CN102201910A - Method for adjusting frequency based on IEEE1588 (institute of electrical and electronic engineers) protocol and network device - Google Patents
Method for adjusting frequency based on IEEE1588 (institute of electrical and electronic engineers) protocol and network device Download PDFInfo
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- CN102201910A CN102201910A CN2011101181513A CN201110118151A CN102201910A CN 102201910 A CN102201910 A CN 102201910A CN 2011101181513 A CN2011101181513 A CN 2011101181513A CN 201110118151 A CN201110118151 A CN 201110118151A CN 102201910 A CN102201910 A CN 102201910A
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Abstract
The invention provides a method for adjusting frequency based on an IEEE1588 (institute of electrical and electronic engineers) protocol and a network device. The method comprises the following steps: after a slave clock device receives messages of the IEEE1588 protocol sent by a master clock device, using first frequency information provided by a clock source module to mark timestamps on the messages of the IEEE15888 protocol; and calculating the frequency difference between the slave clock device and the master clock device in accordance with master clock information carried by the messages of the IEEE15888 protocol and the timestamps, and using the frequency difference to adjust second frequency information provided by the clock source module to be the frequency information which has the same frequency as the master clock device. According to the invention, an open-loop control system and the IEEE1588 protocol are utilized to realize the frequency synchronization, thus reducing the design cost of the system effectively, decreasing the control links and improving the accuracy effectively.
Description
Technical field
The present invention relates to data communication field, particularly relate to a kind of method and network equipment of adjusting frequency based on the IEEE1588 agreement is provided.
Background technology
Carrying out clock synchronization by the IEEE1588 agreement at present mainly is Phase synchronization, calculates master clock and from the time difference of clock, carries out the phase place adjustment by the IEEE1588 agreement.Recover the ethernet line clock in the mode that the system design of frequency retrieval is adopted for passing through the synchronous ethernet technology; Perhaps adopt IEEE1588 agreement closed-loop system, the clock frequency by algorithm change hardware is the speed that stabs of influence time simultaneously, realizes realizing by the IEEE1588 agreement algorithm of frequency retrieval, and as shown in Figure 1, existing closed-loop system comprises following components:
Crystal oscillator: be used to from clock equipment frequency information is provided, frequency information is offered DPLL(Digital Phase Locked Loop, DPLL digital phase-locked loop) module;
The DPLL module, by the controlling value that recording controller provides the frequency information that crystal oscillator provides is adjusted, obtain the frequency with the master clock device synchronization, and adjusted frequency information is exported to the timestamp module, adjusted frequency can be stabbed the speed that module is played stamp by influence time;
Timestamp module: according to the frequency information that the DPLL module provides the IEEE1588 protocol massages that receives is played stamp, then IEEE1588 protocol massages and the timestamp of beating are sent to phase discriminator;
Phase discriminator:, calculate master clock equipment and, time difference information is exported to recording controller from time difference of clock equipment by the timestamp that IEEE1588 protocol massages and timestamp module are beaten;
Recording controller calculated from the difference on the frequency of clock equipment with respect to master clock equipment according to the described time difference, and difference on the frequency is filtered the controlled value in back, and this controlling value is exported to the DPLL module.
Above-mentioned two kinds of methods are the main methods for designing of present equipment vendors and chip design manufacturer.But there are a lot of drawbacks in these methods, must support the function of synchronous ethernet as hardware designs, support the IEEE1588 protocol with hardware to influence the speed etc. that hardware is beaten timestamp when needing closed loop frequency adjustable, this will bring the complexity of system design, and cost of hardware design.
Summary of the invention
The technical problem to be solved in the present invention provides a kind of method and network equipment of adjusting frequency based on the IEEE1588 agreement, to reduce controlling unit, effectively improves precision.
In order to solve the problems of the technologies described above, the invention provides a kind of method of adjusting frequency based on the IEEE1588 agreement, comprising:
Receive the IEEE1588 protocol massages of master clock equipment transmission from clock equipment after, the first frequency information of utilizing this equipment to provide is beaten timestamp to described IEEE1588 protocol massages;
Master clock information of carrying according to described IEEE1588 protocol massages and described timestamp calculate described from the difference on the frequency of clock equipment with respect to described master clock equipment, the second frequency information of utilizing described difference on the frequency that this equipment is provided be adjusted into and described master clock equipment with frequency information frequently.
Further, said method also has following characteristics: described master clock information of carrying according to described IEEE1588 protocol massages from clock equipment and described timestamp calculate and describedly comprise from the step of clock equipment with respect to the difference on the frequency of described master clock equipment:
Described master clock information and the described timestamp that from the twice IEEE1588 protocol massages reciprocal process that clock equipment basis and described master clock equipment carry out, carries, calculate mutual time difference Offset1 and the Offset2 of IEEE1588 protocol massages respectively twice, calculate described by following formula from the difference on the frequency of clock equipment with respect to the unit interval of described master clock equipment:
（Offset2-?Offset1）/（T2-T1），
Wherein, T1, T2 be respectively for the first time and for the second time in the IEEE1588 protocol massages reciprocal process master clock equipment send moment of sync message.
Further, said method also has following characteristics: described after the clock calculation of equipments goes out difference on the frequency, also comprise: described difference on the frequency is filtered.
In order to address the above problem, the present invention also provides the network equipment of a kind of conduct from clock equipment, comprising:
The clock source module is used to the timestamp module that first frequency information is provided, and provides second frequency information for frequency regulation block;
Described timestamp module after being used to receive the IEEE1588 protocol massages of master clock equipment transmission, utilizes first frequency information that described IEEE1588 protocol massages is beaten timestamp;
Micro control module, the master clock information and the described timestamp that are used for carrying according to described IEEE1588 protocol massages calculate described from the difference on the frequency of clock equipment with respect to described master clock equipment;
Described frequency regulation block is used to utilize described difference on the frequency that second frequency information is adjusted into and the frequency information of described master clock equipment with frequency.
Further, above-mentioned network equipment also has following characteristics: described micro control module comprises:
Protocol processing unit, be used for the master clock information and the described timestamp that carry according to the adjacent twice IEEE1588 protocol massages reciprocal process of carrying out with described master clock equipment, calculate mutual time difference Offset1 and the Offset2 of IEEE1588 protocol massages respectively twice;
The difference on the frequency computing unit is used for calculating by following formula described from the difference on the frequency of clock equipment with respect to the unit interval of described master clock equipment: (Offset2-Offset1)/(T2-T1),
Wherein, T1, T2 be respectively for the first time and for the second time in the IEEE1588 protocol massages reciprocal process master clock equipment send moment of sync message.
Further, above-mentioned network equipment also has following characteristics: described micro control module also comprises:
The digital filtering unit is used for the difference on the frequency that described difference on the frequency computing unit calculates is filtered, and then exports to described frequency regulation block.
Further, above-mentioned network equipment also has following characteristics: described clock source module is a crystal oscillator.
Further, above-mentioned network equipment also has following characteristics: described network equipment is for supporting switch, router, base station or the Packet Transport Network of IEEE1588.
To sum up, the invention provides a kind of method and network equipment of adjusting frequency, realize Frequency Synchronization, effectively reduce the system design cost, reduce controlling unit, effectively improve precision by open-loop control system and IEEE1588 agreement based on the IEEE1588 agreement.
Description of drawings
Fig. 1 is the schematic diagram of the closed-loop system of prior art;
Fig. 2 is the schematic diagram of network element of the present invention;
Fig. 3 is the flow chart of a kind of method of adjusting frequency based on the IEEE1588 agreement of the present invention.
Embodiment
Provided by the inventionly be that from clock equipment and difference from clock equipment of the prior art recording controller is exported to a frequency adjuster with controlling value, adjust frequency by frequency adjuster, and adjusted can influence time stab module beat the stamp frequency.
For making the purpose, technical solutions and advantages of the present invention clearer, hereinafter will be elaborated to embodiments of the invention in conjunction with the accompanying drawings.Need to prove that under the situation of not conflicting, embodiment among the application and the feature among the embodiment be combination in any mutually.
As shown in Figure 2, the conduct that the embodiment of the invention provides comprises following module from the network equipment of clock equipment:
The clock source module: be used for providing frequency information to this from clock equipment, in the present embodiment, the clock source module offers frequency information timestamp module and frequency regulation block simultaneously; The clock source module of present embodiment is preferably crystal oscillator, can certainly be other devices that frequency information can be provided.
The timestamp module: the frequency information that is used for providing according to the clock source module is played stamp to the IEEE1588 protocol massages that receives, and then IEEE1588 protocol massages and the timestamp of beating is issued micro control module;
Micro control module, the master clock information and the described timestamp that are used for carrying according to described IEEE1588 protocol massages calculate described from the difference on the frequency of clock equipment with respect to described master clock equipment;
Described frequency regulation block is used to utilize described difference on the frequency that the frequency information that receives is adjusted into and the frequency information of described master clock equipment with frequency.
In a preferred embodiment, described micro control module can comprise:
Protocol processing unit, be used for the master clock information and the described timestamp that carry according to the adjacent twice IEEE1588 protocol massages reciprocal process of carrying out with described master clock equipment, calculate mutual time difference Offset1 and the Offset2 of IEEE1588 protocol massages respectively twice;
The difference on the frequency computing unit is used for calculating by following formula described from the difference on the frequency of clock equipment with respect to described master clock equipment: (Offset2-Offset1)/(T2-T1),
Wherein, T1, T2 be respectively for the first time and for the second time in the IEEE1588 protocol massages reciprocal process master clock equipment send moment of sync message.
In another preferred embodiment, described micro control module can also comprise:
The digital filtering unit is used for the difference on the frequency that described difference on the frequency computing unit calculates is filtered, and exports to described frequency regulation block then.
In the actual scene, there is the network equipment in stabilizing clock source can be as master clock, if: a switch connects a GPS(Global Positioning System, global positioning system), this switch is supported IEEE1588, the equipment time service that the mode that can pass through IEEE1588 for synchronously the time of oneself GPS is given other, and such equipment just can be master clock equipment, also have other master clock equipment, not necessarily use GPS.
Support that the equipment of IEEE1588 can be as from clock equipment, recovery time and the frequency from the IEEE1588 message as long as this equipment is had the ability, for example, switch, router, base station, PTN(Packet Transport Network, Packet Transport Network) as long as support that IEEE1588 just can work as from clock equipment.
The embodiment of the invention realizes realizing by IEEE 1588 agreements the open cycle system of frequency retrieval, for calculate master clock by 1588 agreements and from the OFFSET(deviation of clock) value, the OFFSET value is passed to frequency adjuster as input parameter, and adjusted frequency is the equipment use that synchronised clock is exported to be needed.In this system, hardware designs does not need to support closed-loop system, the phase place adjustment of synchronous ethernet, frequency adjustment, only needs hardware to provide the timestamp of certain precision to beat the stamp function, has reduced the error stack of controlling unit, effectively reduces cost.
Because the system of the embodiment of the invention is an open-loop control system; it or not the frequency of directly adjusting crystal oscillator; beat the speed of stamp and the controlling value of synchronizing frequency needs and do not have feedback element; reduce the complexity that Filtering Model is set up; the availability of effective elevator system; reduce the modeling link, effectively improve the Frequency Synchronization precision.
Fig. 3 is the flow chart of method of adjusting frequency based on the IEEE1588 agreement of the present invention, and as shown in Figure 3, this method comprises following step:
S10, receive the IEEE1588 protocol massages that master clock equipment sends from clock equipment after, utilize the frequency information of this equipment that described IEEE1588 protocol massages is beaten timestamp;
S20, the master clock information of carrying according to described IEEE1588 protocol massages and described timestamp calculate described from the difference on the frequency of clock equipment with respect to described master clock equipment, utilize described difference on the frequency that the frequency information of this equipment is adjusted into and described master clock equipment with frequency information frequently.
With a specific embodiment method of the present invention is described in detail below.
Master clock equipment and as follows from the mutual complete procedure of IEEE 1588 protocol massages between the clock equipment:
A, master clock equipment are to from synchronous (SYNC) message of clock device broadcasts, master clock equipment is write down the delivery time TM1 of this moment, in two step modules, can TM1 be carried to from clock equipment by following (FOLLOW_UP) message, in a step mode, when sending the SYNC message, TM1 is added in the SYNC message by hardware.
B, receive the SYNC message from clock equipment after, write down the TS1 time of reception of this moment, to master clock equipment forward delay interval request (DELAY_REQ) message, write down delivery time TS2 then;
After c, master clock equipment are received the DELAY_REQ message, write down the TM2 time of reception, reply (DELAY_RESP) message to send out pound time-delay from clock equipment then, time stamp T M2 is carried to from clock equipment,
D, from clock equipment according to four time stamp T M1, TS1, TS2 and TM2 collecting, and two formula calculate respectively:
Time delay (Delay)=0.5(TS1-TM1+ TM2-TS2)
Time deviation (Offset)=TS1-TM1-Delay.
In the present embodiment, calculate Offset1 and Offset2 alternately by adjacent twice IEEE, 1588 protocol massages, calculate difference on the frequency by following formula then with respect to the unit interval of described master clock equipment from clock equipment:
（Offset2-?Offset1）/（TM1’-TM1），
Wherein, TM1 ' is the moment that master clock equipment sends the SYNC message in the IEEE 1588 protocol massages reciprocal processes second time.
Because the existence of link flapping noise inputs to digital filter from clock equipment to the frequency departure with the unit interval, carries out noise filtering, the controlling value that the frequency frequency difference after the filtration is adjusted as frequency.
Because the method for present embodiment is embodied as the system of open loop type, does not have integral element, so the result who calculates directly is the controlling value of frequency adjustment, need not add up, reduce the error stack of accumulative total link, improve synchronization accuracy.
One of ordinary skill in the art will appreciate that all or part of step in the said method can instruct related hardware to finish by program, described program can be stored in the computer-readable recording medium, as read-only memory, disk or CD etc.Alternatively, all or part of step of the foregoing description also can use one or more integrated circuits to realize.Correspondingly, each the module/unit in the foregoing description can adopt the form of hardware to realize, also can adopt the form of software function module to realize.The present invention is not restricted to the combination of the hardware and software of any particular form.
Below only be the preferred embodiments of the present invention; certainly; the present invention also can have other various embodiments; under the situation that does not deviate from spirit of the present invention and essence thereof; those of ordinary skill in the art work as can make various corresponding changes and distortion according to the present invention, but these corresponding changes and distortion all should belong to the protection range of the appended claim of the present invention.
Claims (8)
1. method of adjusting frequency based on the IEEE1588 agreement comprises:
Receive the IEEE1588 protocol massages of master clock equipment transmission from clock equipment after, the first frequency information of utilizing this equipment to provide is beaten timestamp to described IEEE1588 protocol massages;
Master clock information of carrying according to described IEEE1588 protocol massages and described timestamp calculate described from the difference on the frequency of clock equipment with respect to described master clock equipment, the second frequency information of utilizing described difference on the frequency that this equipment is provided be adjusted into and described master clock equipment with frequency information frequently.
2. the method for claim 1 is characterized in that: described master clock information of carrying according to described IEEE1588 protocol massages from clock equipment and described timestamp calculate and describedly comprise from the step of clock equipment with respect to the difference on the frequency of described master clock equipment:
Described master clock information and the described timestamp that from the twice IEEE1588 protocol massages reciprocal process that clock equipment basis and described master clock equipment carry out, carries, calculate mutual time difference Offset1 and the Offset2 of IEEE1588 protocol massages respectively twice, calculate described by following formula from the difference on the frequency of clock equipment with respect to the unit interval of described master clock equipment:
（Offset2-?Offset1）/（T2-T1），
Wherein, T1, T2 be respectively for the first time and for the second time in the IEEE1588 protocol massages reciprocal process master clock equipment send moment of sync message.
3. method as claimed in claim 1 or 2 is characterized in that: described after the clock calculation of equipments goes out difference on the frequency, also comprise:
Described difference on the frequency is filtered.
4. a conduct comprises from the network equipment of clock equipment:
The clock source module is used to the timestamp module that first frequency information is provided, and provides second frequency information for frequency regulation block;
Described timestamp module after being used to receive the IEEE1588 protocol massages of master clock equipment transmission, utilizes first frequency information that described IEEE1588 protocol massages is beaten timestamp;
Micro control module, the master clock information and the described timestamp that are used for carrying according to described IEEE1588 protocol massages calculate described from the difference on the frequency of clock equipment with respect to described master clock equipment;
Described frequency regulation block is used to utilize described difference on the frequency that second frequency information is adjusted into and the frequency information of described master clock equipment with frequency.
5. network equipment as claimed in claim 4 is characterized in that: described micro control module comprises:
Protocol processing unit, be used for the master clock information and the described timestamp that carry according to the adjacent twice IEEE1588 protocol massages reciprocal process of carrying out with described master clock equipment, calculate mutual time difference Offset1 and the Offset2 of IEEE1588 protocol massages respectively twice;
The difference on the frequency computing unit is used for calculating by following formula described from the difference on the frequency of clock equipment with respect to the unit interval of described master clock equipment: (Offset2-Offset1)/(T2-T1),
Wherein, T1, T2 be respectively for the first time and for the second time in the IEEE1588 protocol massages reciprocal process master clock equipment send moment of sync message.
6. network equipment as claimed in claim 5 is characterized in that: described micro control module also comprises:
The digital filtering unit is used for the difference on the frequency that described difference on the frequency computing unit calculates is filtered, and then exports to described frequency regulation block.
7. as each described network equipment of claim 4-6, it is characterized in that:
Described clock source module is a crystal oscillator.
8. as each described network equipment of claim 4-6, it is characterized in that: described network equipment is for supporting switch, router, base station or the Packet Transport Network of IEEE1588.
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| CN2011101181513A CN102201910A (en) | 2011-05-09 | 2011-05-09 | Method for adjusting frequency based on IEEE1588 (institute of electrical and electronic engineers) protocol and network device |
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| CN2011101181513A CN102201910A (en) | 2011-05-09 | 2011-05-09 | Method for adjusting frequency based on IEEE1588 (institute of electrical and electronic engineers) protocol and network device |
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Cited By (4)
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| CN102769505A (en) * | 2012-07-19 | 2012-11-07 | 中兴通讯股份有限公司 | Method and device for realizing clock synchronization |
| CN102780554A (en) * | 2012-07-17 | 2012-11-14 | 中兴通讯股份有限公司 | Method and system for realizing synchronization through 1588 protocol |
| CN104660359A (en) * | 2013-11-21 | 2015-05-27 | 中兴通讯股份有限公司 | Clock frequency offset detection method, device and equipment |
| EP2869662A4 (en) * | 2012-06-28 | 2015-06-10 | Huawei Tech Co Ltd | Multi-mode base station and implementation method thereof |
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| CN101977104A (en) * | 2010-11-13 | 2011-02-16 | 上海交通大学 | IEEE1588 based accurate clock synchronization protocol system and synchronization method thereof |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2869662A4 (en) * | 2012-06-28 | 2015-06-10 | Huawei Tech Co Ltd | Multi-mode base station and implementation method thereof |
| US9178689B2 (en) | 2012-06-28 | 2015-11-03 | Huawei Technologies Co., Ltd. | Multimode base station and implementation method thereof |
| CN102780554A (en) * | 2012-07-17 | 2012-11-14 | 中兴通讯股份有限公司 | Method and system for realizing synchronization through 1588 protocol |
| CN102769505A (en) * | 2012-07-19 | 2012-11-07 | 中兴通讯股份有限公司 | Method and device for realizing clock synchronization |
| CN102769505B (en) * | 2012-07-19 | 2015-09-16 | 中兴通讯股份有限公司 | A kind of method and device realizing clock synchronous |
| CN104660359A (en) * | 2013-11-21 | 2015-05-27 | 中兴通讯股份有限公司 | Clock frequency offset detection method, device and equipment |
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Application publication date: 20110928 |