What tests does PFV perform on message rates / inter-message intervals?
PFV can test both average message rates and inter-message intervals. The tests performed are dependent on the message type. The sections below detail the tests performed for each message type as well as references to relevant standards.
Background
IEEE 1588, clause 7.7.2.1 states:
For each of the message types Announce, Sync, Delay_Req, and Pdelay_Req, the mean time interval between successive messages shall be represented as the logarithm to the base 2 of this time interval measured in seconds on the local clock of the device sending the message.
The mean time interval is carried in the PTP common header in a field called logMessageInterval. This is log2 of the mean interval. The table below shows logMessageInterval values for some of the common PTP rates:
| Message Interval (s) | 0.03125 | 0.0625 | 0.125 | 0,25 | 0.5 | 1 | 2 | 4 | 8 | 16 | 32 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Message Rate (per second) | 32 | 16 | 8 | 4 | 2 | 1 | 1/2 | 1/4 | 1/8 | 1/16 | 1/32 |
| logMessageInterval | -5 | -4 | -3 | -2 | -1 | 0 | 1 | 2 | 3 | 4 | 5 |
Announce message
Expected rates / intervals
The expected message
Tests
Standards
Sync message
Expected rates / intervals
Tests
Standards
Delay-Response message
Expected rates / intervals
Tests
Standards
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