Customer Service Center

Latency measurement schemes setup in Spirent TestCenter (FIFO, FILO, LIFO and LILO)

• Spirent TestCenter
• PGA

Transmit and Receive timestamp reference locations can be set independently in Spirent TestCenter

At Traffic Generator ("Advanced" button above "Port Load" button)

• If the transmit timestamp reference location is at the start of the frame, transmit time of the frame is marked at the first bit the leaves the generator. After traversing the wire, this will be the first bit that goes into the DUT. So, generator “Start of Frame” timestamp equals FI (First In to the DUT).
• If the transmit timestamp reference location is at the end of the frame, transmit time of the frame is marked at the last bit that leaves the generator. This would be the last bit that enters the DUT. So, generator “End of Frame” timestamp equals LI (Last In to the DUT).

At Traffic Analyzer ("Timestamp Reference Locations" under "Advanced" tab)

• if the receive timestamp reference location is to be at the start of the frame, the receive time of the frame is marked at the first bit that is received. This would be the first bit out of the DUT. Analyzer “Start of Frame” = FO (First Out of the DUT).
• if the receive timestamp reference location is to be at the end of a frame, the receive time of the frame is marked at the last bit we receive. This would be the last bit out of the DUT. Analyzer “End of Frame” = LO (Last Out of the DUT).

• For basic traffic tests, start of frame reference is set for both generator and analyzer and thus FIFO
• For RFC 2544 tests, end of frame reference is set for both generator and analyzer and thus LILO