CN108011682B

CN108011682B - Method for determining time source and network equipment

Info

Publication number: CN108011682B
Application number: CN201610960943.8A
Authority: CN
Inventors: 王天明
Original assignee: Beijing Huawei Digital Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd; XFusion Digital Technologies Co Ltd
Priority date: 2016-10-27
Filing date: 2016-10-27
Publication date: 2020-09-08
Anticipated expiration: 2036-10-27
Also published as: CN108011682A

Abstract

The invention discloses a method for determining a time source and network equipment. The method comprises the following steps: the method comprises the steps that first network equipment using a first time source obtains time source information of a second time source used by second network equipment; and if the time source information of the second time source is the same as the time source information of the first time source, the first network device prohibits switching the time source of the first network device from the first time source to the second time source. Therefore, by comparing the current time source of the network device with the time sources acquired from other network devices, the time source switching can be avoided when the information of the two time sources is the same, and the extra overhead caused by unnecessary time source switching is avoided.

Description

Method for determining time source and network equipment

Technical Field

The present invention relates to the field of communications, and in particular, to a method and a network device for determining a time source in the field of communications.

Background

In a communications network, the normal operation of many services requires network clock synchronization, i.e. the time or frequency error between devices throughout the network is kept within reasonable error levels. With the development of communication technology, the requirement of the current network for time synchronization is higher and higher (for example, for a base station in a 3G/4G/5G communication network), and the commercial deployment of the time synchronization function is wide.

In the scenario, if the main time source device, such as an optical module of an atomic global positioning System (ATOM global positioning System, abbreviated as "ATOM GPS"), fails, a device in the network, such as a Boundary Clock (BC) device, reports a source selection switching event and a time loss lock alarm in the process of reselecting a source to track the backup time source device. And then if the original main ATOM GSP optical module is recovered in fault or a new ATOM GPS optical module with high priority is inserted again, the BC device reselects a source to track the ATOM GPS optical module with high priority again, a source selection switching event and a time lock losing alarm are reported in the process, and due to the fact that Clock IDs of all devices are different, the device temporarily loses a time source in the process of source selection algorithm re-decision making, so that short lock losing is caused, and then a new Clock source can be locked again. In this scenario, if the key parameters such as the accuracy, stability, and phase of the time source provided by each ATOM GPS are equivalent (for example, all the parameters are from GPS satellite signals), there is no actual benefit in switching the time source, but there are also related events and alarm reports, which increases unnecessary explanation and maintenance costs, and may also accompany jump and degradation of the time performance in the process of switching the source.

Disclosure of Invention

In view of this, embodiments of the present invention provide a method for determining a time source and a network device, which can avoid unnecessary time source switching.

In a first aspect, a method for determining a time source is provided, the method comprising: the method comprises the steps that first network equipment using a first time source obtains time source information of a second time source used by second network equipment; and if the time source information of the second time source is the same as the time source information of the first time source, the first network device prohibits switching the time source of the first network device from the first time source to the second time source.

That is, the network device that has currently tracked and locked time source a acquires another available time source B, and at this time, the network device needs to determine whether the new time source B and the currently tracked time source a are homologous (for example, both of them are from the same GPS satellite system); if time source B and time source A are co-located, the network device does not have to switch sources to tracking time source B, even if time source B has a higher priority than time source A.

Therefore, the network equipment compares the current time source with the time sources acquired from other network equipment, and does not perform time source switching when the information of the two time sources is the same, so that the time source switching action without profit is reduced, unnecessary source switching events and alarm reporting are avoided, and the maintenance cost of the current network is reduced.

Optionally, the time source information of the first network device includes a time source identification ID of the first time source and a hop count of the first time source, where the time source ID of the first time source is used to identify the first time source; the time source information of the second network device includes a time source ID of the second time source and a hop count of the second time source, and the time source ID of the second time source is used to identify the second time source.

That is, if the time source ID of the first time source is the same as the time source ID of the second time source, and the hop count of the time source of the first network device is the same as the hop count of the time source of the second network device, the first network device does not perform time source switching, that is, does not switch the time source currently used by itself to the time source from the second network device.

The time source ID of the first time source is used for identifying the first time source, the time source ID of the second time source is used for identifying the second time source, and each time source ID is used for identifying a unique time source.

The hop count of the time source of the first network device represents the number of networks passed by the time source of the first network device to the first network device in the network, and the hop count of the time source of the second network device represents the number of networks passed by the time source of the first network device to the second network device in the network.

Optionally, the time source information of the second network device further includes first indication information, where the first indication information is used to indicate that the first network device prohibits switching the time source of the first network device from the first time source to the second time source when the time source information of the second time source is the same as the time source information of the first time source;

wherein, if the time source information of the second network device is the same as the time source information of the first network device, the first network device prohibits switching the time source of the first network device from the first time source to the second time source, including: and the first network equipment prohibits switching the time source of the first network equipment from the first time source to the second time source when the time source information of the second network equipment is the same as the time source information of the first network equipment according to the first indication information.

It should be understood that a specific value may be set in the first indication information acquired by the first network device to indicate that the non-rollback mode is enabled, that is, the first network device is instructed not to perform time source switching when the time source information of the second time source is the same as the time source information of the first time source; the indication information may also be set with other different specific values to indicate that the non-switchback mode is not enabled, that is, the first network device is instructed to determine an optimal time source from the first time source and the second time source according to the source selection algorithm, and the time source of the first network device is switched from the first time source to the optimal time source.

For example, the first network device may obtain time source information of the second network device, and obtain the following information from the time source information of the second device: (1) the first indication information indicates that the time source is not switched back to the mode enable; (2) the time source ID of the second time source used by the second network device, and the time source ID of the second time source is the same as the time source ID of the first time source and has a value different from 0, indicating that the true time sources received by the two interfaces of the first network device are the same, i.e. the time sources are consistent; (3) and the hop count of the time source of the second time source is the same as the hop count of the time source of the first time source in value. At this time, the first network device determines whether the time source ID of the second time source is the same as the time source ID of the first network device and whether the time source hop count of the second time source is the same as the time source hop count of the first network device according to the time source information of the second time source, and the first network device does not need to perform source selection operation according to the indication of the first indication information if the time source ID and the time source hop count of the first network device are the same, and even if the second time source is from the main time source device (the priority of the second time source is higher than that of the first time source), the first network device does not switch the current time source from the first time source to the second time source. That is, if the three conditions (1) to (3) are satisfied at the same time, the source switching operation is not performed.

Here, it may be indicated that the upstream device does not deliver the parameter to the network device by using a time source ID of 0, for example, if the time source ID is 0 in the time source information acquired by the first network device from the second network device, it indicates that the second network device does not deliver the time source ID of the second time source to the first network device. At this time, the first network device may determine an optimal time source from the first time source and the second time source according to a source selection algorithm, and switch the time source of the first network device from the first time source to the optimal time source.

Optionally, the obtaining, by the first network device using the first time source, the time source information of the second time source used by the second network device includes: and using the first network equipment of a first time source to receive a Precision Time Protocol (PTP) message sent by the second network equipment, wherein a reserved field of the PTP message comprises time source information of the second time source.

It can be seen that there is a Reserved field (Reserved) in the PTP message content, and this field may be used to transmit time source information including parameter values including a time source ID, for example, the setting and meaning of the value of the Reserved field may be as follows: (1) the default value is all 0, which indicates that the non-rollback mode is not enabled, and at this time, the high-priority time source can be selected according to the source selection algorithm and the current time source is switched to the high-priority time source, so that the compatibility of the downstream equipment can be maintained. (2) Setting the bit value on the highest bit position to be 1 to indicate that the non-cutting mode is enabled, namely if the time source ID and the time source hop count are the same, the source selection switching can not be carried out; (3) the value on the remaining 7 bits can represent the time source ID, for example, the value of the time source ID from the GPS satellite system can be specified to be 1, the value of the time source ID from the beidou satellite system is 2, and the value of 3-31 can be reserved for subsequent use and cannot be occupied; the remaining 7 bits are all 0, which may indicate that the information of the time source ID is not transferred (i.e. the upstream device does not transfer the parameter), and at this time, even if the network device has enabled the no-return mode, the network device performs normal source selection or switching. (4) The values 32-127 may be used as planned by the actual situation when deploying the time-synchronized network; (5) the time synchronized network device needs to support the capability of being able to recognize the information of the reserved field; (6) the network device and the time source device for time synchronization need to have the capability of transmitting the information in the reserved field to the downstream device, that is, the time source information in the reserved field can be transmitted downstream through the Announce message.

Optionally, the obtaining, by a first network device using a first time source, time source information of a second time source used by a second network device includes: and using the first network equipment of a first time source to receive a notification Announce message sent by the second network equipment, wherein a TLV field carried by the Announce message comprises time source information of the second time source.

That is to say, the second network device may deliver the time source information including the parameter value of the time source ID to the downstream device in a manner that the Announce packet carries the TLV. The TLV field may be attached to the tail of the Announce packet to convey some additional information, so that an additional TLV field may be added to encapsulate and convey additional time source ID information.

Optionally, the first network device includes a boundary clock BC device, and the second network device includes a BC device or a time source device.

Optionally, the time source device comprises a global positioning system GPS satellite, a beidou satellite, a glonass satellite, a galileo satellite or a separate atomic clock.

Optionally, the method further comprises: if the time source information of the second time source is different from the time source information of the first time source, the first network device determines an optimal time source in the first time source and the second time source, and switches the time source of the first network device from the first time source to the optimal time source.

In a second aspect, a network device is provided, which may be configured to perform the processes performed by the first network device in the method for determining a time source in the first aspect and various implementations. The first network device includes an acquisition unit and a processing unit. The acquiring unit is used for acquiring time source information of a second time source used by the second device; the processing unit is configured to prohibit switching the time source of the first network device from the first time source to the second time source when the time source information of the second time source is the same as the time source information of the first time source used by the first network device.

In a third aspect, a system chip is provided, where the system chip includes an input interface, an output interface, a processor and a memory, where the processor is configured to execute codes in the memory, and when the codes are executed, the processor may implement each process performed by the first network device in the method for determining a time source in the foregoing first aspect and various implementations. Wherein the processor is configured to: acquiring time source information of a second time source used by second network equipment; and when the time source information of the second time source is the same as the time source information of the first time source used by the first network equipment, prohibiting switching the time source of the first network equipment from the first time source to the second time source.

In a fourth aspect, a method of determining a time source is provided, the method comprising: the method comprises the steps that a second network device sends time source information of a second time source used by the second network device to a first network device using a first time source, so that the first network device prohibits switching of the time source of the first network device from the first time source to the second time source when the time source information of the second time source is the same as the time source information of the first time source.

Therefore, the network equipment sends the own time source information to other network equipment, so that other network equipment can not perform time source switching when the time source information of the time source is the same as the time source information of other time sources, thereby reducing non-profit time source switching actions, avoiding unnecessary source switching events and alarm reporting, and reducing the maintenance cost of the existing network.

Optionally, the time source information of the first time source includes a time source identification ID of the first time source and a hop count of the first time source, the time source ID of the first time source is used to identify the first time source, the time source information of the second time source includes a time source ID of the second time source and a hop count of the second time source, and the time source ID of the second time source is used to identify the second time source.

Optionally, the time source information of the second time source further includes first indication information, where the first indication information is used to indicate that the first network device prohibits switching the time source of the first network device from the first time source to the second time source when the time source information of the second time source is the same as the time source information of the first time source.

Optionally, the sending, by the second network device, time source information of a second time source used by the second network device to the first network device using the first time source includes: and the second network equipment sends a Precision Time Protocol (PTP) message to the first network equipment using the first time source, wherein a reserved field of the PTP message comprises time source information of the second time source.

Optionally, the sending, by the second network device, time source information of a second time source used by the second network device to the first network device using the first time source includes: and the second network equipment sends a notification Announce message to the first network equipment using the first time source, wherein a TLV field carried by the Announce message comprises time source information of the second time source.

In a fifth aspect, a network device is provided, which may be configured to perform the processes performed by the second network device in the method for determining a time source in the fourth aspect and various implementations. The second network device comprises a sending unit, configured to send, to a first network device using a first time source, time source information of a second time source used by the second network device, so that the first network device prohibits switching of the time source of the first network device from the first time source to the second time source when the time source information of the second time source is the same as the time source information of the first time source.

In a sixth aspect, a system chip is provided, where the system chip includes an input interface, an output interface, a processor and a memory, where the processor is configured to execute code in the memory, and when the code is executed, the processor may implement the processes performed by the network device in the method for determining a time source in the fourth aspect and various implementations. The transmitter is configured to transmit, to a first network device using a first time source, time source information of a second time source used by a second network device, so that the first network device prohibits switching of the time source of the first network device from the first time source to the second time source when the time source information of the second time source is the same as the time source information of the first time source.

In a seventh aspect, a computer-readable storage medium is provided, which stores a program that causes a network device to execute the method for determining a time source of the first aspect, and any of its various implementations.

In an eighth aspect, a computer-readable storage medium is provided, which stores a program that causes a network device to execute the method of determining a time source of the fourth aspect, and any of its various implementations.

Based on the technical scheme of the embodiment of the invention, the network equipment compares the current time source with the time sources obtained from other network equipment, and does not switch the time sources when the information of the two time sources is the same, thereby reducing the time source switching action without profit, avoiding unnecessary source switching events and alarm reporting, and reducing the maintenance cost of the current network.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments of the present invention will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic diagram of an application scenario of an embodiment of the present invention.

Fig. 2 is a schematic flow chart of a method of determining a time source of an embodiment of the present invention.

Fig. 3 is a schematic diagram of an Announce message.

Fig. 4 is a block diagram of a network device according to an embodiment of the present invention.

Fig. 5 is a block diagram of a network device according to an embodiment of the present invention.

Fig. 6 is a schematic structural diagram of a system chip according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, shall fall within the scope of protection of the present invention.

As used in this specification, the terms "component," "module," "system," and the like are intended to refer to a computer-related entity, either hardware, firmware, a combination of hardware and software, or software in execution. For example, a component may be, but is not limited to being, a process running on a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a computing device and the computing device can be a component. One or more components can reside within a process and/or thread of execution and a component can be localized on one computer and/or distributed between 2 or more computers. In addition, these components can execute from various computer readable media having various data structures stored thereon. The components may communicate by way of local and/or remote processes such as in accordance with a signal having one or more data packets (e.g., data from two components interacting with another component in a local system, distributed system, and/or across a network such as the internet with other systems by way of the signal).

It should be understood that the technical solutions of the embodiments of the present invention can be applied to various communication systems, for example: global System for Mobile communications (GSM) System, Code Division Multiple Access (CDMA) System, Wideband Code Division Multiple Access (WCDMA) System, Long Term Evolution (LTE) System, LTE Frequency Division Duplex (FDD) System, LTE Time Division Duplex (TDD), Universal Mobile Telecommunications System (UMTS), and future 5G Communication System.

The network device in the embodiment of the present invention may be a device for communicating with a terminal device, and for example, may be a Base Station (BTS) in a GSM system or a CDMA system, a Base Station (NodeB, NB) in a WCDMA system, an evolved Node B (eNB) in an LTE system, or an evolved Node B (eNodeB), or the network device may be a relay Station, an access point, a vehicle-mounted device, a wearable device, a network-side device in a future 5G network, or a network device in a future evolved PLMN network, or the like.

In communication networks, the normal operation of many services requires that the network clocks be synchronized, i.e. that the time or frequency difference between devices throughout the network be kept within reasonable error levels. Time Synchronization (Phase Synchronization) is performed until the frequency and Phase of signals are consistent, i.e., the Phase difference between signals is constant at zero.

Fig. 1 is a schematic diagram of an application scenario of an embodiment of the present invention. Fig. 1 shows at least one network device (or referred to as time device, device), which includes BC devices 11 to 16 located at a convergence layer, BC device 17, BC device 18, an Ordinary Clock (OC) device 19, base stations NodeB 20 and NodeB 21 located at an access layer, and an atomic global positioning system (ATOM GPS)22 and an ATOM GPS 23, where the ATOM GPS 22 is a master time source device and the ATOM GPS 23 is a backup time source device. Fig. 1 is a simplified schematic diagram of an example, and other types of network devices, which are not shown in fig. 1, may be included in the network.

If the optical module of the ATOM GPS 22 has a fault, a network device, such as a BC device, reports a source selection switching event and a time out-of-lock alarm in the process of reselecting a source to track the port where the optical module of the standby ATOM GPS 21 is located. Then, if the optical module of the original ATOM GPS 22 recovers from the failure, or a new ATOM GPS optical module with high priority is inserted again, the BC device will reselect the source to track the ATOM GPS optical module with high priority again. In this scenario, if the time sources provided by the ATOM GPS 22 and the ATOM GPS 23 are all from GPS satellite signals, and the key parameters such as the accuracy, stability, and phase of the time sources are equivalent, the process of switching the time sources does not have actual benefits, but related events and alarms are reported, which increases unnecessary explanation and maintenance costs, and may involve jump and degradation of the time performance during the process of switching the sources.

The embodiment of the invention avoids the extra expense brought by unnecessary time source switching by comparing the current time source of the network equipment with the time sources acquired from other network equipment and not switching the time sources when the information of the two time sources is the same.

Fig. 2 shows a schematic flow chart of a method for determining a time source according to an embodiment of the present invention, which is described by taking a time source switching of a first device as an example, where the first device may be any one of the network devices shown in fig. 1. The method for determining the time source comprises the following steps:

s210, the first network device of the first time source is used for obtaining the time source information of the second time source used by the second network device.

S220, if the time source information of the second time source is the same as the time source information of the first time source, the first network device prohibits switching the time source of the first network device from the first time source to the second time source.

Specifically, a time source currently used by a first network device is a first time source, and when a second time source occurs, for example, a new time source device is inserted into a network or a function of an original Master time source device is restored, in the prior art, the first network device needs to perform a source selection procedure to reselect a better time source and perform time source switching, for example, the first network device may perform the selection and switching of the time source according to a Best Master Clock (BMC, for short) source selection procedure. However, if the time source information of the second time source is the same as the time source information of the first time source, the first network device may not perform the selection and switching of the time source in the embodiment of the present invention.

The second network device sends the time source information of the second time source used by the second network device to the first network device using the first time source, so that the first network device does not switch the time source of the first network device from the first time source to the second time source when the time source information of the second time source is the same as the time source information of the first time source.

For example, the network device that has currently tracked and locked time source a acquires another available time source B, and at this time, the network device needs to determine whether the new time source B and the currently tracked time source a are homologous (for example, both time sources are from a GPS satellite system); if time source B and time source A are co-located, the network device does not have to switch sources to tracking time source B, even if time source B has a higher priority than time source A.

Optionally, the method may further include: if the time source information of the second network device is different from the time source information of the first time source, the first network device determines an optimal time source from the first time source and the second time source, and switches the time source of the first network device from the first time source to the optimal time source.

Specifically, if the time source information of the second time source is not the same as the time source information of the first time source, S220 is not performed, but the optimal time source is determined from the first time source and the second time source, for example, the determination of the optimal time source is implemented by a BMC source selection algorithm, and the time source of the first network device is switched from the first time source to the optimal time source.

Optionally, the first time source information includes a time source identifier ID of the first time source and a hop count of the first time source; the second time source information includes a time source ID of the second time source and a hop count of the second time source.

Wherein the time source ID of the first time source is used for identifying the first time source, and the time source ID of the second time source is used for identifying the second time source.

The hop count of the time source of the first network device represents the number of network elements passed by the time source of the first network device to the first network device in the network, and the hop count of the time source of the second network device represents the number of network elements passed by the time source of the first network device to the second network device in the network.

Specifically, the first network device may determine whether to perform time source switching, that is, whether to switch the time source of the first network device from the first time source to the second time source, according to the time source information of the first time source currently used by the first network device and the time source information of the second time source used by the second network device. After the first network device acquires the time source information of the second time source, if it is determined that the time source information of the second time source is the same as the time source information of the first time source, it may be considered that the first time source and the second time source are from the same time source device, such as a GPS satellite system, and their synchronization times should also be the same, so that it may not be necessary to switch the time sources, that is, to switch the time source currently used by the first network device from the first time source to the second time source.

It should be noted that one condition for not performing time source switching as referred to herein is that the time source ID of the first time source and the time source ID of the second time source are the same. The time source ID of the first time source and the time source ID of the second time source are the same indicating that the first time source and the second time source are identical, i.e. the first time source and the second time source are both from the same time source device, e.g. both from a GPS satellite, or both from a beidou satellite, or from the same independent atomic clock. In this case, the first time source and the second time source should ensure that the time sources have consistent accuracy and stability, and the key parameters such as the phase and the like are consistent. If the first time source currently used by the first network device and the second time source from the second network device are from two different time source devices (for example, the first time source is from a GPS satellite, and the second time source is from a beidou satellite), even if the time source accuracy and stability of the two different time source devices are consistent, the requirement of time source consistency cannot be met, because it cannot be guaranteed that the phases of the first time source and the second time source are consistent, and even if the phases at this time are the same, it cannot be guaranteed that the phases can still be kept the same afterwards.

It should also be understood that different time source IDs are used to identify different time sources, and the same time source ID represents a unique time source, i.e., a time source ID is used to identify an independent time source.

For example, in general, an independent time source corresponding to a time source ID and other time sources except the independent time source are respectively sourced from different time source devices, and the parameters of precision, stability, phase and the like are not completely the same. For example, if the first time source is from a first atomic clock and the second time source is from a second atomic clock, the first time source from the first atomic clock and the second time source from the second atomic clock have different parameters such as accuracy, stability, or phase, and the time source ID of the first time source and the time source ID of the second time source are different, for example, the time source ID of the first time source from the first atomic clock is 1 and the time source ID of the second time source from the second atomic clock is 2. However, there is a case where, if all the parameters of the first time source from the first atomic clock and the second time source from the second atomic clock are the same, the first time source and the second time source are identical time sources, and the time source ID of the first time source and the time source ID of the second time source are the same time source ID. For example, the frequency, phase, etc. of the first time source are respectively adjusted to a fixed value, and the frequency, phase, etc. of the second time source are also respectively adjusted to the same parameter value, then the first time source and the second time source are exactly the same time source, i.e. the frequency, accuracy, stability, phase, etc. of the first time source and the second time source are all consistent, so the time source IDs of the first time source and the second time source are also the same.

Since the precision and stability of the time source can be transferred to the downstream device, but even if the precision and stability are the same, the same source cannot be guaranteed, so that a new parameter, namely the time source ID, is provided in the embodiment of the present invention to characterize the uniqueness of each time source and can be transferred to the downstream device.

The Clock device Identity (Clock Identity, abbreviated as "Clock ID") is different from the existing Clock device Identity of the network device in that: each network device in the time synchronization network has its own Clock ID for uniquely marking each network device in the networking, for example, for the optical module of ATOM GPS, the integrated timing Supply System (just "BITS") device, etc., they all have their own Clock ID, but they cannot provide a high-precision time source by themselves, and are both a time source for receiving GPS satellites or an independent atomic Clock, etc., and then transmit the time source to the downstream device. The newly added time source IDs are used to characterize the true source of their time sources.

That is, here, when the time source ID of the first network device is the same as the time source ID of the second network device, and the hop count of the time source of the first network device is the same as the hop count of the time source of the second network device, the first network device does not perform time source switching, that is, does not switch the time source currently used by itself from the first time source to the second time source from the second network device.

It should be understood that the more network elements are passed through by a time source when the time source is transmitted in the network, the larger the error is introduced, and therefore, a time source with a smaller hop count (Steps Removed) value needs to be selected in the same case. If the time source ID of the second time source is the same as the time source ID of the first time source, but the hop count is different, then the first network device may select the time source with the smaller hop count of the time source from the first time source and the second time source, and switch its own time source as the first time source to the time source with the smallest hop count.

It should also be understood that the second network device may be referred to as an upstream device of the first network device, the first network device may be referred to as a downstream device of the second network device, the upstream device may be capable of delivering its own time source for the downstream device, and the downstream device may receive the time source delivered by the upstream device. The first network device and the second network device may each include two ports, one of which is configured to communicate its time source to the downstream device to issue the synchronization time, and the other of which is configured to receive the time source of the upstream device or the time source device to receive the synchronization time.

Optionally, the time source information of the second network device may further include first indication information, where the first indication information is used to indicate that the first network device prohibits switching the time source of the first network device from the first time source to the second time source when the time source information of the second time source is the same as the time source information of the first time source;

in S220, if the time source information of the second time source is the same as the time source information of the first time source, the first network device prohibits switching the time source of the first network device from the first time source to the second time source, including: and the first network equipment switches the time source of the first network equipment from the first time source to the second time source according to the first indication information when the time source information of the second time source is the same as the time source information of the first time source.

Specifically, the second network device may send, to the first network device, first indication information, where the first indication information is used to indicate that the first network device does not switch the time source of the first network device from the first time source to the second time source when the time source information of the second time source is the same as the time source information of the first time source, that is, the first indication information indicates that the time source non-switchback mode is enabled. Further, the first indication information may be carried in the time source information of the second time source, after the first network device acquires the time source information of the second time source, the first indication information may be acquired from the time source information of the second time source, and according to the first indication information, the time source information of the first time source and the time source information of the second time source are compared, and when the time source information of the first time source is the same as the time source information of the second time source, the time source is not switched, that is, the time source currently used by the first network device is not switched from the first time source to the second time source, even if the priority of the second time source is higher.

It should be understood that a specific value may be set in the first indication information acquired by the first network device to indicate that the non-rollback mode is enabled, that is, to indicate that the first network device does not perform time source switching when the time source information of the second time source is the same as the time source information of the first time source; the first indication information may also be set with other different specific values to indicate that the non-switchback mode is not enabled, that is, to instruct the first network device to determine an optimal time source from the first time source and the second time source according to a source selection algorithm, and switch the time source of the first network device from the first time source to the optimal time source.

For example, assume that the time source of the current second network device is from the primary time source device or the device newly joining the network, and the time source of the first network device is from the backup time source device. At this time, due to reasons such as the main time source device being restored from a failure state to an operating state or a new network device being added, a new time source may be brought into the first network device, and at this time, the first network device needs to re-determine its own time source. The first network device may obtain time source information of a second time source used by the second network device, and obtain the following information from the time source information of the second time source: (1) the first indication information indicates that the time source is not switched back to the mode enable; (2) the time source ID of the second time source used by the second network device, and the time source ID of the second time source is the same as the time source ID of the first time source and has a value different from 0, indicating that the true time sources received by the two interfaces of the first network device are the same, i.e. the time sources are consistent; (3) and the hop count of the time source of the second time source is the same as the hop count of the time source of the first time source in value. At this time, the first network device determines whether the time source ID of the second time source is the same as the time source ID of the first network device and whether the time source hop count of the second time source is the same as the time source hop count of the first network device according to the time source information of the second time source, and the first network device does not need to perform source selection operation according to the indication of the first indication information if the time source ID and the time source hop count of the first network device are the same, and even if the second time source is from the main time source device (the priority of the second time source is higher than that of the first time source), the first network device does not switch the current time source from the first time source to the second time source. That is, if the three conditions (1) to (3) are satisfied at the same time, the source switching operation is not performed.

Here, it may be indicated that the upstream device does not deliver the parameter to the network device by using a time source ID of 0, for example, if the time source ID is 0 in the time source information acquired by the first network device from the second network device, it indicates that the second network device does not deliver the time source ID of the second time source to the first network device. At this time, the first network device may determine an optimal time source from the first time source and the second time source according to a source selection algorithm, and switch the first time source of the first network device to the optimal time source.

Optionally, the first network device may include a boundary clock BC device, and the second network device may include a BC device or a time source device.

The time source device may be, for example, a GPS satellite, a beidou satellite, a glonass satellite, a galileo satellite, or a separate atomic clock.

In S210, the first network device obtains the time source information of the second time source used by the second network device, which may specifically be described in detail in two ways, respectively with reference to fig. 4 and 5.

Mode 1

One way to obtain the time source information of the second time source is: the first network device receives a Precision Time Protocol (PTP) message sent by the second network device, where a reserved field of the PTP message includes Time source information of the second Time source.

For example, fig. 3 is a schematic diagram of a notification (Announce) packet, where the packet includes a PTP packet header and a PTP packet content field, a shaded portion in fig. 3 is the packet header, and a packet content field is below the packet header. The message content field in the Announce message at least comprises:

the value of the start time Stamp (origin time Stamp) field is 0 or an estimate of the Announce message transmission time;

the Current UTC Offset field carries an Offset value between the Current international atomic Time (TAI) and Universal Time Coordinated (UTC), in seconds(s);

the Priority 1(Grandmaster Priority 1) field of the master time source is the Priority 1 attribute of the master time source (Grandmaster), is used for comparing the Priority in the BMC algorithm, wherein the smaller the value is, the higher the Priority is, and the master time source refers to the time source signal transmitted by the upstream time source equipment;

the Clock Quality (Grandmaster Clock Quality) field of the master time source is the Clock Quality (Clock Quality) attribute of the master time source, including the level and precision of the master time source;

a Priority 2(Grandmaster Priority 2) field of the master time source is a Priority 2 attribute of the master time source and is used for comparing priorities in the BMC algorithm, wherein the smaller the value is, the higher the Priority is;

the Master Identity field is the Clock Identity (Clock ID) attribute of the Master Source;

a hop count (Steps moved) field indicates the number of hops through the link between the local clock that issued the earlier message and the higher level clock;

a main Time Source (Time Source) field indicates a Source of a main Time Source, for example, the Source is from an atomic clock, a GPS, a PTP, a Network Time Protocol (NTP for short), and the like;

the Reserved field is a Reserved field.

It can be seen that there is a reserved field in the PTP message content, and the present invention can use this field to transmit time source information including a parameter value of a time source ID, for example, the setting and meaning of the value of the reserved field may be as follows:

(1) the default value is all 0, which indicates that the non-rollback mode is not enabled, and at this time, the high-priority time source can be selected according to the source selection algorithm and the current time source is switched to the high-priority time source, so that the compatibility of the downstream equipment can be maintained.

(2) Setting the bit value on the highest bit position to be 1 to indicate that the mode which can not be cut back is enabled, and indicating that if the time source ID is the same as the time source hop count, the source selection switching can not be carried out;

(3) the numerical values of the remaining 7 bits can represent a time source ID, and a unique time source (for example, a time source from a GPS satellite, a time source from a beidou satellite, etc.) in the world needs to be allocated with a fixed time source value to ensure intercommunication, for example, the time source ID value of the GPS can be specified to be 1, the time source ID value of the beidou satellite can be 2, and the values from 3 to 31 can be reserved for subsequent use and cannot be occupied;

the remaining 7 bits are all 0, which may indicate that the information of the time source ID is not transferred (i.e. the upstream device does not transfer the parameter), and at this time, even if the network device has enabled the no-return mode, the network device performs normal source selection or switching.

(4) The values 32-127 can be planned and used according to the actual situation when the time synchronization network is deployed, and can be manually configured, and the network planning can refer to the use limit of Clock ID to avoid the scene with the same time source ID value in the whole network;

(5) the time synchronized network device needs to support the capability of being able to recognize the information of the reserved field;

(6) the network device and the time source device for time synchronization need to have the capability of transmitting the information in the reserved field to the downstream device, that is, the time source information in the reserved field can be transmitted downstream through the Announce message.

Mode 2

Another way to obtain the time source information of the second time source is as follows: and the first network equipment receives a TLV field carried by the Announce message sent by the second network equipment, wherein the TLV field comprises time source information of the second time source. That is to say, the second network device may deliver the time source information including the parameter value of the time source ID to the downstream device in a manner that the Announce packet carries the TLV.

Type-Length-Value (TLV) is a data format, and the Length of TLV fields is required to be even bytes, and the structure is as follows:

wherein tlvType represents the type of TLV, indicating the meaning of the current data packet, e.g. indicating the type of a single packet or the type of a nested packet; the length field indicates the length of the TLV field in bytes, and the size comprises three parts, namely tlvType, length field and value field; the valueField indicates the content body of the data in the TLV field, including the actual content of the data packet.

The TLV field may be attached to the tail of the Announce packet to convey some additional information. The new time source ID information can be encapsulated and communicated by adding one such TLV field. The second network device may send the time source information of the second time source to the first network device through the TLV field.

Therefore, in the embodiment of the invention, the network equipment compares the current time source with the time sources acquired from other network equipment, and does not switch the time sources when the information of the two time sources is the same, so that the time source switching action without profit is reduced, unnecessary source switching events and alarm reports are avoided, and the maintenance cost of the current network is reduced.

It should be understood that, in various embodiments of the present invention, the sequence numbers of the above-mentioned processes do not mean the execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

In the following, with reference to fig. 4 to fig. 6, a network device according to an embodiment of the present invention will be described, and the technical features described in the above method embodiments may be applied to the following apparatus embodiments.

Fig. 4 shows a network device 400 according to an embodiment of the invention. As shown in fig. 4, the network device 400 is a first network device, and the network device 400 includes:

an obtaining unit 410, configured to obtain time source information of a second time source used by a second device;

a processing unit 420, configured to prohibit switching the time source of the first network device from the first time source to the second time source when the time source information of the second time source acquired by the acquiring unit 420 is the same as the time source information of the first time source used by the first network device.

Therefore, the network device does not perform time source switching by comparing the current time source with the time sources acquired from other network devices when the information of the two time sources is the same, thereby avoiding the additional overhead caused by unnecessary time source switching.

Optionally, the time source information of the first time source includes a time source identification ID of the first time source and a hop count of the first time source, where the time source ID of the first time source is used to identify the first time source; the time source information of the second time source comprises a time source ID of the second time source and hop count of the second time source, and the time source ID of the second time source is used for identifying the second time source.

Optionally, the time source information of the second time source further includes first indication information, where the first indication information is used to indicate that the first network device prohibits switching the time source of the first network device from the first time source to the second time source when the time source information of the second time source is the same as the time source information of the first time source;

wherein the processing unit 420 is specifically configured to: according to the first indication information, when the time source information of the second time source is the same as the time source information of the first time source, switching the time source of the first network equipment from the first time source to the second time source is prohibited.

Optionally, the obtaining unit 410 is specifically configured to: and receiving a Precision Time Protocol (PTP) message sent by the second network equipment, wherein a reserved field of the PTP message comprises time source information of the second time source.

Optionally, the obtaining unit 420 is specifically configured to: and receiving a notification Announce message sent by the second network device, wherein a type-length-value (TLV) field carried by the Announce message includes time source information of the second time source.

Optionally, the processing unit 420 is further configured to: when the second time source information is different from the first time source information, determining an optimal time source from the first time source and the second time source, and switching the time source of the first network equipment from the first time source to the optimal time source.

It should be noted that in the embodiment of the present invention, the obtaining unit 410 and the processing unit 420 may be implemented by a processor. As shown in fig. 5, network device 500 may include a processor 510, a transceiver 520, and a memory 530. The transceiver 520 may include a receiver 521 and a transmitter 522, and the memory 530 may be used to store time source information of a time source used by a network device or code executed by the processor 510, etc. The various components in network device 500 may be coupled together by a bus system 540, where bus system 540 includes a power bus, a control bus, a status signal bus, and the like, in addition to a data bus. Where network device 500 is a first network device, processor 510 is configured to:

acquiring time source information of a second time source used by second equipment;

and when the time source information of the second time source is the same as the time source information of the first time source used by the first network equipment, prohibiting switching the time source of the first network equipment from the first time source to the second time source.

wherein the processor 510 is specifically configured to: according to the first indication information, when the time source information of the second time source is the same as the time source information of the first time source, switching the time source of the first network equipment from the first time source to the second time source is prohibited.

Optionally, the receiver 521 is specifically configured to: and receiving a Precision Time Protocol (PTP) message sent by the second network equipment, wherein a reserved field of the PTP message comprises time source information of the second time source.

Optionally, the receiver 521 is specifically configured to: and receiving a notification Announce message sent by the second network device, wherein a type-length-value (TLV) field carried by the Announce message includes time source information of the second time source.

Optionally, the processor 510 is further configured to: when the second time source information is different from the first time source information, determining an optimal time source from the first time source and the second time source, and switching the time source of the first network equipment from the first time source to the optimal time source.

Fig. 6 is a schematic structural diagram of a system chip of an embodiment of the present invention. The system chip 600 in fig. 6 includes an input interface 601, an output interface 602, at least one processor 603, and a memory 604, where the input interface 601, the output interface 602, the processor 603, and the memory 604 are connected via a bus 605, the processor 603 is configured to execute codes in the memory 604, and when the codes are executed, the processor 603 implements the method executed by the network device in fig. 2 and fig. 3. The bus 605 is only an example of a connection manner, and in the embodiment of the present invention, the input interface 601, the output interface 602, the processor 603, and the memory 604 may be connected by other manners, which is not limited herein.

The network device 400 shown in fig. 4, the network device 500 shown in fig. 5, or the system chip 600 shown in fig. 6 can implement each process implemented by the network device in the foregoing method embodiments of fig. 2 and fig. 3, and in order to avoid repetition, details are not repeated here.

Those of ordinary skill in the art will appreciate that the elements and algorithm steps of the examples described in connection with the embodiments disclosed herein may be embodied in electronic hardware, computer software, or combinations of both, and that the components and steps of the examples have been described in a functional general in the foregoing description for the purpose of illustrating clearly the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may also be an electric, mechanical or other form of connection.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment of the present invention.

In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.

The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention essentially or partially contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.

While the invention has been described with reference to specific embodiments, the invention is not limited thereto, and various equivalent modifications and substitutions can be easily made by those skilled in the art within the technical scope of the invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method of determining a time source, the method comprising:

using a first network device of a first time source to obtain time source information of a second time source used by a second network device, wherein the time source information of the second time source comprises a time source ID of the second time source and hop count of the second time source, and the time source ID of the second time source is used for identifying the source of the second time source;

if the time source information of the second time source is the same as the time source information of the first time source, the first network device prohibits switching the time source of the first network device from the first time source to the second time source, the time source information of the first time source includes a time source Identification (ID) of the first time source and hop count of the first time source, and the time source ID of the first time source is used for identifying the source of the first time source.

2. The method of claim 1, wherein the time source information of the second time source further includes first indication information, and the first indication information is used to indicate to the first network device that the time source of the first network device is prohibited from being switched from the first time source to the second time source when the time source information of the second time source is the same as the time source information of the first time source;

wherein, if the time source information of the second time source is the same as the time source information of the first time source, the first network device forbids switching the time source of the first network device from the first time source to the second time source, including:

and the first network equipment prohibits switching the time source of the first network equipment from the first time source to the second time source when the time source information of the second time source is the same as the time source information of the first time source according to the first indication information.

3. The method of claim 1, wherein the obtaining, by the first network device using the first time source, time source information of the second time source used by the second network device comprises:

and using the first network equipment of a first time source to receive a Precision Time Protocol (PTP) message sent by the second network equipment, wherein a reserved field of the PTP message comprises time source information of the second time source.

4. The method of claim 1, wherein the obtaining, by the first network device using the first time source, time source information of the second time source used by the second network device comprises:

and using the first network equipment of a first time source to receive a notification Announce message sent by the second network equipment, wherein a type-length-value (TLV) field carried by the Announce message comprises time source information of the second time source.

5. The method of claim 1, wherein the first network device comprises a Boundary Clock (BC) device and the second network device comprises a BC device or a time source device.

6. The method of claim 5, wherein the time source device comprises a Global Positioning System (GPS) satellite, a Beidou satellite, a Glonass satellite, a Galileo satellite, or a standalone atomic clock.

7. The method according to any one of claims 1 to 6, further comprising:

if the time source information of the second time source is different from the time source information of the first time source, the first network device determines an optimal time source in the first time source and the second time source, and switches the time source of the first network device from the first time source to the optimal time source.

8. A network device for determining a time source, wherein the network device is a first network device, and wherein the first network device comprises:

an obtaining unit, configured to obtain time source information of a second time source used by a second network device, where the time source information of the second time source includes a time source ID of the second time source and a hop count of the second time source, and the time source ID of the second time source is used to identify a source of the second time source;

a processing unit, configured to prohibit switching the time source of the first network device from the first time source to the second time source when the time source information of the second time source acquired by the acquiring unit is the same as the time source information of the first time source used by the first network device, where the time source information of the first time source includes a time source identification ID of the first time source and a hop count of the first time source, and the time source ID of the first time source is used to identify the source of the first time source.

9. The network device according to claim 8, wherein the time source information of the second network device further includes first indication information, the first indication information is used to indicate to the first network device that the time source of the first network device is prohibited from being switched from the first time source to the second time source when the time source information of the second time source is the same as the time source information of the first time source;

wherein the processing unit is specifically configured to:

according to the first indication information, when the time source information of the second time source is the same as the time source information of the first time source, switching the time source of the first network equipment from the first time source to the second time source is prohibited.

10. The network device of claim 8, wherein the obtaining unit is specifically configured to:

and receiving a Precision Time Protocol (PTP) message sent by the second network equipment, wherein a reserved field of the PTP message comprises time source information of the second time source.

11. The network device of claim 8, wherein the obtaining unit is specifically configured to:

and receiving a notification Announce message sent by the second network device, wherein a type-length-value (TLV) field carried by the Announce message includes time source information of the second time source.

12. The network device of claim 8, wherein the first network device comprises a Boundary Clock (BC) device and the second network device comprises a BC device or a time source device.

13. The network device of claim 12, wherein the time source device comprises a Global Positioning System (GPS) satellite, a Beidou satellite, a Glonass satellite, a Galileo satellite, or a standalone atomic clock.

14. The network device of any of claims 8-13, wherein the processing unit is further configured to:

when the second time source information is different from the first time source information, determining an optimal time source from the first time source and the second time source, and switching the time source of the first network equipment from the first time source to the optimal time source.