WO2012068844A1

WO2012068844A1 - Method and system for synchronizing clock of master-slave clock devices

Info

Publication number: WO2012068844A1
Application number: PCT/CN2011/074300
Authority: WO
Inventors: 常伟; 廖俊锋; 李福军
Original assignee: 中兴通讯股份有限公司
Priority date: 2010-11-25
Filing date: 2011-05-19
Publication date: 2012-05-31
Also published as: CN101997671A; CN101997671B

Abstract

A method and system for synchronizing the clock of master-slave clock devices are disclosed in the present invention. The method includes that: when a slave clock device requests authorization, the type of a requested service and a previously assigned group identifier (ID) are carried in a transmitted multicast request authorization message; after receiving the request authorization message, a master clock device in a same logic group with the slave clock device transmits a unicast authorization response message to the slave clock device, and transmits, according to the type of the requested service, corresponding service message to the slave clock device. Compared with the prior art, the present invention realizes dynamic deployment of the master-slave clock devices, realizes dynamic notification of Internet Protocol (IP) address of the master devices and slave devices by Precision Time Protocol (PTP) interaction, and supports the master-slave clock device grouping, thus improving the adaptability of the network element framework design scheme.

Description

Clock synchronization method and system for master-slave clock device

Technical field

The present invention relates to the field of clock synchronization technologies, and in particular, to a clock synchronization method and system for a master-slave clock device.

Background technique

Mobile networks have strict requirements for high-precision clock synchronization. The purpose of clock synchronization is to synchronize the clocks of the nodes in the network to the same reference. A wireless system based on FDD (Frequency Division Duplex), such as UMTS (Universal Mobile Telecommunications System), requires frequency synchronization between nodes, and TDD (Time Division Duplex)-based wireless Systems such as TD-SCDMA (Time Division-Synchronous Code Division Multiple Access) / CDMA2000 require synchronization of clock frequency and phase.

At present, the clock synchronization in the mobile network is more than the GPS (Global Positioning System) timing method, but the GPS timing has high cost, difficult installation (requires 120 degree clearance requirement, etc.), and there is a risk of unavailability. The IEEE (Institute of Electrical and Electronics Engineers) 1588 standard, which appeared in 2002, is the Precision Time Protocol (PTP) for networked measurement and control systems. The clock synchronization scheme allows other clocks in the network to be synchronized with the most accurate clock in the network, so PTP can be an alternative to GPS.

The PTP protocol implements time synchronization by interacting with PTP packets between the master clock and the slave device. As shown in Figure 1, four types of messages are defined in the PTP protocol: Sync, Follow_up, Delay_req, and Delay-resp. The slave clock device in the PTP system uses these four types of messages to obtain a timestamp from which to determine the time offset from the master clock device to adjust its own clock. Where tl is the time at which the synchronization packet is sent by the master clock device; t2 is the time when the slave clock device receives the synchronization packet; t3 is the time when the delay request packet is sent from the clock device; t4 is the delay received by the master clock device The time when the message was requested. Then, the time offset Offset between the master and slave clock devices has the following relationship with the network transmission Delay:

T2-tl=Delay+Offset;

T4-t3=Delay-Offset.

As can be seen from the above, the time offset Offset=[(t2-tl)-(t4-t3)]/2, therefore, the slave clock device can adjust its own local clock according to the calculated Offset, that is, the phase difference between the master and the slave. Thereby achieving the purpose of synchronizing the master and slave clock devices.

The PTP protocol stipulates that the master clock device and the slave clock device can communicate through unicast or multicast UDP files.

Currently, when there are multiple master clock devices and slave clock devices in a network, there are two main deployment methods:

(1) Configure the IP address of each slave clock device to be connected to it on each master, and configure the IP address of the master clock device to which the clock device is provided on the slave clock device. The master clock device uses unicast mode. Perform packet exchange from the clock device.

In this way, once the IP address of the primary clock device changes, you need to manually synchronize the IP address of each slave clock device.

(2) Configure a multicast address for each clock device. The master clock device and the slave clock device are added to the same multicast group. The master clock device interacts with the slave clock device through multicast.

In this mode, only the primary clock device needs to periodically send multicast packets in the multicast group without knowing the network attributes such as the IP address of the slave clock device. Since the protocol already specifies a multicast group, if multiple master clock devices in the network are simultaneously multicast, it is necessary to physically separate each master clock device from the slave clock device it serves as a group. If the packet is received from the clock device, the multicast packets of the master clock device cannot be synchronized. The multicast packets on the network are also likely to cause network congestion.

In summary, the above two traditional methods lack flexibility in deployment, increase operation and maintenance costs, and bring great difficulties to the implementation of the project.

Summary of the invention The technical problem to be solved by the present invention is to provide a clock synchronization method and system for a master-slave clock device, and realize clock synchronization of a master-slave clock device based on the PTP protocol.

To solve the above technical problem, the present invention provides a clock synchronization method for a master-slave clock device, and the method includes:

When requesting authorization from the clock device, the type of the requested service and the pre-assigned logical group ID are carried in the sent multicast request authorization message;

After receiving the request authorization message, the master clock device of the same logical group as the slave clock device sends a unicast authorization response message to the slave clock device, and according to the type of the requested service, to the slave The clock device sends the corresponding service message.

Preferably, the method further includes:

All master clock devices and slave clock devices are logically grouped in advance, and the corresponding logical group IDs are assigned to the divided logical groups, wherein each logical group contains at least one master clock device.

Preferably, the step of sending the unicast authorization response message to the slave clock device after the master clock device of the same logical group receives the request authorization message includes: receiving, by the master clock device of the same logical group When the authorization message is requested, the IP address of the slave clock device is recorded, and the unicast authorization response message is sent to the slave clock device according to the recorded IP address.

Preferably, the method further includes:

And when the slave clock device receives the authorization response packet, recording an IP address of the master clock device;

After the service requested by the clock device expires, the unicast request authorization message is resent to the master clock device according to the recorded IP address of the master clock device.

Preferably, the type of the request service includes one or any combination of the following: Announce request authorization, Synchronization (Sync) request authorization, Delay resp request authorization.

Preferably, the method further includes:

After the requesting authorization message is sent from the clock device, if the authorization response message or the service message of the primary clock device is not received within the set time, the request authorization message is resent; When the IP address changes, the request authorization message is resent. Preferably, the slave clock device carries the logical group ID by using a header reservation field of the request authorization message.

The present invention also provides a clock synchronization system for a master-slave clock device, the system comprising: an authorization request initiation unit from a slave clock device, and an authorization request processing unit in the master clock device, wherein

The authorization request initiating unit is configured to send a multicast request authorization message when requesting authorization from the clock device, and carry the judgment of the type of the request service and the pre-assigned logical group ID in the sent request authorization message; The type of the request service includes one or any combination of the following: an Announce request 4 is authorized, a Sync request 4 is authorized, and a Delay_resp request 4 is authorized;

The authorization request processing unit is configured to authorize the logical group ID carried in the packet according to the received request, and if it is determined that the slave clock device and the authorization request processing unit belong to the same logical group, The slave clock device sends a unicast authorization response message, and sends a corresponding service message to the slave clock device according to the type of the requested service.

Preferably, the system further comprises a logical grouping unit, configured to logically group all the master clock devices and the slave clock devices in advance, and assign a corresponding logical group ID to the divided logical groups, wherein each logical group includes at least one Master clock device.

Preferably, the authorization request processing unit is further configured to, according to the logical group ID, record the IP address of the slave clock device if it is determined that the slave clock device and the authorization request processing unit belong to the same logical group And sending a unicast authorization response message to the slave clock device according to the recorded IP address;

The authorization request initiating unit is further configured to: when receiving the authorization response message, record an IP address of the master clock device, and after the requested service expires, according to the recorded IP address of the master clock device The address resends the unicast request authorization message to the master clock device.

Preferably, the authorization request initiating unit is further configured to: after sending the request authorization message, if the authorization response message or the service message of the primary clock device is not received within the set time, resending the Requesting an authorization message; and/or resending the request authorization message when the IP address of the slave clock device changes.

Preferably, the authorization request initiating unit is further configured to: use the header of the request authorization message The reserved field carries the logical group ID.

Compared with the prior art, the dynamic deployment of the master-slave clock device is realized, and the dynamic notification of the IP address of the master-slave device is realized through the PTP protocol interaction, and the grouping of the master-slave clock device is supported, and the grouping is improved. The flexibility of the network element design.

BRIEF abstract

The drawings are intended to provide a further understanding of the invention, and are intended to be illustrative of the invention. In the drawing:

FIG. 1 is a schematic diagram of PTP 4 艮 text interaction of a PTP protocol master-slave clock device;

2 is a BSS architecture diagram of a PTP protocol according to Embodiment 1 of the present invention;

3 is a schematic diagram of interaction signaling between a master and slave clock device according to Embodiment 2 of the present invention;

4 is a schematic diagram of a process flow of a slave clock device PTP according to a third embodiment of the present invention; FIG. 5 is a schematic diagram of a process flow of a master clock device PTP according to Embodiment 4 of the present invention; FIG. 6 is a PTP protocol according to Embodiment 1 of the present invention; Schematic diagram of the header field structure.

Preferred embodiment of the invention

The core idea of the present invention is that, firstly, a logical group is logically assigned to a master-slave clock device in a network, and each master-slave device is configured with a group number to which it belongs, and a reservation in the PTP protocol is used in the process of packet interaction. The field is used to distinguish which packets need to respond by themselves. This solves the problem that multiple master-slave clock devices cannot be distinguished in the second deployment scheme mentioned in the background. On the basis of configuring logical packets, the slave clock device periodically The master clock device sends a multicast request to authorize the PTP packet. After receiving the multicast packet, the master clock device can determine whether the clock synchronization service needs to be provided to the slave clock device according to the logical group number carried in the PTP packet. If yes, The unicast mode sends the authorization packet and saves the IP address of the slave clock device. After receiving the authorization from the clock device, the IP address of the master clock device is obtained from the authorization packet and saved. This interaction method is used to learn the IP address of the peer end, thereby solving the need for manual configuration and dimensioning in the first deployment scheme mentioned in the background art. Disadvantages of each device IP information. Because the interaction mode is to use multicast when starting the negotiation, the unicast is captured when the real clock synchronization service interacts. Therefore, the number of multicast packets is greatly reduced, and whether the response needs to be determined according to the group number is not This can cause a large number of multicast packets on the network, causing network congestion.

Based on the above idea, the present invention provides a clock synchronization method for a master-slave clock device, and specifically uses the following technical solutions:

After receiving the request authorization message, the master clock device of the same logical group sends a unicast authorization response message to the slave clock device, and sends a corresponding service to the slave clock device according to the type of the requested service. Message.

The type of the request service includes one or any combination of the following: Announce request authorization, Sync request authorization, and Delay-resp request authorization.

The method further includes:

All master clock devices and slave clock devices are logically grouped and pre-assigned corresponding logical group IDs, where each logical group contains at least one master clock device.

Preferably, the primary clock device of the other logical group discards the request authorization message according to the logical group ID included in the multicast request packet.

Preferably, when receiving the request authorization message, the master clock device of the same logical group records the IP address of the slave clock device, and sends the authorization response report to the slave clock device according to the recorded IP address. Text.

Preferably, after receiving the authorization response message, the slave clock device records an IP address of the master clock device; and after the requested service expires, according to the recorded IP address of the master clock device. Sending a unicast request authorization message to the master clock device.

Preferably, the slave clock device carries the logical group ID by using a header reservation field of the request authorization message.

Preferably, the method further includes: After the slave device sends the request authorization message, if the authorization response message or the service message of the master clock device is not received within the set time, the request authorization message is resent.

Preferably, the method further includes:

After the change of the IP address of the slave clock device, the request authorization message is resent.

In order to facilitate the description of the present invention, the implementation of the technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, in the case of no conflict, the features in the embodiments and the embodiments in the present application may be arbitrarily combined with each other.

Embodiment 1

In this embodiment, a mobile communication BSS (Base Station System) is taken as an example to introduce a PTP dynamic deployment solution of the present invention.

As shown in FIG. 2, when a BTS (Base Station Transceiver) of a plurality of BSSs is connected to a Base Station Controller (BSC), some of the BTSs are connected to the GPS as a master clock device. Provide time synchronization services for other BTS base stations.

In the first step, all BTSs are logically grouped, and each group is guaranteed to have at least one BTS connected to the GPS as the master clock device.

The devices between the divided logical groups do not overlap. That is, the primary clock device or the secondary clock device can only belong to one logical group, but cannot belong to multiple logical groups at the same time. In this embodiment, as shown in FIG. 2, the two groups are divided into two groups: group one and group two.

The second step is to configure the logical group ID of each BTS, that is, Group1 or Group2, and configure its PTP-related clock parameters (including but not limited to the parameters inherent in the clock quality and clock domain).

In the third step, the BTS that is the slave clock device sends a multicast request to the PTS packet after the power is turned on, and the PTP packet carries its own group number and the type of the requested service.

Specifically, the reserved field of the PTP packet header may be used to carry the group number, as shown in the reserved field in FIG. 6.

In the fourth step, since the slave device sends multicast packets, all BTS base stations can receive After the request is received, the BTS, which is the master clock device, receives the packet requesting the authorization, and then extracts the logical group number from the ΡΤΡ packet header, and determines whether the slave clock device is the same logical group according to the logical group number. If yes, the IP address is taken from the IP packet, the IP address of the BTS of the slave clock device is recorded, and the slave device responds to the unicast authorization response PTP packet. If not, the packet is discarded. Record any information.

In the fifth step, at the same time, the BTS as the master clock device also provides the corresponding service content to the slave clock device according to the type of the requested service, that is, the service message for sending the response.

In the sixth step, after receiving the PTP packet of the master clock device from the BTS of the clock device, the IP address of the master clock device is taken out from the packet and recorded; and according to the service packet sent by the master clock device, Clock synchronization starts between clock devices.

In the seventh step, the BTS as the slave clock device resends the unicast request authorization message to the master clock device according to the recorded IP address of the master clock device after the requested authorization service expires.

In this deployment mode, when the IP address of the BTS base station changes, there are two cases:

(1) When the IP address of the BTS base station as the master clock device changes, for example, from IP0 to IP1, the BTS base station as the slave clock device determines that the IP address from the master clock device is not received for IP0 for a period of time. The packet or the synchronization service packet is forwarded to the first step in the above step, and the multicast request authorization packet is resent, so as to dynamically obtain the IP address of the master clock device.

(2) As the IP address of the BTS base station of the slave clock device changes, the slave clock device resends the multicast request authorization message and directly performs the first step in the above steps, so that the master clock device can also reacquire the slave clock. IP address of the device.

Embodiment 2

FIG. 3 shows an interactive signaling process for implementing clock synchronization of a master-slave clock device according to an embodiment of the present invention. As shown in FIG. 3, the process is specifically described as follows:

Step 1: Sending a multicast request from the clock device to authorize a PTP packet, and carrying the own group number in the PTP packet, using the reserved field in the PTP packet header; and carrying the synchronization in the PTP packet. (Sync) Request authorization service information. Step 2: After receiving the multicast request to authorize the PTP packet, the master clock device extracts the group number from the PTP packet, and determines whether the slave clock device is in the same group according to the group number. If yes, The IP address of the slave clock device is recorded, and the slave clock device is responsive to the unicast authorized PTP message.

Step 3: The master clock device starts to send a unicast Sync clock synchronization message to the slave clock device, and the clock synchronization is started between the master and the slave.

After receiving the authorized PTP packet from the clock device, the IP address of the master clock device in the packet is recorded. After that, when the authorized service requested by the clock device expires, the master clock device is sent to the master clock device. Resend the unicast request authorization message.

Embodiment 3

FIG. 4 is a schematic diagram of a synchronization process performed from a clock device PTP module according to an embodiment of the present invention. As shown in FIG. 4, the process is specifically described as follows:

Step 401: Send a multicast request authorization message periodically from the clock device.

Step 402: The master clock device determines whether the received authorization packet is in the same group as itself. If yes, the next step 403 is performed; otherwise, the process returns to step 401;

Step 403: Record an IP address of the master clock device.

Step 404, determining whether the clock synchronization service message is received, if yes, proceeding to step 405, otherwise, returning to step 401;

Step 405: The slave clock device synchronizes the local clock according to the received clock synchronization service message. Step 406: The slave clock device resends the unicast request authorization message to the master clock device after the requested authorization service expires.

Embodiment 4

FIG. 5 is a schematic diagram of a synchronization process performed by a PTP module of a master clock device according to an embodiment of the present invention. As shown in FIG. 5, the process is specifically described as follows:

Step 501: The master clock device receives the multicast request authorization packet, and the master clock device is in the request authorization packet. Include a logical group ID, and include type information of the request service in the request authorization message, for example, information related to a clock synchronization service request;

The type information of the request service may include one of Announce request authorization, Sync request authorization, Delay-resp request authorization, and may include any two types of request authorization information, and may also include all three types of request authorization.

Step 502: The master clock device determines whether the received request authorization message is in the same group as itself. If yes, step 503 is performed; otherwise, the process returns to step 501;

Step 503: The master clock device creates a new logical port for the slave clock device, and records the information contained in the slave clock device packet, including the IP address of the slave clock device, and the clock signal sent by the master clock device. Information such as interval time, duration, etc.

Step 504: The master clock device sends a unicast authorization response message to the slave clock device, and simultaneously sends a clock synchronization service message.

In this embodiment, when the master clock device receives the request for the authorization message, it determines that the authorization response message is directly sent if the authorization is required to be authorized; and the master clock device authorizes the message according to the request sent by the clock device in step 501. The information about the clock synchronization service request contained in the packet starts to send the clock synchronization service message. After receiving the request authorization message from the clock device, the master clock device creates a new logical port for the clock device. The port records the information carried in the slave clock device packet. This includes not only the IP address but also the subsequent master clock device. The information about the interval, duration, and other information of the clock synchronization is sent. When the master clock device does not receive the PTP packet from the slave clock device for a period of time, the logical port is deleted.

In addition, the embodiment of the present invention further provides a clock synchronization system for a master-slave clock device, the system mainly includes: an authorization request initiation unit in the slave clock device, and an authorization request processing unit in the master clock device, where

The authorization request initiating unit is configured to send a multicast request authorization message when requesting authorization from the clock device, and carry the type of the request service and the pre-assigned logical group ID in the sent request authorization message; The type of the request service includes one or any combination of the following: Announce request authorization, Sync request authorization, Delay-resp request authorization; The authorization request processing unit is configured to: according to the received request, authorize the logical group ID carried in the packet, and if it is determined to be the same logical group, send the unicast authorization response report to the slave clock device. And sending, according to the type of the requested service, the corresponding service message to the slave clock device.

Preferably, the system further comprises a logical grouping unit, configured to logically group all the master clock devices and the slave clock devices in advance, and assign corresponding logical group IDs, wherein each logical group contains at least one master clock device.

Preferably, the authorization request processing unit is further configured to, according to the logical group ID, record the IP address of the slave clock device and determine the slave clock according to the recorded IP address, if it is determined to be the same logical group The device sends a unicast authorization response packet.

Preferably, the authorization request initiating unit is further configured to carry the logical group ID by using a header reserved field of the request authorization message.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention. The present invention may be embodied in various other embodiments without departing from the spirit and scope of the invention. Various changes and modifications may be made to the invention, and such changes and modifications are intended to be included within the scope of the appended claims.

Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general-purpose computing device, which can be concentrated on a single computing device or distributed over a network composed of multiple computing devices. Alternatively, they may be implemented by program code executable by the computing device, such that they may be stored in the storage device for execution by the computing device, and And in some cases, the steps shown or described may be performed in a different order than that herein, or they may be separately fabricated into individual integrated circuit modules, or a plurality of modules or steps thereof may be fabricated into a single integrated circuit. Module to achieve. Thus, the invention is not limited to any specific combination of hardware and software.

Industrial Applicability The present invention provides a clock synchronization method and system for a master-slave clock device, which realizes clock synchronization of a master-slave clock device based on a PTP protocol. Compared with the prior art, the dynamic deployment of the master-slave clock device is realized, and the dynamic notification of the IP address of the master-slave device is realized through the PTP protocol interaction, and the grouping of the master-slave clock device is supported, and the grouping is improved. The flexibility of the network element design.

Claims

Claim

A clock synchronization method for a master-slave clock device, comprising:

2. The method of claim 1 further comprising:

The method of claim 2, wherein the step of sending the unicast authorization response message to the slave clock device after the master clock device of the same logical group receives the request authorization message includes: When receiving the request authorization message, the master clock device of the same logical group records the IP address of the slave clock device, and sends a unicast authorization response message to the slave clock device according to the recorded IP address.

4. The method of claim 3, further comprising:

5. The method of claim 1, 2, 3 or 4, wherein

The type of the request service includes one of the following or any combination thereof: Announce Request Authorization, Synchronization (Sync) Request Authorization, Delay Response (Delay_resp) Request Authorization.

6. The method of claim 1, 2, 3 or 4, further comprising:

After the requesting authorization message is sent from the clock device, if the authorization response message or the service message of the primary clock device is not received within the set time, the request authorization message is resent; When the IP address changes, the request authorization message is resent.

7. The method according to claim 1, wherein the slave clock device carries the logical group ID by using a header reservation field of the request authorization message.

A clock synchronization system for a master-slave clock device, comprising: an authorization request initiating unit from a clock device; and an authorization request processing unit in the master clock device, wherein

The authorization request initiating unit is configured to: send a multicast request authorization message when requesting authorization from the clock device, and carry the type of the request service and the pre-assigned logical group ID in the sent request authorization message; The type of the request service includes one of the following or any combination thereof: Announce request authorization, Sync request authorization, Delay-resp request authorization;

The authorization request processing unit is configured to: determine, according to the received logical group ID carried in the request authorization message, if it is determined that the slave clock device and the authorization request processing unit belong to the same logical group, And sending a unicast authorization response message to the slave clock device, and sending a corresponding service message to the slave clock device according to the type of the request service.

9. The system of claim 8 further comprising a logical grouping unit,

The logical grouping unit is configured to: logically group all the master clock devices and the slave clock devices in advance, and assign a corresponding logical group ID to the divided logical groups, wherein each logical group includes at least one master clock device.

10. The system of claim 8 wherein

The authorization request processing unit is configured to determine according to the logical group ID, and if it is determined that the slave clock device and the authorization request processing unit belong to the same logical group, record an IP address of the slave clock device, And sending a unicast authorization response to the slave clock device according to the recorded IP address;

11. The system of claim 8, 9 or 10, wherein

The authorization request initiating unit is further configured to: after sending the request authorization message, if the authorization response message or the service message of the primary clock device is not received within the set time, the request authorization report is resent Resending the request when the IP address of the clock device changes Right message.

12. The system of claim 8, 9 or 10, wherein

The authorization request initiating unit is configured to carry the logical group ID by using a header reserved field of the request authorization message.