Methods of performing time-of-day synchronization in packet processing networks
View Patent ↗Methods of performing time-of-day synchronization in a packet processing network include accumulating timestamps transmitted in packets between master and slave devices, which are synchronized to respective master and slave clocks and separated from each other by the packet processing network. Operations are also performed to determine whether first timestamps accumulated in a first direction across the packet network demonstrate that a first packet delay variation (PDV) sequence observed from the first timestamps is stationary. A phase offset between the master and slave clocks is then adjusted using a time-of-day (ToD) estimation algorithm. This adjusting can include evaluating a location-dependent statistic of the first PDV sequence.
1. A method of performing time-of-day synchronization in a packet processing network, comprising:
accumulating timestamps transmitted in packets between master and slave devices, which are synchronized with respective master and slave clocks;
determining whether first timestamps accumulated in a first direction across the packet network demonstrate that a first packet delay variation (PDV) sequence observed from the first timestamps is stationary;
adjusting a phase offset between the master and slave clocks using a time-of-day estimation algorithm, said adjusting comprising determining a location-dependent statistic of the first PDV sequence; and
comparing a distribution of the first PDV sequence against distributions associated with a library of stored PDV sequences to determine a match therebetween.
2. The method of claim 1 , wherein said comparing comprises determining a distance between a signature vector associated with the first PDV sequence and at least one signature vector associated with a stored PDV sequence in the library.
3. The method of claim 1 , wherein said comparing comprises determining a location-independent statistic of the first PDV sequence.
4. The method of claim 3 , wherein the location-independent statistic is selected from a group consisting of a standard deviation, a variance, a mean absolute deviation from the mean, a skewness, a full empirical discrete probability density function and a kurtosis.
5. The method of claim 4 , wherein the location-dependent statistic is selected from a group consisting of mean, minimum, maximum and mode.
6. The method of claim 1 , wherein the location-dependent statistic is selected from a group consisting of mean, minimum, maximum and mode.