NTP
  bez spirent
    8 minutes
      QNX + ptp master <-> switch <-> QNX + ptp slave

  spirent
    18 hours
      [spirent_bi-directional]
      QNX + ptp master <-> switch <-> switch <-> QNX + ptp slave
                                             <-> spirent transceiver
                                  <-> spirent transceiver
      [spirent_uni-directional]
      QNX + ptp master <-> switch <-> switch <-> QNX + ptp slave
                                             <-> spirent receiver
                                  <-> spirent transmitter
      [spirent_uni-directional]
      QNX + ptp master <-> switch <-> switch <-> QNX + ptp slave
                                             <-> spirent transmitter
                                  <-> spirent receiver

    8 minutes
      #performance of PTP/NTP QNX implementation
        QNX + ptp master <-> switch <-> QNX + ptp slave + receiver of spirent
                                                          dummy packets
                                    <-> spirent transmitter
        QNX + ptp slave <-> switch <-> QNX + ptp master + receiver of spirent
                                                          dummy packets
                                   <-> spirent transmitter

THOUGHTS
  "calibration" (establishing the accuracy of the FitKit crystal) using
    GPS periodical edge generator
  influence of decreasing and increasing (16 seconds like NTP) the PTP period
  QNX + ptp master <-> QNX PTP relay/transparent <-> QNX + ptp slave
  QNX + ntp master stratum 0 <-> QNX NTP master stratum 1 <-> QNX + ntp slave
                                                                    updating
                                                                    from
                                                                    stratum 1

measurements was first done after at least 10 minutes of synchronization
  using PTP above protocols and 30 minutes (though the accuracy si highly
    dependent on the intial frequency error - see
    http://www.ntp.org/ntpfaq/NTP-s-algo.htm#FIG-NTP-INIT) of
    synchronization using NTP
  on isolated LAN segment consisting only from switches
  describe in detail the configuration for PTP and NTP used for measurements
  PTP: specify inbound + outbound latency in nsec (compesate e.g. sockets usage)
    ptpd -l IN,OUT
