5 Replies Latest reply on Mar 19, 2018 12:16 AM by Intel Corporation

    Time Sensitive Networking (AVB) delays measurement



      I am testing the Intel I210 TSN Card (AVB). By measuring the Propagation Delays between a PC and a switch, it appears that the values are lower for 100 Mb/s speed link than for 1 Gb/s speed.


      Link Delay             PC-> Switch    Switch -> PC

      1 m cable: 100 Mb/s          86 ns          82 ns
                    1 Gb/s         220 ns         212 ns

      25 m cable: 100 Mb/s         194 ns         192 ns
                    1 Gb/s         305 ns         303 ns

      It's quite strange. I wonder if this result comes from the RX and TX PHY compensations applied to the Timestamps.
      Indeed, PHY compensations defined by Intel are :


                           100 Mb/s      1 Gb/s
      TX PHY Compensation:   1044 ns      184 ns
      RX PHY Compensation:   2133 ns      382 ns


      Questions are:
      - How RX & TX PHY are computed?
      - How we can explain the above measured values?
      - What is the "correct" PDelay?


      Thanks to answer if you have done the same type of testing ou have ideas about that.


      Have a nice day.