CN102404105A - Device and method for realizing time synchronization on Ethernet switch - Google Patents
Device and method for realizing time synchronization on Ethernet switch Download PDFInfo
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- CN102404105A CN102404105A CN2011104170737A CN201110417073A CN102404105A CN 102404105 A CN102404105 A CN 102404105A CN 2011104170737 A CN2011104170737 A CN 2011104170737A CN 201110417073 A CN201110417073 A CN 201110417073A CN 102404105 A CN102404105 A CN 102404105A
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Abstract
The invention discloses a method and a device for realizing time synchronization on an Ethernet switch. The device comprises a Switch module, a plurality of PHY (Physical layer) modules, a CPU module and a clock processing module, wherein the clock processing module comprises a clock synchronization sub-module and a clock production sub-module. The clock can be synchronized according to the clock provided by the PHY module through adopting the time delay measuring technology provided by the synchronic Ethernet (SyncE, SynchronousEthernet) protocol and the IEEE1588 protocol, then the reference input clock needed by the relative modules in the system can be produced, and the frequencies of the main device and the auxiliary device are synchronized. Because of adopting the PHY chip with SyncE function, the frequency synchronization precision is very high, which can reach nanosecond level.
Description
Technical field
The present invention relates to the network exchange machine technology, relate in particular to the device and method of realizing nanosecond precision time synchronized on a kind of Ethernet switch.
Background technology
In industrial network, often need the distinct device of this network all to be in synchronous regime, come the communication between the Mediation Device with this understanding.At present, the networking technology of Ethernet is one of fastest-rising technology in the industrial market, therefore on the EPA switch, realizes time synchronized, is well positioned to meet current industrial networks development demand.
Some have used NTP (NTP above the industrial switch now; Network Time Protocol) and the IRIG-B sign indicating number carry out time synchronized, wherein, NTP is the standard agreement that is used for the Internet time synchronized; Adopt the method for statistics and probability theory; To screening from the information of different time server, draw side-play amount near the true deviant of local clock, then with this side-play amount through local clock adjusting module adjustment local clock.In addition, through local Route Selection algorithm and time background program, server can be redistributed the standard time to realize clock synchronization.
IRIG-B be the U.S. target range commandant committee formulate a kind of to the time standard, be widely used in numerous areas such as military affairs, commerce, industry now.At present, China have intelligent substation equipment greatly to the time system adopt the IRIG-B sign indicating number to the time system.As shown in Figure 1; The IRIG-B sign indicating number to the time circuit system basic principle be; Handle IRIG-B sign indicating number sequences of pulsed signals through interrupting (IQR) input port; Resolve the temporal information of synchronizing information and IRIG-B sign indicating number earlier and come; Through to the time module serial port (comprising Serial Peripheral Interface SPI and serial communication interface SCI) and each functional module of system and CPU module communication, transmit concrete time code and message, output " second " pulse of the I/O port through a Transistor-Transistor Logic level simultaneously or " branch " pulse signal carry out time synchronized to the host CPU module.
Yet, no matter be NTP or IRIG-B sign indicating number, its synchronization accuracy can only reach Millisecond usually, and cost is often higher, transmission range is limited.In view of this, be necessary very much to provide the method that realizes time synchronized on the higher Ethernet switch of a kind of precision.
Summary of the invention
The object of the present invention is to provide the device of realizing time synchronized on a kind of Ethernet switch; It adopts IEEE1588 and synchronous ethernet (SyncE; Synchronous Ethernet) agreement arrives nanosecond with the timing tracking accuracy that promotes Ethernet switch.
Corresponding to said device, the present invention also provides the method that realizes time synchronized on a kind of Ethernet switch.
For realizing one of foregoing invention purpose, the invention provides the device of realizing time synchronized on a kind of Ethernet switch, this device comprises:
The Switch module: the timestamp that is used for discerning the IEEE1588 message and extracts message, with the IEEE1588 message reporting to the CPU module;
Some PHY modules: be used for recovering the clock on the circuit, and clock is delivered to the clock processing module through synchronous ethernet (SyncE) agreement;
CPU module: be used to move Precision Time Protocol (PTP, Precision Time Protocol) stack with synchro system administrative time; And
The clock processing module: said clock processing module comprises the synchronous submodule of a clock: be used to receive the clock that the PHY module passes over, and obtain best input clock and carry out clock synchronization;
And one clock produce submodule: be used for reference input clock according to synchronised clock generation system correlation module needs.
As further improvement of the present invention, said Switch module also is used for:
In message, insert timestamp, and the message that will insert behind the timestamp sends to relevant device.
As further improvement of the present invention, said Switch module is beaten timestamp through hardware mode.
For realizing another goal of the invention of the present invention, realize the method for time synchronized on a kind of Ethernet switch, this method comprises the steps:
S1, the clock and the highest clock in the network of main equipment carried out synchronously;
S2, main equipment insert the PHY module with the frequency information of synchronised clock, and send to slave unit;
S3, slave unit recover frequency information and send to the clock processing module to carry out synchronously;
S4, clock processing module send to the Switch module to accomplish the Frequency Synchronization between main equipment and the slave unit with the clock after synchronous;
S5, obtain the time offset between main equipment and the slave unit, and the local zone time of slave unit is proofreaied and correct according to this time offset.
As further improvement of the present invention, the step of " obtaining the time offset between main equipment and the slave unit " among the said step S5 is specially:
Main equipment periodically sends the Sync message to slave unit according to specified time interval, and the record transmitting time is t1; After slave unit receives this Sync message, recorder time t2;
Main equipment after sending the Sync message, and then send one carry t1 the Follow_Up message;
After slave unit receives the Follow_Up message; Send a Delay_Req message to main equipment; The record transmitting time is t3, and main equipment receives and resolve this Delay_Req message, recorder time t4; And reply the Delay_Resp message carry t4 to slave unit, calculate one-way line time-delay Δ t=[(t2 – t1)+(t4 – t3)]/2 that obtain master and slave equipment room;
Slave unit continues to receive Sync message and the Follow_Up message that main equipment periodically sends to slave unit; Slave unit receives this Sync message and the recorder time is t6; Receiving this Follow_Up message and writing down the time that main equipment sends the Sync message is t5, obtains the time offset Offset=t6-t5-Δ t between slave unit and the main equipment.
As further improvement of the present invention, said step S5 also comprises:
Whether the judgement time side-play amount equals 0; If finish the time synchronized between the master and slave equipment; If not, the local zone time of slave unit is proofreaied and correct.
Compared with prior art; The present invention adopts IEEE1588 and synchronous ethernet (SyncE; Synchronous Ethernet) agreement; And adopt PHY chip realizing the time synchronized between the main equipment and slave unit in the network with SyncE function, the timing tracking accuracy of Ethernet switch is risen to nanosecond, and cost is lower.
Description of drawings
Fig. 1 be in the prior art IRIG-B sign indicating number to the time system basic principle schematic;
Fig. 2 is a structural representation of realizing the device of time synchronized on the Ethernet switch in an embodiment of the present invention;
Fig. 3 representes to invent the workflow diagram of realizing the method for time synchronized on the Ethernet switch in the execution mode;
Fig. 4 is a time point sketch map of realizing the sync message transmittance process among the present invention.
Embodiment
Below will combine embodiment shown in the drawings to describe the present invention.But these execution modes do not limit the present invention, and the conversion on the structure that those of ordinary skill in the art makes according to these execution modes, method or the function all is included in protection scope of the present invention.
As shown in Figure 2; In the embodiment of the invention; In order to reach the purpose of time synchronized; Realize the device of time synchronized on a kind of Ethernet switch that is provided, comprising: CPU (CPU) module 101, exchange (Switch) module 102, physics (PHY) module 103 and clock processing module 104.
Wherein, Switch module: it can comprise through port (1,2 ... N), be connected to N physics (PHY) module with realize with they between communicate by letter.The Switch module is mainly used in identification IEEE1588 message and extract the timestamp in the message, with the IEEE1588 message reporting to the CPU module; The effect of Switch module is that also it can insert timestamp in message, and the message that will insert behind the timestamp sends to relevant device.Preferably, in this execution mode, said Switch module is to beat timestamp through hardware, the time that it has consumed when having reduced the IEEE1588 message through the PTP protocol stack, has guaranteed so also that port message is sent and the precision of reception time stamp.
PHY module: be used for recovering the clock on the circuit, and clock is delivered to the clock processing module through synchronous ethernet (SyncE) agreement; In this execution mode, said PHY module can be set to one or more, promptly can be configured to N according to actual needs, and N is not less than 1 integer.
CPU module: be used to move Precision Time Protocol (PTP, Precision Time Protocol) stack with synchro system administrative time; And
The clock processing module: the clock that is used for providing according to the PHY module carries out clock synchronization, and the reference input clock that correlation module needs in the generation system.Preferably, clock processing module 104 also can be subdivided into synchronous submodule 104a of a clock and clock generation submodule 104b.Wherein, the clock synchronization submodule is used to receive the clock that the PHY module passes over, and obtains best input clock and carry out clock synchronization; And the clock generating submodule is used for the reference input clock according to synchronised clock generation system correlation module needs.Produce correlation module (Switch module and each PHY module) needed with reference to input clock after, just corresponding sending in the correlation module gone.
One embodiment of the method for using said apparatus realization time synchronized for the present invention is a kind of shown in Figure 3, as shown in Figure 3, this method can be arranged on and describe in main equipment and the slave unit, so this method comprises the steps:
S1, the clock and the highest clock in the network of main equipment carried out synchronously; Wherein, highest clock (GMC, Grandmaster Clock) is a standard that needs the synchronous time in the network.Only main equipment be in highest clock synchronization after, correspondingly slave unit is just meaningful synchronously.
S2, main equipment insert the PHY module with the frequency information of synchronised clock, and send to slave unit; Preferably, transmit through ethernet link.
S3, slave unit recover frequency information and send to the clock processing module to carry out synchronously; Preferably, recover frequency information from ethernet link, give the clock processing module then and carry out synchronously through the PHY module of supporting the SyncE function.
S4, clock processing module send to the Switch module to accomplish the Frequency Synchronization between main equipment and the slave unit with the clock after synchronous; Because time synchronized is further developing of Frequency Synchronization, so the Frequency Synchronization in this step also is a very crucial step.
S5, obtain the time offset between main equipment and the slave unit, and the local zone time of slave unit is proofreaied and correct according to this time offset.Wherein, in this execution mode,, can be easier to realize the time synchronized of master and slave equipment through the two-way interactive of message message as long as after master and slave device frequency obtained synchronously, the Time delay measurement that adopts the IEEE1588 agreement to provide again was technological.
In conjunction with Fig. 4, in step S5, the step of " obtaining the time offset between main equipment and the slave unit " is specially:
Main equipment periodically sends the Sync message to slave unit according to specified time interval when default (be 2 seconds), and the record transmitting time is t1; After slave unit receives this Sync message, recorder time t2;
Main equipment after sending synchronously (Sync) message, and then send one carry t1 follow (Follow_Up) message;
After slave unit receives the Follow_Up message; Send time-delay request (Delay_Req) message to main equipment; The record transmitting time is t3; Main equipment receives also and resolves this Delay_Req message, recorder time t4, and reply time-delay (Delay_Resp) message that carries t4 to slave unit.At this moment, slave unit has just had these four timestamps of t1～t4.Can calculate the total time-delay of coming and going of master and slave equipment room thus and be [(t2 – t1)+(t4 – t3)], hypothetical network is symmetrical, so the one-way line of master and slave equipment room time-delay Δ t=[(t2 – t1)+(t4 – t3)]/2;
Slave unit continues to receive Sync message and the Follow_Up message that main equipment periodically sends to slave unit; Slave unit receives this Sync message and the recorder time is t6; Receiving this Follow_Up message and writing down the time that main equipment sends the Sync message is t5, and the circuit delay Δ t that utilizes previous calculations to obtain can obtain the time offset Offset=t6-t5-Δ t between slave unit and the main equipment.Utilize this Offset value that the local zone time of slave unit is proofreaied and correct then;
And then, slave unit continues to receive Sync message and the Follow_Up message that main equipment periodically sends to slave unit again, constantly calculates the Offset value, and whether the judgement time side-play amount equals 0 simultaneously; If finish the time synchronized between the master and slave equipment; If not, continue the local zone time of slave unit to be proofreaied and correct according to top step.
The present invention can carry out the frequency of master and slave equipment synchronously through the method for SyncE, owing to adopt the PHY chip with SyncE function, the Frequency Synchronization precision is very high, can reach nanosecond.SyncE is the method that adopts ethernet link code stream recovered clock, does not receive the link traffic flow effect, can keep high accuracy, stable Frequency Synchronization with the main equipment end.Simultaneously; Because time synchronized is further developing of Frequency Synchronization; After as long as master and slave device frequency obtains synchronously, the Time delay measurement that adopts the IEEE1588 agreement to provide again is technological, can be easier to realize the time synchronized of master and slave equipment through the two-way interactive of message message.Wherein the time stamp processing delay is one of principal element that influences synchronization accuracy; IEEE1588 message time stamp of the present invention is handled and is accomplished by the Switch chip; Promptly adopt hardware to beat the mode of time stamp; The time that has consumed when having reduced the IEEE1588 message through the PTP protocol stack, guaranteed that so also port message sends and receive the precision of time stamp.
In addition; Adopting SyncE to carry out implementing the IEEE1588 agreement on the basis of Frequency Synchronization; Help the quick convergence of time synchronized, and can reduce the IEEE1588 message and send frequency, when network load is heavier; Also influence time precision not makes time synchronized have more high reliability and more high accuracy.
Method of the present invention realizes simple, technology maturation, and required hardware device is fewer, adopts existing Ethernet link transmission time synchronization information, need not to set up special-purpose Time Synchronization Network, and cost is lower.
For the convenience of describing, be divided into various unit with function when describing above the device and describe respectively.Certainly, when implementing the application, can in same or a plurality of softwares and/or hardware, realize the function of each unit.
Device embodiments described above only is schematic; Wherein said unit as the separating component explanation can or can not be physically to separate also; The parts that show as the unit can be or can not be physical locations also; Promptly can be positioned at a place, perhaps also can be distributed on a plurality of NEs.Can realize the purpose of this execution mode scheme according to the needs selection some or all of module wherein of reality.Those of ordinary skills promptly can understand and implement under the situation of not paying creative work.
Be to be understood that; Though this specification is described according to execution mode; But be not that each execution mode only comprises an independently technical scheme, this narrating mode of specification only is for clarity sake, and those skilled in the art should make specification as a whole; Technical scheme in each execution mode also can form other execution modes that it will be appreciated by those skilled in the art that through appropriate combination.
The listed a series of detailed description of preceding text only is specifying to feasibility execution mode of the present invention; They are not in order to restriction protection scope of the present invention, allly do not break away from equivalent execution mode or the change that skill of the present invention spirit done and all should be included within protection scope of the present invention.
Claims (6)
1. realize the device of time synchronized on the Ethernet switch, this device comprises:
The Switch module: the timestamp that is used for discerning the IEEE1588 message and extracts message, with the IEEE1588 message reporting to the CPU module;
Some PHY modules: be used for recovering the clock on the circuit, and clock is delivered to the clock processing module through synchronous ethernet (SyncE) agreement;
CPU module: be used to move Precision Time Protocol (PTP, Precision Time Protocol) stack with synchro system administrative time; And
The clock processing module;
It is characterized in that said clock processing module comprises the synchronous submodule of a clock: be used to receive the clock that the PHY module passes over, and obtain best input clock and carry out clock synchronization;
And one clock produce submodule: be used for reference input clock according to synchronised clock generation system correlation module needs.
2. device according to claim 1 is characterized in that, said Switch module also is used for:
In message, insert timestamp, and the message that will insert behind the timestamp sends to relevant device.
3. device according to claim 1 and 2 is characterized in that, said Switch module is beaten timestamp through hardware mode.
4. an application rights requires any described device in 1 to 3 to realize the method for time synchronized, it is characterized in that this method comprises the steps:
S1, the clock and the highest clock in the network of main equipment carried out synchronously;
S2, main equipment insert the PHY module with the frequency information of synchronised clock, and send to slave unit;
S3, slave unit recover frequency information and send to the clock processing module to carry out synchronously;
S4, clock processing module send to the Switch module to accomplish the Frequency Synchronization between main equipment and the slave unit with the clock after synchronous;
S5, obtain the time offset between main equipment and the slave unit, and the local zone time of slave unit is proofreaied and correct according to this time offset.
5. method according to claim 4 is characterized in that, the step of " obtaining the time offset between main equipment and the slave unit " among the said step S5 is specially:
Main equipment periodically sends the Sync message to slave unit according to specified time interval, and the record transmitting time is t1; After slave unit receives this Sync message, recorder time t2;
Main equipment after sending the Sync message, and then send one carry t1 the Follow_Up message;
After slave unit receives the Follow_Up message; Send a Delay_Req message to main equipment; The record transmitting time is t3, and main equipment receives and resolve this Delay_Req message, recorder time t4; And reply the Delay_Resp message carry t4 to slave unit, calculate one-way line time-delay Δ t=[(t2 – t1)+(t4 – t3)]/2 that obtain master and slave equipment room;
Slave unit continues to receive Sync message and the Follow_Up message that main equipment periodically sends to slave unit; Slave unit receives this Sync message and the recorder time is t6; Receiving this Follow_Up message and writing down the time that main equipment sends the Sync message is t5, obtains the time offset Offset=t6-t5-Δ t between slave unit and the main equipment.
6. method according to claim 5 is characterized in that, said step S5 also comprises:
Whether the judgement time side-play amount equals 0; If finish the time synchronized between the master and slave equipment; If not, the local zone time of slave unit is proofreaied and correct.
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| CN102916758A (en) * | 2012-10-10 | 2013-02-06 | 北京东土科技股份有限公司 | Ethernet time synchronization device and network equipment |
| CN103915899A (en) * | 2014-03-27 | 2014-07-09 | 广州南方电力集团科技发展有限公司 | Autonomous networking structure and method for electric power automatic terminals |
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| CN106160905A (en) * | 2015-03-24 | 2016-11-23 | 上海航天有线电厂有限公司 | Heterogeneous network clock system and method thereof |
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| CN109305046A (en) * | 2018-09-30 | 2019-02-05 | 湖南中车时代通信信号有限公司 | The transmission control system and method for train traction location data |
| CN111107020A (en) * | 2019-12-31 | 2020-05-05 | 盛科网络（苏州）有限公司 | Method for time synchronization of multi-core Ethernet switching chip |
| CN111107020B (en) * | 2019-12-31 | 2022-01-11 | 苏州盛科通信股份有限公司 | Method for time synchronization of multi-core Ethernet switching chip |
| CN113225152A (en) * | 2021-07-08 | 2021-08-06 | 浙江华睿科技股份有限公司 | Method and device for synchronizing cameras and computer readable medium |
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Application publication date: 20120404 |