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Spirent KB Article
Doc ID: FAQ12831
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Spirent TestCenter: How can we set the rate at which the PTP packets can be sent?
The maximum rate at which PTP packets can be sent is 128pps.
1588 uses a Logarithmic scale for setting rate for all messages. The fields to change interval or rate highlighted listed below
For example above:
Announce message rate is 2 ^0 = 1pps
Sync rate is 2 ^-4 = 16pps
Delay request rate= 16pps
In order to get packet rates of 128pps set the log interval = -7
Basically its 2 to the power of n, where n = the interval value entered in those fields
What is the frame rate for values -4 and +4?
-4 = 1/(2^4) = 0.0625s interval (this means 16 packets per second)
+4 = 2^4 = 16s interval (this means 1 packet every 16 seconds)
What is the frame rate for values -128 and +127?
-128 = 1/(2^128) interval in seconds
+127 = 2^127 interval in seconds
If you need to do a large number of slaves at high rates use Scale Mode=GenTx, in this mode there are no clock statistics since the rates are very high
Note that the 1588v2 message rate counter in the GUI has some limitations:
With 98 slaves receiving packets at 64 pps or 128 pps, the message rate counter may show ranges greater than 10% differences.
Also if slaves receive a rate of 0.125 pps, the message rate counter minimum vlaue may show zero instead.
Product : Spirent TestCenter,Spirent TestCenter,IEEE 1588