WO2015184763A1

WO2015184763A1 - Method, apparatus and system for instructing to select synchronization time source

Info

Publication number: WO2015184763A1
Application number: PCT/CN2014/094420
Authority: WO
Inventors: 张建军; 江涛; 杨明杰
Original assignee: 中兴通讯股份有限公司
Priority date: 2014-07-11
Filing date: 2014-12-19
Publication date: 2015-12-10
Also published as: CN105323086B; CN105323086A

Abstract

Disclosed are a method, apparatus and system for instructing to select a synchronization time source. The method comprises: a first node determines that clock synchronization of the first node is abnormal; and the first node outputs time state information of the first node, the time state information comprising indication information for indicating the clock synchronization anomaly of the first node, and instructing other nodes to select output time of a second node other than the first node as a synchronization time source.

Description

Method, device and system for indicating synchronization time source selection

Technical field

The present invention relates to the field of communications, and in particular to a method, device and system for indicating synchronization time source selection.

Background technique

To achieve clock time synchronization in the WDM system of the bearer network, first achieve clock synchronization. Only when the clock is synchronized, can time synchronization be achieved. The common practice in the industry in the WDM system is to use the Synchronization Status Message (SSM) algorithm for clock synchronization, and the 1588 algorithm for time synchronization.

In the clock synchronization SSM algorithm, the clock source of the node is determined by combining the physical quality of the clock judged by the clock chip and the SSM byte information that identifies the clock quality level received regularly on the line, and finally completes the clock of the node by configuring the clock chip Switch. As shown in Figure 1, in the clock synchronization SSM algorithm, if node 3 is set to import the clocks of node 1 and node 2. The clock chip on node 3 judges whether the physical quality of the clocks from node 1 and node 2 is good enough. First, the clock that does not meet the clock lock threshold on node 3 is excluded. Then node 3 judges the level of each clock according to the definition in the G.781 standard for the clock that meets the lock threshold (as shown in Table 1), and judges and compares the quality of the clocks uploaded by the node 1 and node 2 lines to identify the respective line clocks. Therefore, a clock that satisfies the clock lock threshold and has a high SSM quality level is preferred. After node 3 selects the clock with the highest quality level, it will configure the clock chip to lock the clock to complete the clock synchronization between the current node and the upstream clock node.

The time synchronization 1588 algorithm is based on the announcement (Announce) message received by the node regularly, and compares the grandmaster priority (grandmasterPriority) 1 and other fields in the Announce message according to the 1588 protocol to complete the time source selection, and finally passes the 1588 protocol. The interaction with the time message described in the Precision Time Protocol (PTP, abbreviation of 1588) with the time source completes the time synchronization with the time source. As shown in Figure 1, node 3 runs the best master clock (Best master clock, BMC) algorithm comparison according to the received Announce messages from node 1 and node 2 (as shown in Table 2) according to the description of the 1588 protocol The time of the better one of node 1 and node 2 is output, so as to determine which time the node needs to synchronize with. The time that the node 3 selects for a certain path is completed according to the time synchronization method specified in the 1588 protocol through the interaction of the PTP time message to complete the time synchronization between the current node and the upstream time node.

Usually the clock time network can be separated. When the clock of the clock network is injected into the source or a clock node on it fails, the time network will be abnormal. In this case, if the clock is not associated, the SSM algorithm is synchronized with the time To With the 1588 algorithm, when a node on the clock network fails to switch, the node on the time network will not switch. As a result, the nodes on the time network select the wrong synchronization time source for time synchronization.

Table 1. Definition of SSM information

Table 2. Announce message definition

Summary of the invention

The embodiment of the present invention provides a method, device and system for indicating the selection of a synchronization time source, so as to at least solve the problem that in the related art, when a node on the clock network fails to switch, the node on the time network will not switch, thereby causing the time network The node chooses the wrong synchronization time source for time synchronization.

According to an embodiment of the present invention, there is provided a method for indicating the selection of a synchronization time source, including: a first node determines that the clock synchronization of the current node is abnormal; the first node outputs time status information of the first node, wherein, The time status information includes indication information indicating that the clock synchronization of the first node is abnormal, and instructs other nodes to select the output time of the second node other than the first node as the synchronization time source.

Optionally, the output of the first node's time status information by the first node includes: the first node outputting a notification message, wherein the notification message is carried by other nodes for time source selection. The value of is the lowest priority value in the WDM system of the bearer network where the first node is located.

Optionally, before the first node outputs the time state information of the first node, the method further includes: the first node determines to enable a clock time correlation function.

Optionally, after the first node outputs the time state information of the first node, the method further includes: the other node receives the time state information, and restarts the time source according to the time state information The source selection algorithm selects the output time of the second node other than the first node as the synchronization time source.

According to another embodiment of the present invention, there is provided a device for instructing the selection of a synchronization time source, comprising: a first determining module configured to determine that the clock synchronization of a first node is abnormal; and an output module configured to output the synchronization time source of the first node Time status information, wherein the time status information includes indication information indicating that the clock synchronization of the first node is abnormal, and instructs other nodes to select the output time of the second node other than the first node as the synchronization time source. To

Optionally, the output module outputs the time status information in the following manner: output a notification message, wherein the value of the priority for other nodes to select the time source carried in the notification message is the value The value of the lowest priority in the WDM system of the bearer network where the first node is located.

Optionally, it further includes: a second determining module configured to determine that the first node starts the clock time correlation function.

According to another embodiment of the present invention, there is provided a system for instructing synchronization time source selection, including: a first node and a bearer network wavelength division system where the first node is located, other than the first node Node; wherein, the first node includes the above-mentioned device, configured to output time status information when the clock synchronization of the first node is abnormal, wherein the time status information includes indicating that the first node clock is synchronized The abnormal indication information instructs other nodes to select the output time of a second node other than the first node as the synchronization time source; the other nodes are set to be based on the time status information output by the first node, Re-run the time source selection algorithm to select the output time of the second node other than the first node as the synchronization time source.

Through the embodiment of the present invention, when the node in the wavelength division system of the bearer network outputs the time status information indicating the abnormal clock synchronization when the clock synchronization is abnormal, when the node on the clock network fails to switch, the nodes on the time network will be based on the time status information Switching the synchronization time source establishes the association between clock synchronization and time synchronization, and avoids the error time synchronization that may be caused when the clock node is abnormal.

Description of the drawings

The drawings described here are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments and descriptions of the present invention are used to explain the present invention, and do not constitute an improper limitation of the present invention. In the attached picture:

Figure 1 is a schematic diagram of multi-node clock time synchronization networking according to related technologies;

2 is a flowchart of a method for indicating synchronization time source selection according to an embodiment of the present invention;

Fig. 3 is a schematic structural diagram of a system for indicating synchronization time source selection according to an embodiment of the present invention;

4 is a schematic structural diagram of an apparatus for indicating synchronization time source selection according to an embodiment of the present invention;

FIG. 5 is a flowchart of a node in an optional embodiment of the present invention to correlate and output time state information according to a clock synchronization state; To

6 is a schematic diagram of selecting a clock time source of a downstream node when the clock synchronization is normal in an optional embodiment of the present invention;

7 is a schematic diagram of the selection of the time source of the downstream node when the switch of the clock time association algorithm is not turned on and the clock synchronization is abnormal in an optional embodiment of the present invention;

FIG. 8 is a schematic diagram of the selection of the time source of the downstream node when the clock synchronization algorithm switch is turned on and the clock synchronization is abnormal in an optional embodiment of the present invention.

Detailed ways

Hereinafter, the present invention will be described in detail with reference to the drawings and in conjunction with the embodiments. It should be noted that the embodiments in the application and the features in the embodiments can be combined with each other if there is no conflict.

In view of the above-mentioned problems in related technologies, the embodiment of the present invention provides a method for indicating synchronization time source selection in a bearer network wavelength division system. The method combines a clock synchronization algorithm (e.g., SSM algorithm) with a time synchronization algorithm (e.g., 1588 algorithm). With this method, when the clock time network is separated, when the clock network node is abnormally switched, the time network node can switch accordingly as needed.

It should be noted that, in the embodiment of the present invention, "the node clock is synchronized normally" means that the node clock chip is locked to the clock from the upstream line. The "clock synchronization abnormality" of the node means that the node clock chip determines that the clock on the upstream line cannot be locked. In addition, in the embodiment of the present invention, the switching of the time source means that the downstream node no longer completes time synchronization with the local node through the PTP time synchronization message, and the downstream node decides a new time source and then performs PTP with the new time source. Interact with time messages to complete time synchronization.

Fig. 2 is a flowchart of a method for indicating synchronization time source selection according to an embodiment of the present invention. As shown in Fig. 2, the method mainly includes the following steps:

In step S202, the first node determines that the clock synchronization of the current node is abnormal.

In the specific implementation process, the first node in the wavelength division system of the bearer network can determine whether its clock synchronization is abnormal according to the existing method. The specific embodiments of the present invention are not limited.

Step S204: The first node outputs the time status information of the first node, where the time status information includes indication information indicating that the clock synchronization of the first node is abnormal, and instructs other nodes to choose to remove the first node. The output time of the second node other than the node is the synchronization time source. To

Optionally, the first node may output the time status information through an Announce message, where the Announce message carries a priority for other nodes to perform time source selection (for example, the Announce message). The value of the grandmasterPriority1 field in the text) is the lowest priority value in the WDM system of the bearer network where the first node is located.

Optionally, before the first node outputs the time state information of the first node, the method further includes: the first node determines to enable a clock time correlation function. In the specific implementation process, a clock time correlation switch can be set in the node, and the clock time correlation function can be turned on or off through the switch. Through this optional implementation manner, the clock time correlation function can be turned on or off, so that various requirements can be met.

In the embodiment of the present invention, after the first node outputs the time state information of the first node, the method further includes: the other nodes receive the time state information, and re-start according to the time state information. The running time source selection algorithm selects the output time of the second node other than the first node as the synchronization time source.

In a preferred implementation of the embodiment of the present invention, when the clock synchronization of the local node in the bearer network's wavelength division system is abnormal, it is necessary to determine whether the clock time correlation algorithm switch is turned on. If the clock time correlation algorithm switch is not turned on, then the time synchronization algorithm It still runs independently, and the time synchronization path remains unchanged. When the clock synchronization of the local node in the WDM system of the bearer network is abnormal, if the clock time correlation algorithm switch is turned on, the time status information output of the local node needs to reflect the clock abnormality. The specific corresponding time synchronization port is as follows: the PTP port of this node The grandmasterPriority1 output of the Announce message sends the lowest priority value in the system. The Announce message of this node received by other nodes in the WDM system of the bearer network changes and contains grandmasterPriority1 as the lowest priority. Other nodes re-run the time source selection algorithm according to the 1588 protocol, due to the source selection algorithm described in the 1588 protocol It will first compare the priority of grandmasterPriority1 to determine the final synchronization time source, so that grandmasterPriority1 is set to the lowest priority, which will cause other nodes to switch to other time sources and no longer synchronize to the output time of this node.

Through the above-mentioned method provided by the embodiments of the present invention, the independent source selection algorithm for clock synchronization and time synchronization can be used more reasonably in the wavelength division system of the bearer network, the association between clock synchronization and time synchronization is established, and the abnormality of the clock node is avoided. It may lead to the wrong time synchronization.

According to an embodiment of the present invention, a system for indicating the selection of a synchronization time source is also provided.

Fig. 3 is a schematic structural diagram of a system for indicating synchronization time source selection according to an embodiment of the present invention. As shown in Fig. 3, the system includes: a first node 30 and a carrier network wavelength division system where the first node is located. Nodes 32 other than the first node; wherein, the first node 32 is set to output time status information when the clock synchronization of the first node is abnormal, wherein the time status information includes an indication of the The indication information that the clock synchronization of the first node is abnormal, instructs other nodes to select the output time of the second node other than the first node as To Synchronize the time source; the other nodes 32 are set to re-run the time source selection algorithm based on the time status information output by the first node 30 to select the second node except the first node 30 The output time is the synchronization time source.

Optionally, the first node 30 may include the device for indicating synchronization time source selection as shown in FIG. 4.

4 is a schematic structural diagram of an apparatus for indicating synchronization time source selection according to an embodiment of the present invention. As shown in FIG. 4, the apparatus mainly includes: a first determining module 40 configured to determine that the clock synchronization of the first node is abnormal; and an output module 42 , Set to output the time status information of the first node, where the time status information includes indication information indicating that the clock synchronization of the first node is abnormal, and instructs other nodes to select the first node other than the first node The output time of the two nodes is the synchronization time source.

Optionally, the output module 42 may output the time status information in the following manner: output a notification message, where the value of the priority for other nodes to select the time source carried in the notification message is The value of the lowest priority in the wavelength division system of the bearer network where the first node is located.

Optionally, the device may further include: a second determining module configured to determine that the first node starts the clock time correlation function.

In the following, an optional embodiment is used to describe the flow of nodes outputting time state information according to the clock synchronization state in the embodiment of the present invention.

Fig. 5 is a flowchart of an optional embodiment of the present invention for nodes to correlate and output time state information according to the clock synchronization state. As shown in Fig. 5, the main steps include the following steps:

Step 501: The first node first determines whether the clock synchronization of the current node is normal according to the clock synchronization SSM algorithm.

Step 502: If the clock synchronization of the current node is normal, the time synchronization 1588 algorithm runs independently and outputs the corresponding Announce message, and the downstream time node source selection algorithm does not switch. As shown in Fig. 6, the clock time of the downstream node 3 is preferably to the node 1 with a higher priority.

Step 503: If the clock synchronization of the current node is abnormal, it is determined whether the clock time correlation algorithm switch is turned on. This correlation algorithm switch is used as an optional judgment. If the clock time correlation algorithm switch is not turned on, the time synchronization 1588 algorithm is the same as step 502. As shown in Figure 7, the time synchronization 1588 algorithm of downstream node 3 is not affected by the clock selection and still selects the time of node 1. At this time, because the clock on node 1 is no longer synchronized, its time is no longer credible, which will cause downstream node 3 to synchronize To the wrong time source. To

Step 504: If the clock synchronization of the current node is abnormal and the clock time correlation algorithm switch is turned on, the priority of grandmasterPriority1 in the Announce message output by the node is set to the lowest priority of the system, so that the downstream node can switch the time source. As shown in Figure 8, the priority of grandmasterPriority1 contained in the Announce message output by node 1 is set to the lowest priority of the system.

Step 505: The downstream node time synchronization 1588 algorithm determines that the received Announce message has changed, and reselects the time source. Since the grandmasterPriority1 priority in the received Announce message is set to the lowest priority of the system, the result of re-running the time source algorithm will cause the time synchronization source of the downstream node to switch to the upstream node with a normal clock. As shown in Fig. 8, the time synchronization 1588 algorithm of the downstream node 3 will be affected by the clock selection, so that the time of the downstream node 3 can be switched to the correct time path. Finally, the node 3 will select the node 2 with a normal clock as the upstream time synchronization source.

Optionally, in the above step 504, it is also possible to output other methods that can cause the downstream node time synchronization 1588 algorithm to switch the time source, so that the downstream node can switch to the time source with the normal clock, so that the entire bearer network system can complete the correct Clock time synchronization.

From the above description, it can be seen that in the embodiment of the present invention, when a node in the bearer network's wavelength division system is abnormal in clock synchronization, it outputs time status information indicating that the clock synchronization is abnormal, and when a node on the clock network fails to switch, The nodes on the time network will switch the synchronization time source according to the time status information, establish the association between clock synchronization and time synchronization, and avoid the error time synchronization that may be caused when the clock node is abnormal.

Obviously, those skilled in the art should understand that the above-mentioned modules or steps of the present invention can be implemented by a general computing device, and they can be concentrated on a single computing device or distributed in a network composed of multiple computing devices. Above, alternatively, they can be implemented with program codes executable by a computing device, so that they can be stored in a storage device for execution by the computing device, and in some cases, they can be executed in a different order than here. Perform the steps shown or described, or fabricate them into individual integrated circuit modules respectively, or fabricate multiple modules or steps of them into a single integrated circuit module for implementation. In this way, the present invention is not limited to any specific combination of hardware and software.

The above are only preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Industrial applicability

As described above, the method, device, and system for indicating the selection of a synchronization time source provided by the embodiments of the present invention To The system has the following beneficial effects: when the nodes in the wavelength division system of the bearer network output the time status information indicating the abnormal clock synchronization, when the nodes on the clock network fail to switch, the nodes on the time network will be based on the time status The information is switched to the synchronization time source, which establishes the association between clock synchronization and time synchronization, and avoids the error time synchronization that may be caused when the clock node is abnormal. To

Claims

A method for indicating synchronization time source selection, including:

The first node determines that the clock synchronization of this node is abnormal;

The first node outputs the time status information of the first node, where the time status information includes indication information indicating that the clock synchronization of the first node is abnormal, and instructs other nodes to select other than the first node The output time of the second node is the synchronization time source.
The method according to claim 1, wherein the output of the first node's time status information by the first node comprises: the first node outputting a notification message, wherein the user information carried in the notification message The value of the priority of time source selection at other nodes is the lowest priority value in the wavelength division system of the bearer network where the first node is located.
The method according to claim 1, wherein before the first node outputs the time state information of the first node, the method further comprises: the first node determines to enable a clock time correlation function.
The method according to any one of claims 1 to 3, wherein, after the first node outputs the time state information of the first node, the method further comprises:

The other node receives the time status information, re-runs the time source selection algorithm according to the time status information, and selects the output time of the second node other than the first node as the synchronization time source.
A device for indicating the selection of a synchronization time source, including:

The first determining module is configured to determine that the clock synchronization of the first node is abnormal;

The output module is configured to output the time status information of the first node, wherein the time status information includes indication information indicating that the clock synchronization of the first node is abnormal, and instructs other nodes to select other than the first node The output time of the second node is the synchronization time source.
The device according to claim 5, wherein the output module outputs the time status information in the following manner: outputting a notification message, wherein the notification message carries a priority for other nodes to select a time source The value of the level is the lowest priority value in the wavelength division system of the bearer network where the first node is located. To
5. The device according to claim 5, further comprising: a second determining module configured to determine that the first node starts the clock time correlation function.
A system for indicating synchronization time source selection, comprising: a first node and other nodes in a wavelength division system of a bearer network where the first node is located except for the first node; wherein,

The first node includes the device according to any one of claims 5 to 7, and is configured to output time status information when the clock synchronization of the first node is abnormal, wherein the time status information includes an indication of the The indication information that the clock synchronization of the first node is abnormal, instructs other nodes to select the output time of the second node other than the first node as the synchronization time source;

The other nodes are configured to re-run the time source selection algorithm according to the time status information output by the first node, and select the output time of a second node other than the first node as the synchronization time source. To