communication apparatus according to claim 9.
The congestion determination unit holds a traffic flow rate threshold value for each predetermined combination of VLAN and priority, and the traffic flow rate of the selected route exceeds the threshold value corresponding to the combination of VLAN and priority of transmission data. In this case, the transmission data is selected as the switching target data.
The communication apparatus according to claim 10.
The priority is set to PCP of a VLAN tag.
The communication device according to any one of claims 8 to 11, wherein:
The switching control means transmits the highest priority to the opposing communication device;
The communication device according to any one of claims 4, 5, 9, and 10.
The switching control means transmits the priority of the transmission data selected as the switching target data to the facing communication device.
The communication apparatus according to claim 6 or 11, wherein
The switching control means, when receiving the highest priority used by the opposing communication device for switching the transmission path from the opposing communication device, the transmission corresponding to the priority below the received highest priority Selecting data as the switching target data,
The communication apparatus according to claim 13.
The switching control means, when receiving the priority used by the opposing communication device for switching the transmission path from the opposing communication device, transmits the transmission data corresponding to the received priority to the switching target data Select as the
The communication device according to claim 14.
A first communication device and a second communication device facing the first communication device, wherein a plurality of communication paths are set between the first communication device and the second communication device. A communication system for performing bidirectional communication,
The first communication device is:
One of the communication paths is a selected path, and when transmitting and receiving data using the selected path, a congestion determination unit that determines whether the selected path is congested;
When the congestion determination unit determines that the selected route is congested, a part of transmission data is selected as switching target data, and the transmission route of the switching target data is a communication route other than the selected route. Switching control means for transmitting the predetermined condition used for selecting the switching target data to the second communication device;
With
The second communication device is:
When the predetermined condition is received from the first communication device, a part of transmission data is selected as instruction switching data based on the predetermined condition, and a transmission path of the instruction switching data is selected as the selection path Instruction switching control means for switching to a communication path other than
Comprising
A communication system characterized by the above.
A path switching method in a communication apparatus in which a plurality of communication paths are set between opposite communication apparatuses,
A congestion determination step for determining whether or not the selected route is congested when one of the communication routes is a selected route and data transmission is performed using the selected route;
If it is determined in the congestion determination step that the selected route is congested, a part of the transmission data is selected as switching target data, and the transmission route of the switching target data is a communication route other than the selected route A switching control step for switching to
A path switching method comprising:
A first communication device and a second communication device facing the first communication device, wherein a plurality of communication paths are set between the first communication device and the second communication device. A path switching method in a communication system for performing bidirectional communication,
Whether or not the selected route is congested when the first communication device uses one of the communication routes as a selected route and transmits and receives data using the selected route. A congestion determination step for determining;
When the first communication device determines that the selected route is congested in the congestion determination step, the first communication device selects a part of the transmission data as switching target data, and transmits the switching target data transmission route. Switching control step of switching to a communication path other than the selected path, and transmitting a predetermined condition used for selecting the switching target data to the second communication device;
When the second communication device receives the predetermined condition from the first communication device, the second communication device selects a part of transmission data as instruction switching data based on the predetermined condition, and the instruction switching An instruction switching control step for switching a data transmission path to a communication path other than the selected path;
including,
A path switching method characterized by that.