CN105323086B - Method, device and system for indicating synchronous time source selection - Google Patents

Abstract

The invention discloses a method, a device and a system for indicating synchronous time source selection. Wherein, the method comprises the following steps: the first node determines that the clock synchronization of the first node is abnormal; the first node outputs time state information of the first node, wherein the time state information comprises indication information indicating that clock synchronization of the first node is abnormal, and other nodes are indicated to select output time of a second node except the first node as a synchronization time source.

Description

Method, apparatus 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 realize clock time synchronization in the WDM system of the bearer network, first realize the clock synchronization. Only when the clocks are synchronized can the time synchronization be realized. A common practice in the industry in the wavelength division system is to use a synchronization status message (Synchronization Status Message, SSM) algorithm for clock synchronization, and a 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 regularly received on the line, and finally completes the clock source 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 determines whether the physical quality of the clocks from node 1 and node 2 is good enough, and first excludes clocks that do not meet the clock lock threshold on node 3. Then node 3 judges the level of the clocks of each channel according to the definition in the G.781 standard for the clocks that meet the locking threshold (as shown in Table 1), and judges and compares the clock quality of the respective lines uploaded by nodes 1 and 2. The SSM line level is selected, so that the clock that meets the clock lock threshold and has a high SSM quality level is selected. After node 3 selects the clock with the highest quality level, it will configure the clock chip to lock the clock of this channel to complete the clock synchronization between the node and the upstream clock node.

The time synchronization 1588 algorithm is based on the Announce message received regularly by the node, according to the 1588 protocol to compare the grandmasterPriority1 and other fields in the Announce message, to complete the time source selection, and finally through the 1588 protocol described with the time source Precision Time Protocol (Precision Time Protocol, PTP, short for 1588) interacts with time messages to complete the time synchronization of the same time source. As shown in Figure 1, node 3 runs the Best master clock (BMC) algorithm comparison according to the description of the 1588 protocol according to the received Announce message (as shown in Table 2) sent by node 1 and node 2 The time of the better route in node 1 and node 2 is output, so as to determine which route the node needs to synchronize with. Node 3 completes the time synchronization between the node and the upstream time node through the interaction of the PTP time-synchronization message to the selected time according to the time synchronization method specified in the 1588 protocol.

Usually, the clock time network can be separated. When the clock injection source of the clock network or a clock node on the clock network fails, the time network will be abnormal. In this case, if the clock synchronization SSM algorithm and the time synchronization 1588 algorithm are not associated, the nodes on the time network will not be switched when the node on the clock network fails to 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. Definition of Annouce message

SUMMARY OF THE INVENTION

In the related art, when a node on the clock network fails to perform switching, the nodes on the time network will not switch. This leads to the problem that nodes on the time network select the wrong synchronization time source for time synchronization. The present invention provides a method, device and system for instructing synchronization time source selection to at least solve the above problem.

According to an aspect of the present invention, there is provided a method for indicating the selection of a synchronization time source, comprising: a first node determining that the clock synchronization of the local node is abnormal; the first node outputting time state information of the first node, wherein the 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 first node outputting the time status information of the first node includes: the first node outputting a notification message, wherein the message carried in the notification message is used for other nodes to select time sources. The value of the priority is the value of the lowest priority in the wavelength division 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 association 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 re-runs 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 aspect of the present invention, there is provided an apparatus for indicating synchronization time source selection, comprising: a first determination module for determining that the clock of the first node is abnormally synchronized; an output module for outputting the time of the first node Status information, wherein the time status information includes indication information indicating that the clock synchronization of the first node is abnormal, instructing other nodes to select the output time of the second node other than the first node as the synchronization time source.

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

Optionally, the method further includes: a second determining module, configured to determine that the first node enables a clock time association function.

According to another aspect of the present invention, a system for indicating synchronization time source selection is provided, comprising: a first node and other nodes other than the first node in the wavelength division system of the bearer network where the first node is located ; wherein, the first node includes the above-mentioned device for outputting time status information when the clock synchronization of the first node is abnormal, wherein the time status information includes an indication that the clock synchronization of the first node is abnormal The indication information, instructing 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 used for resetting the time status information output by the first node The time source selection algorithm is run, and the output time of the second node other than the first node is selected as the synchronization time source.

Through the present invention, when the clock synchronization is abnormal, the nodes in the bearer network wavelength division system output the time state information indicating the abnormal clock synchronization. When the node on the clock network fails to perform switching, the nodes on the time network will synchronize according to the time state information. The switching of the time source establishes the association between the clock synchronization and the time synchronization, and avoids the wrong time synchronization that may be caused when the clock node is abnormal.

Description of drawings

The accompanying drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the attached image:

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

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

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;

5 is a flowchart of a node according to an optional embodiment of the present invention outputting time state information associated with a clock synchronization state;

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

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

Detailed ways

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings and in conjunction with embodiments. It should be noted that the embodiments in the present application and the features of the embodiments may be combined with each other in the case of no conflict.

In view of the above problems existing in the related art, an embodiment of the present invention provides a method for indicating synchronization time source selection in a wavelength division system of a bearer network. The method combines a clock synchronization algorithm (for example, SSM algorithm) with a time synchronization algorithm (for example, 1588 algorithm) associated. Through this method, when the clock network node is separated, when the clock network node switches abnormally, the time network node can perform corresponding switching according to the needs.

It should be noted that, in the embodiment of the present invention, "node clock synchronization is normal" means that the node clock chip is locked to the clock from the upstream line. The node "clock synchronization is abnormal" 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 synchronizes the time synchronization with the current node through PTP, and the downstream node will perform PTP with the new time source after deciding on a new time source. Time synchronization is accomplished by interacting with time messages.

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

Step S202, the first node determines that the clock synchronization of the node is abnormal.

In a 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 time state information of the first node, wherein the time state information includes indication information indicating that the clock synchronization of the first node is abnormal, instructing other nodes to select the first node except the first node. The output time of the second node other than the node is the synchronization time source.

Optionally, the first node may output the time status information through an announcement (Announce) packet, where the priority carried in the announcement packet for other nodes to select a time source (for example, an Announce packet). The value of the grandmasterPriority1 field in the text is the value of the lowest priority in the wavelength division 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 association function. In a 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 this 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 regenerate the time state information according to the time state information. The time source selection algorithm is run, and the output time of the second node other than the first node is selected 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 WDM system of the bearer network is abnormal, it is necessary to judge whether the clock time correlation algorithm switch is turned on. If the clock time correlation algorithm switch is not turned on, the time synchronization algorithm Still running independently, the time synchronization path remains the same. 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 value of the lowest priority in the sending system of the grandmasterPriority1 sent by the Announce message. The Announce message received by other nodes in the WDM system of the bearer network changes and contains grandmasterPriority1 as the lowest priority. Other nodes rerun the time source selection algorithm according to the 1588 protocol. Because the source selection algorithm described in the 1588 protocol It will first compare the priority of grandmasterPriority1 to determine the final synchronization time source. In this way, setting grandmasterPriority1 to the lowest priority will cause other nodes to switch to other time sources and no longer synchronize to the output time of this node.

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

According to an embodiment of the present invention, a system for indicating synchronization time source selection 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 wavelength division system of a bearer network where the first node is located. other nodes 32 other than the first node; wherein, the first node 32 is configured to output time status information when the clock synchronization of the first node is abnormal, wherein the time status information contains instructions indicating the The indication information of the abnormal clock synchronization of the first node, instructing other nodes to select the output time of the second node other than the first node as the synchronization time source; the other nodes 32 are used for outputting according to the first node 30 The time state information is obtained, re-run the time source selection algorithm, and select the output time of the second node other than the first node 30 as the synchronization time source.

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

FIG. 4 is a schematic structural diagram of an apparatus for instructing selection of a synchronization time source according to an embodiment of the present invention. As shown in FIG. 4 , the apparatus mainly includes: a first determination module 40 for determining an abnormal clock synchronization of the first node; an output module 42 , used to output the time state information of the first node, wherein the time state 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: outputting a notification message, wherein the value of the priority carried in the notification message for other nodes to select a time source is a value of The value of the lowest priority in the WDM system of the bearer network where the first node is located.

Optionally, the apparatus may further include: a second determination module, configured to determine that the first node enables the clock time association function.

An optional embodiment is used below to describe the process of the node outputting time state information according to the clock synchronization state in the embodiment of the present invention.

FIG. 5 is a flowchart of a node according to an optional embodiment of the present invention outputting time state information associated with a clock synchronization state. As shown in FIG. 5 , it mainly includes the following steps:

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

Step 502: If the clock synchronization of the local 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 the node 1 with a higher priority.

Step 503 : If the clock synchronization of the local node is abnormal, it is judged whether the clock time correlation algorithm switch is turned on. This correlation algorithm switch is an optional judgment. 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, since the clock on node 1 is no longer synchronized, its time is no longer reliable, which will cause downstream node 3 to synchronize. to the wrong time source.

Step 504: If the clock synchronization of the local node is abnormal and the clock time correlation algorithm switch is turned on, the grandmasterPriority1 priority in the Announce message output by the local 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 grandmasterPriority1 priority contained in the Announce packet 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 packet is set to the lowest priority of the system, the result of re-running the time source selection algorithm will cause the time synchronization source of the downstream node to switch to the upstream node with a normal clock. As shown in Figure 8, the time synchronization 1588 algorithm of downstream node 3 will be affected by the clock selection, so that the time of downstream node 3 can be switched to the correct time path, and finally node 3 will select 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 a normal clock, so that the entire bearer network system can complete the correct time source. Clock time synchronization.

From the above description, it can be seen that, in this embodiment of the present invention, when a node in the WDM system of the bearer network is abnormal in clock synchronization, it outputs time status information indicating abnormal clock synchronization. The nodes on the time network will switch the synchronization time source according to the time status information, and establish the association between the clock synchronization and the time synchronization, so as to avoid the wrong 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-purpose computing device, which can be centralized on a single computing device, or distributed in a network composed of multiple computing devices Alternatively, they may be implemented in program code executable by a computing device, such that they may be stored in a storage device and executed by the computing device, and in some cases, in a different order than here The steps shown or described are performed either by fabricating them separately into individual integrated circuit modules, or by fabricating multiple modules or steps of them into a single integrated circuit module. As such, the present invention is not limited to any particular combination of hardware and software.

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

Claims (3)

1. A method for indicating synchronized time source selection, comprising:

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

the first node outputs the time state information of the first node, including: the first node outputs an announcement message, wherein the value of the priority for other nodes to perform time source selection carried in the announcement message is the value of the lowest priority in a wavelength division system of a bearer network where the first node is located, wherein the time state information comprises indication information indicating that the clock synchronization of the first node is abnormal, and the time state information indicates that other nodes select the output time of a second node except the first node as a synchronization time source;

before the first node outputs the time state information of the first node, the method further comprises: the first node determines to start a clock time correlation function, wherein the first node independently runs a time synchronization algorithm when the clock time correlation function is determined not to be started; under the condition that the clock time correlation function is determined to be started, the first node acquires the value of the priority of the time selection source through a port, and the other nodes operate the time selection source algorithm again;

wherein after the first node outputs the time state information of the first node, the method further comprises: and the other nodes receive the time state information, operate a time source selection algorithm again according to the time state information, and select the output time of the second nodes except the first node as a synchronous time source.

2.An apparatus for indicating synchronized time source selection, comprising:

the first determining module is used for determining that the clock synchronization of the first node is abnormal;

an output module, configured to output time status information of the first node, including: outputting an announcement message, wherein a value of a priority for time source selection of other nodes carried in the announcement message is a value of a lowest priority in a carrier network wavelength division system where the first node is located, wherein the time state information includes indication information indicating that clock synchronization of the first node is abnormal, and indicates that other nodes select output time of a second node except the first node as a synchronization time source;

wherein the apparatus further comprises: a second determining module, configured to determine that the clock time correlation function is started by the first node, where the first node independently runs a time synchronization algorithm when it is determined that the clock time correlation function is not started; under the condition that the clock time correlation function is determined to be started, the first node acquires the value of the priority of the time selection source through a port, and the other nodes operate the time selection source algorithm again;

the device is further configured to, after the first node outputs the time status information of the first node and the other nodes receive the time status information, run a time source selection algorithm again according to the time status information, and select the output time of the second node except the first node as a synchronization time source.

3. A system for indicating synchronized time source selection, comprising: a first node and other nodes except the first node in a bearing network wavelength division system where the first node is located; wherein,

the first node comprises the device in claim 2, and is configured to output time status information when the clock synchronization of the first node is abnormal, where the time status information includes indication information indicating that the clock synchronization of the first node is abnormal, and indicates other nodes to select output time of a second node other than the first node as a synchronization time source;

and the other nodes are used for running the time source selection algorithm again according to the time state information output by the first node, and selecting the output time of the second node except the first node as a synchronous time source.

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