JP7127481B2 - Communication system, communication device, and communication method - Google Patents

Description

The present invention relates to a communication system, communication device, and communication method.

Control protocols are known for controlling communications between communication devices. Examples of control protocols include Link OAM (Operations, Administration, Maintenance), LACP (Link Aggregation Control Protocol), ETH-OAM (Ethernet OAM), and MQTT (Message Queuing Telemetry Transport).

Many control protocols define a timeout that disconnects a session if no data is received from the opposite device for a certain period of time. When a timeout occurs, data transfer between communication devices stops. Therefore, it is desirable not to cause a timeout when it is not necessary.

In Non-Patent Document 1, processors that process control protocols are configured redundantly, and even if one processor becomes unusable due to a failure or the like, another processor continues data transfer without disconnecting the session. A system is disclosed that can.

Cisco NSF/SSO (Nonstop Forwarding/Stateful Switchover) Introduction Guide, [online], [searched on October 11, 2018], Internet <https://www.cisco.com/web/JP/product/ hs/switches/cat6500/prodlit/nfssdg_dg.html>

However, the system disclosed in Non-Patent Document 1 has a problem that the configuration is complicated.

The present disclosure includes the following inventions. However, the present invention is defined by the claims.

A communication system according to an aspect of the present invention comprises a first communication device and a second communication device, wherein the first communication device, during a control protocol session with the second communication device, a determination unit that determines whether or not a cause for stopping communication with the second communication device according to the control protocol occurs in the first communication device; and a timeout when the determination unit determines that the cause occurs. a transmission unit that transmits extension request data for requesting an extension of time, wherein the second communication device includes a reception unit that receives the extension request data transmitted by the first communication device; and a setting unit configured to change a setting from a first timeout period to a second timeout period longer than the first timeout period when the extension request data is received by the receiving unit.

A communication device according to an aspect of the present invention is a communication device that performs communication with a counterpart communication device according to a control protocol, wherein during a session of the control protocol with the counterpart communication device, a determination unit for determining whether or not a cause for stopping communication with a communication device occurs in the own device; and an extension request for requesting an extension of the timeout period when the determination unit determines that the cause occurs. and a transmission unit that transmits data to the counterpart communication device.

A communication device according to an aspect of the present invention is a communication device that performs communication with a counterpart communication device according to a control protocol, wherein during a session of the control protocol with the counterpart communication device, a message is transmitted by the counterpart communication device. a receiving unit for receiving extension request data for requesting extension of the timeout period, and when the extension request data is received by the receiving unit, from the first timeout period to the first timeout period a setting unit for changing the setting to a longer second timeout period.

A communication method according to an aspect of the present invention is a communication method in which a first communication device and a second communication device communicate according to a control protocol, wherein the first communication device communicates with the second communication device a step of determining whether or not a cause for stopping communication with the second communication device by the control protocol occurs in the first communication device during the session of the control protocol of; a step of transmitting extension request data for requesting extension of the timeout period when it is determined that a cause has occurred; and the second communication device receiving the extension request data transmitted by the first communication device. and changing the setting from a first timeout period to a second timeout period longer than the first timeout period when the second communication device receives the extension request data.

The present invention can be realized not only as a communication device having the characteristic processing unit as described above, but also as a communication method having steps of such characteristic processing, and for causing a computer to execute such steps. can be implemented as a computer program. Moreover, part or all of the communication device can be implemented as a semiconductor integrated circuit, or a communication system including the communication device can be implemented.

ADVANTAGE OF THE INVENTION According to this invention, the disconnection of the session by timeout generation|occurrence|production can be avoided, while making a communication system a simple structure.

It is a figure which shows an example of a structure of the communication system which concerns on embodiment. 4 is a block diagram showing an example of the internal configuration of a master station device; FIG. 4 is a block diagram showing an example of a hardware configuration of a controller in the master station device; FIG. FIG. 4 is a schematic diagram showing the format of an Information OAM frame; 4 is a block diagram showing an example of an internal configuration of a slave station device; FIG. 4 is a block diagram showing an example of a hardware configuration of a control unit in a child station device; FIG. 9 is a flowchart showing the procedure of timeout time control processing by the communication system according to the embodiment; FIG. 2 is a schematic diagram showing the format of an LACP frame; FIG. FIG. 4 is a schematic diagram showing the format of a VSM frame; FIG. 13 is a diagram showing an example of a configuration of a communication system according to a third modified example; FIG. FIG. 4 is a schematic diagram showing the format of a CONNECT packet;

<Overview of Embodiments of the Present Invention>
Hereinafter, the outline of the embodiments of the present invention will be listed and described.
(1) A communication system according to the present embodiment includes a first communication device and a second communication device, and the first communication device, during a control protocol session with the second communication device, a determination unit for determining whether or not the first communication device causes the communication with the second communication device to stop according to the control protocol; and when the determination unit determines that the cause occurs, a transmission unit that transmits extension request data for requesting extension of the timeout period, wherein the second communication device includes a reception unit that receives the extension request data transmitted by the first communication device; a setting unit configured to change a setting from a first timeout period to a second timeout period longer than the first timeout period when the extension request data is received by the receiving unit. As a result, the timeout period can be extended before a cause for stopping communication with the second communication device occurs. Therefore, it is possible to avoid disconnection of a session due to the occurrence of a timeout while simplifying the configuration of the communication system.

(2) Further, in the communication system according to the present embodiment, the extension request data may include an area specifying the second timeout period as the timeout period after extension. This allows an arbitrary second timeout period to be specified in the first communication device.

(3) Further, in the communication system according to the present embodiment, the transmission unit transmits shortening request data requesting reduction of the timeout period after the setting of the second timeout period is changed, and the setting unit may change the setting from the second timeout period to a timeout period shorter than the second timeout period when the shortening request data is received by the receiving unit. As a result, the extended timeout period can be shortened.

(4) Further, in the communication system according to the present embodiment, the shortening request data may include an area specifying a timeout period after shortening. As a result, an arbitrary shortened timeout period can be specified in the first communication device.

(5) Further, in the communication system according to the present embodiment, when the second timeout period is set, the setting unit sets a timeout period shorter than the second timeout period after the timeout occurs. You can change it. As a result, the extended timeout period can be shortened after timeout occurs.

(6) Further, in the communication system according to the present embodiment, the transmission unit requests reduction of the timeout period when an abnormality occurs due to the cause after the setting of the second timeout period is changed. Shortening request data is transmitted, and when the shortening request data is received by the receiving unit, the setting unit may change the setting from the second timeout period to a shorter timeout period than the second timeout period. good. This makes it possible to shorten the extended timeout period when an abnormality occurs as a cause for stopping communication and communication is no longer stopped.

(7) Further, in the communication system according to the present embodiment, the cause may be update of a control program in the first communication device. As a result, even if communication is stopped while updating the control program, disconnection of the session due to the occurrence of timeout can be avoided.

(8) In the communication system according to the present embodiment, the control protocol includes Link OAM (Operations, Administration, Maintenance), LACP (Link Aggregation Control Protocol), ETH-OAM (Ethernet OAM), MQTT (Message Queuing Telemetry Transport). As a result, in at least one of Link OAM, LACP, ETH-OAM, and MQTT, it is possible to avoid session disconnection due to the occurrence of a timeout.

(9) A communication device according to the present embodiment is a communication device that performs communication with a counterpart communication device using a control protocol, wherein during a session of the control protocol with the counterpart communication device, the a determination unit for determining whether or not a cause for stopping communication with the opposite communication device occurs in the own device; and an extension for requesting an extension of the timeout period when the determination unit determines that the cause occurs. and a transmitting unit configured to transmit request data to the counterpart communication device. As a result, the timeout period can be extended before a cause for stopping communication with the counterpart communication device occurs. Therefore, it is possible to avoid disconnection of a session due to the occurrence of a timeout while simplifying the configuration of the communication system.

(10) A communication device according to the present embodiment is a communication device that performs communication with a counterpart communication device according to a control protocol, wherein during a session of the control protocol with the counterpart communication device, a receiving unit for receiving the transmitted extension request data for requesting extension of the timeout period; a setting unit for changing the setting to a longer second timeout period. This makes it possible to extend the timeout period during the control protocol session with the opposite communication device. Therefore, it is possible to avoid disconnection of a session due to the occurrence of a timeout while simplifying the configuration of the communication system.

(11) A communication method according to the present embodiment is a communication method in which a first communication device and a second communication device communicate according to a control protocol, wherein the first communication device communicates with the second communication device. determining whether the first communication device causes the communication with the second communication device according to the control protocol to stop during the session of the control protocol in; transmitting extension request data for requesting extension of the timeout period when it is determined that the cause occurs; and transmitting the extension request data transmitted by the first communication device to the second communication device. receiving; and changing the setting from a first timeout period to a second timeout period longer than the first timeout period when the second communication device receives the extension request data. . As a result, the timeout period can be extended before a cause for stopping communication with the second communication device occurs. Therefore, it is possible to avoid disconnection of a session due to the occurrence of a timeout while simplifying the configuration of the communication system.

<Details of the embodiment of the present invention>
Hereinafter, details of embodiments of the present invention will be described with reference to the drawings. At least part of the embodiments described below may be combined arbitrarily.

In this embodiment, a communication system that performs communication by Link OAM will be described.

[1. Configuration of communication system]
FIG. 1 is a diagram showing an example of the configuration of a communication system according to this embodiment. As shown in FIG. 1 , a communication system 10 includes a master station device (first communication device) 1 , a slave station device (second communication device) 2 , and a communication line 3 .

The first and second communication devices 1 and 2 are communication devices functioning as line termination devices, respectively. Therefore, the communication line 3 terminates at the connection ends with the first and second communication devices 1 and 2 .

The communication line 3 consists of a communication cable such as an optical fiber or a coaxial cable. Instead of the communication line 3, a transmission line for wireless communication can also be adopted. In this embodiment, it is assumed that the communication line 3 is an optical fiber.
A first communication device 1 positioned on the upper side of the communication system 10 is communicably connected to the upper network 5, and a second communication device 2 positioned on the lower side of the communication system 10 is communicably connected to the lower network 6. It is The lower network 6 is composed of, for example, an in-house LAN (Local Area Network) or an in-house LAN.

The first and second communication devices 1 and 2 are communication devices capable of transmitting and receiving communication data, which are PDUs (Protocol Data Units) such as Ethernet (registered trademark) frames and IP packets, and are compatible with ETH-OAM. Also, the first and second communication devices 1 and 2 have a Link OAM function defined in IEEE802.3ah.
Link OAM is an OAM function and a control protocol premised on P2P (Point to Point) use for the purpose of monitoring physical lines and communication states between a pair of Ethernet devices.

In the example of FIG. 1, the first communication device 1, which is the line termination device on the upper side, is the "master station device 1", and the second communication device 2, which is the line termination device on the lower side, is the "slave station device 2". be.

[2. Internal configuration of master station device]
FIG. 2 is a block diagram showing an example of the internal configuration of the master station device 1. As shown in FIG. In FIG. 2, solid-line arrows indicate the transmission direction of communication data, and broken-line arrows indicate internal buses for control signals.
As shown in FIG. 2, the master station device 1 of the present embodiment includes an upper side interface section 11, a control section 12, a reception processing section 13, a transmission processing section 14, a counterpart side interface section 15, an up buffer 16, and a down buffer. 17.

The upper interface unit 11 includes an integrated circuit that performs layer 1 and layer 2 communication processing for upstream and downstream electrical signals.
The control unit 12, the reception processing unit 13, and the transmission processing unit 14 are integrated circuits (for example, MAC chip).

FIG. 3 is a block diagram showing an example of the hardware configuration of the controller 12. As shown in FIG. In a specific example, the control unit 12 includes a CPU (Central Processing Unit) 12a, a non-transitory memory 12b consisting of a ROM (Read Only Memory), and a transient memory 12c consisting of a RAM (Random Access Memory). , and an input/output unit 12d for inputting/outputting communication data and control signals.

A control program 12e is stored in the non-transitory memory 12b. The master station device 1 comprises a computer, and the setting function of the master station device 1 is exhibited by the CPU 12a executing a control program 12e, which is a computer program stored in the storage device of the computer. The control program 12e can be stored in a recording medium such as a CD-ROM. The CPU 12a can execute the control program 12e. By executing the control program 12e by the CPU 12a, the master station device 1 can execute processing described later.

In addition, the structure of the control part 12 is not restricted above. The control unit 12 may be configured by an FPGA (Field-Programmable Gate Array).

Refer to FIG. 2 again. The reception processing unit 13 and the transmission processing unit 14 are composed of logic circuit devices designed to enable specific information processing, and include at least one of ASIC (Application Specific Integrated Circuit) and FPGA, for example.

The opposite side interface unit 15 is composed of an optical communication device (for example, a pluggable optical transceiver) including elements for transmitting and receiving optical signals.
The opposite side interface unit 15 converts the optical signal received from the optical fiber 3 into communication data consisting of an electrical signal, and outputs the converted communication data to the reception processing unit 13 . The opposite side interface section 15 converts the communication data from the transmission processing section 14 into an optical signal and sends the converted optical signal to the optical fiber 3 .

The reception processing unit 13 can execute a "control protocol determination process". This process is a process of determining whether or not the communication data input from the opposite-side interface section 15 is control data of a control protocol (hereinafter referred to as "control protocol data"). The control protocol data includes communication frames of Link OAM, LACP, and ETH-OAM, and communication packets of MQTT. In this embodiment, the control protocol data is a Link OAM communication frame. That is, in the control protocol determination process, it is determined whether the input communication data is a Link OAM communication frame or other PDU.

The reception processing unit 13 outputs the control protocol data to the control unit 12 when it is determined that the input communication data is the control protocol data. The reception processing unit 13 outputs the communication data to the upstream buffer 16 when it is determined that the input communication data is not the control protocol data.

The upper interface unit 11 converts the carrier signal received from the upper network 5 into communication data, and outputs the converted communication data to the down buffer 17 .
If there is communication data in the upstream buffer 16 , the upper interface section 11 converts the communication data into a carrier signal and sends the converted carrier signal to the upper network 5 .

If there is communication data in the downlink buffer 17 , the transmission processing unit 14 takes out the communication data from the downlink buffer 17 and outputs it to the opposite side interface unit 15 between the control protocol data being input from the control unit 12 .

The control unit 12 can execute a "state management process", a "first determination process", a "second determination process", an "extension request data generation process", and a "shortening request data generation process". .

The state management process is a process of determining whether a session is established by the control protocol or disconnected.

The first determination process is a process of determining whether or not the master station device 1 causes the communication with the slave station device 2 to stop according to the control protocol during the session of the control protocol with the slave station device 2. is. As a specific example, the reason for stopping the communication with the slave station device 2 based on the control protocol is the updating of the control program 12e. That is, in the first determination process, the CPU 12a of the control unit 12 determines whether or not it is necessary to update the control program 12e during the control protocol session with the slave station device 2 .

The second determination process is a process of determining whether or not an abnormality has occurred as a cause for stopping communication with the slave station device 2 according to the control protocol. As a specific example, in the second determination process, the CPU 12a determines whether or not an abnormality has occurred in the update process of the control program 12e.

The "extension request data generation process" is control protocol data for requesting an extension of the timeout period when it is determined in the first determination process that a cause for stopping communication with the slave station device 2 by the control protocol has occurred. This is the process of generating the extension request data.

"Shortening request data generation processing" requests shortening of the timeout time when the cause for stopping the communication with the slave station device 2 by the control protocol disappears, or when it is determined that the cause is abnormal. This is the process of generating the shortened request data, which is the control protocol data for doing. That is, the CPU 12a generates the shortening request data when the update of the control program 12e is completed. The CPU 12a generates shortening request data when it is determined that an abnormality has occurred in the updating process of the control program.

In this embodiment, the extension request data and shortening request data are generated as Link OAM Information OAM frames. FIG. 4 is a schematic diagram showing the format of the Information OAM frame. An Information OAM frame is a type of Ethernet frame and has fields such as destination address, source address, length/type, and data. A data field of the Information OAM frame includes a Local Information TLV field, a Remote Information TLV field, and an Information TLV#3 field.

In the communication system 10 according to this embodiment, a timeout period is specified in the Information TLV#3 field.

In the extension request data, the extended timeout period (second timeout period) is specified in the Information TLV#3 field. The Information TLV#3 field has three subfields of type (Type), length (Length), and value (Value). In a specific example, the Type field of the Information TLV #3 field in the extension request data is specified with 0xFE indicating a vendor-specific type, the Length field is specified with 0x02 indicating 2 bytes, and the Value field is after the extension. A timeout period is specified.

In the shortening request data, the timeout time after shortening is specified in the Information TLV#3 field. In a specific example, the Type field of the Information TLV #3 field in the shortened request data is specified with 0xFE indicating a vendor-specific type, the Length field is specified with 0x02 indicating 2 bytes, and the Value field is after shortening. A timeout period is specified.

Refer to FIG. 2 again. The control unit 12 generates control protocol data and outputs it to the transmission processing unit 14 . When receiving downlink control protocol data from the control unit 12 , the transmission processing unit 14 outputs the input control protocol data to the opposite side interface unit 15 . The opposite side interface unit 15 sends out the input downlink control protocol data to the optical fiber 3 .

When the control protocol data of the transmission source of the slave station device 2 is input from the reception processing unit 13, the control unit 12 executes a predetermined process according to the contents of the control protocol data as information processing related to the control protocol data. .
For example, the control unit 12 changes the transmission/reception speed of the opposite side interface unit 15 or the upper side interface unit 11, or stop or start the operation of

[3. Internal configuration of slave station device]
FIG. 5 is a block diagram showing an example of the internal configuration of the slave station device 2. As shown in FIG. In FIG. 5, solid-line arrows indicate the transmission direction of communication data, and broken-line arrows indicate internal buses for control signals.
As shown in FIG. 5, the slave station device 2 of the present embodiment includes a lower-side interface section 21, a control section 22, a reception processing section 23, a transmission processing section 24, a counter-side interface section 25, an up-buffer 26, and a down-buffer. 27.

The lower interface unit 21 includes an integrated circuit that performs layer 1 and layer 2 communication processing for upstream and downstream electrical signals.
The control unit 22, the reception processing unit 23, and the transmission processing unit 24 are integrated circuits (for example, MAC chip).

FIG. 6 is a block diagram showing an example of the hardware configuration of the controller 22. As shown in FIG. In a specific example, the control unit 22 includes a CPU 22a, a non-transitory memory 22b made up of ROM, a transient memory 22c made up of RAM, and an input/output unit 22d for inputting/outputting communication data and control signals. have

A control program 22e is stored in the non-transitory memory 22b. The slave station device 2 includes a computer, and the setting function of the slave station device 2 is exhibited by the CPU 22a executing a control program 22e, which is a computer program stored in the storage device of the computer. The control program 22e can be stored in a recording medium such as a CD-ROM. The CPU 22a can execute the control program 22e. By executing the control program 22e by the CPU 22a, the slave station device 2 can execute processing as described later.

In addition, the structure of the control part 22 is not restricted above. The control unit 22 may be configured by FPGA.

Refer to FIG. 5 again. The reception processing unit 23 and the transmission processing unit 24 are composed of logic circuit devices designed to enable specific information processing, and include at least one of ASIC and FPGA, for example.

The opposite side interface unit 25 is composed of an optical communication device (for example, a pluggable optical transceiver) including elements for transmitting and receiving optical signals.
The opposite side interface unit 25 converts the optical signal received from the optical fiber 3 into communication data consisting of an electrical signal, and outputs the converted communication data to the reception processing unit 23 . The opposite side interface section 25 converts the communication data from the transmission processing section 24 into an optical signal and sends out the converted optical signal to the optical fiber 3 .

The reception processing unit 23 can execute a "control protocol determination process". This process is a process of determining whether or not the communication data input from the opposite side interface unit 25 is control protocol data. That is, in the control protocol determination process, it is determined whether the input communication data is a Link OAM communication frame or other PDU.

The reception processing unit 23 outputs the control protocol data to the control unit 22 when it is determined that the input communication data is the control protocol data. The reception processing unit 23 outputs the communication data to the upstream buffer 26 when it is determined that the input communication data is not the control protocol data.

The lower interface unit 21 converts the carrier signal received from the lower network 6 into communication data, and outputs the converted communication data to the upstream buffer 26 .
If there is communication data in the downstream buffer 27 , the lower interface section 21 converts the communication data into a carrier signal and sends the converted carrier signal to the lower network 6 .

If there is communication data in the upstream buffer 26 , the transmission processing unit 24 retrieves the communication data from the upstream buffer 26 between inputs of control protocol data from the control unit 22 and outputs the communication data to the opposite side interface unit 25 .

The control unit 22 can execute a “state management process” and a “timeout time setting process”.

The state management process is a process of determining whether or not a session is in progress according to the control protocol.

The timeout period setting process is a process of setting a timeout period. As a specific example, in the timeout period setting process, when the input control protocol data is extension request data, the CPU 22a of the control unit 22 changes the timeout period (first timeout period) from the currently set timeout period (first timeout period). , the setting is changed to the timeout period (second timeout period) specified by the extension request data. When the input control protocol data is shortening request data, the CPU 22a changes the setting from the currently set timeout period to the timeout period specified by the shortening request data.

The control unit 22 generates control protocol data. The control unit 22 sends the generated control protocol data to the transmission processing unit 24 . When the upstream control protocol data is input from the control unit 22 , the transmission processing unit 24 outputs the input control protocol data to the opposite side interface unit 25 . The opposite side interface unit 25 sends out the input upstream control protocol data to the optical fiber 3 .

When the control protocol data from the transmission source of the master station device 1 is input from the reception processing unit 23, the control unit 22 executes a predetermined process according to the contents of the control protocol data as information processing related to the control protocol.
For example, the control unit 22 changes the transmission/reception speed of the opposite side interface unit 25 or the lower side interface unit 21, or stop or start the operation of

Although omitted in FIGS. 2 and 5, the master station device 1 can execute "timeout time setting processing" in the same way as the slave station device 2, and the slave station device 2 and the master station device 1 Similarly, "first determination processing", "second determination processing", "extension request data generation processing" and "shortening request data generation processing" can be executed. However, in this embodiment, to simplify the explanation, the master station device 1 executes the "first determination process", the "second determination process", the "extension request data generation process", and the "shortening request data generation process". Then, the slave station device 2 executes the "timeout time setting process".

[4. Operation of communication system]
The operation of the communication system 10 according to this embodiment will be described below. Link OAM has a default timeout value of 5 seconds. Each of the master station device 1 and the slave station device 2 transmits an Information OAM frame in a cycle of 1 second. An information OAM frame must be received from the opposite communication device (the opposite communication device for the master station device 1 is the slave station device, and the opposite communication device for the slave station device 2 is the master station device 1) for 5 seconds or more. , a timeout occurs.

A control protocol session has two states. One state is a state in which a session is disconnected (hereinafter referred to as "session disconnected state"), and the other state is a state in which a session is established (hereinafter referred to as "session established state"). When a timeout occurs, the Link OAM session is disconnected.

The CPU 22a of the slave station device 2 determines whether the session is established or disconnected. When the session is established, the CPU 22a operates the lower interface section 21 to communicate with the lower network 6. FIG. When the session is disconnected, the CPU 22a stops the lower interface unit 21 and stops communication with the lower network 6. FIG. Therefore, when the session is disconnected, data transfer by the slave station device 2 is stopped.

Note that the master station device 1 can also perform the same operation. That is, the CPU 12a determines whether the session is established or disconnected. In the session disconnection state, the CPU 12a stops the host side interface unit 11. FIG.

The communication system 10 according to the present embodiment executes a timeout period control process for extending the timeout period of the slave station apparatus 2 in order to prevent data transfer from being stopped by the slave station apparatus 2 as described above.

FIG. 7 is a flowchart showing the procedure of timeout period control processing by the communication system 10 according to this embodiment.

The CPU 12a of the master station device 1 determines whether there is a cause for stopping communication with the slave station device 2 (step S101). As a specific example, the CPU 12a determines whether or not the control program 12e will be updated.

If there is no reason to stop communication (NO in step S101), the CPU 12a executes the process of step S101 again. As a result, the process of step S101 is repeated until a cause for stopping communication occurs.

If there is a cause for stopping communication (YES in step S101), CPU 12a generates extension request data (step S102). Specifically, the CPU 12a determines a time (for example, 100 seconds) longer than 5 seconds, which is the default value of the timeout time in Link OAM, as the extended timeout time. More preferably, the timeout period after the extension is set to a period of time sufficient to eliminate the cause of stopping the communication. The CPU 12a generates, as extension request data, an Information OAM frame in which a timeout period after extension is specified in the Information TLV#3 field.

The CPU 12a outputs the generated extension request data to the transmission processing unit 14 (step S103). The transmission processing unit 14 outputs the extension request data, which is an electric signal, to the opposite side interface unit 15 . The opposite side interface unit 15 converts the input electrical signal into an optical signal, and transmits the extension request data to the slave station device 2 as an optical signal.

The opposite side interface unit 25 of the slave station device 2 receives the optical signal. The opposite side interface section 25 converts the received optical signal into the original electrical signal and outputs the converted electrical signal to the reception processing section 13 . The reception processing unit 13 determines whether or not the input communication data is control protocol data. Since the extension request data is control protocol data, the reception processing unit 13 outputs the input extension request data to the control unit 12 .

The CPU 22a of the slave station device 2 determines whether or not the extension request data has been received (step S104). If the extension request data is not input to the control unit 12 (NO in step S104), the CPU 22a executes the process of step S104 again. As a result, the process of step S104 is repeated until the slave station device 2 receives the extension request data.

When the extension request data is received by the slave station device 2 (YES in step S104), the CPU 22a extends the timeout period (step S105). In other words, the CPU 22a changes the current timeout period (first timeout period) to a new, longer timeout period. For example, when the default value of the Link OAM timeout time is set to 5 seconds, the CPU 22a changes the setting to a longer timeout time (for example, 100 seconds) than the default value. As a specific example, the CPU 22a sets the timeout period specified in the extension request data as the new timeout period.

After transmitting the timeout period extension request data, the CPU 12a of the master station device 1 starts updating the control program 12e (step S106). The CPU 12a cannot process control protocol data while the control program 12e is being updated. Therefore, while the control program 12e is being updated, the communication with the slave station device 2 by the control protocol is stopped.

The CPU 12a determines whether or not an abnormality has occurred as a cause for stopping communication (step S107). As a specific example, the CPU 12a determines whether an error has occurred in updating the control program 12e.

If no abnormality has occurred as a cause for stopping communication (NO in step S107), the CPU 12a determines whether or not there is no cause for stopping communication (step S108). As a specific example, the CPU 12a determines whether or not the control program 12e has been updated.

If the cause for stopping communication has not disappeared (NO in step S108), the CPU 12a returns the process to step S107. As a result, the processes of steps S107 and S108 are repeated until an abnormality occurs in the cause for stopping communication or until the cause for stopping communication disappears.

If an abnormality has occurred as a cause for stopping communication (YES in step S107), or if there is no cause for stopping communication (YES in step S108), the CPU 12a generates shortening request data (step S109). Specifically, when an abnormality occurs in the update of the control program 12e or when the update of the control program 12e ends, the CPU 12a sets a time shorter than the extended timeout period (for example, 100 seconds) after shortening. time-out period. The shortened timeout period may be the default value (5 seconds) of the timeout period, or may be a value other than the default value. The CPU 12a generates, as shortening request data, an Information OAM frame in which the shortened timeout time is specified in the Information TLV#3 field.

The CPU 12a outputs the generated shortening request data to the transmission processing unit 14 (step S110). The transmission processing unit 14 outputs the shortening request data, which is an electric signal, to the opposite side interface unit 15 . The opposite side interface unit 15 converts the input electrical signal into an optical signal, and transmits the shortening request data to the slave station device 2 as an optical signal.

The opposite side interface unit 25 of the slave station device 2 receives the optical signal. The opposite side interface 25 converts the received optical signal into the original electrical signal and outputs the converted electrical signal to the reception processing unit 13 . The reception processing unit 13 determines whether or not the input communication data is control protocol data. Since the shortened request data is control protocol data, the reception processing unit 13 outputs the input shortened request data to the control unit 12 .

The CPU 22a of the slave station device 2 determines whether or not the shortening request data has been received (step S111). If the shortening request data is not input to the control unit 12 (NO in step S111), the CPU 22a determines whether or not the timeout time has elapsed without receiving the control protocol data from the master station device 1, that is, whether a timeout has occurred. It is determined whether or not (step S112).

When timeout has not occurred (NO in step S112), the CPU 22a returns the process to step S111. As a result, the processing of steps S111 and S112 is repeated until the shortening request data is received or a timeout occurs.

If the child station device 2 has received the shortening request data (YES in step S111), or if a timeout has occurred (YES in step S112), the CPU 22a shortens the timeout period (step S113).

When the slave station device 2 receives the shortening request data including the specification of the timeout period, the CPU 22a sets the timeout period specified in the received shortening request data as a new timeout period.

When a timeout occurs, the CPU 22a sets a new timeout period shorter than the extended timeout period. The shortened timeout period may be the default value of the timeout period, or may be a timeout period other than the default value.

With this, the timeout time control process is completed.

The extension request data and shortening request data may not specify a new timeout period. In this case, the slave station device 2 stores the timeout time after extension and the timeout time after shortening in, for example, the non-transitory memory 22b. , and when the shortening request data is received, the setting is changed to the stored timeout time after extension.

[5. Modification]
[5-1. First modification]
In the first modified example, the communication system 10 extends the timeout period in LACP.

In a first variant, the extension request data and shortening request data are generated as LACP frames. FIG. 8 is a schematic diagram showing the format of the LACP frame. A LACP frame is a type of Ethernet frame and has fields such as destination address, source address, length/type, and data. The data field of the LACP frame contains the Other TLVs field.

In the communication system 10 according to the first modified example, a timeout period is specified in the Other TLVs field.

In the extension request data, the timeout period after extension (second timeout period) is specified in the Other TLVs field. The Other TLVs field has three subfields of type (Type), length (Length), and value (Value). In a specific example, 0xA0 indicating a standard undefined type is specified in the Type field of the Other TLVs field in the extension request data, 0x02 indicating 2 bytes is specified in the Length field, and timeout after extension is specified in the Value field. time is specified.

In the shortened request data, the shortened timeout time is specified in the Other TLVs field. In a specific example, 0xA0 indicating a standard undefined type is specified in the Type field of the Other TLVs field in the shortened request data, 0x02 indicating 2 bytes is specified in the Length field, and the timeout after shortening is specified in the Value field. time is specified.

In LACP, each of the master station device 1 and the slave station device 2 periodically transmits LACP frames, with the value (time) specified in LACP_Timeout of Actor_State of the LACP frame being set as one period. If the LACP frame is not received from the counterpart communication device (the counterpart communication device for the master station device 1 is the slave station device, and the counterpart communication device for the slave station device 2 is the master station device 1) for three or more cycles, A timeout occurs. That is, the default value for the timeout period is three times the value specified for LACP_Timeout in Actor_State.

The CPU 22a of the slave station device 2 determines whether the session is established or disconnected. When the session is established, the CPU 22a operates the opposite side interface unit 25 to communicate with the master station device 1. FIG. When the session is disconnected, the CPU 22a stops the opposite side interface unit 25 and stops communication with the master station device 1. FIG. Therefore, when the session is disconnected, the communication between the master station device 1 and the slave station device 2 is stopped.

Note that the master station device 1 can also perform the same operation. That is, the CPU 12a determines whether the session is established or disconnected. In the session disconnected state, the CPU 12a stops the opposite side interface unit 15. FIG.

The communication system 10 according to the first modification executes a timeout time control process for extending the timeout time of the slave station device 2 in order to suppress the stoppage of communication between the master station device 1 and the slave station device 2 as described above. do.

In the first modified example, in step S102 of FIG. 7, the CPU 12a determines a time longer than the default value of the timeout time in LACP (for example, time for 100 cycles) as the extended timeout time. The CPU 12a generates, as extension request data, an LACP frame in which the timeout period after extension is specified in the Other TLVs field.

In step S105, the CPU 22a changes the current timeout period (first timeout period) to a new, longer timeout period. For example, when the default value of the LACP timeout period is set, the CPU 22a changes the setting to a timeout period longer than the default value (for example, 100 cycles). As a specific example, the CPU 22a sets the timeout period specified in the Other TLVs field in the extension request data as a new timeout period.

In step S109, the CPU 12a determines a time shorter than the extended timeout time (for example, time for 100 cycles) as the shortened timeout time. The shortened timeout period may be the default value (three cycles) of the timeout period, or may be a value other than the default value. The CPU 12a generates, as reduction request data, an LACP frame in which the shortened timeout time is specified in the Other TLVs field.

When the slave station device 2 receives the shortened request data including the specification of the timeout period, in step S113, the CPU 22a sets the timeout period specified in the Other TLVs field of the received shortened request data as a new timeout period. do.

[5-2. Second modification]
In the second modified example, the communication system 10 extends the timeout period in ETH-OAM.

In a first variant, the extension request data and shortening request data are generated as ETH-OAM VSM (Vendor-Specific OAM Message) frames. FIG. 9 is a schematic diagram showing the format of the VSM frame. A VSM frame is a type of Ethernet frame and has fields such as destination address, source address, length/type, and data. The VSM frame has MEL, Version, OpCode, Flags, TLV Offset, OUI, SubOpCode, optional VSM data, and End TLV fields.

The MEL field specifies the MEL (MEG Level) of the MEP (MEG (Maintenance Entity Group) End Point) that specifies the timeout period. The master station device 1 is the MEP, and the MEL of the master station device 1 is specified in the MEL field of the extension request data and shortening request data.

In the Flags field, "0" is specified when specifying the timeout period, and "1" is specified when canceling the specification of the timeout period. "0" is specified in the Flags field of the extension request data and shortening request data. If the shortening request data is data requesting cancellation of extension of the timeout period (that is, restoration to the default value), "1" is specified in the Flags field.

In the extension request data and shortening request data, "4" is specified in the TLV Offset field, "00-25-DC" is specified in the OUI (Organizationally Unique Identifier) field, and "0" is specified in the SubOpCode field. be.

In the communication system 10 according to the first modified example, the timeout period is specified in the optional VSM data field of the VSM frame.

In the extension request data, the optional VSM data field specifies a timeout period after extension (second timeout period). The optional VSM data field has three subfields: Type, Length, and Value. In a specific example, 0x01 is specified in the Type field of the optional VSM data field in the extension request data, 0x02 indicating 2 bytes is specified in the Length field, and the timeout time after extension is specified in the Value field. .

In the shortened request data, the timeout time after shortening is specified in the optional VSM data field. In a specific example, 0x01 is specified in the Type field of the optional VSM data field in the shortening request data, 0x02 indicating 2 bytes is specified in the Length field, and the timeout time after shortening is specified in the Value field. .

In ETH-OAM, each of the parent station device 1 and the child station device 2 periodically transmits a CCM frame with a value (time) specified in a Period field of a CCM (Continuity Check Message) frame set as one period. A CCM frame must be received from the opposite communication device (the opposite communication device for the master station device 1 is the slave station device, and the opposite communication device for the slave station device 2 is the master station device 1) for 3.5 cycles or more. timeout occurs. That is, the default value of the timeout period is 3.5 times the value specified in the Period field of the CCM frame.

The CPU 22a of the slave station device 2 determines whether the session is established or disconnected. When the session is established, the CPU 22a operates the lower side interface section 21 and the opposite side interface section 25 to perform communication with the lower network 6 and the master station device 1. FIG. When the session is disconnected, the CPU 22a stops at least one of the lower-level interface section 21 and the opposite-side interface section 25. FIG. Therefore, when the session is disconnected, data transfer by the slave station device 2 is stopped.

Note that the master station device 1 can also perform the same operation. That is, the CPU 12a determines whether the session is established or disconnected. In the session disconnected state, the CPU 12a stops at least one of the host side interface section 11 and the opposite side interface section 15. FIG.

The communication system 10 according to the second modification executes a timeout period control process for extending the timeout period of the slave station apparatus 2 in order to prevent the slave station apparatus 2 from stopping data transfer as described above.

In the second modification, in step S102 of FIG. 7, the CPU 12a determines a time longer than the default value of the timeout time in ETH-OAM (for example, 100 cycles) as the extended timeout time. The CPU 12a generates, as extension request data, a VSM frame in which a timeout period after extension is specified in the optional VSM data field.

In step S105, the CPU 22a changes the current timeout period (first timeout period) to a new, longer timeout period. For example, when the default value of the ETH-OAM timeout period is set, the CPU 22a changes the setting to a timeout period longer than the default value (for example, 100 cycles). As a specific example, the CPU 22a sets the timeout specified in the optional VSM data field in the extension request data as a new timeout.

In step S109, the CPU 12a determines a time shorter than the extended timeout time (for example, time for 100 cycles) as the shortened timeout time. The shortened timeout period may be the default value (3.5 cycles) of the timeout period, or may be a value other than the default value. The CPU 12a generates, as shortening request data, a VSM frame in which the shortened timeout time is specified in the optional VSM data field. Also, the CPU 12a may generate a VSM frame in which "1" is specified in the Flags field as shortening request data.

When the slave station device 2 receives the shortened request data including the specification of the timeout period, in step S113, the CPU 22a sets the timeout period specified in the optional VSM data field of the received shortened request data as a new timeout period. set.

[5-3. Third modification]
In the second modified example, the communication system 10 extends the timeout period in MQTT.

FIG. 10 is a diagram showing an example of the configuration of communication system 10 according to the third modification. A communication system 10 according to the third modification is of a 1:N type connection configuration, and a plurality of slave station devices 2 are connected to one master station device 1 . That is, the master station device 1 establishes an MQTT session with each of the connected slave station devices 2, and performs MQTT communication. In MQTT, the master station device 1 is called a broker and the slave station device 2 is called a client.

In the third modification, the broker multicasts CONNECT packets to each client. The extension request data and shortening request data are generated as CONNECT packets. FIG. 11 is a schematic diagram showing the format of a CONNECT packet. A CONNECT packet is one of IP packets and includes Ethernet header, IP header, TCP header and TCP data fields. The TCP data field includes a Keep Alive Timer field.

In the communication system 10 according to the third modified example, a timeout period is specified in the Keep Alive Timer field of the CONNECT packet. The Keep Alive Timer field includes a Keep Alive Timer MSB field and a Keep Alive Timer LSB field. The Keep Alive Timer MSB field specifies the upper 8 bits of the total 16-bit timeout period, and the Keep Alive Timer LSB field specifies the lower 8 bits of the timeout period.

In the extension request data, the extended timeout period (second timeout period) is specified in the Keep Alive Timer field.

In the shortening request data, the shortened timeout time is specified in the Keep Alive Timer field.

In MQTT, each client sends a PINGREQ packet to the broker at regular intervals. When the broker receives a PINGREQ packet, it sends back a PINGRESPONSE packet. A timeout occurs if the client does not receive the PINGRESPONSE packet for a specified period of time. The timeout period is specified in the Keep Alive Timer field of the CONNECT that the client sends to the broker when starting a session.

The CPU 22a of the slave station device 2 determines whether the session is established or disconnected. When the session is established, the CPU 22a operates the lower interface section 21 to communicate with the lower network 6. FIG. If the session is disconnected, the CPU 22a stops the lower interface section 21. FIG. Therefore, when the session is disconnected, data transfer by the slave station device 2 is stopped.

The communication system 10 according to the third modification executes a timeout period control process for extending the timeout period of the slave station apparatus 2 in order to prevent data transfer from being stopped by the slave station apparatus 2 as described above.

In the third modification, in step S102 of FIG. 7, the CPU 12a sets a time longer than the initial value (for example, 5 seconds) of the timeout period (for example, 100 seconds) specified by the slave station device 2 (client) at the start of the session. ) to the extended timeout period. The CPU 12a generates, as extension request data, a CONNECT packet in which a timeout period after extension is specified in the Keep Alive Timer field.

In step S105, the CPU 22a changes the current timeout period (first timeout period) to a new, longer timeout period. For example, when the initial value of the timeout period (eg, 5 seconds) is set, the CPU 22a changes the setting to a timeout period longer than the initial value (eg, 100 seconds). As a specific example, the CPU 22a sets the timeout period specified in the Keep Alive Timer field in the extension request data as the new timeout period.

In step S109, the CPU 12a determines a time shorter than the extended timeout period (for example, 100 seconds) as the shortened timeout period. The shortened timeout period may be the initial value of the timeout period, or may be a value other than the initial value. The CPU 12a generates, as shortening request data, a CONNECT packet in which the shortened timeout time is specified in the Keep Alive Timer field.

When the slave station device 2 receives the shortening request data including the specification of the timeout period, in step S113, the CPU 22a sets the timeout period specified in the Keep Alive Timer field of the received shortening request data as the new timeout period. set.

[5-4. Other Modifications]
Note that the master station device 1 may specify invalidation of the timeout period in the extension request data instead of specifying the timeout period after the extension. For example, in the case of Link OAM, in the Vlue field of the TLV of the Information OAM frame, in the case of LACP, in the Value field in the Other TLVs field of the LACP frame, and in the case of ETH-OAM, in the optional VSM data field of the VSM frame. In the Value field of MQTT, in the Keep Alive Timer field of the CONNECT packet sent by the broker in the case of MQTT, a value (for example, 0xFFFF) indicating invalidation of the timeout period is specified instead of the extended timeout period. good too. The slave station device 2 that receives such communication data can invalidate the timeout period.

The master station device 1 may transmit shortening request data for canceling invalidation of the timeout period when there is no cause for stopping communication. For example, in the case of Link OAM, in the Vlue field of the TLV of the Information OAM frame, in the case of LACP, in the Value field in the Other TLVs field of the LACP frame, and in the case of ETH-OAM, in the optional VSM data field of the VSM frame. In the Value field of MQTT, in the Keep Alive Timer field of the CONNECT packet sent by the broker in the case of MQTT, a value (e.g., 0x0000) indicating cancellation of invalidation of the timeout period is specified instead of the shortened timeout period. may be Upon receiving such communication data, the slave station device 2 can cancel the invalidation of the timeout period.

[6. effect]
As described above, the communication system 10 includes the first communication device 1 and the second communication device 2 . During the session of the control protocol with the second communication device 2, the first communication device 1 determines whether or not the first communication device 1 causes the communication with the second communication device by the control protocol to stop. and a transmission unit for transmitting extension request data for requesting extension of the timeout period when the determination unit determines that a cause has occurred. The second communication device 2 includes a receiving unit that receives the extension request data transmitted by the first communication device 1, and when the extension request data is received by the receiving unit, from the first timeout period to the first timeout period a setting unit that changes the setting to a second timeout period longer than the As a result, the timeout period can be extended before a cause for stopping communication with the second communication device 2 occurs. Therefore, it is possible to avoid disconnection of a session due to the occurrence of a timeout while simplifying the configuration of the communication system 10 .

The extension request data may include an area specifying a second timeout period as the timeout period after extension. As a result, an arbitrary second timeout period can be specified in the first communication device 1 .

The first communication device 1 may transmit shortening request data requesting shortening of the timeout period after changing the setting to the second timeout period. The second communication device 2 may change the setting from the second timeout period to a timeout period shorter than the second timeout period when the shortening request data is received. As a result, the extended timeout period can be shortened.

The shortening request data may include an area specifying a timeout period after shortening. As a result, an arbitrary shortened timeout period can be specified in the first communication device 1 .

When the second timeout period is set, the second communication device 2 may change the setting to a timeout period shorter than the second timeout period after the timeout occurs. As a result, the extended timeout period can be shortened after timeout occurs.

The first communication device 1 may transmit shortening request data requesting shortening of the timeout period when an abnormality occurs as a cause for stopping communication after the setting of the second timeout period is changed. The second communication device may change the setting from the second timeout period to a timeout period shorter than the second timeout period when the shortening request data is received. This makes it possible to shorten the extended timeout period when an abnormality occurs as a cause for stopping communication and communication is no longer stopped.

The cause of stopping communication may be the update of the control program 12e in the first communication device 1 . As a result, even if communication stops while the control program 12e is being updated, disconnection of the session due to the occurrence of timeout can be avoided.

The control protocol may include at least one of Link OAM (Operations, Administration, Maintenance), LACP (Link Aggregation Control Protocol), ETH-OAM (Ethernet OAM), and MQTT (Message Queuing Telemetry Transport). As a result, in at least one of Link OAM, LACP, ETH-OAM, and MQTT, it is possible to avoid session disconnection due to the occurrence of a timeout.

[7. Addendum]
The embodiments disclosed this time are illustrative in all respects and are not restrictive. The scope of rights of the present invention is indicated by the scope of claims rather than the above-described embodiments, and includes equivalent meanings and all modifications within the scope of the scope of claims.

1 first communication device (master station device)
2 Second communication device (slave station device)
3 Communication line (optical fiber)
5 upper network 6 lower network 10 communication system 11 upper interface section 12 control section 12a CPU
12b non-transient memory 12c transient memory 12d input/output unit 12e control program 13 reception processing unit 14 transmission processing unit 15 opposite side interface unit 16 up buffer 17 down buffer 21 lower side interface unit 22 control unit 22a CPU
22b non-transient memory 22c transient memory 22d input/output unit 22e control program 23 reception processing unit 24 transmission processing unit 25 opposite side interface unit 26 upstream buffer 27 downstream buffer

Claims (9)

a first communication device;
a second communication device;
with
The first communication device is
a determination unit that determines whether or not the first communication device causes the communication with the second communication device to stop according to the control protocol during a session of the control protocol with the second communication device; ,
a transmission unit that transmits extension request data for requesting an extension of the timeout period when the determination unit determines that the cause occurs;
has
The second communication device is
a receiving unit that receives the extension request data transmitted by the first communication device;
a setting unit configured to change a setting from a first timeout period to a second timeout period longer than the first timeout period when the extension request data is received by the receiving unit;
has
When the second timeout period is set, the setting unit sets a timeout period shorter than the second timeout period regardless of the timeout period specified by the first communication device after a timeout occurs. to change the
Communications system. The extension request data includes an area that specifies the second timeout time as the timeout time after extension,
A communication system according to claim 1. The transmitting unit transmits shortening request data requesting shortening of the timeout period after the setting of the second timeout period is changed,
The setting unit changes the setting from the second timeout period to a timeout period shorter than the second timeout period when the shortening request data is received by the receiving unit.
A communication system according to claim 1 or 2. The shortening request data includes an area that specifies a timeout period after shortening,
A communication system according to claim 3. The transmission unit transmits reduction request data requesting reduction of the timeout period when an abnormality occurs in the cause after the setting of the second timeout period is changed,
The setting unit changes the setting from the second timeout period to a timeout period shorter than the second timeout period when the shortening request data is received by the receiving unit.
A communication system according to any one of claims 1 to 4. The cause is an update of the control program in the first communication device,
A communication system according to any one of claims 1 to 5. The control protocol is Link OAM (Operations, Administration, Maintena
nce), LACP (Link Aggregation Control Protocol), ETH-OAM (Ethernet OAM), MQTT (Message Queuing Telemetry Transport).
A communication system according to any one of claims 1 to 6. A communication device that communicates with an opposite communication device according to a control protocol,
a receiving unit that receives extension request data for requesting an extension of the timeout period, which is transmitted by the counterpart communication device during the control protocol session with the counterpart communication device;
a setting unit configured to change a setting from a first timeout period to a second timeout period longer than the first timeout period when the extension request data is received by the receiving unit;
with
When the second timeout period is set, the setting unit changes the setting to a timeout period shorter than the second timeout period after timeout occurs, regardless of the timeout period specified by the counterpart device. do,
Communication device. A communication method in which a first communication device and a second communication device communicate according to a control protocol,
Whether the first communication device causes the first communication device to stop communication with the second communication device according to the control protocol during the session of the control protocol with the second communication device a step of determining whether
the first communication device transmitting extension request data for requesting an extension of the timeout period when it is determined that the cause occurs;
receiving, by the second communication device, the extension request data transmitted by the first communication device;
changing the setting from a first timeout period to a second timeout period longer than the first timeout period when the second communication device receives the extension request data;
When the second timeout period is set, the timeout period of the second communication apparatus is shorter than the second timeout period regardless of the timeout period specified by the first communication apparatus after timeout occurs. changing the setting to
having
Communication method.

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