Communication device, communication method, and computer program

Abstract

The invention provides a communication apparatus, a communication method, and a computer program. A communication device is provided with a processing unit that transmits and receives a frame generated in accordance with an IEEE802.1 AS protocol, and a storage unit that stores feature information of timestamps included in a frame to be received, and the processing unit collects timestamps included in a frame received from a specific transmission source and transmits the timestamps to the storage unit. And a determination unit that determines whether or not the timestamp included in the frame received from the transmission source is normal by comparing the collected feature information of the timestamp with the feature information of the timestamp stored in the storage unit.

Description

Technical Field

[0001] The present invention relates to a communication device, a communication method and a computer program.

[0002] This application claims the priority based on Japanese application No. 2022-096068 for which it applied on June 14, 2022, and cites all the contents described in the said Japanese application. Background Art

[0003] Conventionally, as a method for detecting abnormality during time synchronization, for example, Patent Document 1 discloses a method of calculating a delay time from a difference between a time stamp and the current time and detecting abnormality based on a recorded history of the delay time.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2018-201110 Summary of the invention

[0007] Problems to be solved by the invention

[0008] In Patent Document 1, abnormality detection is performed based on the recorded history of delay time, but abnormality cannot be detected based on characteristic information of the time stamp itself.

[0009] The present invention has been made in view of such a situation, and its object is to provide a communication device, a communication method and a computer program that focus on characteristic information of the timestamp to determine whether the timestamp included in a frame sent from a specific sending source is normal.

[0010] Means for solving problems

[0011] A communication device according to one embodiment of the present invention includes a processing unit and a storage unit, which transmit and receive frames generated according to the IEEE802.1AS protocol, wherein the storage unit stores characteristic information of timestamps contained in frames to be received, and the processing unit collects timestamps contained in frames received from a specific transmission source, and the processing unit determines whether the timestamps contained in the frames received from the transmission source are normal by comparing the characteristic information of the collected timestamps with the characteristic information of the timestamps stored in the storage unit.

[0012] Effects of the Invention

[0013] According to the present disclosure, it is possible to determine whether a time stamp included in a frame transmitted from a specific transmission source is normal by focusing on characteristic information of the time stamp. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1It is an explanatory diagram for explaining a configuration example of a communication system according to the present embodiment.

[0015] Figure 2A This is an explanatory diagram for explaining characteristic information of a timestamp.

[0016] Figure 2B This is an explanatory diagram for explaining characteristic information of a timestamp.

[0017] Figure 2C This is an explanatory diagram for explaining characteristic information of a timestamp.

[0018] Figure 3 This is a timing diagram when calculating the synchronization time.

[0019] Figure 4 This is a timing diagram when the Sync frame is relayed.

[0020] Figure 5 This is a timing diagram when calculating propagation delay.

[0021] Figure 6 This is a flowchart showing the processing steps of abnormality detection performed by the communication device. DETAILED DESCRIPTION

[0022] (1) A communication device according to one embodiment of the present disclosure includes a processing unit and a storage unit, and transmits and receives frames generated according to the IEEE802.1AS protocol, wherein the storage unit stores characteristic information of time stamps contained in frames to be received, and the processing unit collects time stamps contained in frames received from a specific transmission source, and the processing unit compares the characteristic information of the collected time stamps with the characteristic information of the time stamps stored in the storage unit to determine whether the time stamps contained in the frames received from the transmission source are normal.

[0023] In this method, by using a frame generated according to the IEEE802.1AS protocol, characteristic information of a timestamp that depends on hardware can be extracted. In addition, the extracted characteristic information can be used to determine whether there is an abnormality in the timestamp.

[0024] (2) A communication device according to one aspect of the present disclosure includes a plurality of communication ports, and the storage unit stores the characteristic information for each communication port.

[0025] In this method, whether the timestamp is normal is determined based on the characteristic information of each communication port. If the timestamp received through one communication port is normal, it can be determined that the communication partner connected to the communication port is a legitimate communication partner. On the other hand, if the timestamp received through another communication port is abnormal, it can be determined that the communication partner connected to the communication port is an improper communication partner.

[0026] (3) In a communication device of one embodiment of the present disclosure, the storage unit stores two or more characteristic information for each communication port, and the processing unit determines that the timestamp received through the one communication port is normal when the characteristic information of the timestamp collected through the one communication port is consistent with the two or more characteristic information stored for the one communication port.

[0027] In this method, two or more types of feature information are stored for each communication port, and the time stamp is judged to be normal only when all the feature information match. The possibility of accidental match of the feature information of the time stamp is reduced, and whether the time stamp is normal can be judged more accurately.

[0028] (4) In the communication device according to one aspect of the present disclosure, the storage unit stores an arrangement of numerical values ​​of specific bits in the time stamp as the feature information.

[0029] In this method, the arrangement of the values ​​of specific bits in the timestamp can be used as feature information. The values ​​of the ones digit, the tens digit, and the last two digits of the timestamp nsec are easily affected by hardware. Therefore, by extracting the arrangement of these values ​​as feature information, it is possible to determine whether the collected timestamp is normal.

[0030] (5) In the communication device according to one aspect of the present disclosure, the characteristic information includes information that fixes the values ​​of the last two digits of the time stamp to 00.

[0031] Depending on the hardware, in order to make the number of digits of the time stamp consistent, 00 may be added to the last two digits. In this method, the time stamp with 00 added to the last two digits can be detected by such hardware.

[0032] (6) In the communication device according to one aspect of the present disclosure, the characteristic information includes information that a value of the last two digits of the time stamp is a multiple of 4.

[0033] Depending on the hardware, the last two digits of the time stamp may be a multiple of 4. In this method, the time stamp generated by such hardware can be detected.

[0034] (7) A communication method according to one aspect of the present disclosure performs the following processing by a computer: receiving frames generated according to the IEEE802.1AS protocol from a specific transmission source; collecting time stamps contained in the received frames; and determining whether the time stamps contained in the frames received from the transmission source are normal by comparing feature information of the collected time stamps with feature information of the time stamps pre-stored in a memory.

[0035] In this method, by using a frame generated according to the IEEE802.1AS protocol, characteristic information that depends on hardware can be extracted, and the presence or absence of an abnormality in the time stamp can be determined using the extracted characteristic information.

[0036] (8) A computer program according to one embodiment of the present invention causes a computer to perform the following processing: receiving frames generated according to the IEEE802.1AS protocol from a specific transmission source; collecting time stamps contained in the received frames; and determining whether the time stamps contained in the frames received from the transmission source are normal by comparing characteristic information of the collected time stamps with characteristic information of the time stamps pre-stored in a memory.

[0037] In this method, by using a frame generated according to the IEEE802.1AS protocol, characteristic information that depends on hardware can be extracted, and the presence or absence of an abnormality in the time stamp can be determined using the extracted characteristic information.

[0038] Hereinafter, the present invention will be described in detail based on the drawings showing embodiments of the present invention.

[0039] (Implementation method 1)

[0040] Figure 1 1 is an explanatory diagram for explaining a configuration example of a communication system according to the present embodiment. The communication system according to the present embodiment includes a communication device 10 and a plurality of ECUs connected to the communication device 10. The communication device 10 is, for example, a communication device such as an ECU (Electronic Control Unit) or a switch device mounted on a vehicle. The communication device 10 includes a processing unit 11, a storage unit 12, a communication unit 13, a first communication port 14, a second communication port 15, a third communication port 16, and the like.

[0041] The processing unit 11 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. The CPU in the processing unit 11 controls the operation of the above hardware by executing the control program stored in the ROM and the program PG stored in the storage unit 12, so that the entire device functions as the communication device of the present application. The RAM in the processing unit 11 stores various data generated during the execution of various programs.

[0042] The processing unit 11 is not limited to the above-mentioned structure, and may be one or more processing circuits including an MCU (Micro Controller Unit), a volatile or non-volatile memory, etc. In addition, the processing unit 11 may also have functions such as a clock that outputs date and time information, a timer that measures the elapsed time from when a measurement start instruction is given to when a measurement end instruction is given, and a counter that counts the number.

[0043] The storage unit 12 is composed of a non-volatile memory such as an EEPROM (Electronically Erasable Programmable Read Only Memory), and stores various data. The data stored in the storage unit 12 includes the time stamp information described later. The program PG stored in the storage unit 12 includes a computer program for executing a process for determining whether the time stamp included in the frame received via the first communication port 14 to the third communication port 16 is normal. The program PG (program product) is provided, for example, by a recording medium that can be read by the processing unit 11. In addition, the program PG stored in the storage unit 12 can also be downloaded from an external server not shown in the figure.

[0044] The communication unit 13 performs processing for communicating with a plurality of communication devices connected via the first communication port 14 to the third communication port 16. In the present embodiment, for example, the first communication port 14 is connected to the first ECU 100, the second communication port 15 is connected to the second ECU 200, and the third communication port 16 is connected to the third ECU 300 via an Ethernet cable.

[0045] The communication device 10 and each ECU 100 to 300 transmit and receive frames generated according to the IEEE802.1AS protocol, and achieve time synchronization by using gPTP (generalized Precision Time Protocol). Figure 1 In the illustrated system configuration, for example, the first ECU 100 is used as a master node, and the communication device 10 and the second ECU 200 are used as slave nodes, and a method of time synchronization is described.

[0046] In this example, a Sync frame including a timestamp based on the master clock is sent from the first ECU 100 to the communication device 10, and the communication device 10 obtains the synchronization time, thereby enabling the time of the communication device 10 to be synchronized with the time (master clock) of the first ECU 100. In addition, the communication device 10 relays the Sync frame from the first ECU 100 to the second ECU 200, and the second ECU 200 obtains the synchronization time in consideration of the propagation delay, thereby enabling the time of the second ECU 200 to be synchronized with the time (master clock) of the first ECU 100.

[0047] Here, when the third ECU 300 pretends to be the master node and transmits a Sync frame including a pretended time stamp from the third ECU 300 , synchronization within the system cannot be ensured.

[0048] In this embodiment, feature information of time stamps used in the system is acquired in advance and stored in the storage unit 12, and by comparing with feature information obtained from newly collected time stamps, it is determined whether the time stamp is normal (abnormality detection).

[0049] Figure 2A 1 to 2 are explanatory diagrams for explaining characteristic information of a time stamp. In this embodiment, characteristic information is extracted in advance with attention paid to the fact that the value of the nsec bit of the time stamp is easily affected by hardware. Figure 2A The example shows that the result of collecting time stamps from the Sync frame transmitted by the first ECU 100 is that all the units of nsec are 6. In this case, the storage unit 12 of the communication device 10 stores characteristic information that all the units of nsec are 6 (or are the same).

[0050] Figure 2B The example in which the result of collecting time stamps from the Sync frame transmitted by the first ECU 100 is that the last two digits of nsec are multiples of 4 is shown. In this case, characteristic information that the last two digits of nsec are multiples of 4 is stored in the storage unit 12 of the communication device 10 .

[0051] Figure 2C The example shows that the last two digits of nsec do not have characteristics as a result of collecting time stamps from the Sync frame transmitted by the first ECU 100. In this case, characteristic information that the last two digits of nsec do not have characteristics is stored in the storage unit 12 of the communication device 10.

[0052] In this way, by collecting timestamps in advance to grasp the characteristics, it is possible to find the characteristic information in advance. The characteristic information is not limited to Figure 2A to Figure 2CThe characteristic information shown may be, for example, characteristic information that all the ones of nsec of the timestamp are even numbers. Alternatively, characteristic information may be characteristic information that the ones of nsec are roughly the same but are shifted little by little in units of seconds. Furthermore, characteristic information may be characteristic information that the frequency of the tens of nsec being even numbers (or odd numbers) is high and the frequency of being odd numbers (or even numbers) is low. Furthermore, characteristic information may be characteristic information that the last two digits of nsec are fixed to 00. The characteristic information of the timestamp is not limited to this, and it is sufficient as long as the characteristic information found in advance is stored in the storage unit 12 of the communication device 10.

[0053] In addition, the storage unit 12 may store, for each communication port, characteristic information of the timestamp of the legitimate ECU that should be connected to the first communication port 14 to the third communication port 16. For example, if the legitimate ECU that should be connected to the first communication port 14 is the first ECU 100, the characteristic information of the timestamp obtained from the first ECU 100 is associated with the first communication port 14 and stored in the storage unit 12. The same is true for the second communication port 15 and the third communication port 16.

[0054] In addition, two or more characteristic information may be stored for each communication port in the storage unit 12. For example, when the characteristic information of the timestamp collected through the first communication port 14 is consistent with the two or more characteristic information stored about the first communication port 14, the processing unit 11 determines that the timestamp received through the first communication port 14 is normal. The same applies to the second communication port 15 and the third communication port 16.

[0055] The communication device 10 uses the characteristic information described above to detect anomalies in the time stamp. The communication device 10 can detect anomalies in the time stamp (1) when calculating the synchronization time, (2) when relaying the Sync frame, and (3) when calculating the propagation delay.

[0056] Figure 3 This is the timing diagram for calculating the synchronization moment. Figure 3 In the timing diagram, the time synchronization master is, for example, the first ECU 100, and the time synchronization slave is the communication device 10. The first ECU 100 generates a timestamp based on the time (t1) output from the master clock of the device, and sends the Sync frame with the timestamp to the communication device 10. After sending the Sync frame, the first ECU 100 may also send a Fllow Up frame as needed.

[0057] When receiving the Sync frame via the communication unit 13, the processing unit 11 of the communication device 10 calculates the synchronization time by referring to the time stamp included in the Sync frame. In the present embodiment, it is assumed that the propagation delay between the first ECU 100 and the communication device 10 is known.

[0058] The processing unit 11 collects the timestamps included in the Sync frame during an appropriate period, and compares the characteristic information obtained from the collected timestamps with the characteristic information of each communication port stored in advance in the storage unit 12, thereby detecting the abnormality of the timestamp. That is, when the characteristic information obtained from the collected timestamps is consistent with the characteristic information of each communication port stored in advance in the storage unit 12, the processing unit 11 determines that the collected timestamps are normal, and when they are inconsistent, the collected timestamps are determined to be abnormal.

[0059] Figure 4 This is the timing diagram when relaying Sync frames. Figure 4 In the timing diagram of , the time synchronization master is, for example, the first ECU 100 , the relay device is the communication device 10 , and the time synchronization slave is, for example, the second ECU 200 .

[0060] The time synchronization slave is the communication device 10 . The first ECU 100 generates a time stamp based on the time ( t1 ) output from the master clock of the own device, and transmits a Sync frame to which the time stamp is added to the communication device 10 .

[0061] When the processing unit 11 of the communication device 10 receives a Sync frame through the communication unit 13, the received Sync frame is forwarded to the second ECU 200. The processing unit 11 collects the time stamps included in the forwarded Sync frames during an appropriate period, and compares the characteristic information obtained from the collected time stamps with the characteristic information of each communication port stored in advance in the storage unit 12, thereby detecting the abnormality of the time stamp. That is, when the characteristic information obtained from the collected time stamps is consistent with the characteristic information of each communication port stored in advance in the storage unit 12, the processing unit 11 determines that the collected time stamps are normal, and when they are inconsistent, the collected time stamps are determined to be abnormal.

[0062] The second ECU 200 receives the Sync frame forwarded via the communication device 10. The second ECU 200 calculates the synchronization time with reference to the timestamp included in the received Sync frame. In addition, in the present embodiment, the propagation delay (t2-t1) between the first ECU 100 and the communication device 10, the relay processing delay (t3-t2) in the communication device 10, the propagation delay (t4-t3) between the communication device 10 and the second ECU 200, etc. are known. In the second ECU 200, if the characteristic information of the timestamp used in the system is stored in advance, the abnormality of the timestamp can also be detected by the same steps as the communication device 10.

[0063] Figure 5 is a timing diagram for calculating propagation delay. Figure 5In the timing diagram of , the time synchronization master is, for example, the first ECU 100, and the time synchronization slave is the communication device 10. The communication device 10 generates a time stamp based on the time (t1) output from its own sub-clock, and transmits a Pdelay_Req message with the time stamp to the first ECU 100.

[0064] The first ECU 100 replies the reception time of the Pdelay_Req message to the communication device 10 through the Pdelay_Res message.

[0065] The processing unit 11 of the communication device 10 calculates the propagation delay time when receiving the Pdelay_Res message from the first ECU 100. The processing unit 11 can calculate the propagation delay time by referring to the time t1 to t4.

[0066] The processing unit 11 collects the timestamps included in the Pdelay_Res message during an appropriate period, and compares the characteristic information obtained from the collected timestamps with the characteristic information of each communication port stored in advance in the storage unit 12, thereby detecting the abnormality of the timestamp. That is, when the characteristic information obtained from the collected timestamps is consistent with the characteristic information of each communication port stored in advance in the storage unit 12, the processing unit 11 determines that the collected timestamps are normal, and when they are inconsistent, the collected timestamps are determined to be abnormal.

[0067] Figure 6 1 is a flowchart showing the processing procedure of abnormality detection executed by the communication device 10. The processing unit 11 of the communication device 10 collects time stamps from frames input through a specific communication port (for example, the third communication port 16) (step S101).

[0068] The processing unit 11 extracts characteristic information from the collected time stamps (step S102 ). The processing unit 11 may extract characteristic information by focusing on the arrangement of the numerical values ​​of the ones digit, the tens digit, and the last two digits of nsec of the time stamp, for example.

[0069] The processing unit 11 compares the characteristic information extracted in step S102 with the characteristic information of a specific communication port (eg, the third communication port 16 ) stored in advance in the storage unit 12 (step S103 ), and determines whether the two are consistent (step S104 ).

[0070] When it is determined that the two coincide with each other ( S104 : YES), the processing unit 11 determines that the time stamp of the ECU connected to the specific communication port is normal (step S105 ).

[0071] If the two are not consistent (S104: No), the processing unit 11 determines that the time stamp of the ECU connected to the specific communication port is abnormal (step S106). If the processing unit 11 determines that the time stamp is abnormal, it may issue a warning or stop communication via the specific communication port.

[0072] exist Figure 6 In the flowchart, the comparison is made with one feature information stored in the storage unit 12, but it can also be made so that a plurality of feature information is stored in the storage unit 12, and when the plurality of feature information are consistent, it is determined to be normal.

[0073] As described above, in this embodiment, by using a frame generated according to the IEEE802.1AS protocol, characteristic information that depends on hardware can be extracted, and the presence or absence of an abnormality in the time stamp can be determined using the extracted characteristic information.

[0074] The embodiments disclosed this time should be considered as illustrative in all aspects and not restrictive. The scope of the present invention is indicated by the claims rather than the above meaning, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0075] Independent claims and dependent claims recorded in the claims are independent of the citation format and can be combined with each other in all combinations. In addition, the claims adopt the recording format of a claim that cites two or more other claims (multiple dependent claim format), but are not limited to this. It is also possible to record multiple dependent claims (multiple-reference-multiple claims) that cite at least one multiple dependent claim.

[0076] Description of Reference Numerals

[0077] 10 communication devices

[0078] 11 Processing Department

[0079] 12 Storage

[0080] 13 Ministry of Communications

[0081] 14 First communication port

[0082] 15 Second communication port

[0083] 16 Third communication port

[0084] 100 First ECU

[0085] 200 Second ECU

[0086] 300 Third ECU

Claims

1. A communication device, comprising a processing unit and a storage unit, for transmitting and receiving frames generated according to the IEEE802.1AS protocol, wherein: The storage unit stores characteristic information of a timestamp included in a frame to be received, The processing unit collects time stamps included in frames received from a specific transmission source, The processing unit determines whether the time stamp included in the frame received from the transmission source is normal by comparing the characteristic information of the collected time stamp with the characteristic information of the time stamp stored in the storage unit.

2. The communication device according to claim 1, wherein: The communication device has a plurality of communication ports. The storage unit stores the characteristic information for each communication port.

3. The communication device according to claim 2, wherein: The storage unit stores two or more types of feature information for each communication port. The processing unit determines that the time stamp received through the one communication port is normal when the feature information of the time stamp collected through the one communication port is consistent with two or more feature information stored for the one communication port.

4. The communication device according to any one of claims 1 to 3, wherein: The storage unit stores an arrangement of numerical values ​​of specific bits in the time stamp as feature information.

5. The communication device according to claim 4, wherein: The characteristic information includes information for fixing the values ​​of the last two digits of the timestamp to 00.

6. The communication device according to claim 4, wherein: The characteristic information includes information that the value of the last two digits of the timestamp is a multiple of 4.

7. A communication method, wherein the computer performs the following processing: Receive frames generated according to the IEEE802.1AS protocol from a specific transmission source; collecting timestamps contained in received frames; and By comparing the collected feature information of the timestamp with the feature information of the timestamp pre-stored in the memory, it is determined whether the timestamp included in the frame received from the transmission source is normal.

8. A computer program for causing a computer to execute the following processing: Receive frames generated according to the IEEE802.1AS protocol from a specific transmission source; collecting timestamps contained in received frames; and By comparing the collected feature information of the timestamp with the feature information of the timestamp pre-stored in the memory, it is determined whether the timestamp included in the frame received from the transmission source is normal.

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