Method and apparatus for controlling delay in a device for transporting packets over optical transport network

• US 10,038,511 B1
• Filed: 06/06/2017
• Issued: 07/31/2018
• Est. Priority Date: 06/06/2017
• Status: Active Grant

• Current Assignee: Aimvalley B.V.
• Original Assignee: Aimvalley B.V.
• Inventors: Bosch, Willem Van Den
• Primary Examiner(s): Dobson, Daniel
• Application Number:
  US15/614,778
• Time in Patent Office: 420 Days
• CPC Class Codes: H04B 10/25 Arrangements specific to fibre transmission
• CPC Class Codes: H04B 10/40 Transceivers
• CPC Class Codes: H04J 2203/0085 Support of Ethernet
• CPC Class Codes: H04J 3/0638 Clock or time synchronisation among nodes; Internode synchronisation synchronization for ring networks H04L12/422; data switching networks with synchronous transmission H04L12/43
• CPC Class Codes: H04J 3/0655 using timestamps
• CPC Class Codes: H04J 3/0682 by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging
• CPC Class Codes: H04J 3/07 using pulse stuffing for systems with different or fluctuating information rates or bit rates
• CPC Class Codes: H04J 3/16 in which the time allocation to individual channels within a transmission cycle is variable, e.g. to accommodate varying complexity of signals, to vary number of channels transmitted H04J3/17, H04J3/24 take precedence
• CPC Class Codes: H04J 3/1652 Optical Transport Network [OTN]
• CPC Class Codes: H04Q 2011/0088 Signalling aspects

Abstract

A method and apparatus for controlling delay over a data path in a device for transporting Ethernet packets over an optical transport network. The device is configured to receive an incoming clock signal having a first frequency and an incoming data signal and to output an outgoing clock signal having a second frequency and an outgoing data signal. One or more delays over the data path in the device are measured in a predetermined measurement period. A phase adjustment amount is determined based on the one or more measured delays over the data path in the predetermined measurement period, and based on the determining phase adjustment amount, a phase of the outgoing clock signal is adjusted by a phase locked loop in such a way that the delay over the data path in the device is substantially equal to a fixed delay value.

Claims

1. A method of controlling a delay over a data path in a device configured to transport Ethernet packets over an optical transport network, the device being configured to receive an incoming clock signal having a first frequency and an incoming data signal and to output an outgoing clock signal having a second frequency and an outgoing data signal, the method comprising:

measuring one or more delays over the data path in the device in a predetermined measurement period, the data path being including an Ethernet client data path;

determining a phase adjustment amount based on the one or more measured delays over the data path in the predetermined measurement period; and

adjusting a phase of the outgoing clock signal via a phase locked loop based on the determined phase adjustment amount such that the delay over the data path in the device is substantially equal to a fixed delay value.

2. The method of claim 1, wherein the incoming clock signal has a fixed frequency relation with respect to the outgoing clock signal, and wherein adjusting a phase of the outgoing clock signal comprises steering the phase locked loop by either decreasing or increasing a phase of the incoming clock signal.

3. The method of claim 2, wherein the first frequency of the incoming clock signal and the second frequency of the outgoing clock signal are substantially the same.

4. The method of claim 1, wherein the fixed delay value comprises an average delay over the data path in the device, or comprises a delay mid-point value between a minimum measured delay and a maximum measured delay measured over the data path in the device for the predetermined measurement period.

5. The method of claim 1, wherein the incoming clock signal does not have any fixed frequency relation with respect to the outgoing clock signal, and wherein adjusting a phase of the outgoing clock signal comprises steering a phase of the phase locked loop based at least on demapping information included in the incoming data signal, the demapping information being comprising stuff indication information.

6. The method of claim 1, wherein the incoming clock signal does not have any fixed frequency relation with respect to an outgoing server clock signal, and wherein a phase of an outgoing client signal is steered based on additional mapping bit stuff information to adjust the phase of the outgoing client signal, the mapping information comprising stuff indication information.

7. The method of claim 5, wherein the incoming data signal comprises an optical transport network (OTN) signal and the outgoing data signal comprises an Ethernet client signal.

8. The method of claim 6, wherein the incoming data signal comprises an Ethernet client signal and the outgoing data signal comprises an optical transport network (OTN) signal.

9. The method of claim 5, wherein steering a phase of the phase locked loop is based on a number of client data bits in the incoming data signal and a latency in the data path in the device.

10. The method of claim 5, wherein steering a phase of the phase locked loop is based on inserting a number of data bits in the outgoing data signal.

11. The method of claim 6, wherein steering a phase of the client Ethernet signal is based on an additional number of mapping data bits in the server data signal to control the latency of the Ethernet client data path in the device.

12. The method of claim 5, wherein adjusting a phase of the outgoing clock signal comprises adding additional de-mapping information to adjust an output frequency of the phase locked loop in such a way that the delay in the data path in the device is substantially equal to a fixed delay value.

13. The method of claim 5, wherein adjusting a phase of the outgoing clock signal comprises adding additional mapping information to adjust an output frequency of the phase locked loop in such a way that the delay in the data path in the device is substantially equal to the fixed delay value.

14. An apparatus for controlling a delay in a data path in a system configured to transport Ethernet packets over an optical transport network, the system being configured to receive an incoming clock signal having a first frequency and an incoming data signal and to output an outgoing clock signal having a second frequency and an outgoing data signal, the apparatus comprising:

a current delay measurement unit configured to measure one or more delays in the data path in the system for a predetermined measurement period;

a delay control unit configured to produce a delay adjustment amount based on the one or more measured delays in the data path in the system; and

a phase adjustment unit coupled to a phase locked loop and configured to receive the delay adjustment amount from the delay control unit and configured to steer the phase locked loop to produce the outgoing clock signal, such that the delay in the data path in the system is substantially equal to a fixed delay value.

15. The apparatus of claim 14, wherein the data path comprises an Ethernet client data path.

16. The apparatus of claim 14, wherein:

the incoming clock signal has a fixed frequency relation with respect to the outgoing clock signal, and

the phase adjustment unit is further configured to decrease or increase a phase of the incoming clock signal to steer the phase locked loop such that the delay in the data path in the system is substantially equal to the fixed delay value.

17. The apparatus of claim 14, wherein the fixed delay value comprises an average delay in the data path in the system or a delay mid-point value between a minimum measured delay and a maximum measured delay measured in the data path for the predetermined measurement period.

18. The apparatus of claim 14, wherein the first frequency of the incoming clock signal and the second frequency of the outgoing clock signal have a same frequency value.

19. The apparatus of claim 14, wherein when the incoming clock signal does not have any fixed frequency relation with respect to the outgoing clock signal, the phase adjustment unit is further configured to steer the phase locked loop based at least on de-mapping information included in the incoming data signal, the de-mapping information comprising stuff indication information.

20. The apparatus of claim 14, wherein when the incoming clock signal does not have any fixed frequency relation with respect to the outgoing clock signal, the phase adjustment unit is further configured to steer the phase of the outgoing client signal based on mapping information inserted in a server data signal, the mapping information comprising stuff indication information.

21. The apparatus of claim 14, wherein:

the phase adjustment unit is further configured to steer the phase locked loop based on a number of client data bits included in the incoming data signal and a latency determined in the data path in the system, and

the incoming data signal comprises an optical transport network signal and the outgoing data signal comprises an Ethernet client signal.

22. The apparatus of claim 14, wherein:

the phase adjustment unit is further configured to steer the phase of the outgoing client signal based on a number of client data bits included in the outgoing server data signal and a latency determined in the data path in the system; and

the incoming data signal comprises an Ethernet client signal and the outgoing data signal comprises an optical transport network signal.

23. The apparatus of claim 14, wherein:

the phase adjustment unit is further configured to add additional de-mapping information to adjust an output frequency of the phase locked loop in such a way that the delay in the data path in the system is substantially equal to a fixed delay value; and

the phase adjustment unit includes a de-mapping synchronizer phase locked loop.