Characterizing slave clock synchronization behavior by means of dropped sync packets

Abstract

Methods, media, and systems are provided for characterizing the synchronization behavior of a slave clock. A sequence of sync packets, usable to synchronize with a grandmaster clock, is transmitted from the grandmaster clock to a slave clock. The sequence of sync packets is modified by dropping one or more sync packets from the sequence, providing a pattern of dropped sync packets. A synchronization output of the slave clock is monitored and, based on the synchronization output, a determination is made as to whether the slave clock is synchronized while the sequence of sync packets is modified. A characterization of the synchronization behavior of the slave clock is stored with respect to the pattern of dropped sync packets. The process may be repeated for various patterns of dropped sync packets.

The invention claimed is: 
     
       1. A method of characterizing a synchronization behavior of a slave device by dropping sync packets, the method comprising:
 transmitting a sequence of sync packets from a grandmaster device to a slave device, wherein the sync packets are received at an intermediate device and forwarded to the slave device; 
 monitoring a synchronization output of the slave device that is usable to determine whether the slave device is synchronized with the grandmaster device; 
 at the intermediate device, dropping one or more of the sync packets, wherein dropping one or more of the sync packets includes dropping one or more of the sync packets in a variety of repetitive patterns such that each of the repetitive patterns is transmitted for a respective period of time; 
 while dropping one or more of the sync packets, determining whether the slave device is synchronized with the grandmaster device; and 
 storing an indication that characterizes the synchronization behavior of the slave device with respect to each variety of the repetitive patterns. 
 
     
     
       2. The method of  claim 1 , wherein the sequence of sync packets is transmitted from the grandmaster device at a selected rate. 
     
     
       3. The method of  claim 1 , wherein the synchronization behavior of the slave device includes whether a frequency of a clock source associated with the slave device is synchronized with a frequency of a reference clock associated with the grandmaster device. 
     
     
       4. The method of  claim 2 , further comprising repeating the monitoring, dropping, determining, and storing for a plurality of selected rates. 
     
     
       5. The method of  claim 1 , wherein the synchronization behavior of the slave device includes how long the slave device remains synchronized in response to dropping one or more of the sync packets. 
     
     
       6. One or more non-transitory computer-readable media having embodied thereon instructions which, when executed by one or more computing devices, perform a method of characterizing a synchronization behavior of a slave device by dropping sync packets, the method comprising:
 transmitting a sequence of sync packets from a grandmaster device to a slave device, wherein the sync packets are received at an intermediate device and forwarded to the slave device; 
 monitoring a synchronization output of the slave device that is usable to determine whether the slave device is synchronized with the grandmaster device; 
 at the intermediate device, dropping one or more of the sync packets; 
 while dropping one or more of the sync packets, determining whether the slave device is synchronized with the grandmaster device; and 
 storing an indication that characterizes the synchronization behavior of the slave device with respect to dropping one or more of the sync packets, wherein the synchronization behavior of the slave device includes how long the slave device remains synchronized in response to dropping one or more of the sync packets. 
 
     
     
       7. The one or more non-transitory computer-readable media of  claim 6 , wherein the sequence of sync packets is transmitted from the grandmaster device at a selected rate. 
     
     
       8. The one or more non-transitory computer-readable media of  claim 6 , wherein dropping one or more of the sync packets includes dropping one or more of the sync packets in a repetitive pattern. 
     
     
       9. The one or more non-transitory computer-readable media of  claim 8 , the method further comprising:
 dropping one or more of the sync packets in a variety of repetitive patterns such that each of the repetitive patterns is transmitted for a respective period of time; and 
 storing an indication that characterizes the synchronization behavior of the slave device with respect to each variety of the repetitive patterns. 
 
     
     
       10. The one or more non-transitory computer-readable media of  claim 6 , wherein the synchronization behavior of the slave device includes whether a frequency of a clock source associated with the slave device is synchronized with a frequency of a reference clock associated with the grandmaster device. 
     
     
       11. The one or more non-transitory computer-readable media of  claim 7 , the method further comprising repeating the monitoring, dropping, determining, and storing for a plurality of selected rates. 
     
     
       12. A system for characterizing a synchronization behavior of a slave device by dropping sync packets, the system comprising:
 a grandmaster device that transmits a sequence of sync packets from the grandmaster device to a slave device, wherein the sync packets are received at an intermediate device and forwarded to the slave device; 
 the intermediate device that drops one or more of the sync packets; 
 a comparator device that
 A) monitors a synchronization output of the slave device that is usable to determine whether the slave device is synchronized with the grandmaster device, 
 B) while the intermediate device drops one or more of the sync packets, determines whether the slave device is synchronized with the grandmaster device, and 
 C) stores an indication that characterizes the synchronization behavior of the slave device with respect to dropping one or more of the sync packets, wherein the synchronization behavior of the slave device includes how long the slave device remains synchronized in response to dropping one or more of the sync packets. 
 
 
     
     
       13. The system of  claim 12 , wherein the sequence of sync packets is transmitted from the grandmaster device at a selected rate. 
     
     
       14. The system of  claim 12 , wherein dropping one or more of the sync packets includes dropping one or more of the sync packets in a repetitive pattern. 
     
     
       15. The system of  claim 14 , wherein the comparator device further:
 drops one or more of the sync packets in a variety of repetitive patterns such that each of the repetitive patterns is transmitted for a respective period of time; and 
 stores an indication that characterizes the synchronization behavior of the slave device with respect to each variety of the repetitive patterns. 
 
     
     
       16. The system of  claim 12 , wherein the synchronization behavior of the slave device includes whether a frequency of a clock source associated with the slave device is synchronized with a frequency of a reference clock associated with the grandmaster device. 
     
     
       17. The system of  claim 13 , wherein the intermediate device and the comparator device further repeat the monitoring, dropping, determining, and storing for a plurality of selected rates.