CN105323086B - Method, device and system for indicating synchronous time source selection - Google Patents
Method, device and system for indicating synchronous time source selection Download PDFInfo
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- CN105323086B CN105323086B CN201410330416.XA CN201410330416A CN105323086B CN 105323086 B CN105323086 B CN 105323086B CN 201410330416 A CN201410330416 A CN 201410330416A CN 105323086 B CN105323086 B CN 105323086B
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- H04—ELECTRIC COMMUNICATION TECHNIQUE
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- H04J3/00—Time-division multiplex systems
- H04J3/02—Details
- H04J3/06—Synchronising arrangements
- H04J3/0635—Clock or time synchronisation in a network
- H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J3/00—Time-division multiplex systems
- H04J3/02—Details
- H04J3/06—Synchronising arrangements
- H04J3/0635—Clock or time synchronisation in a network
- H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation
- H04J3/0658—Clock or time synchronisation among packet nodes
- H04J3/0661—Clock or time synchronisation among packet nodes using timestamps
- H04J3/0667—Bidirectional timestamps, e.g. NTP or PTP for compensation of clock drift and for compensation of propagation delays
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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
Technical Field
The invention relates to the field of communication, in particular to a method, a device and a system for indicating synchronous time source selection.
Background
The clock time synchronization is realized in the carrier network wavelength division system, the clock synchronization is realized firstly, and the time synchronization can be realized only if the clock is synchronized. The common practice in the industry of wavelength division systems is to use a 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 decided by combining the clock physical quality judged by a clock chip and SSM byte information which is received on a line at regular time and identifies the clock quality level, and finally, the switching of the node clock is completed by configuring the clock chip. As shown in fig. 1, in the clock synchronization SSM algorithm, it is assumed that the node 3 is provided with clocks leading to the node 1 and the 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 locking threshold on node 3. Then, the node 3 judges the level of each clock according to the definition in the g.781 standard for the clock meeting the locking threshold (as shown in table 1), and judges and compares the SSM line levels that respectively identify the high and low quality of each line clock and are uploaded by the lines of the node 1 and the node 2, thereby preferably selecting the clock meeting the locking threshold and having the high SSM quality level. After the node 3 preferably selects the clock with the highest quality level, a clock chip is configured to lock the path of clock, and clock synchronization between the node and the upstream clock node is completed.
The Time synchronization 1588 algorithm compares fields such as grant priority1 in an Announce message according to the Announce message received by the node at regular Time and according to a 1588 Protocol, completes Time source selection, and finally completes Time synchronization with a Time source by interaction with a Time source Precision Time Protocol (short for Precision Time Protocol, PTP, 1588) Time synchronization message described by the 1588 Protocol. As shown in fig. 1, the node 3 operates an optimal master clock (BMC) algorithm according to descriptions of a 1588 protocol according to received Announce messages (shown in table 2) sent by the node 1 and the node 2 to compare the time of a more optimal path in the node 1 and the node 2, so as to determine which path the node needs to synchronize with. And the node 3 completes the time synchronization of the node and the upstream time node according to the time synchronization method specified in the 1588 protocol through the interaction of the PTP time synchronization messages to a certain preferred path of time.
Usually, the clock time network is separable, and when a clock injection source of the clock network or a certain clock node on the clock network fails, the clock time network is 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 nodes on the clock network are switched due to a failure. Thereby causing nodes on the time network to select the wrong synchronized time source for time synchronization.
TABLE 1 definition of SSM information
TABLE 2 definition of Annouce messages
Disclosure of Invention
In the related art, when the nodes on the clock network fail to switch, the nodes on the time network do not switch. The invention provides a method, a device and a system for indicating selection of a synchronous time source, which at least solve the problem of time synchronization by selecting the wrong synchronous time source by a node on a time network.
According to an aspect of the present invention, there is provided a method of indicating a synchronized time source selection, comprising: 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 indicates other nodes to select output time of a second node except the first node as a synchronization time source.
Optionally, the outputting, by the first node, the time state information of the first node includes: and the first node outputs an announcement message, wherein the value of the priority carried in the announcement message and used for other nodes to perform time source selection 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 status information of the first node, the method further includes: the first node determines to turn on a clock time correlation function.
Optionally, after the first node outputs the time status information of the first node, the method further includes: 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.
According to another aspect of the present invention, there is provided an apparatus for indicating a synchronized time source selection, comprising: the first determining module is used for determining that the clock synchronization of the first node is abnormal; and the output module is used for outputting the time state information of the first node, wherein the time state information comprises indication information indicating that the clock synchronization of the first node is abnormal, and indicates other nodes to select the output time of a second node except the first node as a synchronization time source.
Optionally, the output module outputs the time status information by: and outputting an announcement message, wherein the value of the priority for time source selection of other nodes carried in the announcement 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 method further comprises: and the second determining module is used for determining that the first node starts a clock time correlation function.
According to yet another aspect of the present invention, there is provided a system for indicating a 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; the first node comprises the above device, 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.
By the invention, when the clock synchronization of the nodes in the carrier network wavelength division system is abnormal, the time state information indicating the abnormal clock synchronization is output, and when the nodes on the clock network are switched due to faults, the nodes on the time network can switch the synchronous time source according to the time state information, thereby establishing the correlation between the clock synchronization and the time synchronization and avoiding the error time synchronization possibly caused when the clock nodes are abnormal.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:
FIG. 1 is a schematic diagram of a multi-node clock time-synchronized networking according to the related art;
FIG. 2 is a flow diagram of a method of indicating synchronized time source selection according to an embodiment of the present invention;
FIG. 3 is a block diagram of a system for indicating synchronized time source selection according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of an apparatus for indicating a source selection of a synchronized time according to an embodiment of the present invention;
FIG. 5 is a flow diagram of a node outputting time state information in accordance with a clock synchronization state association in accordance with an alternate embodiment of the present invention;
FIG. 6 is a schematic diagram of an alternative embodiment of the invention for clock synchronization of the clock time source of the downstream node during normal operation;
FIG. 7 is a schematic diagram showing the selection of the time source of the downstream node when the clock time correlation algorithm switch is not turned on and the clock synchronization is abnormal in an alternative embodiment of the present invention;
FIG. 8 is a schematic diagram of a selection of a time source of a downstream node when a clock time correlation algorithm switch is turned on for clock synchronization and exception in an alternative embodiment of the invention.
Detailed Description
The invention will be described in detail hereinafter with reference to the accompanying drawings in conjunction with embodiments. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.
In view of the above problems in the related art, embodiments of the present invention provide a method for indicating synchronization time source selection in a carrier network wavelength division system, which associates a clock synchronization algorithm (e.g., SSM algorithm) with a time synchronization algorithm (e.g., 1588 algorithm). By the method, under the condition of clock time network separation, when the clock network node is switched abnormally, the time network node can be switched correspondingly according to the requirement.
It should be noted that, in the embodiment of the present invention, that "the node clock is synchronized normally" means that the node clock chip is locked to the clock coming from the upstream line. The node "clock synchronization abnormity" means that the node clock chip judges that the clock on the upstream line can not be locked. In addition, in the embodiment of the present invention, the switching of the time source means that the downstream node does not synchronize the time of the PTP synchronization packet with the local node any more, and the downstream node determines a new time source and then performs PTP synchronization packet interaction with the new time source to complete time synchronization.
Fig. 2 is a flowchart of a method for indicating a synchronized 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 node is abnormal.
In the implementation process, the first node in the carrier network wavelength division system may determine whether its clock synchronization is abnormal according to the existing manner. The specific embodiments of the present invention are not limited.
Step S204, the first node outputs 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 indicates other nodes to select output time of a second node other than the first node as a synchronization time source.
Optionally, the first node may output the time status information through an announcement (Announce) message, where a value of a priority (e.g., a grandmaster priority1 field in the Announce message) used by another node for time source selection is a value of a lowest priority in a wavelength division system of a bearer network where the first node is located.
Optionally, before the first node outputs the time status information of the first node, the method further includes: the first node determines to turn on a clock time correlation function. In a specific implementation, a clock time correlation switch may be provided in a node, and the clock time correlation function is turned on or off through the switch. With this alternative embodiment, the clock time correlation function can be turned on or off, thereby meeting a variety of requirements.
In an embodiment of the present invention, after the first node outputs the time status information of the first node, the method further includes: 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.
In a preferred implementation manner of the embodiment of the present invention, when the clock synchronization of the node in the carrier network wavelength division system is abnormal, it is necessary to determine whether the clock time correlation algorithm switch is turned on, and if the clock time correlation algorithm switch is not turned on, the time synchronization algorithm still operates independently, and the time synchronization path remains unchanged. When the clock synchronization of the node in the carrier network wavelength division system is abnormal, if the clock time correlation algorithm switch is turned on, the time state information output of the node needs to reflect the clock abnormality, and the specific corresponding time synchronization port is as follows: the grant priority1 output by the Announce message of the PTP port of the node sends the value of the lowest priority in the system. The announcing messages of the node received by other nodes in the bearer network wavelength division system change and contain the grandmaster priority1 with the lowest priority, and the other nodes operate the time source selection algorithm again according to the 1588 protocol, because the source selection algorithm described in the 1588 protocol can firstly decide the final synchronization time source compared with the grandmaster priority1, so that the grandmaster priority1 is set to the lowest priority, the other nodes are switched to other time sources, and the output time of the node is not synchronized any more.
By the method provided by the embodiment of the invention, the clock synchronization and time synchronization independent source selection algorithm can be more reasonably applied in the carrier network wavelength division system, the correlation between the clock synchronization and the time synchronization is established, and the error time synchronization possibly caused when the clock node is abnormal is avoided.
According to the embodiment of the invention, the invention also provides a system for indicating the selection of the synchronous time source.
Fig. 3 is a schematic structural diagram of a system for indicating synchronized time source selection according to an embodiment of the present invention, as shown in fig. 3, the system includes: a first node 30 and other nodes 32 except the first node in the wavelength division system of the bearing network where the first node is located; the first node 32 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; the other nodes 32 are configured to run the time source selection algorithm again according to the time state information output by the first node 30, and select output time of a second node other than the first node 30 as a synchronization time source.
Alternatively, the first node 30 may comprise means for indicating the selection of the source of the synchronization time as shown in fig. 4.
Fig. 4 is a schematic structural diagram of an apparatus for indicating selection of a synchronous time source 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, configured to output time status information of the first node, where the time status information includes indication information indicating that 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.
Alternatively, the output module 42 may output the time status information by: and outputting an announcement message, wherein the value of the priority for time source selection of other nodes carried in the announcement 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 apparatus may further include: and the second determining module is used for determining that the first node starts a clock time correlation function.
The following describes a flow of outputting time status information by a node according to a clock synchronization status association in an embodiment of the present invention by an optional embodiment.
Fig. 5 is a flowchart of a node outputting time status information according to a clock synchronization status association according to an alternative embodiment of the present invention, as shown in fig. 5, which mainly includes the following steps:
step 501: the first node firstly judges whether the clock synchronization of the node is normal according to a clock synchronization SSM algorithm.
Step 502: if the clock synchronization of the node is normal, the time synchronization 1588 algorithm operates independently to output a corresponding Announce message, and the downstream time node source selection algorithm is not switched. As shown in fig. 6, the downstream node 3 clock time is preferred to the node 1 with the higher priority.
Step 503: if the clock synchronization of the node is abnormal, whether the clock time correlation algorithm switch is turned on or not is judged, the correlation algorithm switch is used as optional judgment, and if the clock time correlation algorithm switch is not turned on, the time synchronization 1588 algorithm is the same as the step 502. As shown in fig. 7, the downstream node 3 time synchronization 1588 algorithm is not affected by clock selection and still selects the time of the node 1, and at this time, since the clocks are not synchronized any more on the node 1, the time is not trusted any more, which may cause the downstream node 3 to synchronize to the wrong time source.
Step 504: if the clock synchronization of the node is abnormal and the clock time correlation algorithm switch is turned on, the priority1 of the grandmaster priority in the Annouce message output by the node is set to be the lowest priority of the system, so that the downstream node can switch the time source. As shown in fig. 8, the priority of the grandmaster priority1 included in the Announce packet output by the node 1 is set as the lowest priority of the system.
Step 505: and the downstream node time synchronization 1588 algorithm judges that the received Announce message changes and reselects a time source. Since the priority1 of the grandmaster priority in the received Announce message is set to the lowest priority of the system, the result of running the time source selection algorithm again will cause the time synchronization source of the downstream node to switch to the upstream node with normal clock. As shown in fig. 8, the time synchronization 1588 algorithm of the downstream node 3 is influenced by clock selection, so that the time of the downstream node 3 can be switched to a correct time path, and finally the node 3 selects the node 2 with a normal clock as an upstream time synchronization source.
Optionally, in the step 504, the downstream node can be switched to the time source with the normal clock by outputting other methods capable of causing the time synchronization 1588 algorithm of the downstream node to switch the time source, so that the entire bearer network system completes correct clock time synchronization.
From the above description, it can be seen that, in the embodiment of the present invention, when a node in a carrier network wavelength division system is abnormal in clock synchronization, time state information indicating that the clock synchronization is abnormal is output, and when a node on the clock network fails and switches, the node on the time network switches a synchronization time source according to the time state information, so as to establish a correlation between the clock synchronization and the time synchronization, thereby avoiding error time synchronization that may be introduced when the clock node is abnormal.
It will be apparent to those skilled in the art that the modules or steps of the present invention described above may be implemented by a general purpose computing device, they may be centralized on a single computing device or distributed across a network of multiple computing devices, and alternatively, they may be implemented by program code executable by a computing device, such that they may be stored in a storage device and executed by a computing device, and in some cases, the steps shown or described may be performed in an order different than that described herein, or they may be separately fabricated into individual integrated circuit modules, or multiple ones of them may be fabricated into a single integrated circuit module. Thus, the present invention is not limited to any specific combination of hardware and software.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in 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 content of the first and second substances,
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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| CN201410330416.XA CN105323086B (en) | 2014-07-11 | 2014-07-11 | Method, device and system for indicating synchronous time source selection |
| PCT/CN2014/094420 WO2015184763A1 (en) | 2014-07-11 | 2014-12-19 | Method, apparatus and system for instructing to select synchronization time source |
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| CN102957488A (en) * | 2011-08-18 | 2013-03-06 | 中兴通讯股份有限公司 | Method and device for selecting time synchronization sources |
| CN103001720A (en) * | 2012-11-12 | 2013-03-27 | 中兴通讯股份有限公司 | Time synchronization method and device |
| CN103138863A (en) * | 2011-12-01 | 2013-06-05 | 中兴通讯股份有限公司 | Time synchronization method and device |
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| JP5560833B2 (en) * | 2010-03-29 | 2014-07-30 | 富士通株式会社 | Optical interface device and input frequency deviation abnormality monitoring method |
| CN102457346A (en) * | 2010-10-29 | 2012-05-16 | 中兴通讯股份有限公司 | Time synchronization realizing method and clock node |
| CN103686982B (en) * | 2012-09-17 | 2017-03-29 | ***通信集团公司 | A kind of method for synchronizing time and node device based on clock information |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102957488A (en) * | 2011-08-18 | 2013-03-06 | 中兴通讯股份有限公司 | Method and device for selecting time synchronization sources |
| CN103138863A (en) * | 2011-12-01 | 2013-06-05 | 中兴通讯股份有限公司 | Time synchronization method and device |
| CN103166750A (en) * | 2011-12-14 | 2013-06-19 | 中兴通讯股份有限公司 | Clock time synchronous resource distribution method and device |
| CN102710358A (en) * | 2012-06-13 | 2012-10-03 | 中兴通讯股份有限公司 | Method, device and system for transmitting GM (Grandmaster Clock) state |
| CN103001720A (en) * | 2012-11-12 | 2013-03-27 | 中兴通讯股份有限公司 | Time synchronization method and device |
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