Customer Service Center
Spirent KB Article
Doc ID: FAQ16373
Email Article Link
Calnex Paragon-X: How is Time Interval Error (TIE) measured/calculated?
TIE is graphed for a couple of different modes – CES, SyncE and Wander measurements.
The principle is the same in each case... Paragon compares actual receive time or clock counts against a reference.
The CES settings in the Configure Capture page define the expected traffic packet gap – for example 1ms, or 1000 packets per second.
When Paragon receives a packet it is assigned a relative arrival time (the first packet of a capture has time = 0). The clocking of this time is based on the selected Reference – either the Paragon’s own internal reference, or an external 10MHz, 2MHz, E1 or T1.
For each packet(n), Paragon calculates the difference between the assigned arrival timestamp and the expected arrival time (n x 1ms). This difference is plotted as TIE.
In this case, Paragon recovers the clock from the physical layer of the incoming Ethernet, which is used to run a counter.
At the same time another counter is running, synchronized to the selected reference clock. At the selected sample rate, the number of clock counts is compared and the difference is plotted as TIE.
The same as SyncE, except that instead of recovering clock from Ethernet, the incoming 2MHz/E1/T1 signal under test is used to drive the counter.
Product : IEEE 1588