JP2023061877A - Time-division schedule adjustment method, communication device, and time-division schedule adjustment method - Google Patents

Abstract

To provide a time-division schedule adjustment system/method and a communication device that adjust and synchronize the start timing of a time-division schedule set in a TSN hub and suppress variations in the start timing.SOLUTION: In a network N, TSN hubs 1 to 5 are equipped with a timer 'ToD' used in 'gPTP' time synchronization and a counter 'TC' which is not affected by time synchronization. The TSN hubs 1 to 5 acquire, from the timer, a time t1 when an arbitrary count number has passed since execution of the TSN time-division schedule. A gate start adjustment time b is calculated on the basis of the time t2+1 seconds=t3 obtained by calculating back the time corresponding to the count number from the time t1 and the start time t3 of the time-division schedule. When the gate start adjustment time b is greater than a preset execution threshold value a, the gate processing is started after waiting for the gate start adjustment time b at the start timing of the next time-division schedule.SELECTED DRAWING: Figure 1

Description

The present invention relates to a technology for adjusting a schedule of a time-divided network by TSN (Time Sensitive Networking).

TSN described in Patent Literature 1 and Non-Patent Literature 1 is a network and network technology that interoperates an industrial network and an IT network extending standard Ethernet (registered trademark). It consists of multiple standards such as "IEEE802.1Qbv".

(1) IEEE802.1AS
The “IEEE802.1AS” standard is abbreviated as “gPTP”. The time synchronous packet by this "gPTP" function is different from the normal PTP time synchronous packet in that only the "PtoP (adjacent devices)" transmission function can be used in the L2 layer.

(2) IEEE802.1Qbv
The IEEE 802.1Qbv time-aware scheduler divides communications on an Ethernet network into fixed lengths and repeats the time cycle. Configure time slices to assign to one or more of the eight Ethernet priorities within these cycles (“traffic scheduling” function).

This makes it possible to grant exclusive use for a limited time to the Ethernet transmission medium for traffic classes that require guaranteed transmission and cannot be interrupted. This is the basic concept of Time Division Multiple Access (TDMA), which allows separating time-critical communications from unimportant background traffic by establishing virtual communications channels at specific time periods.

JP 2020-107943

“Overview and implementation of 'TSN' that fuses IT and OT networks”, [online], retrieved on March 3, 2021, Internet <URL: http:ednjapan.com/edn/arrticies/1803/23/news014 .html>

It is often the case that each communication device on a network wishes to simultaneously use traffic sheeping by the traffic scheduling function of TSN's "IEEE802.1Qbv".

In this case, after synchronizing the time between each communication device using TSN's "IEEE802.1AS (gPTP)", using "IEEE802.1Qbv" traffic seeping at the same time, the target port of each communication device set the gate to

That is, set the passable packet level using "IEEE802.1Qbv" for the target port of each communication device, create a time-division schedule for each level, and operate the time-division schedule at a constant cycle. Set gate opening/closing (hereafter referred to as gate setting).

After that, with the passage of time, the set gates and times may differ between communication devices due to differences in crystal precision, etc., but the time of each communication device is corrected at regular intervals by the time synchronization processing of "gPTP".

At this time, the gate can be reset at a certain time according to the time synchronization processing, but in order to operate using the same time between each communication device, it is necessary to detect the target time and reset the gate after that detection. becomes. Therefore, there is a high degree of dependence on the CPU performance and processing status of communication devices, and there is a risk that non-negligible variations may occur between communication devices. This may adversely affect the accuracy of gate start timing between communication devices.

The present invention has been made to solve such conventional problems, by synchronizing the start timing (gate opening/closing timing) of the time-division schedule set for each communication device on the network, and suppressing variations in the start timing. This is the problem to be solved.

(1) One aspect of the present invention synchronizes time between communication devices on a network,
A method for adjusting a time-division schedule set for each level of packets that can pass through a target port of each communication device,
A gate is set for the target port of each communication device to operate the time-division schedule for each level at a constant cycle,
calculating the adjustment time of the start timing of the time-division schedule by repeatedly executing the opening and closing of the gate in synchronization with the time synchronization;
It is characterized by offsetting the start timing of the time-division schedule according to the calculated adjustment time.

(2) Another aspect of the present invention is a communication device that is arranged on a network so as to be time-synchronizable and in which a time-division schedule is set for each level of packets that can pass through a target port,
The target port is set to open and close a gate for operating the time-division schedule for each level at a constant cycle,
calculating the adjustment time of the start timing of the time-division schedule by repeatedly executing the setting of the gate opening and closing in synchronization with the time synchronization;
It is characterized by offsetting the start timing of the time-division schedule according to the calculated adjustment time.

(3) Still another aspect of the present invention synchronizes time between communication devices on a network,
A method for adjusting the time-division schedule, wherein the target port of each communication device is set to open and close a gate for operating the time-division schedule for each passable packet level at a constant cycle,
a step of calculating an adjustment time for the start timing of the time-division schedule by repeatedly executing the gate opening/closing setting in synchronization with time synchronization;
and offsetting the start timing of the time-division schedule according to the calculated adjustment time.

According to the present invention, it is possible to synchronize the start timings of the time-division schedules set for each communication device on the network, and suppress variations in the start timings.

FIG. 2 is a configuration diagram showing an example of a network according to the first embodiment; FIG. The flowchart which shows the gate setting of each TSN hub. FIG. 3 is a sequence diagram showing details of S04 to S07 in FIG. 2; (a) is a sequence diagram showing steps S04 to S07 showing operation processing of the first embodiment, and (b) is an explanatory diagram showing steps S08 and S09. FIG. 11 is a configuration diagram showing an example of a network according to the second embodiment; FIG. FIG. 4 is a schematic diagram of an example of gate opening/closing according to the time-division schedule of the first embodiment; FIG. 4 is a sequence diagram showing time synchronization and gate tuning in Patent Document 1; FIG. 11 is a schematic diagram showing an example of opening and closing gates according to a time-division schedule according to the second embodiment; FIG. 4 is a sequence diagram showing time synchronization and synchronization with a gate; Other network diagrams. FIG. 4 is an explanatory diagram showing gate correction of an edge-side port by an edge-side correction packet; FIG. 4 is an explanatory diagram showing gate correction of a main side port by a main side correction packet; 10 is a flowchart showing overall processing of gate correction according to the second embodiment; FIG. 14 is a flowchart showing details of S27 in FIG. 13; FIG. 14 is a flowchart showing details of S24 in FIG. 13; FIG. 14 is a flowchart showing details of S26 in FIG. 13; FIG.

A time-division schedule adjustment method (adjustment method) according to the embodiment of the present invention will be described below. Here, a layer 2 (L2) switching hub (hereinafter referred to as a TSN hub) corresponding to TSN is used as an example of a communication device to which the present invention is applied.

The TSN hub is equipped with the 'gPTP' function of 'IEEE802.1AS' and the traffic scheduling function of 'IEEE802.1Qbv'. As a result, it is possible to synchronize the time between the TSN hubs and create a time-division schedule to transmit priority packets without delay.

That is, on the premise that TNS hubs arranged on the network are time-synchronized by the "gPTP" function, highly accurate gate setting using time synchronization is possible. Details will be described below based on the first and second embodiments.

Example 1 will be described with reference to FIGS. 1 to 4. FIG. The TSN hub can be used while connected to a bus-type, ring-type, or more complicated network. In this embodiment, the network N shown in FIG. 1 is assumed as an example.

The network N is composed of TSN hubs 1-5. Here, the TSN hubs 1 to 5 are capable of time synchronization by the "gPTP" function, and the "gPTP" ports 1a to 5b, which require a time division schedule, are gated for each packet transmission direction A to D by the traffic scheduling function. is set.

For example, in the TSN hubs 1 and 3, gates are set to the "gPTP" ports 1a and 3a for packets sent in the transmission direction A, and gates are set to the "gPTP" ports 1b and 3b for packets sent in the transmission direction B. It is

In the TSN hubs 4 and 5, gates are set to the "gPTP" ports 4a and 5a for packets transmitted in the transmission direction C, and gates are set to the "gPTP" ports 4b and 5b for packets transmitted in the transmission direction D. ing.

The TSN hub 2 has a gate set to the "gPTP" port 2a for packets sent in the transmission direction A, a gate set to the "gPTP" port 2b for packets sent in the transmission direction B, and a gate set to the "gPTP" port 2b for packets sent in the transmission direction C. A gate is set to the "gPTP" port 2c for packets, and a gate is set to the "gPTP" port 2d for packets transmitted in the transmission direction D.

Inside such TSN hubs 1 to 5, there are timers (can be expressed up to nsec) used in "gPTP" time synchronization, and counters on the order of "nsec (cycle)" per count. The gate start adjustment time is calculated using this timer and counter, and the start timing of the next gate (the start timing of the operation cycle of the time division schedule) is set based on the calculated gate start adjustment time. Hereinafter, the timer will be indicated as "ToD" and the counter will be indicated as "TC", and the details of the gate setting will be described.

≪Gate setting processing contents≫
The gate setting processing steps (S01 to S09) in the TSN hubs 1 to 5 will be described with reference to FIGS. 2 and 3. FIG. Here, the TSN hubs 1 to 5 are in a state where the "gPTP" function and the traffic scheduling function are operating normally.

S01: When the process is started, the TSN hubs 1 to 5 check their own port states and acquire information on the ports that require gate setting. For example, the TSN hub 2 acquires the information of the "gPTP" ports 2a to 2d.

S02: A target port for gate setting is selected based on the port information acquired in S01. For example, for the TSN hub 2, the "gPTP" ports 2a→2d are selected in this order.

S03: Check whether or not gate setting has been completed for all target ports selected in S02 (for example, "gPTP" ports 2a to 2d in the case of TSN hub 2). As a result of the confirmation, if it is completed, the process is terminated, and if it is not completed, the process proceeds to S04.

S04: In order to measure the start timing of gate processing (gate opening/closing), period measurement is performed by "TC" which is not affected by time synchronization by the "gPTP" function.

Here, as shown in FIG. 3, when the period measurement of "TC" is "0 (nsec)", that is, when "TC0 (nsec)", gate processing is started (gate is started). For example, if the "gPTP" port 2a of the TSN hub 2 is the target port, gate processing of the port 2a is started at "TC0 (nsec)".

S05: After "TC" has passed "arbitrary count × T (nsec)", that is, after "TC1 = T (nsec)", "ToD" time "t1 = HH" synchronized with "gPTP" time :MM:SS.zzzzzzzz" (see Figure 3).

S06: From the time "t1" collected in S05, the time "t2" of "ToD" at the gate start time of S04, that is, "TC0 (nsec") is calculated backward.

To explain the details based on FIG. 3, first, in order to calculate the difference between TCs, the calculation of "TC1-TC0" is executed (S06-1). Next, the calculation result of S06-1 is subtracted from "t1" collected in S05 (S06-2) to calculate (estimate) time "t2=HH:MM:SS.yyyyyyyyy".

S07: Calculate the gate start adjustment time based on the time "t2" calculated in S06-1. At this time, the time "t3" is defined as in equation (1).
Formula (1): Time “t3”=Time “t2” of gate start (start of gate opening/closing)+1 second=HH:MM:SS+1.000000000
Then, by subtracting the time "t2" from the time "t3", the difference between the two "t2" and "t3", that is, the "difference data (nsec)" is obtained (S07-1). Further, the "difference data (nsec)" is divided by the gate period (1 msec) to obtain the remainder (remainder) (S07-2). This remainder is used as the gate start adjustment time b (nsec).

S08: Compare the gate start adjustment time b (nsec) of S07 with the preset execution threshold a (nsec). As a result of the comparison, if the gate start adjustment time b (nsec) is longer, the process proceeds to S09, otherwise the process ends.

S09: At the timing of the start of the next gate, the setting is adjusted so that the gate processing is started after waiting for the gate start adjustment time b (nsec). Here, the gate is assumed to have a function of setting the gate start adjustment time b (nsec), and the process is terminated after the setting.

<<Operation processing example>>
An example of operation processing will be described based on FIG. Here, a 125 MHZ 32-bit counter [1 count = 8 nsec (1000000000/125000000)] is used as "TC", and the gate period is set to "1 msec" as described above.

(1) S04 to S07
An example of operation processing of S04 to S07 will be described based on FIG. 4(a). Here, the gate start of S04 is performed when "TC0=5 count X 8 nsec=40 (nsec)".

Also, when "TC1=1255 count X 8 nsec=10040 (nsec)", "time t1=10:20:30.759004560" of S05 is collected.

When calculating the gate start adjustment time b (nsec) (S07), the time "t2" in S06 is calculated backward in advance. That is, the TC difference "10040-40=10000 nsec" is calculated (S06-1). Also, the TC difference "10000 nsec" is subtracted from "time t1=10:20:30.759004560" in S05 to calculate "time t2=10:20:30:758994560" (S06-2).

After that, the gate start adjustment time b (nsec) is calculated based on "time t2=10:20:30:758994560". At this time, the time is defined as "t3=10:20:31.00000000" according to the formula (1). Also, as shown in equation (2) in FIG. 4A, "difference data (nsec)=241005440 (nsec)" is calculated (S07-1).

The "difference data (nsec)" calculated here is divided by the gate period (1 msec=1000000 nsec) as shown in equation (3) in FIG. 4(a). From the remainder at that time, "gate start adjustment time b (nsec)=5440 (nsec)" is calculated (S07-2).

(2) S08, S09
An example of operation processing of S08 and S09 will be described based on FIG. 4(b). Here, the calculated gate start adjustment time b "5440 (nsec)" is compared with the execution threshold value a (nsec) (S08).

At this time, if "execution threshold value a (nsec)=10000 (nsec)" as indicated by arrow P, gate start adjustment is not performed. On the other hand, if "execution threshold value a (nsec)=5000 (nsec)" as indicated by arrow Q, wait for the gate start adjustment time "5440 (nsec)" at the next gate start timing as indicated in S09. Execute the start of gate processing. As a result, the following effects A to C are obtained.

A: The gate start timings set in the TSN hubs 1 to 5 are adjusted in advance according to the gate start adjustment time b (nsec), as shown in S09. As a result, it is possible to synchronize the gate start times among the TSN hubs 1 to 5 and suppress the variation.

In this case, the CPU load is added to the process of acquiring the ToD time used for time synchronization of "gPTP" as described above, but that process is only S05, and "TC" is used for other counts. to reduce the CPU load. In this respect, the influence on the accuracy of time synchronization is reduced, and the accuracy of time synchronization is improved.

B: The gate start adjustment time b (nsec) is used to adjust the start timing of gate processing when it is greater than the execution threshold a (nsec), as shown in S08. By setting the execution threshold value a (nsec) to the gate start adjustment time b (nsec) in this way, it becomes possible to synchronize the gate processing between the TSN hubs 1 to 5 with an accuracy higher than expected.

C: Patent Document 1 adjusts the time-division schedule by offsetting it according to the distance between TSN hubs. Here, an investigation packet is transmitted from the TSN hub at the end of the network, and the offset value is adjusted according to the reception timing of the investigation packet of other TSN hubs.

Therefore, by applying the offset value of Patent Document 1 to the gate start adjustment time b (nsec), it becomes possible to set the gate in consideration of the packet delay between the TSN hubs.

A second embodiment will be described with reference to FIGS. 5 to 16. FIG. In this embodiment, using "IEEE802.1AS" of TSN hubs, "IEEE802.1Qbv" between TSN hubs is tuned with high accuracy, and further delay due to distance between server and client devices via TSN hubs is eliminated. A correction is applied to "IEEE802.1Qbv".

The TSN hub has the functions of "IEEE802.1AS (time synchronization)" and "IEEE802.1Qbv (time division schedule)" as described above. For example, assume the network example shown in FIG.

1 to 3 in FIG. 5 denote TSN hubs (hereinafter referred to as hubs 1 to 3), and servers and terminal devices are connected via the hubs 1 to 3. FIG. In addition, although only one terminal device is shown in FIG. 5, a plurality of terminal devices may be connected, and information (status, voice, etc.) is periodically sent from the terminal device to the server in response to a request from the server.・Images, etc.) shall be transferred. The information transmitted from the terminal device includes important information whose omission is not allowed, and image information whose omission is not a problem depending on the situation.

Conventionally, when each hub 1 to 3 time-shares at the same timing by time synchronization, as shown in FIG. . As a result, the timing of opening and closing the gate does not match, and packets are transmitted later than expected, and in the worst case, packets may be lost.

Therefore, Patent Document 1 proposes a method of offsetting a time-division schedule by a transmission delay. According to this offset, it is possible to operate the TSN in a long-distance system by opening and closing the gate at a timing delayed by the transmission delay.

However, when the network shape or route changes due to functions such as STP (Spanning Tree Protocol)/RSTP (Rapid Spanning Tree Protocol), the transmission delay also changes, so the offset value must also be changed.

However, since the transmission-delayed time-synchronized packet makes a round trip, it takes time to calculate the offset value, which may delay the processing. In order to solve this point, the present embodiment proposes a method of easily acquiring the offset value of the time-division schedule.

≪Details of operation and processing≫
The operation and processing of this embodiment will be described with reference to FIGS. 5 to 8. FIG. Here, a TSN hub to which a server or the like is connected is called a main hub, and a TSN hub at the end of the network is called an edge hub. According to the network configuration of FIG. 5, hub 1 indicates the main hub and hub 3 indicates the edge hub.

(1) Basic Idea FIG. 6 shows a time-division schedule in which the TSN of each hub 1 to 3 is set to a valid port (synonymous with the "gPTP" port in Embodiment 1; hereinafter referred to as the TSN port). It shows gate settings (examples of gate opening/closing settings), and sets the type of packet to be allowed to pass and the passage time for each interval A to E. FIG. In Example 1, the gate setting is repeatedly executed in synchronization with time synchronization.

As shown in FIG. 6, hubs 1 to 3 have a function of time synchronization and a function of synchronizing time synchronization and gates, and the gates of hubs 1 to 3 are network trunk lines set to TSN ports. becomes. Gates are opened and closed by packet transmission. As shown in FIG. 7, gates 1 and 3 are used for packet transmission from hub 1 to hub 3, and gates 2 and 4 are used for packet transmission from hub 3 to hub 1. be done.

At this time, if each gate opens and closes at the same timing due to time synchronization, the packet arrives late due to the transmission distance, so there is a risk that the time-division schedule cannot be kept. For example, in FIG. 7, transmission delays occur at times B and C when a packet is transmitted from hub 1 to hub 3 .

As described above, in Patent Document 1, the time division schedule is offset in consideration of such transmission delay. Although this method enables operation according to the transmission delay of a long-distance system, it may not be possible to calculate the offset in a short time when the network shape or route changes.

Therefore, in this embodiment, as shown in FIG. 8, the period of the correction packet is added to the beginning of the gate setting, and the time-division schedule is offset according to the passage time of the correction packet. This correction packet is transmitted at the main hub (hub 1) and the edge hub (hub 3) with the gates opened only during the correction packet period of the time-division schedule.

As a result, the correction packets are transmitted from the hubs 1 and 3 at the timing according to the time synchronization and the time division schedule. On the other hand, since the intermediate hub 2 can always transfer packets, it also performs a simple transfer process for correction packets. Note that the gate interval S in FIG. 8 is set to allow only one packet (correction packet) to pass.

At this time, even if the network shape or route changes, the time synchronization is maintained, but the transmission delay time changes depending on the transmission route. Therefore, the hub 2 will receive the correction packet from a port different from the conventional one, and if the reception timing can be obtained, it will be possible to calculate the transmission delay and apply a new offset.

In this regard, unlike Patent Document 1, it is not necessary to wait for the round trip of packets due to time synchronization, and the offset can be calculated in a short time even if the network shape or route changes.

Then, the correction packet transmitted from the main hub (hub 1) reaches the edge hub (hub 3) and the transfer is completed. On the other hand, when the correction packet transmitted from the edge hub (hub 3) reaches the main hub (hub 1), it is terminated there by a function such as an access list. At this time, a plurality of edge hubs may exist depending on the network shape, etc. In such cases, a plurality of correction packets join the main hub.

(2) Example of operation processing An example of operation processing will be described based on FIG. Here, as shown in FIG. 5, hubs 1 to 3 are connected by TSN ports, hub 1 of the main hub corresponds to the grand master (GM) for time synchronization, and hubs 2 and 3 correspond to slaves synchronized with hub 1. do. Therefore, the timer times (ToD times) of hubs 2 and 3 match the ToD time of hub 1 by time synchronization.

S11: First, hub 1 transmits a correction packet (1581 bytes) from its own TSN port to hub 3 at ToD time (00.000000000 seconds at XX:00000000000000000000000000000000000000000000).

Here, it is assumed that the transmission time of "00.000000000 seconds" can be determined by the gate function of the hub 1, the correction packet transmitted from the hub 1 is called the correction packet 1, and the ToD time when the correction packet 1 is transmitted is the ToD time A, correction packet 1 is transmitted including ToD time A. Note that the size of the correction packet is not limited to "1581 bytes", and other sizes may be used.

S12, S13: The correction packet 1 transmitted by the hub 1 is received by the hub 2 and transferred to the hub 3 (S12). That is, since the gate is always open during the correction packet period of the hub 2, the data is transferred by store-and-forward.

At this time, since the hub 2 can acquire the timing at which the correction packet 1 is received, the transmission delay can be acquired from the difference from the timer time (ToD time) of the hub 2 and used as the offset value.

Here, the ToD time when the correction packet 1 collected by the hub 2 is received is ToD time B (XX: ZZ: 00.0000yyyyy seconds). Let t1 be the time taken to collect .

In this case, transit time B from hub 1 to hub 2 is a time obtained by subtracting ToD time A and "t1" from ToD time B, as shown in equation (4) in FIG. Transit time B calculated by equation (4) is equal to the packet delay time from hub 1 to hub 2, so transit time B is the time between the next ToD time of hub 2 and gate 3 (edge side port). It is added as gate correction time at the time of tuning (S13). This allows for accurate gate settings.

Correction packet 1 is then received by hub 3 . Since the hub 3 is an edge hub, there is no need to calculate the transmission delay.

S14-S16: Next, the hub 3 opens the gate for the correction packet period from its own TSN port to the ToD time (XX:00:00:00:00:00), and transmits the correction packet (1581 bytes) to the hub 1 (S14). .

Here, it is assumed that the transmission time of "00.00000000 seconds" can be determined by the gate function of the hub 3, the correction packet transmitted from the hub 3 is called the correction packet 2, and the ToD time when the correction packet 2 is transmitted is the ToD time C, and correction packet 2 is transmitted including ToD time C.

The correction packet 2 transmitted by the hub C is received by the hub 2 and transferred to the hub 1 (S15), and the same processing as in S13 is executed. Here, the ToD time at which the correction packet 2 collected by the hub 2 is received is ToD time B' (XX hours ZZ minutes 00.00a0zzzzz seconds). Let "t2" be the time taken to collect B'.

In this case, the transit time B' from the hub 3 to the hub 2 is calculated by the formula (5) in FIG. It is added as gate correction time (S16).

(4) Other Examples of Operation Processing Another example of operation processing will be described with reference to FIGS. 10 to 12. FIG. FIG. 10 shows another network configuration example. Here, hub 1 corresponds to the main hub, hubs 5, 7, and 8 correspond to edge hubs, gates 2, 4, 6, 8, 9, 10, and 12 indicate main side port gates, gates 1, 3, 5, 7 and 11 indicate the gates of edge side ports.

The hub 1, as shown in FIG. 11, transmits an edge-side correction packet (corresponding to the aforementioned correction packet 1) to hubs 5, 7, and 8. FIG. This edge-side correction packet is sequentially transferred by hubs 2-4 and 6. FIG. At this time, the transit time of hubs 2 to 4, 6 is added to gates 1, 3, 5, 7, 11 to perform gate correction for edge side ports.

On the other hand, the hubs 5, 7, and 8 transmit the main side correction packet (corresponding to the correction packet 2 described above) to the hub 1, as shown in FIG. This main side correction packet is sequentially transferred by hubs 2-4 and 6. FIG.

At this time, correction of the main side gates 4 and 10 of the hubs 3 and 6 is duplicated in the hub 2, and correction of the main side gates 8 and 9 of the hubs 5 and 7 is duplicated in the hub 4. When the gate correction paths of the main side port overlap in this way, the time with the longer passage time is adopted as the offset value.

≪Detailed processing contents≫
Details of the gate correction process will be described with reference to FIG. Here, it is assumed that the following data are inputted in advance by commands and written in the gate correction information file.
・Edge delay number ・Main flag ・Edge flag ・TSN port number for operating TSN (hereinafter referred to as TSN port number)
S21: Read the gate correction information file at the start of processing. As a result, the edge delay number, main flag, edge flag, and TSN port number are set in the TSN hub as internal data. It is assumed that the main flag is set in the main hub and the edge flag is set in the edge hub.

S22-S27: Set the gate for the gate correction packet for the TSN port (S22). After that, it is checked whether or not the edge side correction packet has been received (S23). As a result of the confirmation, if the edge side correction packet has been received, the process proceeds to the edge side correction packet reception processing of S24.

If not received, the process proceeds to S25. In S25, it is checked whether or not the main side correction packet has been received. As a result of the confirmation, if the main side correction packet has been received, the process proceeds to the main side correction packet reception processing of S26. On the other hand, if it has not been received, the process proceeds to the gate correction packet transmission process of S27.

(1) Details of Gate Correction Packet Transmitting Process Details of the gate correction packet transmitting process of S27 will be described with reference to FIG. Here, the processing contents differ between the main hub and the edge hub.

S31: When the process is started, it is checked whether it is the main hub. This confirmation is performed depending on whether the main flag is set or not. On the other hand, if the main flag is not set, it does not correspond to the main hub, and the process proceeds from S36 onwards.

S32-S35: The time of time synchronization (ToD time) is acquired from the timer (S32). The remaining time from the acquired ToD time to the next one second is calculated (S33), and it is confirmed whether the calculated remaining time is equal to or less than the gate period (S34).

As a result of confirmation, if it is not equal to or less than the gate period, the process is terminated. On the other hand, if it is equal to or less than the gate period, the edge-side correction packet is transmitted from the TSN port of the TSN port number read in S21 (S35), and the process ends.

S36: It is checked whether it is an edge hub. This confirmation is performed depending on whether or not the edge flag is set. If the edge flag is not set, the process is terminated.

S37-S42: It is checked whether or not the main side correction packet has been received (S37). This confirmation is confirmed by whether or not the received flag of the main side correction packet is set (S38). If the received flag is not set, the main side correction packet has not been received, and the processing is terminated. On the other hand, if the received flag is set, the main-side correction packet has already been received, so the process proceeds to S39.

In S39, an edge delay time (edge delay number.times.gate period) is set in a waiting timer to avoid collision of edge side correction packets. After that, it is checked whether or not the delay time set in S39 has passed (S40).

As a result of the confirmation, if the time has not passed, the process is terminated. If the time has passed, the main side correction packet is transmitted from the TSN port of the TSN port number read in S21 (S41). After this transmission, the received flag of the edge-side correction packet is cleared (S42), and the process ends.

(2) Details of Edge Side Correction Packet Reception Processing Details of the edge side correction packet reception processing of S24 will be described with reference to FIG.

S51: When the process is started, it is checked whether or not it corresponds to the main hub. This confirmation is performed depending on whether or not the main flag is set. If the main flag is set, the process is terminated. If the main flag is not set, the process proceeds to S52.

S52: It is checked whether the device itself corresponds to an edge hub. This confirmation is performed depending on whether or not the edge flag is set. If the edge flag is set, the reception completion flag of the edge side correction packet is set (S59), and the process is terminated. On the other hand, if the edge flag is not set, the process proceeds to S53 and subsequent steps.

S53-S58: First, the reception port for the edge-side correction packet is saved as the transmission port for the main-side correction packet (S53). Next, the time for time synchronization (ToD time) is acquired from the timer (S54), and the elapsed time "t1" from the port reception of the edge side correction packet is acquired using the time stamp function for time synchronization (S55).

After obtaining the elapsed time "t1", the gate correction time is calculated by equation (4) (S56). Also, based on the edge-side port number and the TSN port number, information on edge-side ports other than the port that received the edge-side correction packet is acquired (S57).

The TSN port of the information acquired here is called a gate correction port. For this correction port, the gate correction time is added to the next gate tuning (S58), and then the processing ends.

(3) Details of Main Side Correction Packet Receiving Processing Details of the main side correction packet receiving processing of S26 will be described with reference to FIG.

S61: When the process is started, it is checked whether or not it corresponds to the main hub. This confirmation is performed depending on whether or not the main flag is set. If the main flag is set, the process is terminated. If the main flag is not set, the process proceeds to S62.

S62: It is confirmed whether or not itself corresponds to an edge hub. This confirmation is performed depending on whether or not the edge flag is set. If the edge flag is set, the process is terminated. If not, the process proceeds to S63 and subsequent steps.

S63-S66: First, the time of time synchronization (ToD time) is obtained from the timer (S63), and the elapsed time "t2" from port reception of the main-side correction packet is obtained using the time-synchronization time stamp function ( S64).

After obtaining the elapsed time "t2", the gate correction time is calculated by Equation (5) (S65). Also, the main side port number is obtained and the gate correction time is added at the next gate tuning of the main side port (S66), and then the process is terminated.

According to this embodiment, since "t1" and "t2" can be obtained from the time stamp function when calculating the offset value of the time-division schedule, the equations (4) and (5) can be used to easily can be calculated.

Above all, if the time synchronization is already established, even if the shape and route of the network change due to functions such as STP/RSTP, the offset value of the time-division schedule can be obtained by acquiring the reception timing of the correction packet, and the time-division schedule can be obtained in a short period of time. calculation becomes possible.

In addition, it is possible to efficiently calculate an offset value when collecting data from a server or the like even in a complicated network configuration without being affected by the shape of the network, the number of TSN hubs, or the like.

For example, even in the network configuration of FIG. 10, accurate gate correction is possible as shown in FIGS. 11 and 12. FIG. As a result, when the server is connected to the main hub (hub 1) and the terminal device is connected to the edge hubs (hubs 5, 7, 8), a certain amount of other packets sent between the server and the terminal device are stabilized. While forwarding, it becomes possible to transmit important packets without loss.

In this embodiment, gate setting for the time-division schedule is necessary, but the offset value is automatically set even if the shape or route of the network changes, so the setting work can be omitted.

1 to 8: TSN hub 1a to 5b: "gPTP" port A to D: packet transmission direction N: network

Claims (14)

Synchronize time between communication devices on the network,
A method for adjusting a time-division schedule set for each level of packets that can pass through a target port of each communication device,
A gate is set for the target port of each communication device to operate the time-division schedule for each level at a constant cycle,
calculating the adjustment time of the start timing of the time-division schedule by repeatedly executing the opening and closing of the gate in synchronization with the time synchronization;
A method for adjusting a time-division schedule, wherein the start timing of the time-division schedule is offset according to the calculated adjustment time. Each communication device includes a timer used in the time synchronization and a counter that is not affected by the time synchronization,
obtaining from the timer the time when the counter has passed an arbitrary number of counts since execution of the schedule;
2. The adjustment of the time-division schedule according to claim 1, wherein the adjustment time is calculated based on the schedule start time and the time obtained by calculating back the time corresponding to the count number from the acquired time. method. executing the schedule when the counter is "0 (sec)";
3. The method of adjusting a time-division schedule according to claim 2, wherein the time is obtained after the count number has elapsed since execution of the schedule. The adjustment time is
A time obtained by adding an arbitrary number of seconds to the time obtained by the back calculation;
a schedule start time;
4. The time-division schedule adjustment method according to claim 2 or 3, wherein the difference is a remainder obtained by dividing the difference between the intervals of the schedule. comparing the adjustment time to a preset execution threshold;
4. The time-division schedule adjustment method according to claim 2, wherein the next start of the schedule is waited for the adjustment time according to the result of the comparison. In setting the gate, the types of packets to be passed and the passage time are set for each gate interval,
adding a correction packet period to the beginning of the gate interval group;
calculating a correction time according to the transmission delay by transferring the correction packet to the communication device group;
2. A method for adjusting a time-division schedule according to claim 1, wherein said calculated correction time is used as said adjustment time. The correction packet is transmitted to the main communication device that assumes a server connection in the network,
the communication device at the end of the network;
while sent from
7. The time-division schedule adjustment system according to claim 6, wherein said intermediate communication device arranged between said main device and said device other than said terminal device sequentially transfers said data. said communication device in between,
a timer time at which the correction packet was collected;
a time taken for the correction packet to arrive at the target port and to collect the timer time;
Calculate the transmission delay time based on
8. The time-division schedule adjustment system according to claim 7, wherein said transmission delay time is calculated as said correction time. A communication device that is arranged on a network so as to be time-synchronized and in which a time-division schedule is set for each level of packets that can pass through a target port,
The target port is set to open and close a gate for operating the time-division schedule for each level at a constant cycle,
calculating the adjustment time of the start timing of the time-division schedule by repeatedly executing the setting of the gate opening and closing in synchronization with the time synchronization;
A communication apparatus, wherein a start timing of the time-division schedule is offset according to the calculated adjustment time. A timer used in the time synchronization and a counter that is not affected by the time synchronization,
obtaining from the timer the time when the counter has passed an arbitrary number of counts since execution of the schedule;
10. The communication apparatus according to claim 9, wherein the adjustment time is calculated based on the schedule start time and the time obtained by calculating back the time corresponding to the count number from the acquired time. In setting the opening and closing of the gate, the types of packets to be allowed to pass and the passage time are set for each gate interval,
adding a correction packet period to the beginning of the gate interval group;
calculating a correction time according to the transmission delay by transferring the correction packet to the communication device group;
10. The communication device according to claim 9, wherein the calculated correction time is used as the adjustment time. Synchronize time between communication devices on the network,
A method for adjusting the time-division schedule, wherein the target port of each communication device is set to open and close a gate for operating the time-division schedule for each passable packet level at a constant cycle,
a step of calculating an adjustment time for the start timing of the time-division schedule by repeatedly executing the gate opening/closing setting in synchronization with time synchronization;
offsetting the start timing of the time-division schedule according to the calculated adjustment time;
A method for adjusting a time-division schedule, comprising: Each communication device includes a timer used in the time synchronization and a counter that is not affected by the time synchronization,
a step of obtaining from the timer the time when the counter has passed an arbitrary number of counts since execution of the schedule;
a step of calculating the adjustment time based on the time obtained by back-calculating the time corresponding to the count number from the acquired time and the schedule start time;
13. The time-division schedule adjustment method according to claim 12, characterized by comprising: In setting the opening and closing of the gate,
The type of packet to be passed and the passage time are set for each gate interval,
adding a correction packet period to the beginning of the gate interval group;
calculating a correction time according to the transmission delay by transferring the correction packet to the communication device group;
13. The time-division schedule adjustment method according to claim 12, wherein the calculated correction time is used as the adjustment time.

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