CN102904662B - Cross-domain clock synchronization method and system based on PTP (Precision Time Protocol) - Google Patents
Cross-domain clock synchronization method and system based on PTP (Precision Time Protocol) Download PDFInfo
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- CN102904662B CN102904662B CN201210374959.2A CN201210374959A CN102904662B CN 102904662 B CN102904662 B CN 102904662B CN 201210374959 A CN201210374959 A CN 201210374959A CN 102904662 B CN102904662 B CN 102904662B
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Abstract
The invention relates to a cross-domain clock synchronization method and system based on a PTP (Precision Time Protocol). The method comprises the steps of judging whether a master clock in the local setting domain loses or not when clock synchronization is carried out by a switchboard according to a set period, judging whether the master clock is connected with other domains or not when the master clock in the local setting domain is determined to be lost; selecting one domain in the stored domains when the master clock is connected with other domains; synchronizing the local clock according to the clock information of the selected domain; and sending the synchronized local clock information. When the master clock in the local setting domain is lost, the local clock information is altered by selecting the clock information of other domains and storing the clock information of other domains so as to realize the clock synchronization of the local setting domain and ensure stable operation of the network.
Description
Technical field
The application relates to precise synchronization agreement (Precision Time Protocol, PTP), particularly relates to a kind of cross-domain clock synchronizing method based on PTP protocol and system.
Background technology
In PTP protocol, the switch in same territory can utilize respective clock information to realize clock synchronous, but switch can not utilize the clock information in other territories to arrange in territory in this locality carries out clock synchronous.In PTP protocol, territory is made up of one or more switches intercomed mutually of protocol definition.Territory define PTP message communicating, state, data set and time target scope.Switch can add multiple territory, but the agreement in general not in same area is run and markers is separate.
Because the devices interconnect of same area does not make mutually to receive message between territory yet, in general, the ID of same area can not arranged, and arranges for territory, can there is the default domain ID in this territory for this locality at switch place.Can process when switch receives the message of default domain, the message receiving other territories then abandons.
Clock synchronous is carried out because switch can not utilize the clock information in other territories to arrange in territory in this locality, if therefore once this locality master clock information dropout arranged in territory this locality will be caused to arrange in territory switch between cannot carry out clock synchronous, and may systemic breakdown be caused, therefore need to find and a kind ofly avoid the cross-domain scheme cannot carrying out clock synchronous.
Summary of the invention
The invention provides a kind of cross-domain clock synchronizing method based on PTP protocol and system, its object is to, the clock information solved in territory is lost, and how to utilize the clock information in other territories to carry out synchronous problem.
The invention provides a kind of cross-domain clock synchronizing method based on PTP protocol, the method comprises: when switch carries out clock synchronous according to the cycle of setting, judges whether the local master clock arranging territory is lost; When determining that described this locality arranges the master clock loss in territory, judge whether self is connected with other territories; When determining that self is connected with other territories described, in other territories described in preserving at self, select a territory; According to the synchronous local clock of the clock information in selected territory, and the local clock information after synchronous is sent.
Preferably, whether the described master clock judging that described this locality arranges territory is lost and is comprised: when not receiving the clock synchronous message that described master clock sends within the time cycle of described setting, determines that the master clock that described this locality arranges territory is lost; Or according to the precedence information that the master clock message received comprises, when the precedence information that described master clock message comprises is greater than the threshold value of setting, determine that described this locality arranges the master clock loss in territory.
Preferably, described preserve at self described in select in other territories a territory to comprise: in other territories described in being connected with self, according to the precedence information in each territory, select a territory that priority is the highest.
Preferably, described selection territory that priority is the highest comprises: the clock information that described switch is corresponding according to other territories described in connecting with self, an optimal clock is selected by optimal clock selection algorithm, and the priority in territory corresponding for described optimal clock is set to the highest, wherein said clock information comprises: priority 1 information, port information, scale of precision information, clock id information, domain name id information and priority 2 information.
Preferably, the synchronous local clock of clock information in the territory selected by described basis comprises: described switch is undertaken alternately by the territory the highest with described priority, obtain the link delay of the highest territory of described priority to self, according to clock information and the described link delay in the highest territory of described priority, local clock is carried out synchronously.
The invention provides a kind of cross-domain clock system based on PTP protocol, this system comprises: the first judge module, during for carrying out clock synchronous according to the cycle of setting, judges whether the local master clock arranging territory is lost; Second judge module, for when determining that described this locality arranges the master clock loss in territory, judges whether described system is connected with other territories; Module is selected in territory, during for losing when the master clock determining to put territory, when judging that described system is connected with other territories described, selects a territory in other territories described in preserving at self; Clock synchronization module, for according to the synchronous local clock of the clock information in selected territory, and sends the local clock information after synchronous.
Preferably, described first judge module, for when not receiving the clock synchronous message that described master clock sends in the time cycle of described setting, determines that described this locality arranges the master clock loss in territory; Or according to the precedence information that the master clock message received comprises, when the precedence information that described master clock message comprises is greater than the threshold value of setting, determine that described this locality arranges the master clock loss in territory.
Preferably, module is selected in described territory, in other territories described in being connected with described system, according to the precedence information in each territory, selects a territory that priority is the highest.
Preferably, module is selected in described territory, for the clock information corresponding according to other territories described in connecting with described system, an optimal clock is selected by optimal clock selection algorithm, and the priority in territory corresponding for described optimal clock is set to the highest, wherein said clock information comprises: priority 1 information, port information, scale of precision information, clock id information, domain name id information and priority 2 information.
Preferably, described clock synchronization module, for being undertaken alternately by the territory the highest with described priority, obtains the link delay of the highest territory of described priority to self, according to clock information and the described link delay in the highest territory of described priority, local clock is carried out synchronously.
The present invention by storing the clock information in other territories, and when the master clock arranging territory in this locality is lost, by with other territories clock information revise local clock information, thus realize the local clock synchronous that territory is set, ensure that network stabilization runs.
Accompanying drawing explanation
These and other features of the present invention, aspect and advantage are described with reference to the accompanying drawing of embodiment, its object is to describe embodiment instead of restriction the present invention.
Fig. 1 is territory ID and port id corresponding relation schematic diagram;
Fig. 2 is the structural representation that a switch is connected with wide area network;
Fig. 3 is the structural representation that two switches are connected with wide area network;
Fig. 4 is the cross-domain clock synchronizing method flow chart based on PTP protocol provided by the invention;
Fig. 5 is the cross-domain clock system schematic diagram based on PTP protocol provided by the invention.
Embodiment
The invention provides a kind of cross-domain clock synchronizing method based on PTP protocol, the method comprises: when switch carries out clock synchronous according to the cycle of setting, judges whether the local master clock arranging territory is lost; When determining that described this locality arranges the master clock loss in territory, judge whether self is connected with other territories; When determining that self is connected with other territories described, in other territories described in preserving at self, select a territory; According to the synchronous local clock of the clock information in selected territory, and the local clock information after synchronous is sent.
By this, when can lose at the master clock that this locality arranges territory, utilize the clock information in other territories that territory is set to this locality and carry out clock synchronous, avoid system because synchronously paralysis cannot be caused.
Specifically, the master clock that this locality arranges territory generally refers to the equipment that can provide precision clock information in network, such as GPS device or be called GPS master clock.After GPS master clock is lost, such as, cannot receive the message that this locality arranges the master clock transmission in territory in the given time, or the precedence information comprised in the master clock message received is greater than default value (such as 128; The value of precedence information is larger, and its priority is lower), in order to ensure that system is normally run, can utilize the clock information synchronous this locality in other territories be directly connected with switch that the clock information in territory is set.After the master clock loss in territory is set in this locality, the clock information of the selection territory (if present) in other territories that switch can self be preserved upgrades local clock and is issued to other switches that this locality arranges territory, thus when this locality arranges territory master clock loss, maintain the normal operation of network.
Preferably, in other territories described in self preservation, a territory is selected to comprise: in other territories described in being connected with self, according to the precedence information in each territory, to select a territory that priority is the highest.Optimal clock selection algorithm is the main algorithm selecting clock in PTP protocol, it mainly utilizes the information in message to judge which clock is optimum, such as, parameter priority 1 information (priority1) in message, clock grade information (class), scale of precision information (accuracy), clock quality information (offsetScaledLogVariance), priority 2 information (priority2), clock id information (clockID), port information (portID), domain name id information (domainID), its concrete algorithm is as follows:
First compare parameter p riority1, selection best domain is elected in the territory that parameter p riority1 value is little as;
When parameter p riority1 is identical, compare parameter class, selection best domain is elected in the territory that parameter class value is little as;
If above two parameters are all identical, then compare parameter accuracy, selection best domain is elected in the territory that accuracy value is little as;
If above three parameters are identical, then compare offsetScaledLogVariance, the territory that offsetScaledLogVariance value is little is best domain;
If also best domain cannot be determined, so adopt similar Measures compare parameter p riority2, clockID, portID, domainID.
It should be noted that, utilize optimal clock algorithm can select in other territories to have a territory of optimum master clock, but those skilled in the art are to be understood that and can utilize other algorithms to select a territory, even can Stochastic choice territory the local clock information of the switch be connected with other territories according to the clock information in this territory, to realize clock synchronous.
Preferably, the synchronous local clock of clock information in the territory selected by described basis comprises: described switch is undertaken alternately by the territory the highest with described priority, obtain the link delay of the highest territory of described priority to self, according to clock information and the described link delay in the highest territory of described priority, local clock is carried out synchronously.After obtaining link delay time, local clock can be upgraded with the clock information that link delay time and other territories send, the local clock after renewal can be made so more accurate.
Preferably, the method also comprises: after described this locality arranges the master clock recovery in territory, the master clock that the described switch be connected with other territories arranges territory according to this locality upgrades local clock information.The master clock arranging territory due to this locality has recovered, use this locality that the master clock in territory is set to upgrade local clock so preferential, and what be connected with selected best domain can be sleep state, the clock information in the message in other territories is made to be received and to store, when losing to facilitate the master clock arranging territory in this locality, utilize the clock information stored that territory is set to this locality in time and carry out synchronously.The master clock that described this locality arranges territory arranges the message that territory sends from this locality and obtains, and the clock information in other territories described obtains from the message that other territories send.
Fig. 1 shows the corresponding relation of a kind of territory and port, corresponding relation list is set up respectively to the port id of not same area ID, after the message sent from port accepts corresponding to port id to other territory, the clock information in this message will be stored in the memory space corresponding with this port id.These corresponding relations are mainly used for determining that message is which territory sends, and from which port accepts, the clock information stored mainly is used for arranging territory to this locality to carry out synchronously.
Fig. 2 shows the annexation schematic diagram of a ring network and wide area network, and in the figure, ring network is made up of switch 1 to switch 6 and terminal equipment.Switch 1 is also connected with wide area network and GPS master clock connects, and therefore, when normal work, switch 1 can receive the clock information of GPS transmission and the clock information (clock information can obtain from message) of wide area network transmission.If the master clock of GPS cannot be received by switch 1, (such as GPS master clock closes PTP function, or the link between switch 1 and GPS master clock disconnects), or the priority level that the master clock received comprises is lower than the value preset, method so provided by the present invention can make switch 1 utilize the clock of wide area network (other territories) to arrange territory (network be namely made up of switch, gps clock and terminal equipment) to this locality to carry out clock synchronous, thus avoids systemic breakdown.
But this locality is arranged in territory may be existed multiple switch and be directly connected with other territories, as shown in Figure 3.Wherein switch 1 is all directly connected with wide area network with switch 5, after the master clock loss in territory is set in this locality, the master clock that switch 1 and switch 5 all utilize above-mentioned method choice provided by the invention to go out a territory carrys out its local clock information synchronous, and the local clock information after synchronous is sent, now because switch 1 and switch 5 all have sent sync message, therefore need to arrange in territory in this locality and utilize optimal clock selection algorithm to select optimum master clock, the clock of such as switch 1 is best, after this when the clock that this locality arranges territory does not recover, sync message is sent by switch 1, and switch 5 no longer sends sync message.
Fig. 4 shows the cross-domain clock synchronizing method flow chart based on PTP protocol provided by the invention, specifically comprises: when switch carries out clock synchronous according to the cycle of setting, judges whether the local master clock arranging territory is lost; When determining that described this locality arranges the master clock loss in territory, judge whether self is connected with other territories; When determining that self is connected with other territories described, in other territories described in preserving at self, select a territory; According to the synchronous local clock of the clock information in selected territory, and the local clock information after synchronous is sent.When this locality arranges territory master clock loss, the clock information in other territories can be utilized to come synchronous this locality territory is set, avoid systemic breakdown by this.
Fig. 5 shows exchange clock synchro system schematic diagram provided by the invention, and it can comprise: the first judge module, during for carrying out clock synchronous according to the cycle of setting, judges whether the local master clock arranging territory is lost; Second judge module, for when determining that described this locality arranges the master clock loss in territory, judges whether described system is connected with other territories; Module is selected in territory, during for losing when the master clock determining to put territory, when judging that described system is connected with other territories described, selects a territory in other territories described in preserving at self; Clock synchronization module, for according to the synchronous local clock of the clock information in selected territory, and sends the local clock information after synchronous.
Preferably, when described first judge module does not receive the clock synchronous message of described master clock transmission within the time cycle of described setting, determine that described this locality arranges the master clock loss in territory; Or according to the precedence information that the master clock message received comprises, when the precedence information that described master clock message comprises is greater than the threshold value of setting, determine that described this locality arranges the master clock loss in territory.
Preferably, described territory selects module in other territories described in being connected with described system, according to the precedence information in each territory, selects a territory that priority is the highest.
Preferably, the clock information that described territory selects module corresponding according to other territories described in connecting with described system, an optimal clock is selected by optimal clock selection algorithm, and the priority in territory corresponding for described optimal clock is set to the highest, wherein said clock information comprises: priority 1 information, port information, scale of precision information, clock id information, domain name id information and priority 2 information.It should be noted that, utilize optimal clock algorithm can select in other territories to have a territory of optimum master clock, but those skilled in the art are to be understood that and can utilize other algorithms to select a territory, even can Stochastic choice territory the local clock information of the switch be connected with other territories according to the clock information in this territory, to realize clock synchronous.
Preferably, described clock synchronization module is undertaken alternately by the territory the highest with described priority, obtain the link delay of the highest territory of described priority to self, according to clock information and the described link delay in the highest territory of described priority, local clock is carried out synchronously.Can link delay be obtained by this, and consider this delay when upgrading local clock, thus can obtain more accurate for synchronous clock.
Above embodiment only in order to technical scheme of the present invention to be described, is not intended to limit; Although with reference to previous embodiment to invention has been detailed description, those of ordinary skill in the art is to be understood that: it still can be modified to the technical scheme described in foregoing embodiments, or carries out equivalent replacement to wherein portion of techniques feature; And these amendments or replacement, do not make the essence of appropriate technical solution depart from the scope of various embodiments of the present invention technical scheme.
Claims (10)
1., based on a cross-domain clock synchronizing method for PTP protocol, it is characterized in that, the method comprises:
When switch carries out clock synchronous according to the cycle of setting, judge whether the local master clock arranging territory is lost;
When determining that described this locality arranges the master clock loss in territory, judge whether self is connected with other territories;
When determining that self is connected with other territories described, in other territories described in preserving at self, select a territory;
According to the synchronous local clock of the clock information in selected territory, and the local clock information after synchronous is sent.
2. method according to claim 1, is characterized in that, whether the described master clock judging that described this locality arranges territory is lost and comprised:
When not receiving the clock synchronous message of described master clock transmission within the time cycle of described setting, determine that described this locality arranges the master clock loss in territory; Or
According to the precedence information that the master clock message received comprises, when the precedence information that described master clock message comprises is greater than the threshold value of setting, determine that described this locality arranges the master clock loss in territory.
3. method according to claim 1, is characterized in that, described preserve at self described in select in other territories a territory to comprise:
In other territories described in being connected with self, according to the precedence information in each territory, select a territory that priority is the highest.
4. method according to claim 3, is characterized in that, described selection territory that priority is the highest comprises:
The clock information that described switch is corresponding according to other territories described in connecting with self, an optimal clock is selected by optimal clock selection algorithm, and the priority in territory corresponding for described optimal clock is set to the highest, wherein said clock information comprises: priority 1 information, port information, scale of precision information, clock id information, domain name id information and priority 2 information.
5. the method according to the arbitrary claim in claim 1-4, is characterized in that, the synchronous local clock of clock information in the territory selected by described basis comprises:
Described switch is undertaken alternately by the territory the highest with described priority, obtains the link delay of the highest territory of described priority to self, according to clock information and the described link delay in the highest territory of described priority, carries out synchronously local clock.
6. based on a cross-domain clock system for PTP protocol, it is characterized in that, this system comprises:
First judge module, during for carrying out clock synchronous according to the cycle of setting, judges whether the local master clock arranging territory is lost;
Second judge module, for when determining that described this locality arranges the master clock loss in territory, judges whether described system is connected with other territories;
Module is selected in territory, during for losing when the master clock determining to put territory, when judging that described system is connected with other territories described, selects a territory in other territories described in preserving at self;
Clock synchronization module, for according to the synchronous local clock of the clock information in selected territory, and sends the local clock information after synchronous.
7. system according to claim 6, is characterized in that, described first judge module, for when not receiving the clock synchronous message that described master clock sends in the time cycle of described setting, determines that described this locality arranges the master clock loss in territory; Or according to the precedence information that the master clock message received comprises, when the precedence information that described master clock message comprises is greater than the threshold value of setting, determine that described this locality arranges the master clock loss in territory.
8. system according to claim 6, is characterized in that, module is selected in described territory, in other territories described in being connected with described system, according to the precedence information in each territory, selects a territory that priority is the highest.
9. system according to claim 8, it is characterized in that, module is selected in described territory, for the clock information corresponding according to other territories described in connecting with described system, an optimal clock is selected by optimal clock selection algorithm, and the priority in territory corresponding for described optimal clock is set to the highest, wherein said clock information comprises: priority 1 information, port information, scale of precision information, clock id information, domain name id information and priority 2 information.
10. the system according to the arbitrary claim in claim 6-9, it is characterized in that, described clock synchronization module, for being undertaken alternately by the territory the highest with described priority, obtain the link delay of the highest territory of described priority to self, according to clock information and the described link delay in the highest territory of described priority, local clock is carried out synchronously.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104125263B (en) * | 2013-04-28 | 2018-02-02 | 广东美的制冷设备有限公司 | A kind of system for carrying out time service for home appliance by Internet of Things |
| EP3104556B1 (en) | 2014-03-05 | 2023-07-05 | Huawei Technologies Co., Ltd. | Clock synchronization method and device, and communication system |
| CN105634714A (en) * | 2014-10-28 | 2016-06-01 | 中兴通讯股份有限公司 | Cross-domain clock synchronization method, device thereof and cross-domain clock synchronization system |
| CN114465690A (en) * | 2021-12-30 | 2022-05-10 | 华为技术有限公司 | Method, device and system for sending precision information |
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Application publication date: 20130130 Assignee: Shanghai Jinzhuo Technology Co.,Ltd. Assignor: KYLAND TECHNOLOGY Co.,Ltd. Contract record no.: X2022990000452 Denomination of invention: A method and system for cross-domain clock synchronization based on PTP protocol Granted publication date: 20150624 License type: Common License Record date: 20220801 |
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