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Transparent clock for precision timing distribution

  • US 9,391,768 B2
  • Filed: 04/17/2014
  • Issued: 07/12/2016
  • Est. Priority Date: 11/10/2009
  • Status: Active Grant
First Claim
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1. A method comprising:

  • receiving, by an optical network unit (ONU) of a network having asymmetric delay, a precision time protocol (PTP) packet including an indication of a time at which the PTP packet was received by an optical line terminal (OLT) of the network, wherein a first clock in the ONU and a second clock in the OLT are synchronized;

    determining, by the ONU and based at least in part on a current time, the asymmetric delay, and one or more pre-forwarding packet processing calculations, a time at which the PTP packet is to be forwarded to a client device;

    determining, by the ONU, a residence time of the PTP packet in the network as the difference between the time at which the PTP packet is to be forwarded and the time at which the PTP packet was received by the OLT;

    adding, by the ONU, the residence time to a time stamp correction field of the PTP packet; and

    forwarding, by the ONU, the PTP packet to the client device.

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