JP2021034863A - Relay and communication system - Google Patents

Abstract

To make it possible to improve an allocation system for packet priority order to minimize communication delay of packets in TSN.SOLUTION: A relay for relaying communication packets having priority information for transferring the communication packets in priority order using a communication method having a communication cycle including a dedicated communication time band corresponding to the priority information includes a switch processing unit that when a communication packet having highest priority information is received within a time limit before finish time of a dedicated communication time band corresponding to the highest priority information, outputs the communication packet to a preferential buffer unit corresponding to the highest priority information of the communication packet, lowers the communication packet's priority information to priority information having the next priority, and additionally outputs the communication packet to a buffer unit of an output buffer unit corresponding to the lowered priority information.SELECTED DRAWING: Figure 6

Description

The present invention relates to repeaters and communication systems.

Conventionally, TSN (Time Sensitive Networking) has been studied in the IEEE (Institute of Electrical and Electronics Engineers) standard. TSN is not a field standard, but a set of various technical standards that extend IEEE 802.1 and can be combined with Ethernet®-based network technology. The technical standards constituting the TSN include IEEE802.1AS (Timening and Synchronization) and IEEE802.1Qbv (Time Aware Shiper).

IEEE802.1AS (Timing and Synchronization) is a technology for improving time synchronization in a network, and implements a time relay function. In the network, the port of the time grand master becomes the clock master (CM), and the port of the switch to which it is connected becomes the clock slave (CS). This is a technology in which time is relayed from CS to CM of another port in the switch, and the switch is connected as CS by a node or cascade at the end of CM, and time relay is performed.

IEEE802.1Qbv (Time Aware Shiper) distinguishes communication frames by traffic class and allocates a communication time zone for each traffic class for one cycle. However, if transmission of a low-priority communication frame starts immediately before the end of the allocated time zone, it will enter the subsequent time zone. May be created.

In this way, TSN is a high-speed, low-latency network standard that is being standardized by the IEEE, and is expected to be used in audio / video distribution networks, in-vehicle networks, and industrial networks that require high real-time performance. Has been done. Further, as described above, in TSN, the communication band set to the high priority is secured by synchronizing the time with all the terminals participating in the network and dividing the time during which the packet can be transmitted according to the priority. ..

As an explanation of the time division method of TSN, an example in which priority is determined by a VLAN (Virtual Local Area Network) priority number (PCP: Priority Code Point) will be described. As an example, the communication with the highest priority has a VLAN priority number of 7, the priority decreases in descending order of numbers 6, 5, 4, and the VLAN priority number 0 is the communication with the lowest priority.

The communication packet of VLAN priority number 7 is assigned to the time zone at the beginning of each cycle, and this time zone is also referred to as a high priority communication dedicated time zone. That is, the high-priority communication dedicated time zone is a time zone in which only the communication packet of the VLAN priority number 7 can be transmitted and received, and the communication packet of other VLAN priority numbers 6 to 0 cannot be transmitted and received. The communication packets having the VLAN priority numbers 6 to 0 are assigned to the time zone following the high priority communication dedicated time zone of each cycle, and transmission / reception is permitted. Communication packets that could not be transmitted in each cycle are transmitted in the next cycle. For example, when the transmission of the communication packet is not completed in the high priority communication dedicated time zone, the communication packet is transmitted in the high priority communication dedicated time zone of the next cycle.

IEEE802.1Qbv (http://www.ieee802.org/1/pages/802.1bv.html)

However, according to the above disclosure of the prior art, communication packets that could not be sent within the high priority communication dedicated time due to propagation delay or the like can be output from the buffer of the repeater until the high priority communication dedicated time of the next cycle is reached. However, there was a problem that the real-time property was greatly impaired. Therefore, an object of the present invention is to provide a means for solving such a problem.

The repeater according to the aspect of the present invention is a communication cycle including a dedicated communication time zone corresponding to the priority information for the communication packet having priority information for transmitting the communication packet in the order of priority. A repeater that relays the communication packet by using the method, extracts the priority information of the communication packet from the input communication packet, and corresponds to the priority information, the buffer unit of the output buffer unit. Includes a switch processing unit that outputs the communication packet, and the switch processing unit traces the communication packet having the highest priority information back from the end time of the dedicated communication time zone corresponding to the highest priority information. If it is received within the time limit, it is output to the priority buffer section of the output buffer section corresponding to the highest priority information of the communication packet, and the priority information of the communication packet is of the next priority. It is preferable to lower the priority information and output the communication packet to the buffer section of the output buffer section corresponding to the lowered priority information.

The time limit is preferably the time until the communication packet having the highest priority information is transferred from the self-repeater to the communication terminal addressed to transmission.

The buffer section of the output buffer section corresponding to the lowered priority information is a normal buffer section, and the priority of the normal buffer section in which the priority information is not rewritten in the normal buffer section. It is preferable that the communication packet corresponding to the information is also stored.

The switch processing unit transmits a communication packet having the highest priority information stored in the priority buffer unit, and the communication packet is transmitted in a dedicated communication time zone corresponding to the highest priority information. If this is the case, it is preferable to delete the communication packet in which the priority information stored in the normal buffer unit has been rewritten.

When the switch processing unit does not complete the transmission of the communication packet having the highest priority information stored in the priority buffer unit in the dedicated communication time zone corresponding to the highest priority information, the switch processing unit said. It is preferable to transmit the communication packet in which the priority information stored in the normal buffer unit is rewritten, and delete the communication packet having the highest priority information stored in the priority buffer unit.

At the end of one communication cycle, the switch processing unit performs the communication when the communication packet whose priority information has been rewritten exists in the buffer unit of the output buffer unit corresponding to the rewritten priority information. It is preferable to return the priority information of the packet to the priority information before being rewritten and move the communication packet to the buffer unit of the output buffer unit corresponding to the priority information before being rewritten.

At the start of one communication cycle, the switch processing unit transfers the communication packet having the highest priority information stored in the priority buffer unit to the communication packet having the highest priority information. It is preferable to transmit in a dedicated communication time zone corresponding to the highest priority information.

The communication method has a high priority communication time zone for transmitting a communication packet having the highest priority and a communication time zone for transmitting a communication packet having another priority in the communication cycle, and the high priority communication method is provided. The priority communication time zone is preferably located at the beginning of each communication cycle.

A communication system according to another aspect of the present invention comprises at least one or more repeaters and at least one or more communication terminals that are directly or indirectly connected to the repeaters and that transmit and receive the communication packets. It is preferable to include it.

According to the present invention, when a communication packet set to a high priority cannot be sent within the high priority communication dedicated time due to propagation delay, the delay is minimized by lowering the priority by one step with a repeater. , It becomes possible to efficiently use the communication resources in the high priority communication dedicated time zone.

It is a figure which shows an example of the network structure of the communication system which concerns on this embodiment. It is a figure which shows an example of the communication cycle of the communication system which concerns on this embodiment. It is a block diagram which shows an example of the repeater included in the communication system which concerns on this embodiment. (A) It is a schematic diagram for demonstrating the priority switching processing time which concerns on this Embodiment. (B) It is a schematic diagram for demonstrating the time limit which concerns on this Embodiment. (C) It is a schematic diagram for demonstrating the calculation method of the time limit which concerns on this Embodiment. It is a flowchart which shows the operation example of a part of the repeater which concerns on embodiment. It is a flowchart which shows the operation example of a part of the repeater which concerns on embodiment. (A) It is a schematic diagram explaining a part operation example of the repeater which concerns on embodiment. (B) It is a schematic diagram explaining a part operation example of the repeater which concerns on embodiment. (C) It is a schematic diagram explaining a part operation example of the repeater which concerns on embodiment. It is a schematic diagram explaining the detection of the change history of the priority number which concerns on this embodiment. It is a figure explaining an example of the operation of the communication system which concerns on this embodiment. It is a figure which shows an example of the in-vehicle network including the electronic device which has the function of the repeater of this embodiment.

(Overview of communication system and communication cycle)
FIG. 1 illustrates an example of the communication system 1000 according to the present embodiment. The communication system 1000 includes communication terminals 1 to N + 1 (N is a natural number of 1 or more), and a repeater C100, a repeater C200, and a repeater C300 that relay communication packets transmitted and received between the communication terminals 1 to N + 1. .. In FIG. 1, three repeaters are disclosed, but any number of repeaters may be arranged as long as there is one or more repeaters. The communication packet can be transmitted by wire or wirelessly.

FIG. 2 illustrates an example of a transmission / reception cycle of communication packets transmitted / received in the communication system 1000. Each communication cycle is divided into communication periods based on the priority in which communication packets should be transmitted and received. That is, the communication packet transmitted / received in the communication system 1000 includes priority information indicating the priority at which the communication packet should be transmitted / received as information such as a header, and a transmission / reception cycle is configured based on the priority information. In the communication system 1000 of FIG. 2, an example in which priority information is determined by a VLAN priority number (PCP (Priority Code Point)) is shown.

As an example of priority information, prioritys 0 to 7 are set as VLAN priority numbers, priority 7 has the highest priority, priority decreases in descending order of numbers, and priority 0 indicates the lowest priority configuration. At the head of each communication cycle, dedicated communication time zones t1 and t3 are provided in which only communication packets having priority 7 are transmitted / received as priority information. That is, a dedicated communication time zone t1 is provided at the beginning of the communication cycle N, and a dedicated communication time zone t3 is provided at the beginning of the communication cycle N + 1. The communication time zones t1 and t3 may be referred to as high priority communication dedicated time zones.

Further, each communication cycle is provided with dedicated communication time zones t2 and t4 in which only communication packets having priority 6 to 0 are transmitted / received as priority information. The communication cycle N is provided with a dedicated communication time zone t2, and the communication cycle N + 1 is provided with a dedicated communication time zone t4. In FIG. 2, the communication time zones t2 and t4 are shown as one division, but the time zones corresponding to the respective priorities 6 to 0 may be further divided and provided. Further, a dedicated time zone may be provided for a plurality of priorities collectively. For example, it is possible to provide a dedicated time zone corresponding to the normal priority of the priority 6 to 4 and a dedicated time zone corresponding to the low priority of the priority 3 to 0.

According to the communication system 1000 according to the present embodiment, when the communication packet set to the high priority cannot be sent within the high priority communication dedicated time due to the propagation delay, the priority is lowered by one step by the repeater. , It becomes possible to minimize the delay. Details will be described below.

(Example of configuration of repeater according to the embodiment)
FIG. 3 is a block diagram showing a configuration image of a repeater C100 such as a switching HUB, a router, and a gateway according to the embodiment. The repeater C200 and the repeater C300 also have the same configuration as the repeater C100.

The repeater C100 includes an input port unit C111, an input buffer unit C120, a switch processing unit C130, an output buffer unit C140, a timer unit C150, and an output port unit C112. Depending on the network usage status and the repeater processing status, the repeater C100 may not be able to immediately perform switch processing or output communication packets to the network. Therefore, the repeater C100 has a buffer for input / output. It has a structure. Further, the output buffer unit C140 has a plurality of buffers for one output port unit C112, and by adjusting the output order from the buffers, priority control of communication packets is performed. The switch processing unit C130 and the output buffer unit C140 according to the present embodiment communicate by lowering the priority of the communication packet by one step when there is a communication packet that cannot be transmitted within the high priority communication dedicated time. It has a function to minimize the delay. Details will be described later.

Communication packets transmitted from electronic devices such as communication terminals and repeaters in the previous stage are input to the input port unit C111 at any time.

The communication packet input to the input port unit C111 is buffered in the input buffer unit C120 until the subsequent processing of the repeater C100 is executed.

The switch processing unit C130 extracts the destination address of the communication packet buffered in the input buffer unit C120, and sends the communication packet to the output buffer unit C140 corresponding to the output port unit C112 which is the connection destination to the terminal having the destination address. Output.

In this case, the switch processing unit C130 also extracts the VLAN priority number of the communication packet and outputs the communication packet to the buffer of the output buffer unit C140 corresponding to the VLAN priority number.

In the method of the prior art, the switch processing unit C130 executes the switching process of the priority number of the communication packet of the VLAN priority number 7 after the end of the high priority communication dedicated time indicated by the VLAN priority number 7. However, since the communication packet transmission processing is started after the priority number switching processing time CT is completed, there is a problem that the communication packet transmission processing is delayed. FIG. 4A shows a schematic diagram illustrating that the transmission processing of the communication packet is delayed. In FIG. 4A, if there is no priority number switching processing time CT, the communication packet transmission processing can be started from timing t1, but since there is priority number switching processing time CT, the communication packet is started from timing t2. Transmission processing is started. That is, after the priority number switching processing time CT has elapsed after the end of the high priority communication dedicated time, the transmission of the communication packet whose priority number has been switched is started. Therefore, in the present embodiment, a configuration using the time limit LT described below is adopted.

As described above, in the present embodiment, the switch processing unit C130 calculates the time limit LT in the high priority communication dedicated time. The time limit LT is a time within the high priority communication dedicated time, but is a time zone within a certain range from the end time of the high priority communication dedicated time. For example, the time limit LT represents a time zone in which communication of communication packets may not be completed within the high priority communication dedicated time. As an example, FIG. 4B shows the relationship between the Nth communication cycle N, the time limit LT, the high priority communication dedicated time, and the like. The high-priority communication-only time is the time zone indicated by the VLAN priority number 7, and the time limit LT is a time zone within a certain range from the end time of the high-priority communication-only time. When the time limit LT ends, it becomes a time zone in which the communication packet indicated by the VLAN priority numbers 6 to 0 can be transmitted.

FIG. 4C shows an example of the calculation method of the time limit LT. This is an example of a method of calculating the time limit LT when a communication packet having a VLAN priority number 7 is transmitted from the communication terminal N to the communication terminal N + 1 via the repeater C100, the repeater C200, and the repeater C300. The line speeds between the communication terminal N and the repeater C100, between the repeater C100 and the repeater C200, between the repeater C200 and the repeater C300, and between the repeater C300 and the communication terminal N + 1 are the same. To do. Further, it is assumed that the transfer times of the communication packets in the repeater C100, the repeater C200 and the repeater C300 are the same or different times. Since the time obtained by dividing the size of the communication packet of the VLAN priority number 7 by the line speed is the transfer time between the devices, the time limit LT is expressed by the following equation (1).
Time limit LT = (communication packet size / line speed) x (number of repeaters passing through + 1) + (total transfer time of each repeater passing through) --- (1)

For example, when the size of the communication packet to be transferred is 100 [byte], the line speed is 100 [Mbps], there are three repeaters passing through, and the transfer time of each repeater is 1.0 [microsecond], the formula ( Calculate the time limit LT from 1). In this case, the time limit LT = (100 [byte] / 100 × 10 ⁶ × 8 [byte / sec]) × (3 + 1) + 1.0 × ^10-6 × 3 = 3.5 [microseconds]. .. The above numerical value is the time limit LT in the communication terminal N, and the time limit LT in the repeater 100, the repeater 200, and the repeater 300 is different. For example, the time limit LT of the repeater 200 is (100 [byte] / 100 × 10 ⁶ × 8 [byte / sec]) × (1 + 1) + 1.0 × ^10-6 × 2 = 2.25 [microseconds]. It becomes. In this way, each repeater can calculate the time limit LT in the own repeater.

When the switch processing unit C130 transfers the communication packet of the VLAN priority number 7, if the time zone is within the time limit LT, the switch processing unit C130 stores the communication packet in the priority buffer unit C141 and sets the VLAN priority number. Lower by one. Then, the communication packet in which the VLAN priority number is lowered by one from 7 to 6 is stored in the normal buffer unit C142. The switch processing unit C130 communicates the communication packet of the VLAN priority number 7 from the priority buffer unit C141, and when the communication fails, the communication packet in which the VLAN priority number is lowered by one from the normal buffer unit C142 to 6 is transmitted. connect. When any communication is successful, the switch processing unit C130 deletes the communication packet stored in the priority buffer unit C141 or the normal buffer unit C142 that has not succeeded in communication.

As an example, the output buffer unit C140 includes a priority buffer unit C141, a normal buffer unit C142, and a low speed buffer unit C143. The priority buffer unit C141 is a buffer unit in which communication packets having the highest priority of the VLAN priority number are stored.

For example, when the communication packet having the VLAN priority number 7 has the highest communication priority, the communication packet having the VLAN priority number 7 is stored in the priority buffer unit C141. The communication packets stored in the normal buffer unit C142 and the low-speed buffer unit C143 correspond to other VLAN priority numbers. For example, when the communication priority is lowered in descending order from the VLAN priority number 7, the normal buffer unit C142 functions as a buffer for storing the communication packets of the VLAN priority numbers 6 to 4. Further, the low-speed buffer unit C143 functions as a buffer for storing communication packets having VLAN priority numbers 3 to 0, but the present invention is not limited to this.

In this way, when the switch processing unit C130 detects the communication packet of the VLAN priority number 7, the switch processing unit C130 outputs the communication packet to the priority buffer unit C141.

The output buffer unit C140 outputs the communication packet stored in the priority buffer unit C141 to the output port unit C112 during the high priority communication dedicated time zone at the beginning of each cycle of the communication frame. Further, the output buffer unit C140 outputs communication packets stored in the normal buffer unit C142 and the low speed buffer unit C143 in order of priority in a time zone other than the high priority communication dedicated time zone of each cycle. Output to.

For example, when the normal buffer unit C142 has communication packets having VLAN priority numbers 6 to 4, the normal buffer unit C142 first outputs the communication packet having the VLAN priority number 6 to the output port unit C112. Next, the normal buffer unit C142 outputs the communication packet of the VLAN priority number 5 to the output port unit C112, and then outputs the communication packet of the VLAN priority number 4 to the output port unit C112.

Further, for example, when the low-speed buffer unit C143 has a communication packet having a VLAN priority number 3 to 0, the low-speed buffer unit C143 first outputs the communication packet having a VLAN priority number 3 to the output port unit C112. Next, the low-speed buffer unit C143 outputs the communication packet of the VLAN priority number 2 to the output port unit C112, and then outputs the communication packet of the VLAN priority number 1 to the output port unit C112. Finally, the low-speed buffer unit C143 outputs the communication packet having the VLAN priority number 0 to the output port unit C112.

Further, when the communication packet stored in the priority buffer unit C141 is output to the output port unit C112, the communication packet may not be output from the repeater C100 during the high priority communication dedicated time zone. In such a case, conventionally, it has been necessary for the communication packet to wait for communication until the high priority communication dedicated time zone of the next cycle. However, in the present embodiment, as an example, the switch processing unit C130 lowers the VLAN priority number of the communication packet from 7 to 6, and sets the communication packet in a time zone other than the high priority communication dedicated time zone of the same cycle. It works to output. The function of the switch processing unit C130 makes it possible to reduce the communication delay of the communication packet having the high priority of the VLAN priority number 7 at the beginning. The time zone other than the high-priority communication dedicated time zone in which the communication packet whose VLAN priority number is lowered from 7 to 6 is transmitted is the time zone corresponding to the VLAN priority number 6. Further, the switch processing unit C130 moves the communication packet whose VLAN priority number has been lowered from 7 to 6 from the state stored in the priority buffer unit C141 to the normal buffer unit C142.

Furthermore, the VLAN priority number is not limited to the case of reducing from 7 to 6. For example, the switch processing unit C130 extracts the VLAN priority number set in the normal buffer unit C142 or the low speed buffer unit C143 for the communication packet of the VLAN priority number 7 that cannot be transmitted in the high priority communication dedicated time zone. The switch processing unit C130 rewrites the extracted VLAN priority number to the highest priority VLAN priority number and moves it from the priority buffer unit C141 to the normal buffer unit C142.

Further, in the present embodiment, the communication packet whose VLAN priority number has been lowered from 7 to 6 passes through the plurality of repeaters, and due to the influence of other communications or the like, the normal buffer unit within the same communication cycle. It is assumed that it may remain in C142. If the communication packet remains in the normal buffer unit C142, it is assumed that the communication packet will be transmitted in the time zone next to the high priority communication dedicated time zone of the next communication cycle, so that the real-time property is impaired. Occurs. Therefore, in the present embodiment, when a communication packet whose VLAN priority number has been lowered from 7 to 6 remains in the normal buffer unit C142 at the end of the communication cycle, the VLAN priority number is returned from 6 to 7. .. Further, in the present embodiment, the communication packet in which the VLAN priority number is returned from 6 to 7 is stored in the priority buffer unit C141, and is transmitted in the high priority communication dedicated time zone of the next communication cycle. ..

The timer unit C150 has a function of synchronizing with other repeaters and communication terminals. Therefore, the start time and end time of the communication cycle, and the start time and end time of the high priority communication dedicated time zone are synchronized in each repeater and communication terminal.

(Flowchart of operation of repeater according to embodiment)
Next, with reference to FIGS. 5 and 6, an example of a flowchart of the operation of the repeater C100 according to the embodiment is shown. The processing procedure of FIGS. 5 and 6 in the repeater C100 is executed by the CPU (Central Processing Unit) according to the program stored in the ROM (Read Only Memory) of the computer included in the repeater C100.

In addition, a part or all of the following processing procedure is executed by hardware such as DSP (Digital Signal Processor) and ASIC (Application Specific Integrated Circuit), for example. However, in this embodiment, a case where the CPU executes according to the ROM program will be described.

FIG. 5 is an example of a flowchart of the operation of the input buffer unit C120, and FIG. 6 is an example of a flowchart of the operation of the switch processing unit C130 and the output buffer unit C140. The operations of FIGS. 5 and 6 can be operated asynchronously, but can also be operated synchronously.

First, an example of a flowchart of the operation of the input buffer unit C120 of FIG. 5 will be described.

In step S510, the input buffer unit C120 determines whether or not a communication packet has been input to the input port unit C111. When a communication packet is input to the input port unit C111 (step S510: YES), the input buffer unit C120 proceeds to step S520. When no communication packet is input to the input port unit C111 (step S510: NO), the input buffer unit C120 repeats step S510.

In step S520, the input buffer unit C120 stores the communication packet input to the input port unit C111 in the input buffer unit C120. The input buffer unit C120 is a FIFO (First In, First Out) type buffer, but is not limited to this. Next, the input buffer unit C120 returns to step S510 and continues the process.

Next, an example of a flowchart of the operation of the switch processing unit C130 and the output buffer unit C140 of FIG. 6 will be described. The flowchart of FIG. 6 shows the processing during one communication cycle, and shows the operation from the start time of one communication cycle.

The processing procedure of FIG. 6 in the repeater C100 is executed by the CPU (Central Processing Unit) according to the program stored in the ROM (Read Only Memory) of the computer included in the repeater C100.

In addition, a part or all of the following processing procedure can be executed by hardware such as DSP (Digital Signal Processor) and ASIC (Application Specific Integrated Circuit). However, in this embodiment, a case where the CPU executes according to the ROM program will be described.

In step S601, the switch processing unit C130 determines whether or not the communication packet stored in the previous cycle exists in the priority buffer unit C141. When the communication packet of the previous cycle exists in the priority buffer unit C141 (step S601: YES), the switch processing unit C130 proceeds to step S604. If the communication packet of the previous cycle does not exist in the priority buffer unit C141 (step S601: NO), the switch processing unit C130 proceeds to step S602. When the repeater C100 is located at the first stage of the communication system 1000, it is not assumed that communication packets remain in the priority buffer unit C141 at the start of the cycle. Details will be described later.

In step S602, the switch processing unit C130 determines whether or not the communication packet is stored in the input buffer unit C120. When the communication packet is stored in the input buffer unit C120 (step S602: YES), the switch processing unit C130 proceeds to step S604. If the communication packet is not stored in the input buffer unit C120 (step S602: NO), the switch processing unit C130 proceeds to step S603.

In step S603, the switch processing unit C130 refers to the timer unit C150 and determines whether or not one cycle for transmitting the communication packet has been completed. Since the TSN is synchronized with all the repeaters of the communication system 1000, it is possible for each repeater to recognize the start time and end time of one cycle for transmitting a communication packet. When one cycle for transmitting the communication packet is completed (step S603: YES), the switch processing unit C130 ends the processing. If one cycle for transmitting the communication packet is not completed (step S603: NO), the switch processing unit C130 returns to step S602 and waits for the input of the communication packet.

In step S604, the switch processing unit C130 determines whether or not the time is dedicated to high priority communication. Since the communication packet that can be transmitted during the high priority communication dedicated time is the communication packet having the highest priority number, the communication packet that proceeds from step S604 to the process of step S605 is the communication packet having the highest priority number. When the communication packet is in the high priority communication dedicated time (step S604: YES), the switch processing unit C130 proceeds to step S605. When the communication packet is not the high priority communication dedicated time (step S604: NO), the switch processing unit C130 proceeds to step S618.

In step S605, the switch processing unit C130 refers to the timer unit C150 and determines whether or not it is within the time limit within the high priority communication dedicated time. If it is within the time limit (step S605: YES), the switch processing unit C130 proceeds to step S606 because there is no margin in the communication processing of the communication packet. If it is not within the time limit (step S605: NO), the switch processing unit C130 proceeds to step S615 because there is a margin in the communication processing of the communication packet.

In step S606, the switch processing unit C130 stores the communication packet in the priority buffer unit C141. Even within the time limit, the communication packet output from the priority buffer unit C141 may complete the communication during the high priority communication dedicated time. Therefore, the switch processing unit C130 sets the communication packet as the priority buffer unit. Store in C141. Next, the switch processing unit C130 proceeds to step S607.

In step S607, the switch processing unit C130 creates a copy of the communication packet stored in the priority buffer unit C141. Next, the switch processing unit C130 proceeds to step S608.

In step S608, the switch processing unit C130 rewrites the priority number of the copied communication packet. For example, the switch processing unit C130 rewrites the VLAN priority number from the highest priority to the next priority. Details of an example of the priority number rewriting process will be described later with reference to FIG. 8 and the like. Next, the switch processing unit C130 proceeds to step S609.

In step S609, the switch processing unit C130 stores the communication packet whose priority number has been rewritten in the normal buffer unit C142. When the communication packet output from the priority buffer unit C141 does not complete the communication during the high priority communication dedicated time, the switch processing unit C130 outputs the communication packet whose priority number has been rewritten from the normal buffer unit C142. .. Next, the switch processing unit C130 proceeds to step S610.

In step S610, communication may be completed even within the time limit, so the switch processing unit C130 outputs the communication packet stored in the priority buffer unit C141 to the output port unit C112. Next, the switch processing unit C130 proceeds to step S611.

In step S611, it is determined whether or not the communication packet output in step S610 has completed communication during the high priority communication dedicated time. When the communication of the communication packet is completed during the high priority communication dedicated time (step S611: YES), the switch processing unit C130 proceeds to step S612. If the communication of the communication packet is not completed during the high priority communication dedicated time (step S611: NO), the switch processing unit C130 proceeds to step S613.

In step S612, since the communication of the highest priority communication packet is completed during the high priority communication dedicated time, the switch processing unit C130 is stored in the normal buffer unit C142 in which the priority of the communication packet is rewritten. Delete the communication packet that is being used. As a result, the switch processing unit C130 prevents the communication packet having the same data from being transmitted twice. Next, the switch processing unit C130 returns to step S601.

In step S613, since the communication of the highest priority communication packet was not completed during the high priority communication dedicated time, the switch processing unit C130 is stored in the normal buffer unit C142 in which the priority of the communication packet is rewritten. Output the communication packet that is being used. In this case, the output communication packet may or may not be completed during the time period corresponding to the normal buffer unit C142. In either case, the switch processing unit C130. Proceeds to step S614.

In step S614, the switch processing unit C130 is stored in the highest priority priority buffer unit C141 before rewriting the priority of the communication packet, regardless of the success or failure of the communication completion of the communication packet output in step S613. Delete the communication packet. As a result, the switch processing unit C130 prevents the communication packet having the same data from being transmitted twice. If the communication of the communication packet output in step S613 is not completed, the communication packet is stored in the priority buffer unit C141 from the normal buffer unit C142 in steps S622 to S624 described later. Therefore, in step S614, even if the communication of the communication packet output in step S613 is not completed, the communication packet stored in the priority buffer unit C141 of the highest priority before rewriting the priority is deleted. To do. Next, the switch processing unit C130 returns to step S601.

In step S615, the switch processing unit C130 determines whether or not the communication packet stored in the previous cycle exists in the priority buffer unit C141. When the communication packet of the previous cycle exists in the priority buffer unit C141 (step S615: YES), the switch processing unit C130 proceeds to step S617. If the communication packet of the previous cycle does not exist in the priority buffer unit C141 (step S615: NO), the switch processing unit C130 proceeds to step S616.

In step S616, the switch processing unit C130 stores the communication packet having the highest priority VLAN priority number from the input buffer unit C120 to the priority buffer unit C141. Next, the switch processing unit C130 proceeds to step S617.

In step S617, the switch processing unit C130 outputs the communication packet having the highest priority VLAN priority number from the priority buffer unit C141 to the output port unit C112. Next, the switch processing unit C130 returns to step S601.

In step S618, the switch processing unit C130 extracts the VLAN priority number of the communication packet extracted from the input buffer unit C120. Next, the switch processing unit C130 proceeds to step S619.

In step S619, the switch processing unit C130 stores the communication packet having the VLAN priority number which is not the highest priority in the normal buffer unit C142 or the low speed buffer unit C143. For example, when the communication priority decreases from the VLAN priority number 7 in descending order, the normal buffer unit C142 corresponds to the VLAN priority numbers 6 to 4, and the low speed buffer unit C143 corresponds to the VLAN priority numbers 3 to 0. However, the relationship between the normal buffer unit C142 or the low speed buffer unit C143 and the VLAN priority number is not limited to this. Next, the switch processing unit C130 proceeds to step S620 to continue the processing.

In step S620, the switch processing unit C130 outputs a communication packet from the normal buffer unit C142 or the low speed buffer unit C143 to the output port unit C112. As an example, the time zone in which the communication packet can be output from the normal buffer unit C142 and the time zone in which the communication packet can be output from the low speed buffer unit C143 may be different. Next, the switch processing unit C130 proceeds to step S621.

In step S621, the switch processing unit C130 determines whether or not the current communication cycle has ended. When the current communication cycle ends (step S621: YES), the switch processing unit C130 proceeds to step S622 and checks for rewriting the priority number of the communication packet. If the current communication cycle has not ended (step S621: NO), the switch processing unit C130 proceeds to step S602 to continue processing.

In step S622, when the communication packet remains without being transmitted to the normal buffer unit C142 or the low-speed buffer unit C143, the switch processing unit C130 has a change history of rewriting the priority number of the communication packet. Is determined. If there is a change history of rewriting the priority number of the communication packet (step S622: YES), the switch processing unit C130 proceeds to step S623. When there is no change history of rewriting the priority number of the communication packet (step S622: NO), the switch processing unit C130 ends the processing of the current communication cycle and starts the processing of the next communication cycle.

In step S623, the switch processing unit C130 rewrites the priority number of the communication packet having the change history of rewriting the priority number to the original priority number. As an example, when a communication packet whose priority number has been rewritten from 7 to 6 exists in the normal buffer unit C142 or the low-speed buffer unit C143, the switch processing unit C130 changes the priority number of the communication packet from 6 to 7. rewrite. Next, the switch processing unit C130 proceeds to step S624.

In step S624, the switch processing unit C130 moves the communication packet whose priority number has been rewritten in step S623 to the output buffer unit C140 corresponding to the rewritten priority number and stores it. As an example, the switch processing unit C130 moves the communication packet stored in the normal buffer unit C142 whose priority number has been rewritten from 6 to 7 in step S623 to the priority buffer unit C141 and stores it. In this way, when the communication packet transmitted in the high priority communication dedicated time cannot be transmitted within the high priority communication dedicated time and the priority number is lowered, the switch processing unit C130 performs the next cycle. Priority is given to transmission in the high-priority communication-only time.

FIG. 7A is an example of a schematic diagram for explaining the operation of steps S606 to S609 of FIG. In step S606, the switch processing unit C130 stores the communication packet P81 in the priority buffer unit C141. In step S607, the switch processing unit C130 creates a copy of the communication packet P81 stored in the priority buffer unit C141 in the switch processing unit C130. In step S608, the switch processing unit C130 rewrites the priority number of the copied communication packet. For example, in FIG. 7A, the switch processing unit C130 rewrites the VLAN priority number from the highest priority 7 to the next priority 6. In step S609, the switch processing unit C130 stores the communication packet whose priority number has been rewritten in the normal buffer unit C142.

FIG. 7B is an example of a schematic diagram for explaining the operation of step S612 of FIG. In step S612, since the communication of the highest priority communication packet is completed during the high priority communication dedicated time, the switch processing unit C130 is stored in the normal buffer unit C142 in which the priority of the communication packet is rewritten. Delete the communication packet that is being used. In FIG. 7B, when the communication of the communication packet P81 having a priority of 7 stored in the priority buffer unit C141 is successful, the transmission completion interrupt notification is transmitted from the output buffer unit C140 to the switch processing unit C130. Upon receiving the transmission completion interrupt notification, the switch processing unit C130 issues an instruction to delete the communication packet stored in the normal buffer unit C142 in which the priority of the communication packet is rewritten from 7 to 6 in the normal buffer unit C142. To transmit to. The normal buffer unit C142 deletes the communication packet whose priority has been rewritten from 7 to 6. As a result, the switch processing unit C130 prevents the communication packet having the same data from being transmitted twice.

FIG. 7C is an example of a schematic diagram for explaining a part of the operation of step S614 of FIG. In step S614, the following processing is executed. That is, regardless of whether or not the communication of the communication packet is completed in the time zone next to the high priority communication dedicated time, the switch processing unit C130 is for prioritizing the highest priority before rewriting the priority of the communication packet. The communication packet stored in the buffer unit C141 is deleted. FIG. 7C describes a case where communication of the communication packet is completed in the time zone next to the high priority communication dedicated time. When the communication of the communication packet P81 having a priority of 6 stored in the normal buffer unit C142 is successful, the transmission completion interrupt notification is transmitted from the output buffer unit C140 to the switch processing unit C130. Upon receiving the transmission completion interrupt notification, the switch processing unit C130 transmits an instruction to delete the communication packet stored in the priority buffer unit C141 before the priority of the communication packet is rewritten to the priority buffer unit C141. .. The priority buffer unit C141 deletes the communication packet whose priority is rewritten to 6 and the previous priority is 7. As a result, the switch processing unit C130 prevents the communication packet having the same data from being transmitted twice. If the communication packet communication is not completed in the time zone next to the high priority communication dedicated time, an interrupt notification of incomplete transmission is generated. Upon receiving the interrupt notification of incomplete transmission, the switch processing unit C130 transmits an instruction to delete the communication packet stored in the priority buffer unit C141 before the priority of the communication packet is rewritten to the priority buffer unit C141. To do. If the communication of the communication packet output in step S613 is not completed, the communication packet is stored in the priority buffer unit C141 from the normal buffer unit C142 in steps S622 to S624 described above. Therefore, in the next communication cycle, the communication packet is preferentially transmitted during the high priority communication dedicated time.

FIG. 8 shows an example of a method of storing the original priority information in a communication packet, and is an example of using a method of encapsulating a communication frame by MAC-in-MAC (IEEE802.1ah). By encapsulating the communication frame of FIG. 8, the switch processing unit C130 can determine whether or not the priority information of the communication packet is rewritten and the original priority information. However, the presence / absence of rewriting of the priority information and the determination process of the original priority information are not limited to the encapsulation of the communication frame.

FIG. 8 shows a configuration example of a communication frame when the priority information of the communication packet is lowered from 7 to 6. The priority information is not rewritten in the header in which the original priority information is stored, but a new header in which the priority information is stored is added. The destination address and destination address of the original communication frame are written before the header in which the new priority information is stored, and encapsulation is executed. The priority of the communication packet is determined by the header in which the new priority information is stored. Further, the presence / absence of the priority change history is determined by the presence / absence of the destination address next to the header in which the new priority information is stored. If the destination address exists next to the header in which the new priority information is stored, communication is performed by the priority information in the header in which the priority information next to the destination address next to the destination address is stored. The original priority of the packet is determined.

As described above, according to the configuration of the present embodiment, when the time limit within the high priority communication dedicated time is reached, the switch processing unit C130 stores the communication packet in the priority buffer unit C141. , Decrease the VLAN priority number by one. Then, the switch processing unit C130 stores the communication packet in which the VLAN priority number is lowered by one from 7 to 6 in the normal buffer unit C142. The switch processing unit C130 communicates the communication packet of the VLAN priority number 7 from the priority buffer unit C141, and when the communication fails, the communication packet in which the VLAN priority number is lowered by one from the normal buffer unit C142 to 6 is transmitted. connect. When any communication is successful, the switch processing unit C130 deletes the communication packet stored in the priority buffer unit C141 or the normal buffer unit C142 that has not succeeded in communication. Further, even when the communication from the normal buffer unit C142 fails, the communication packet before the VLAN priority number stored in the priority buffer unit C141 is rewritten is deleted. As a result, the switch processing unit C130 prevents the communication packet having the same data from being transmitted twice. Further, since the switch processing unit C130 executes the above processing before the high priority communication dedicated time ends, there is no delay due to the rewriting processing of the VLAN priority number and the like, so that the real-time performance can be improved. Become.

In addition, if the communication packet whose priority has been rewritten cannot be transmitted within the current cycle, it will be transmitted in the time zone after the high priority communication dedicated time of the next communication cycle, so that the real-time property is impaired. It will be lost. Therefore, according to the above embodiment, the priority of the communication packet whose priority has been rewritten is rewritten to the original priority, and if the original priority is, for example, the highest priority, the communication packet is moved to the priority buffer unit C141. Let and store. Therefore, in the next communication cycle, the communication packet can be preferentially transmitted in the high priority communication dedicated time.

FIG. 9 is a higher-level conceptual diagram of the operation of the present embodiment when a communication packet having a VLAN priority number 7 is transmitted from the communication terminal N to the communication terminal N + 1.

The communication packet P1s having the VLAN priority number 7 is transmitted from the communication terminal N to the repeater C100. Since the repeater C100 that has received the communication packet P1s can transmit the communication packet P1s in the high priority communication dedicated time zone, the communication packet P1s is transmitted to the repeater C200 as the communication packet P1s'. Since the repeater C200 that has received the communication packet P1s'can transmit the communication packet P1s' in the high priority communication dedicated time zone, the communication packet P1s' is transmitted to the repeater C300 as the communication packet P1s ″.

Since the repeater C300 that has received the communication packet P1s'' cannot transmit the communication packet P1s'' in the high priority communication dedicated time zone, the VLAN priority number of the communication packet P1s'' is changed from 7 to 6. Lower. The repeater C300 transmits the communication packet P1s ″ having the VLAN priority number 6 as the communication packet P1s ″ to the communication terminal N + 1 in the communication time zone corresponding to the VLAN priority number 6.

As described above, when a communication packet set to high priority cannot be sent within the high priority communication dedicated time due to propagation delay, the delay is minimized by lowering the priority one step at the repeater. It becomes possible to do. Further, since it is not necessary to adjust the number of communication packets and the communication interval in the high priority communication dedicated time zone of TSN, communication resources can be used efficiently.

(Modification example)
In the above description, the case where the improved function of the TSN according to the present embodiment is implemented in the repeater has been described, but the improved function of the TSN can also be used in the in-vehicle network.

FIG. 10 illustrates an example of an in-vehicle network. The configuration of FIG. 10 includes a camera S100, an ECU (Electronic Control Unit: E100, E200, E300, E400), a sensor S200, and a SW (vehicle-mounted switching hub: A100, A200). Further, the configuration of FIG. 10 includes a GW (vehicle-mounted gateway: A300), an RT (vehicle-mounted router: A400), a communication module T100, and a CAN (Controller Area Network: N100) connected to the GW.

In the vehicle-mounted network of FIG. 10, the improved functions of the TSN can be implemented in the vehicle-mounted switching hubs A100 and A200, the vehicle-mounted gateway A300, and the vehicle-mounted router A400.

Therefore, when a communication packet set to a high priority between the ECUs (E100, E200, E300, E400), the communication module T100 and the CAN (N100) cannot be sent within the high priority communication dedicated time due to propagation delay. Executes the following processing. That is, the delay can be minimized by executing the process of lowering the priority of the communication packet set to the high priority by one step. Further, since it is not necessary to adjust the number of communication packets and the communication interval in the high priority communication dedicated time zone of TSN, communication resources can be used efficiently.

In the above-described embodiment, an example in which the priority of the communication packet having the VLAN priority number of 7 is lowered by one has been described, but the priority of the communication packet having the VLAN priority number of 6 to 1 is lowered by one. It is also possible. In this case, a dedicated communication time zone may be set for each VLAN priority number. Further, a dedicated communication time zone may be set for each of a plurality of VLAN priority numbers.

It is also possible to configure each communication packet to include a cycle number identifier for specifying the cycle number in addition to the VLAN priority number.

The features of the repeater C100 and the communication system 1000 of this embodiment will be described below.

The repeater C100 according to the first aspect of the present disclosure sets a dedicated communication time zone corresponding to the priority information in the communication cycle for the communication packet having the priority information for transmitting the communication packet in the order of priority. Use the including communication method. The repeater C100 that relays the communication packet extracts the priority information of the communication packet from the input communication packet, and outputs the communication packet to the buffer unit of the output buffer unit C140 corresponding to the priority information. including. When the switch processing unit C130 receives the communication packet having the highest priority information within the time limit retroactive from the end time of the dedicated communication time zone corresponding to the highest priority information, the switch processing unit C130 executes the following processing. To do. The communication packet having the highest priority information is output to the priority buffer unit C141 of the output buffer unit C140 corresponding to the highest priority information. Further, the priority information of the communication packet is lowered to the priority information of the next priority, and the communication packet is output to the buffer section of the output buffer section C140 corresponding to the lowered priority information.

According to the above configuration, when a communication packet set to a high priority cannot be sent within the high priority communication dedicated time due to propagation delay, the delay is minimized by lowering the priority one step at the repeater. , It becomes possible to efficiently use the communication resources in the high priority communication dedicated time zone.

The repeater C100 according to the second aspect of the present disclosure relates to the repeater C100 according to the first aspect, and the time limit is such that the communication packet having the highest priority information is transferred from the self-repeater to the communication terminal to be transmitted. It is the time until it is done.

According to the above configuration, when the communication packet having the highest priority information is transmitted and the time limit is within the LT, the communication of the communication packet may be incomplete. In this case, by storing the communication packet in the priority buffer unit C141 and the buffer unit corresponding to the lowered priority information, it is possible to increase the probability that the communication of the communication packet is completed.

The repeater C100 according to the third aspect of the present disclosure corresponds to the lowered priority information with respect to the repeater C100 according to the first aspect or the second aspect, and the buffer part of the output buffer part C140 is for normal use. The buffer unit C142. Communication packets corresponding to the priority information of the normal buffer unit C142 whose priority information has not been rewritten are also stored in the normal buffer unit C142.

According to the above configuration, when a communication packet having the highest priority information is transmitted within the time limit LT, it is stored in the priority buffer unit C141, and the priority information is set to the next priority of the highest priority information. Is rewritten to and stored in the normal buffer unit C142. Therefore, the communication packet having the highest priority information may be transmitted in the time zone next to the high priority communication dedicated time or the high priority communication dedicated time, so that the propagation delay of the communication packet set to the highest priority may be delayed. Can be minimized.

The repeater C100 according to the fourth aspect of the present disclosure relates to the repeater C100 according to the third aspect, and the switch processing unit C130 transmits a communication packet having the highest priority information stored in the priority buffer unit C141. Send. When the communication packet is completed in the dedicated communication time zone corresponding to the highest priority information, the switch processing unit C130 deletes the communication packet in which the priority information stored in the normal buffer unit C142 is rewritten. To do.

According to the above configuration, when the transmission of the communication packet having the highest priority information within the time limit LT is completed, the priority stored in the normal buffer unit C142 is stored in order to prevent double transmission of the communication packet. Delete the communication packet whose information has been rewritten.

The above time limit LT is a theoretical value at which communication cannot be terminated within the high priority communication dedicated time. That is, theoretically, when the time limit LT is exceeded, the priority of the communication packet should be lowered and the process of storing the communication packet in the buffer one step lower should be performed. However, normally, the transfer time of the repeater C100 is not always constant and changes depending on the processing load or the like. Therefore, even if the time limit LT is exceeded, communication may be completed within the high priority communication dedicated time. Conceivable. Therefore, communication should be attempted within the high priority communication dedicated time, and if the communication is successful, the communication can be completed with the minimum delay time.

The repeater C100 according to the fifth aspect of the present disclosure relates to the repeater C100 according to the fourth aspect, and the switch processing unit C130 is a communication packet having the highest priority information stored in the priority buffer unit C141. Send a send. If the communication packet is not completed in the dedicated communication time zone corresponding to the highest priority information, the switch processing unit C130 transmits a communication packet in which the priority information stored in the normal buffer unit C142 is rewritten. To do. Then, the switch processing unit C130 deletes the communication packet having the highest priority information stored in the priority buffer unit C141.

According to the above configuration, when the transmission of the communication packet having the highest priority information within the time limit LT is not completed, the communication packet in which the priority information stored in the normal buffer unit C142 is rewritten is transmitted. The communication packet stored in the priority buffer unit C141 is deleted. This configuration makes it possible to prevent double transmission of communication packets. In addition, if communication cannot be completed while trying to communicate within the high-priority communication dedicated time, the priority can be lowered without requiring unnecessary delay time, so communication is performed with the delay time minimized. It will be possible to complete.

The repeater C100 according to the sixth aspect of the present disclosure relates to any of the repeaters C100 according to the first to fifth aspects. At the end of one communication cycle, the switch processing unit C130 determines whether or not the communication packet whose priority information has been rewritten exists in the buffer unit of the output buffer unit C140 corresponding to the rewritten priority information. .. If there is a communication packet whose priority information has been rewritten, the priority information of the communication packet is returned to the priority information before being rewritten, and the communication packet corresponds to the priority information before being rewritten. Move to the buffer section of the output buffer section C140.

If a communication packet whose priority information has been rewritten exists in the low priority buffer section of the output buffer section C140 at the end of one communication cycle, the transmission timing of the communication packet is delayed in the next communication cycle. It ends up. However, according to the above configuration, the priority information is returned to the priority information before being rewritten and moved to the high priority buffer unit corresponding to the priority information before being rewritten, so that the transmission timing is not delayed and is real-time. It is possible not to impair the sex.

The repeater C100 according to the seventh aspect of the present disclosure relates to the repeater C100 according to the sixth aspect. When the communication packet having the highest priority information stored in the priority buffer unit C141 exists at the start of one communication cycle, the switch processing unit C130 sets the communication packet having the highest priority information to the highest. It is transmitted in the dedicated communication time zone corresponding to the priority information of.

According to the above configuration, the communication packet returning to the highest priority information before the priority information is rewritten is transmitted in the dedicated communication time zone corresponding to the highest priority information, so that the transmission timing is not delayed. It is possible not to impair the real-time property.

The repeater C100 according to the eighth aspect of the present disclosure relates to any of the repeaters C100 according to the first to seventh aspects. The communication method has a high-priority communication time zone for transmitting the communication packet having the highest priority and a communication time zone for transmitting a communication packet having other priority in the communication cycle, and high-priority communication. The time zone is located at the beginning of each communication cycle.

According to the above configuration, since the communication cycle is provided with a high priority communication time zone for transmitting the communication packet having the highest priority, important communication such as a communication packet requiring urgent communication is provided. It is possible to reduce the delay in packet transmission. Further, according to the above configuration, since the communication time zone of an important communication packet such as a communication packet requiring urgent communication is provided at the beginning of the communication cycle, the communication packet can be preferentially transmitted. become. Further, since it is expected that the communication packet whose priority is lowered from the priority is also transmitted quickly, the communication performance can be improved.

The communication system 1000 according to the ninth aspect of the present disclosure is a communication packet directly or indirectly connected to the repeater C100 according to any one of the first to eighth aspects and the repeater C100. Includes at least one or more communication terminals N for transmitting and receiving.

According to the above configuration, when a communication packet set to a high priority cannot be sent within the high priority communication dedicated time due to propagation delay, the delay is minimized by lowering the priority one step at the repeater. , It becomes possible to efficiently use the communication resources in the high priority communication dedicated time zone.

As described above, according to the present embodiment, it is possible to minimize the delay of the communication packet that could not be transmitted within the high priority communication dedicated time of the TSN. The frequency, impact, and permissible time of delay will vary depending on the network design and application, but the effects obtained by introducing this embodiment will be obtained. In the case of vehicle-related applications, it is expected that applications such as ADAS and autonomous driving, in which delays are fatal, will become widespread, and therefore, the effect obtained by introducing this embodiment is great.

Further, as described above, according to the present embodiment, it is possible to efficiently use the band of the high priority communication dedicated time of the TSN. The optimum band differs depending on the number of terminals, the amount of communication, and the band required by each application, but the effect can be obtained by introducing this embodiment. Since there is a concern that the amount of communication will continue to increase in both the IT network and the in-vehicle network, the effect obtained by introducing this embodiment is great. In particular, in the case of vehicle-related applications, applications that have not been installed so far, such as ADAS, autonomous driving, and acquisition / transmission of information by V2X, are becoming more widespread, and it is expected that the amount of communication will increase. The effect obtained by introducing is great.

Although various examples have been described above, some or all of these examples can be combined into new examples.

C100, C200, C300 Repeater C111 Input port part C112 Output port part C120 Input buffer part C130 Switch processing part C140 Output buffer part C141 Priority buffer part C142 Normal buffer part C143 Low speed buffer part 1000 Communication system

Claims (9)

For the communication packet having priority information for transmitting the communication packet in the order of priority, the communication packet is relayed by using a communication method in which a communication cycle includes a dedicated communication time zone corresponding to the priority information. It is a repeater that
A switch processing unit that extracts the priority information of the communication packet from the input communication packet and outputs the communication packet to the buffer unit of the output buffer unit corresponding to the priority information is included.
When the switch processing unit receives the communication packet having the highest priority information within the time limit retroactive from the end time of the dedicated communication time zone corresponding to the highest priority information, the communication packet Output to the priority buffer unit of the output buffer unit corresponding to the highest priority information, the priority information of the communication packet is lowered to the priority information of the next priority, and the communication packet is lowered. A repeater that outputs to the buffer section of the output buffer section corresponding to the priority information. The repeater according to claim 1, wherein the time limit is the time until a communication packet having the highest priority information is transferred from the self-repeater to the communication terminal addressed to transmission. The buffer section of the output buffer section corresponding to the lowered priority information is a normal buffer section, and the priority of the normal buffer section in which the priority information is not rewritten in the normal buffer section. The repeater according to claim 1 or 2, wherein a communication packet corresponding to the information is also stored. The switch processing unit transmits a communication packet having the highest priority information stored in the priority buffer unit, and the communication packet is transmitted in a dedicated communication time zone corresponding to the highest priority information. If this is the case, the repeater according to claim 3, wherein the communication packet in which the priority information stored in the normal buffer unit is rewritten is deleted. When the switch processing unit does not complete the transmission of the communication packet having the highest priority information stored in the priority buffer unit in the dedicated communication time zone corresponding to the highest priority information, the switch processing unit said. The fourth aspect of claim 4, wherein the communication packet in which the priority information is rewritten stored in the normal buffer unit is transmitted, and the communication packet having the highest priority information stored in the priority buffer unit is deleted. Repeater. At the end of one communication cycle, the switch processing unit performs the communication when the communication packet whose priority information has been rewritten exists in the buffer unit of the output buffer unit corresponding to the rewritten priority information. Any of claims 1 to 5 in which the priority information of the packet is returned to the priority information before being rewritten and the communication packet is moved to the buffer section of the output buffer section corresponding to the priority information before being rewritten. The repeater described in item 1. At the start of one communication cycle, the switch processing unit transfers the communication packet having the highest priority information stored in the priority buffer unit to the communication packet having the highest priority information. The repeater according to claim 6, which transmits in a dedicated communication time zone corresponding to the highest priority information. The communication method has a high priority communication time zone for transmitting a communication packet having the highest priority and a communication time zone for transmitting a communication packet having another priority in the communication cycle, and the high priority communication method is provided. The repeater according to any one of claims 1 to 7, wherein the priority communication time zone is located at the head of each communication cycle. The repeater according to any one of claims 1 to 8.
A communication system including at least one communication terminal that transmits and receives the communication packet, which is directly or indirectly connected to the repeater.

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