WO2019233759A1

WO2019233759A1 - Method for operating a network device, network device and motor vehicle having the network device

Info

Publication number: WO2019233759A1
Application number: PCT/EP2019/062996
Authority: WO
Inventors: Stefan Brunner; Julian BRAND
Original assignee: Continental Automotive Gmbh
Priority date: 2018-06-06
Filing date: 2019-05-20
Publication date: 2019-12-12
Also published as: DE102018208895A1; DE102018208895B4

Abstract

The invention relates to a method for operating a network device (1), wherein a process of sending a data frame (6) is initiated and an express data frame (3) having a higher priority than the data frame (6) is received. A size of the data frame (6) is determined, and if the size of the data frame (6) has a value that is greater than a predefined minimum frame size (7) and also less than twice the predefined minimum frame size (7), a process of filling the data frame (6) is performed before or during the sending process. In the process of filling, placeholder data (14) are added to the data frame in order to achieve twice the predefined minimum frame size (7). After a part of the data frame (6) having the minimum frame size (7) has been sent, the process of sending the data frame (6) is interrupted by means of a frame preemption method. Subsequently, a process of sending the express data frame (3) is completely performed and the process of sending a remaining part of the data frame (6) is performed.

Description

description

Method for operating a network device, network device and motor vehicle with the network device

The invention relates to a method for operating a network device, a network device for carrying out the proceedings, and a motor vehicle with the network device.

To enable the communication of devices in a motor vehicle, the development is going to use a network according to the Ethernet standard in motor vehicles. The use of the Ethernet standard is problematic for devices which require a slight delay in the transmission of data frames, also called data frames. Thus, a delay in a transmission of data frames with a high priority, so-called express data frames, occur when for this purpose an already initiated transmission of a tenframes low-priority data is interrupted. This is based on the nature of the Ethernet standard, according to which data frames must have a predetermined minimum frame size in order to be able to be sent.

If a transmission of a data frame with a low priority must be interrupted in order to be able to send an express data frame, an interruption due to the minimum frame size of 64 bytes mentioned above is not possible at all times. An interruption can only be carried out at the limits of the minimum frame size. The data frame to be interrupted must have a minimum size of 128 bytes. This specification results in a maximum waiting time of 127 bytes, which occurs when the data frame to be interrupted has a size of 1 byte.

For some network devices, a small delay in transmission is essential. The resulting maximum possible delay is greater than the allowable time for these devices. Thus, these devices can not be operated in a network according to the Ethernet standard. These devices can For example, deal with airbag releases. For this reason, it is necessary to provide additional networks in a vehicle for these devices in order to meet the required latencies. This has the disadvantage that additional networks must be provided in the vehicle, resulting in an additional space requirement. The addition of another network is also associated with costs, which increases the price of the vehicle.

It is an object of the invention to provide a solution by which the maximum delay in the transmission of express data frames can be reduced.

The invention provides a method for operating a network device. In a first method step, a sending process of a data frame is turned on. In a second step, an express data frame having a higher priority than the data frame is received. In a next step, a size of the data frame is determined. If the size of the data frame has a value which is greater than a predetermined minimum frame size and at the same time less than twice the predetermined minimum frame size, a filling-in operation of the data frame is performed before or during the sending process. In the padding process, dummy data is supplied to the data frame to achieve twice the predetermined minimum frame size. The sending process of the data frame is interrupted after the sending of a part of the data frame which has the minimum frame size. The interruption can take place by means of a predetermined frame-preemption procedure. Thereupon, a transmission process of the express data frame is completed. After the sending process of the export data frame has been carried out, a sending process of a remaining part of the data frame is carried out. The steps described are carried out in particular in the order given.

In other words, a transmission of the data frame is initiated by the network device in the method. After the Dispatching process was initiated, is received by the network device, the express data frame, which should be sent with a higher priority than the data in the transmission process data frame. The network device determines the size of the data frame in the send process. If the data frame has a size that is between the predetermined minimum frame size and twice the minimum frame size, then a pop-up of the data frame is performed. As part of the padding process, the size of the data frame is extended by adding the dummy data to twice the predetermined minimum frame size. This process occurs before or during the sending process of the data frame. The sending process of the data frame is interrupted after a part of the data frame has been sent in minimum frame size. This is done by means of the predetermined Framepre emptionverfahrens. After the dispatch process of the data frame is interrupted, the sending process of the express data frame is initiated and terminated only after a complete transmission of the express data frame. After the sending process of the express data frame has been completely finished, the sending process of the data frame is continued. The remainder of the data frame, which has not yet been sent, is sent.

The advantage of the invention is that the transmission process of the data frame can be interrupted, even if the data frame has no size required to carry out a separation.

It can be provided, for example, that the method described is applied by the network device of a network. The network device may, for example, be a so-called switch. The sending process of the data frame can be, for example, sending the data frame to a destination network device which is connected to the network. The data frame may include data that is sent from the network device to the destination network device. It can also be provided that the data frame has data which is from a Originating network device to be sent to the destination network device, wherein the network device through which the method is performed acts as an intermediate point. In other words, the data frame can be sent from the source network device to the network device. The network device can receive the data frame and initiate the sending process to the destination network device. Thus, several so-called hops can be performed.

The data frame may have a predetermined priority. The priority may affect an order of sending data frames in the network and, for example, be stored in a value of the data frame. It can be a priority value after an 802. IQ VLAN tag of the data frame. The transmission of the data frame can be initiated by the network device. After starting the data frame transfer, the express data frame can be received by the network device. The express data frame may be a data frame that has a higher priority than the data frame whose dispatch process has already been initiated. It can be provided that the dispatch process of the express data frame must be initiated at a next possibility. For this it may be necessary that the transmission process of the data frame must be interrupted. It can be provided that, in order to interrupt the transmission process of the data frame, it is necessary to divide the data frame into two partial data frames. Due to a network standard, it may be necessary for a data frame to have a minimum frame size in order to be shipped. In this case, sending a part of the data frame may be excluded if the data frame is smaller than twice the minimum frame size. In this case, the data frame can not be split into two valid partial data frames, each of which has the minimum frame size. This can occur, for example, if the data frame has a size that lies between the minimum frame size and the double minimum frame size. In order to enable a splitting of the data frame, it may be provided that the size of the Data frames is determined and in the case that the size is in the said range between the simple minimum frame size and the double minimum frame size, a padding process is performed. This may be, for example, a filling process after the padding process. During the padding process, the size of the data frame can be reduced to twice the minimum frame size by adding dummy data, known as "dummy data." The said dummy data, also known as "padding data," is data that contains information of the data frame do not change. Thus the data frame before the filling process can have the same content as after the filling process. Due to the filling of the data frame with the placeholder data, the data frame after filling can have a size of two minimum frame sizes and thus be divisible. It is thus possible to divide the data frame into two sub-data frames, wherein a respective sub-data frame may have the minimum frame size. Thus, it may be possible that the sending process of the data frame after sending a part of the data frame, which may have the minimum frame size, can be interrupted by means of the predetermined framepreemption method. After interruption, the sending process of the express data frame can be completed. After the sending process of the express data frame has been completed, it can be provided that the sending process of the data frame is continued. For this purpose, the execution process of a remaining part of the data frame can be carried out.

A development of the method provides that the network tool is a device that meets the Ethernet standard. In other words, it is provided that the network device is set up to send data frames in accordance with the IEEE 802.3 standard. This has the advantage that the method can be used in networks, which are constructed according to the Ether net standard. Thus, it can be provided that the network device is a device with a microprocessor and / or a microcontroller, which can be used for this purpose. is designed to communicate over an Ethernet network. It may, for example, be a switch or an interface of a device.

A development of the method provides that the frame preemption method according to an IEEE 802. lQbu standard and / or an IEEE 802.3br standard is performed. In other words, the method is adapted to the frame preprocessing method for interrupting the sending process of the data frame either according to the IEEE 802 standard. lQbu and / or the IEEE 802.3br standard. This has the advantage that a common standard can be used in the process. For example, it may be provided that the interruption of the sending process of the data frame in the media access control layer of an Ethernet interface is initiated during the mailing process.

A further development of the method provides that the filling process of the data frame is carried out when the express data frame arrives. In other words, the completion of the padding operation in which the dummy data is carried to the data frame is performed at a time when the express data frame is received from the network device. This has the advantage that the filling process takes place at the earliest possible time. For example, it can be seen that the network device includes the data frame

Padding wildcard data as soon as it receives the express data frame.

A development of the method provides that the Ex pressdatenframe is a brake signal. In other words, the express data frame is a signal designed to contain information about an initiation of a braking operation. Such an express data frame can be generated in a motor vehicle. This results in the advantage that a braking process can be initiated via the network, without a significant delay must be taken out. It may for example be provided the express data frame comprises data describing a brake intensity of a brake.

A development of the method provides that the Ex pressdatenframe is a trigger signal of an airbag. In other words, the express data frame is a data frame comprising information for triggering an airbag. This results in the advantage that a separate network for airbags is not required. It can be provided that a network device is an impact sensor of the motor vehicle, which is connected to an igniter of the airbag via the network. Detects the impact sensor impact, for example by means of a pressure sensor, this can send the trigger signal as Expressda tenframe to the igniter of the airbag. The Expressda tenframe may include instructions for deployment of the airbag.

A development of the method provides that the placeholder data is assigned an identification point. In other words, the data frame includes a value or a string identifying a range of the wildcard data. This has the advantage that the dummy data of the data frame are identified, whereby a network device receiving the data frame can ignore the dummy data. For example, it may be possible to have a predetermined string at the beginning of the

Placeholder data is inserted. The network device which receives the data frame can be set up to recognize the point of identification and, for example, to terminate a readout process of the data frame from the identification point.

A further development provides that the minimum frame size is 64 bytes. In other words, a data frame must have a size that is at least 64 bytes. This has the advantage that the minimum frame size of the Ethernet standard is used in the context of the method. For example, it may be provided that a data frame is considered valid only if it has 64 bytes or more. The invention also encompasses a network device which is set up to carry out an embodiment of the method according to the invention.

The invention also includes a motor vehicle with a network tool for performing the method.

The invention also includes developments of the inventions to the invention network device and the invention

Motor vehicle having characteristics, as have already been described in connection with the developments of the method according to the invention. For this reason, the corresponding developments of the network device according to the invention and the motor vehicle according to the invention are not described again here.

In the following, an embodiment of the invention will be described. To illustrate this:

Fig. 1 shows an embodiment of the invention Ver

driving;

Fig. 2 shows another embodiment of the invention

Procedure.

The exemplary embodiment explained below is a preferred embodiment of the invention. In the exemplary embodiment, the described components of the embodiment each represent individual features of the invention that are to be considered independently of one another, which also each independently further develop the invention and thus also individually or in a different combination than the one shown as part of the invention. Furthermore, the described embodiment can also be supplemented by further features of the invention already described.

In the figures, functionally identical elements are each provided with the same reference numerals. Fig. 1 shows an embodiment of the method according to the invention. The method may be, for example, the network device

I be carried out. In Fig. 1 is a comparison of a delay 2 to an initiation of the sending process of the Expressdatenframes 3 in an application of a method according to the prior art, compared with a delay 4 to an initiation of the sending process of the Expressda tenframes 3 using the method according to the invention described , The express data frame 3 may be, for example, the trigger signal of the airbag or the brake signal. It can be provided that the sending process of the data frame 6 is initiated by the network device 1 at an initial time 5. After the initiation of the sending process of the data frame 6 at the start time 5, it may be necessary, for example, to send the Expressda tenframes 3 received by the network device 1, which may have a higher priority than the data frame 6. If the data frame 6 has a size of, for example, 65-127 bytes, wherein 64 bytes may be the minimum frame size 7, the data frame 6 may have a size which lies between the minimum frame size 7 and twice the minimum frame size 7 and thus can not be divided , Each data frame 6.3 can have a priority value of 8. Thus, it is not possible to interrupt the sending process of the data frame 6, for example according to the predetermined preemption procedure. As a result, the sending of the express data frame 3 can be initiated only when the sending process of the data frame 6 is ended at an end time 9. The delay 2, also called latency, can thus be the period between the initiation time 5 at which the transmission process of the data frame 6 is initiated and the end time 9 at which the transmission process of the data frame 6 is terminated. In one implementation of the method, it may be provided that the said data frame 6 is interrupted at a point of interruption 11 after a transmission of the partial data frame 10, which may have the minimum frame size 7. After the interruption time

II, the sending process of the Expressdatenframes 3 be performed. After the sending process of the Ex press data frame 3 is terminated at an Expressendzeitpunkt 12, a second subframe 13 can be sent, wherein the second subframe 13 may have wildcard data 14, which may be supplied to the data frame 6 in the filling process. Due to the filling process, the second partial frame 13 may have the minimum frame size 7. A delay 4, which results in the application of the method according to the invention, determined from the period between the start time 5 and the interruption time 11. The occurring when using the inventions to the invention process delay 4 is generally smaller than the delay 2, which at a Application of a method according to the prior art occurs.

Thus, Figure 1 shows the old scenario if the dispatch process of the data frame 6 can not be interrupted and the improvement can be interrupted if, by additional padding, the addition of dummy data 14, a data frame of an original size of 65-127 bytes can be interrupted. The method can therefore be used for all data frames with a size of 65-127 bytes. For this purpose, it must first be determined whether an Expressdatenframe 3 is present, which should be privileged. If this is the case, it still has to be checked whether padding is necessary at all or whether the data frame can also be paused without padding. If this is not the case, the payload of the data frame 6 is padded with placeholder data 14 by means of padding. For this purpose, it may be necessary for a data area filled with dummy data 14 to have a defined identification point 15, also called an identifier, so that a receiver can see that this is only an artificial increase in the payload, ie Dummy data, acts. The identification point 15 can thus identify the place holder data 14. The identification point 15 may, for example, identify an initial portion of the wildcard data 14. A network device 1 receiving the wildcard data 14 may be configured to ignore a data area of the data frame 6 after the identification point 15 So when reading the data frame 6 as dummy data or empty data to handle.

Fig. 2 shows a possible sequence of an embodiment of the method according to the invention. In a step S2, after the beginning of the method Sl, an entity of an express data frame 3 to be sent can be checked by the network device 1. If this is the case, it can be provided in a step S3 that a sending process of the express data frame 3 is initiated. In a step S4 it can be checked whether the transmission of the express data frame 3 has ended. When the transmission of the Expressdatenframes 3 is finished, it can be checked again for a presence of the Expressdatenframes 3 (S2). If, on the other hand, it turns out in step S2 that there is noexpress data frame 3, it can be provided that a presence of a data frame 6, which can be divisible (preemptable frame), is checked (S5). If this is not the case, the presence of the express data frame 3 is checked again

(52). If it is predicted in step S5 that the data frame 6 is present, the transmission process for transmitting the data frame 6 can be initiated (S6). After the beginning of the transmission of the data frame 6, it can be checked in a step S7 whether there is an express data frame 3 to be transmitted. If this is not the case, it can be checked in a step S8 whether the transmission of the express data frame 3 has ended. If this is not the case, the presence of the express data frame 3 is checked (S1). If the transmission of the express data frame 3 has ended, the method can be continued at step S2. If, on the other hand, it is determined in step S7 that an express data frame 3 is present, it can be checked in a step S9 whether an interruption of the sending process of the data frame 6 is possible. If this is possible, an interruption of the sending process of the data frame 6 can be performed in a step S10. After the interruption has been made, the sending process of the express data frame 3 can be initiated

(53). If it is found out in step S9 that an interruption of the data frame 6 is not possible, it can be checked in a step S11 whether the size of the data frame 6 has a value which is greater than the minimum frame size 7 and less than twice the minimum frame size 7. This condition may be satisfied if the minimum frame size 7 is 64 bytes and the size of the data frame 6 is, for example, between 65 and 125 bytes. If this is not the case, it can be checked in a step S8 whether the sending process of the data frame 6 has ended. If the size of the data frame 6 is in a range between the minimum frame size 7 and twice the minimum frame size 7, the size of the data frame 6 can be increased in step S12 by adding the dummy data 14 in the padding process. After supplying the placeholder data, the data frame 6 can have twice the minimum size 7 as a size. This may interrupt the sending process of the data frame 6. In a step S10, the interruption of the transmission process of the data frame 6 can be performed after the first partial data frame 10 has been sent. The interruption can be carried out, for example, by the network device 1, which can be arranged in a motor vehicle 16. After the interruption S10, the sending process of the express data frame 3 can be started (S3). It can also be provided that the filling process is initiated as soon as the Expressda tenframe 3 is received.

In Ethernet networks, prior to the introduction of the "frame preemption" procedure, it was not possible to stop the sending of data packets whose transmission had already begun so that a higher-priority data packet could overtake them.

There were therefore high delays when the transmission of a frame with the maximum length of 1500 or 1982 bytes was started and just then a higher priority frame was ready for sending.

With the standardization of "Frame Preemption" in the IEEE 802.1Qbu and IEEE 802.3br standards, this has been changed so that it is now possible to pause a transmission and prefer a higher-priority frame by dividing the data traffic into two classes in Express Traffic for express data frames 3, which, on the other hand, can overtake pre-emptible data packets, such as data frames 6. The standard stipulates that this interruption is possible only at the limits of 64 bytes, which may be the minimum frame size 7. This specification results in the maximum waiting time of 127 bytes (128 bytes is the smallest frame size yet to be interrupted (minimum frame size 7), the next smaller size, which can not be interrupted, corresponds to 127 bytes). The aim of the invention is to provide a method which further reduces these 127 bytes, so that the maximum length can be reduced to 64 bytes.

Especially with regard to the standardization of a 10 Mbit Ethernet technology, the EM is gaining in importance.

With 10 Mbit Ethernet technology, the speed is greatly reduced compared to 100/1000 Mbit, so a longer packet size has a greater impact on the absolute delay.

Currently no solution is known to reduce the size. It is only possible in the network itself to allow no longer data frames, but in this area, the efficiency is reduced so much that it is useless.

A method is proposed in which the frame to be interrupted is artificially extended so that a further interruption is possible. This method is commonly known as "padding" in the context of Ethernet.

By using padding in combination with frame preemption, the frame can be artificially lengthened. If a frame is 127 bytes long and thus could not be interrupted, it is extended by 1 byte by means of padding so that it has the necessary size of 128 bytes for a division. Thus, the higher-priority packet (Express Data Frame 3), which is to be privileged, does not have to wait 127 bytes, but "only" 64 bytes, which almost results in an improvement in latency by half. Overall, the example shows how the invention can provide a method of reducing the maximum delay in uninterrupted packet shipping.

LIST OF REFERENCE NUMBERS

1 network device

2 delay

3 express data frame

4 delay

5 start time

6 data frame

7 minimum frame size

8 priority value

9 End time

10 partial data frames

11 interrupt _Z eitpunkt 12 Express end point

13 subframe

14 placeholder data

15 identification point

16 motor vehicle

S1-S12 process steps

Claims

claims

A method of operating a network device (1), wherein

a dispatch process of a data frame (6) is initiated,

an express data frame (3) having a higher priority than the data frame (6) is received,

a size of the data frame (6) is determined,

- If the size of the data frame (6) has a value which is greater than a predetermined minimum frame size (7) and at the same time smaller than twice the predetermined minimum frame size (7), before or during the United send process a filling of the data frame (6) is performed in which dummy data (14) are supplied to the data frame (6) in the filling process in order to achieve twice the predetermined minimum frame size (7),

the sending process of the data frame (6) is interrupted after the sending of a part of the data frame (6) having the minimum frame size (7),

a sending process of the express data frame (3)

is completed, and

the posting process of a remaining part of the

Data frames (6) is performed.

2. The method of claim 1, wherein the network device (1) meets the Ethernet standard.

3. The method according to any one of the preceding claims, wherein a ver for the interruption of the sending process used frame pre-emptying after the

IEEE 802nd lQbu standard or the IEEE 802.3br standard.

4. The method according to any one of the preceding claims, wherein the filling process of the data frame (6) upon arrival of the Expressdatenframes (3) is performed.

5. The method according to any one of the preceding claims, wherein the express data frame (3) is a brake signal.

6. The method according to any one of the preceding claims, wherein the express data frame (3) is a trigger signal of an airbag.

7. The method according to any one of the preceding claims, wherein the dummy data (14) an identification point (15) is assigned.

8. The method according to any one of the preceding claims, wherein the minimum frame size (7) is 64 bytes.

9. Network device (1), arranged for carrying out a method according to one of claims 1 to 8.

10. motor vehicle (16), comprising a network device (1) according to claim 9.