# US 2017/0288802 A1 · Time Synchronization Method and Apparatus

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- Number: US 2017/0288802 A1
- Document ID: US20170288802A1
- Status: Published application
- Kind: A1
- Application number: 15/625,649
- Filed: 2017-06-16
- Published: 2017-10-05
- Earliest claimed: 2014-12-16
- Assignees: Huawei Technologies Co., Ltd.
- Applicants: Huawei Technologies Co., Ltd.
- Inventors: Lizhong Qiao; Yawei Zhang; Huanle Wang; Dejian Xu
- Web page: https://patentgrep.com/patent/US20170288802A1

## CPC

- 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)}
- 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}
- H04J 3/0682: {by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging}
- H04L 7/00: Arrangements for synchronising receiver with transmitter {(synchronisation of generators of electric oscillations or pulses H03L7/00)}
- H04L 9/40: Network security protocols
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

A time synchronization method includes, a boundary device of a third-party network side receives a synchronization packet carrying a time synchronization offset and is delivered by a boundary device of an upstream network side on the basis that boundary devices in an entire network are all boundary clock (BC) devices, where the time synchronization offset is a time offset between a time domain of the upstream network and a time domain of the third-party network, and the boundary device of the third-party network side transparently transmits the synchronization packet carrying the time synchronization offset to a boundary device of a downstream network side such that the boundary device of the downstream network side performs time synchronization with the boundary device of the upstream network side according to the time synchronization offset. Thus time synchronization among multiple time domains in a network.

## Claims

### Claim 1

A time synchronization method, comprising:
receiving, by a boundary device of a third-party network side, a synchronization packet carrying a time synchronization offset delivered by a boundary device of an upstream network side, wherein the time synchronization offset is a time offset between a time domain of the upstream network and a time domain of the third-party network, and wherein boundary devices in an entire network are all boundary clock (BC) devices; and
transparently transmitting, by the boundary device of the third-party network side, the synchronization packet carrying the time synchronization offset to a boundary device of a downstream network side such that the boundary device of the downstream network side performs time synchronization with the boundary device of the upstream network side according to the time synchronization offset.

### Claim 2 (depends on 1)

The method according to claim 1, wherein receiving the synchronization packet comprises:
sending, by a second BC device of the boundary device of the third-party network side using a second Precision Time Protocol (PTP) port preset to a master clock state, the synchronization packet to a first PTP port of a first BC device of the boundary device of the upstream network side preset to a passive clock state or a monitor clock state;
receiving, by the second BC device using the second PTP port, a peer delay-request packet from the first BC device using the first PTP port;
sending, by the second BC device, a peer delay-response packet to the first PTP port of the first BC device using the second PTP port; and
receiving, by the second BC device using the second PTP port, the synchronization packet carrying the time synchronization offset from the first BC device using the first PTP port,
wherein the first BC device is an interface device that interfaces with the boundary device of the third-party network side and is in the upstream network, and
wherein the second BC device is an interface device that interfaces with the boundary device of the upstream network side and is in the third-party network.

### Claim 3 (depends on 1)

The method according to claim 1, wherein receiving the synchronization packet comprises:
sending, by a second BC device of the boundary device of the third-party network side using a second Precision Time Protocol (PTP) port preset to a master clock state, the synchronization packet to a first PTP port of a first BC device of the boundary device of the upstream network side preset to a monitor clock state;
receiving, by the second BC device using the second PTP port, a delay-request packet from the first BC device using the first PTP port;
sending, by the second BC device, a delay-response packet to the first BC device using the second PTP port; and
receiving, by the second BC device using the second PTP port, the synchronization packet carrying the time synchronization offset from the first BC device using the first PTP port,
wherein the first BC device is an interface device that interfaces with the boundary device of the third-party network side and is in the upstream network, and
wherein the second BC device is an interface device that interfaces with the boundary device of the upstream network side and is in the third-party network.

### Claim 4 (depends on 2)

The method according to claim 2, wherein transparently transmitting the synchronization packet comprises:
sending, by the second BC device using the second PTP port, the synchronization packet carrying the time synchronization offset to a third PTP port of a third BC device preset to a master clock state; and
transparently transmitting, by the third BC device, the synchronization packet to the boundary device of the downstream network side, wherein the third BC device is an interface device that interfaces with the boundary device of the downstream network side in the third-party network.

### Claim 5

A time synchronization method, comprising:
determining, by a boundary device of an upstream network side, a time synchronization offset from a time domain of a third-party network, wherein the time synchronization offset is a time offset between a time domain of the upstream network and the time domain of the third-party network, and wherein boundary devices in an entire network are all boundary clock (BC) devices; and
delivering, by the boundary device of the upstream network side, a synchronization packet carrying the time offset to a boundary device of the third-party network side such that the boundary device of the third-party network side transparently transmits the synchronization packet to a boundary device of a downstream network side, and the boundary device of the downstream network side performs time synchronization with the boundary device of the upstream network side according to the time synchronization offset.

### Claim 6 (depends on 5)

The method according to claim 5, wherein determining the time synchronization offset comprises:
receiving, by a first BC device of the boundary device of the upstream network side using a first Precision Time Protocol (PTP) port preset to a passive clock state or a monitor clock state, the synchronization packet from a second BC device of the boundary device of the third-party network side using a second PTP port preset to a master clock state;
sending, by the first BC device, a peer delay-request packet to the second PTP port of the second BC device using the first PTP port;
receiving, by the first BC device using the first PTP port, a peer delay-response packet from the second BC device using the second PTP port;
determining, by the first BC device, a mean path delay according to timestamp information generated by the peer delay-request packet and the peer delay-response packet;
determining, by the first BC device, the time synchronization offset according to the mean path delay and timestamp information generated by the synchronization packet; and
sending, by the first BC device using the first PTP port, the synchronization packet carrying the time synchronization offset to the second PTP port of the second BC device,
wherein the first BC device is an interface device that interfaces with the boundary device of the third-party network side and is in the upstream network, and
wherein the second BC device is an interface device that interfaces with the boundary device of the upstream network side and is in the third-party network.

### Claim 7 (depends on 5)

The method according to claim 5, wherein determining the time synchronization offset comprises:
receiving, by a first BC device of the boundary device of the upstream network side using a first Precision Time Protocol (PTP) port preset to a monitor clock state, the synchronization packet from a second BC device of the boundary device of the third-party network side using a second PTP port preset to a master clock state;
sending, by the first BC device, a delay-request packet to the second PTP port of the second BC device using the first PTP port;
receiving, by the first BC device using the first PTP port, a delay-response packet from the second PTP port of the second BC device;
determining, by the first BC device, a mean path delay according to timestamp information generated by the delay-request packet and the delay-response packet;
determining, by the first BC device, the time synchronization offset according to the mean path delay and timestamp information generated by the synchronization packet; and
sending, by the first BC device using the first PTP port, the synchronization packet carrying the time synchronization offset to the second PTP port of the second BC device,
wherein the first BC device is an interface device that interfaces with the boundary device of the third-party network side and is in the upstream network, and
wherein the second BC device is an interface device that interfaces with the boundary device of the upstream network side and is in the third-party network.

### Claim 8

A time synchronization method, comprising:
receiving, by a boundary device of a downstream network side, a synchronization packet that carries a time synchronization offset, from a boundary device of an upstream network side, and is transparently transmitted by a boundary device of a third-party network side, wherein the time synchronization offset is a time offset between a time domain of the upstream network and a time domain of the third-party network, and wherein boundary devices in an entire network are all boundary clock (BC) devices; and
performing, by the boundary device of the downstream network side, time synchronization with the boundary device of the upstream network side according to the time synchronization offset.

### Claim 9 (depends on 8)

The method according to claim 8, wherein performing the time synchronization with the boundary device of the upstream network side comprises:
receiving, by a fourth BC device of the boundary device of the downstream network side using a fourth Precision Time Protocol (PTP) port preset to a slave clock state, the synchronization packet carrying the time synchronization offset from a third BC device of the boundary device of the third-party network side using a third PTP port that is preset to a master clock state;
determining, by the fourth BC device, a preliminary clock adjustment value for the time synchronization with the third BC device;
setting, by the fourth BC device, a sum of the time synchronization offset and the preliminary clock adjustment value as a final clock adjustment value; and
performing clock adjustment according to the final clock adjustment value,
wherein the third BC device is an interface device that interfaces with the boundary device of the downstream network side and is in the third-party network, and
wherein the fourth BC device is an interface device that interfaces with the boundary device of the third-party network side and is in the downstream network.

### Claim 10

A time synchronization device, comprising:
a receiver configured to receive a synchronization packet carrying a time synchronization offset delivered by a boundary device of an upstream network side, wherein the time synchronization offset is a time offset between a time domain of the upstream network and a time domain of a third-party network; and
a transmitter coupled to the receiver and configured to transparently transmit the synchronization packet carrying the time synchronization offset to a boundary device of a downstream network side such that the boundary device of the downstream network side performs time synchronization with the boundary device of the upstream network side according to the time synchronization offset.

### Claim 11 (depends on 10)

The device according to claim 10, wherein the receiver is a second boundary clock (BC) device whose second Precision Time Protocol (PTP) port is preset to a master clock state, and wherein the second BC device is configured to:
send, using the second PTP port, the synchronization packet to a first PTP port of a first BC device of the boundary device of the upstream network side preset to a passive clock state or a monitor clock state;
receive a peer delay-request packet from the first BC device using the first PTP port;
send a peer delay-response packet to the first BC device; and
receive the synchronization packet carrying the time synchronization offset from the first BC device using the first PTP port,
wherein the first BC device is an interface device that interfaces with the boundary device of the third-party network side and is in the upstream network, and
wherein the second BC device is an interface device that interfaces with the boundary device of the upstream network side and is in the third-party network.

### Claim 12 (depends on 10)

The device according to claim 10, wherein the receiver is a second boundary clock (BC) device whose second Precision Time Protocol (PTP) port is preset to a master clock state, and wherein the second BC device is configured to:
send, using the second PTP port, the synchronization packet to a first PTP port of a first BC device of the boundary device of the upstream network side preset to a monitor clock state;
receive a delay-request packet from the first BC device using the first PTP port;
send a delay-response packet to the first BC device; and
receive the synchronization packet carrying the time synchronization offset from the first BC device using the first PTP port,
wherein the first BC device is an interface device that interfaces with the boundary device of the third-party network side and is in the upstream network, and
wherein the second BC device is an interface device that interfaces with the boundary device of the upstream network side and is in the third-party network.

### Claim 13 (depends on 11)

The device according to claim 11, wherein the transmitter is a third BC device whose third PTP port is preset to a master clock state, and wherein the third BC device is configured to:
receive, using the third PTP port, the synchronization packet carrying the time synchronization offset from the second BC device using the second PTP port; and
transparently transmits the synchronization packet to the boundary device of the downstream network side, wherein the third BC device is an interface device that interfaces with the boundary device of the downstream network side and is in the third-party network.

### Claim 14

A time synchronization boundary clock (BC) device, comprising:
a processor configured to determine a time synchronization offset from a time domain of a third-party network, wherein the time synchronization offset is a time offset between a time domain of an upstream network and the time domain of the third-party network; and
a transmitter coupled to the processor and configured to deliver a packet carrying the time offset to a boundary device of the third-party network side such that the boundary device of the third-party network side transparently transmits the packet to a boundary device of a downstream network side, and the boundary device of the downstream network side performs time synchronization with a boundary device of the upstream network side according to the time synchronization offset.

### Claim 15 (depends on 14)

The device according to claim 14, wherein the processor is further configured to:
receive, using a first Precision Time Protocol (PTP) port preset to a passive clock state or a monitor clock state, a synchronization packet from a second BC device of the boundary device of the third-party network side using a second PTP port preset to a master clock state;
send a peer delay-request packet to the second PTP port of the second BC device using the first PTP port;
receive, using the first PTP port, a peer delay-response packet from the second BC device using the second PTP port;
determine a mean path delay according to timestamp information generated by the peer delay-request packet and the peer delay-response packet;
determine the time synchronization offset according to the mean path delay and timestamp information generated by the synchronization packet; and
send, using the first PTP port, the synchronization packet carrying the time synchronization offset to the second PTP port of the second BC device,
wherein the second BC device is an interface device that interfaces with the boundary device of the upstream network side in the third-party network.

### Claim 16 (depends on 14)

The device according to claim 14, wherein the processor is further configured to:
receive, using a first Precision Time Protocol (PTP) port preset to a monitor clock state, a synchronization packet from a second BC device of the boundary device of the third-party network side using a second PTP port preset to a master clock state;
send a delay-request packet to the second PTP port of the second BC device using the first PTP port;
receive, using the first PTP port, a delay-response packet from second PTP port of the second BC device;
determine a mean path delay according to timestamp information generated by the delay-request packet and the delay-response packet;
determine the time synchronization offset according to the mean path delay and timestamp information generated by the synchronization packet; and
send, using the first PTP port, the synchronization packet carrying the time synchronization offset to the second PTP port of the second BC device,
wherein the second BC device is an interface device that interfaces with the boundary device of the upstream network side and is in the third-party network.

### Claim 17

A time synchronization boundary clock (BC) device, comprising:
a receiver configured to receive a synchronization packet carrying a time synchronization offset, from a boundary device of an upstream network side, and is transparently transmitted by a boundary device of a third-party network side, wherein the time synchronization offset is a time offset between a time domain of the upstream network and a time domain of the third-party network; and
a processor coupled to the receiver and configured to perform time synchronization with the boundary device of the upstream network side according to the time synchronization offset.

### Claim 18 (depends on 17)

The device according to claim 17, wherein the processor is further configured to:
receive, using a fourth Precision Time Protocol (PTP) port preset to a slave clock state, the synchronization packet carrying the time synchronization offset from a third BC device of the boundary device of the third-party network side using a third PTP port preset to a master clock state;
determine a preliminary clock adjustment value for time synchronization with the third BC device;
set a sum of the time synchronization offset and the preliminary clock adjustment value as a final clock adjustment value; and
perform clock adjustment according to the final clock adjustment value,
wherein the third BC device is an interface device that interfaces with the boundary device of the downstream network side and is in the third-party network.

### Claim 19

A time synchronization processing apparatus, comprising:
a receiver;
a processor coupled to the receiver; and
a memory coupled to the processor,
wherein the memory is configured to store a computer execution instruction,
wherein the receiver is configured to receive, on the basis that boundary devices in an entire network are all boundary clock (BC) devices, a synchronization packet carrying a time synchronization offset delivered by a boundary device of an upstream network side,
wherein the time synchronization offset is a time offset between a time domain of the upstream network and a time domain of a third-party network, and
wherein the computer execution instruction stored in the memory causes the processor to be configured to transparently transmit the synchronization packet carrying the time synchronization offset to a boundary device of a downstream network side such that the boundary device of the downstream network side performs time synchronization with the boundary device of the upstream network side according to the time synchronization offset.

### Claim 20

A time synchronization processing apparatus, comprising:
a transmitter;
a processor coupled to the transmitter; and
a memory coupled to the processor,
wherein the memory is configured to store a computer execution instruction,
wherein the computer execution instruction stored in the memory causes the processor to be configured to determine, on the basis that boundary devices in an entire network are all boundary clock (BC) devices, a time synchronization offset from a time domain of a third-party network,
wherein the time synchronization offset is a time offset between a time domain of an upstream network and the time domain of the third-party network, and
wherein the transmitter is configured to deliver a packet carrying the time offset to a boundary device of the third-party network side such that the boundary device of the third-party network side transparently transmits the synchronization packet to a boundary device of a downstream network side, and the boundary device of the downstream network side performs time synchronization with a boundary device of the upstream network side according to the time synchronization offset.

### Claim 21

A time synchronization processing apparatus, comprising:
a receiver;
a processor coupled to the receiver; and
a memory coupled to the processor,
wherein the memory is configured to store a computer execution instruction,
wherein the receiver is configured to receive, on the basis that boundary devices in an entire network are all boundary clock (BC) devices, a synchronization packet carrying a time synchronization offset from a boundary device of an upstream network side, transparently transmitted by a boundary device of a third-party network side,
wherein the time synchronization offset is a time offset between a time domain of the upstream network and a time domain of the third-party network, and
wherein the computer execution instruction stored in the memory causes the processor to be configured to perform time synchronization with the boundary device of the upstream network side according to the time synchronization offset.