METHOD FOR EXCHANGING TIME SYNCHRONIZATION PACKET AND NETWORK APPARATUS

• US 20190327010A1
• Filed: 06/27/2019
• Published: 10/24/2019
• Est. Priority Date: 12/30/2016
• Status: Active Grant

• Current Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Inventors: WANG, Jinhui, XU, Chuan
• Granted Patent: US 11,095,383 B2
• Time in Patent Office: Days
• CPC Class Codes: H04J 3/065 using timestamps
• CPC Class Codes: H04J 3/0655 using timestamps
• CPC Class Codes: H04J 3/0661 using timestamps
• CPC Class Codes: H04J 3/0667 Bidirectional timestamps, e.g. NTP or PTP for compensation of clock drift and for compensation of propagation delays arrangements for monitoring round trip delays in packet switching networks H04L43/0864
• CPC Class Codes: H04J 3/0673 using intermediate nodes, e.g. modification of a received timestamp before further transmission to the next packet node, e.g. including internal delay time or residence time into the packet
• CPC Class Codes: H04W 56/001 Synchronization between nodes

Abstract

A method for exchanging a clock synchronization packet performed by a network apparatus, including: exchanging a clock synchronization packet with a first clock source, where the network apparatus includes a boundary clock; determining a first time deviation of the boundary clock relative to the first clock source according to the clock synchronization packet exchanged with the first clock source, where the boundary clock avoids performing an operation of calibrating a time of a local clock of the boundary clock according to the first time deviation; and sending a clock synchronization packet to a first slave clock of the boundary clock, where the clock synchronization packet includes a first timestamp, a value of the first timestamp is equal to a first corrected value, and the first corrected value is a value obtained by the boundary clock by correcting the time of the local clock by using the first time deviation.

Claims

1. A method for exchanging a clock synchronization packet, comprising:

exchanging, by a network apparatus, a clock synchronization packet with a first clock source by using a first slave port, wherein the network apparatus comprises a boundary clock (BC), and the BC comprises the first slave port and a first master port;

determining, by the network apparatus, a first time deviation of the BC relative to the first clock source according to the clock synchronization packet exchanged with the first clock source, wherein the BC avoids performing an operation of calibrating a time of a local clock of the BC according to the first time deviation; and

sending, by the network apparatus, a clock synchronization packet to a first slave clock of the BC by using the first master port, wherein the clock synchronization packet sent by the network apparatus to the first slave clock comprises a first timestamp generated by the BC, a value of the first timestamp is equal to a first corrected value, and the first corrected value is a value obtained by the BC by correcting a time t1 of the local clock by using the first time deviation, wherein the time t1 is a time at which the BC generates the first timestamp.

2. The method according to claim 1, wherein after the exchanging, by a network apparatus, a clock synchronization packet with a first clock source by using a first slave port, and before the sending, by the network apparatus, a clock synchronization packet to a first slave clock of the BC by using the first master port, the method further comprises:

determining, by the network apparatus, a first frequency deviation of the BC relative to the first clock source according to the clock synchronization packet exchanged with the first clock source, wherein the BC avoids performing an operation of calibrating a frequency of the local clock of the BC according to the first frequency deviation, and the first corrected value is a value obtained by the BC by correcting t1 by using the first time deviation and the first frequency deviation.

3. The method according to claim 2, wherein

the first corrected value is equal to a sum of t1, the first time deviation, and a first phase deviation, and the first phase deviation is a phase deviation that is of the local clock relative to the first clock source and that is caused by the first frequency deviation within duration from a time at which the local clock determines the first frequency deviation to the time at which the BC generates the first timestamp.

4. The method according to claim 1, wherein the method further comprises:

exchanging, by the network apparatus, a clock synchronization packet with a second clock source by using a second slave port, wherein the BC comprises the second slave port and a second master port;

determining, by the network apparatus, a second time deviation of the BC relative to the second clock source according to the clock synchronization packet exchanged with the second clock source, wherein the BC avoids performing an operation of calibrating the time of the local clock of the BC according to the second time deviation; and

sending, by the network apparatus, a clock synchronization packet to a second slave clock of the BC by using the second master port, wherein the clock synchronization packet sent by the network apparatus to the second slave clock comprises a second timestamp generated by the BC, a value of the second timestamp is equal to a second corrected value, and the second corrected value is a value obtained by correcting a time t2 of the local clock by using the second time deviation, wherein the time t2 is a time at which the BC generates the second timestamp.

5. The method according to claim 4, wherein after the exchanging, by the network apparatus, a clock synchronization packet with a second clock source by using a second slave port, and before the sending, by the network apparatus, a clock synchronization packet to a second slave clock of the BC by using the second master port, the method further comprises:

determining, by the network apparatus, a second frequency deviation of the BC relative to the second clock source according to the clock synchronization packet exchanged with the second clock source, wherein the BC avoids performing an operation of calibrating the frequency of the local clock of the BC according to the second frequency deviation, and the second corrected value is a value obtained by the BC by correcting t2 by using the second time deviation and the second frequency deviation.

6. The method according to claim 5, wherein

the second corrected value is equal to a sum of t2, the second time deviation, and a second phase deviation, and the second phase deviation is a phase deviation that is of the local clock relative to the second clock source and that is caused by the second frequency deviation within duration from a time at which the local clock determines the second frequency deviation to the time at which the BC generates the second timestamp.

7. A network apparatus, comprising:

a transceiver, configured to exchange a clock synchronization packet with a first clock source by using a first slave port, wherein the network apparatus comprises a boundary clock (BC), and the BC comprises the first slave port and a first master port;

a processor communicated with the transceiver, configured to determine a first time deviation of the BC relative to the first clock source according to the clock synchronization packet exchanged with the first clock source, wherein the BC avoids performing an operation of calibrating a time of a local clock of the BC according to the first time deviation; and

the transceiver is further configured to send a clock synchronization packet to a first slave clock of the BC by using the first master port, wherein the clock synchronization packet sent by the network apparatus to the first slave clock comprises a first timestamp generated by the BC, a value of the first timestamp is equal to a first corrected value, and the first corrected value is a value obtained by the BC by correcting a time t1 of the local clock by using the first time deviation, wherein the time t1 is a time at which the BC generates the first timestamp.

8. The network apparatus according to claim 7, wherein the processor is further configured to:

after the interaction unit exchanges the clock synchronization packet with the first clock source by using the first slave port, and before the sending unit sends the clock synchronization packet to the first slave clock of the BC by using the first master port,

determine a first frequency deviation of the BC relative to the first clock source according to the clock synchronization packet exchanged with the first clock source, wherein the BC avoids performing an operation of calibrating a frequency of the local clock of the BC according to the first frequency deviation, and the first corrected value is a value obtained by the BC by correcting t1 by using the first time deviation and the first frequency deviation.

9. The network apparatus according to claim 7, wherein

the transceiver is further configured to exchange a clock synchronization packet with a second clock source by using a second slave port, wherein the BC comprises the second slave port and a second master port;

the processor is further configured to determine a second time deviation of the BC relative to the second clock source according to the clock synchronization packet exchanged with the second clock source, wherein the BC avoids performing an operation of calibrating the time of the local clock of the BC according to the second time deviation; and

the transceiver is further configured to send a clock synchronization packet to a second slave clock of the BC by using the second master port, wherein the clock synchronization packet sent by the network apparatus to the second slave clock comprises a second timestamp generated by the BC, a value of the second timestamp is equal to a second corrected value, and the second corrected value is a value obtained by correcting a time t2 of the local clock by using the second time deviation, wherein the time t2 is a time at which the BC generates the second timestamp.

10. The network apparatus according to claim 9, wherein the processor is further configured to:

after the interaction unit exchanges the clock synchronization packet with the second clock source by using the second slave port, and before the sending unit sends the clock synchronization packet to the second slave clock of the BC by using the second master port,

determine a second frequency deviation of the BC relative to the second clock source according to the clock synchronization packet exchanged with the second clock source, wherein the BC avoids performing an operation of calibrating the frequency of the local clock of the BC according to the second frequency deviation, and the second corrected value is a value obtained by the BC by correcting t2 by using the second time deviation and the second frequency deviation.

11. A method for exchanging a clock synchronization packet, comprising:

exchanging, by a network apparatus, a clock synchronization packet with a first clock source;

exchanging, by the network apparatus, a clock synchronization packet with a second clock source;

after the network apparatus exchanges the clock synchronization packet with the first clock source and after the network apparatus exchanges the clock synchronization packet with the second clock source, sending, by the network apparatus, a first clock synchronization packet to a first slave clock of the network apparatus, wherein the first clock synchronization packet carries a first timestamp generated by the network apparatus, and a time indicated by the first timestamp is equal to a time that is of the first clock source and at which the network apparatus sends the first clock synchronization packet; and

after the network apparatus exchanges the clock synchronization packet with the first clock source and after the network apparatus exchanges the clock synchronization packet with the second clock source, sending, by the network apparatus, a second clock synchronization packet to a second slave clock of the network apparatus, wherein the second clock synchronization packet carries a second timestamp generated by the network apparatus, and a time indicated by the second timestamp is equal to a time that is of the second clock source and at which the network apparatus sends the second clock synchronization packet.

12. The method according to claim 11, wherein a value of the first timestamp is determined in the following manner:

after the network apparatus exchanges the clock synchronization packet with the first clock source, determining, by the network apparatus, a first time deviation of the network apparatus relative to the first clock source according to the clock synchronization packet exchanged with the first clock source, wherein the network apparatus avoids performing an operation of calibrating a time of a local clock of the network apparatus according to the first time deviation; and

determining, by the network apparatus, that the value of the first timestamp is equal to a first corrected value, wherein the first corrected value is a value obtained by the network apparatus by correcting a time t1 of the local clock by using the first time deviation, wherein the time t1 is a time at which the network apparatus generates the first timestamp.

13. The method according to claim 12, wherein the value of the first timestamp is specifically determined in the following manner:

after the network apparatus exchanges the clock synchronization packet with the first clock source, determining, by the network apparatus, a first frequency deviation of the network apparatus relative to the first clock source according to the clock synchronization packet exchanged with the first clock source, wherein the network apparatus avoids performing an operation of calibrating a frequency of the local clock according to the first frequency deviation; and

determining, by the network apparatus, that the value of the first timestamp is equal to the first corrected value, wherein the first corrected value is a value obtained by the network apparatus by correcting t1 by using the first time deviation and the first frequency deviation.

14. The method according to claim 13, wherein the first corrected value is equal to a sum of t1, the first time deviation, and a first phase deviation, and the first phase deviation is a phase deviation that is of the local clock relative to the first clock source and that is caused by the first frequency deviation within duration from a time at which the local clock determines the first frequency deviation to the time at which the network apparatus generates the first timestamp.

15. A network apparatus, comprising:

a first transceiver, configured to exchange a clock synchronization packet with a first clock source;

a second transceiver, configured to exchange a clock synchronization packet with a second clock source;

the first transceiver is further configured to;

after the first interaction unit exchanges the clock synchronization packet with the first clock source and after the second interaction unit exchanges the clock synchronization packet with the second clock source, send a first clock synchronization packet to a first slave clock of the network apparatus, wherein the first clock synchronization packet carries a first timestamp generated by the network apparatus, and a time indicated by the first timestamp is equal to a time that is of the first clock source and at which the network apparatus sends the first clock synchronization packet; and

the second transceiver is further configured to;

after the first interaction unit exchanges the clock synchronization packet with the first clock source and after the second interaction unit exchanges the clock synchronization packet with the second clock source, send a second clock synchronization packet to a second slave clock of the network apparatus, wherein the first clock synchronization packet carries a second timestamp generated by the network apparatus, and a time indicated by the second timestamp is equal to a time that is of the second clock source and at which the network apparatus sends the second clock synchronization packet.

16. The network apparatus according to claim 15, further comprising a processor, wherein

the processor is configured to:

after the first interaction unit exchanges the clock synchronization packet with the first clock source, determine a first time deviation of the network apparatus relative to the first clock source according to the clock synchronization packet exchanged with the first clock source, wherein the network apparatus avoids performing an operation of calibrating a time of a local clock of the network apparatus according to the first time deviation; and

the processor is further configured to determine that a value of the first timestamp is equal to a first corrected value, wherein the first corrected value is a value obtained by the network apparatus by correcting a time t1 of the local clock by using the first time deviation, wherein the time t1 is a time at which the network apparatus generates the first timestamp.

17. The network apparatus according to claim 16, wherein the processor is further configured to:

after the first interaction unit exchanges the clock synchronization packet with the first clock source, determine a first frequency deviation of the network apparatus relative to the first clock source according to the clock synchronization packet exchanged with the first clock source, wherein the network apparatus avoids performing an operation of calibrating a frequency of the local clock according to the first frequency deviation, and the first corrected value is a value obtained by the network apparatus by correcting t1 by using the first time deviation and the first frequency deviation.

18. The network apparatus according to claim 17, wherein the first corrected value is equal to a sum of t1, the first time deviation, and a first phase deviation, and the first phase deviation is a phase deviation that is of the local clock relative to the first clock source and that is caused by the first frequency deviation within duration from a time at which the local clock determines the first frequency deviation to the time at which the network apparatus generates the first timestamp.