Synchronization transport over passive optical networks

An optical line terminal (OLT) for clock transport in an Ethernet Passive Optical Network (EPON), comprising:

• a clock generator, coupled to a reference clock, configured to generate an OLT clock based on a frequency-reference signal corresponding to the reference clock;
• an optical transceiver, coupled to the clock generator, configured to transmit the OLT clock to a downstream optical network unit (ONU);
• and
• a phase-synchronization mechanism, coupled to the reference clock, configured to receive a phase-reference signal associated with the frequency-reference signal and to broadcast the phase information in an Operation Administration Management (OAM) message having a count number indicating a Multipoint Control Protocol (MPCP) time corresponding to the phase-reference signal.

An optical network unit (ONU) for clock transport in an Ethernet Passive Optical Network (EPON), comprising:

• an optical transceiver configured to receive an optical signal from an upstream optical line terminal (OLT);
• a clock-recovery module, coupled to the optical transceiver, configured to:
• recover a frequency-reference signal from the received optical signal, and
• receive phase information associated with a phase-reference signal from an Operation Administration Management (OAM) message broadcast by the upstream OLT, the OAM message including a count number indicating a Multipoint Control Protocol (MPCP) time corresponding to the phase-reference signal;
• a phase reference mechanism configured to synchronize a phase of the recovered frequency-reference signal to a phase of the phase-reference signal based on the received phase information;
• and
• a clock output mechanism configured to output the recovered frequency-reference signal to facilitate transport of the frequency-reference signal over the EPON.

A method for receiving a clock in an Ethernet Passive Optical Network (EPON), comprising:

• receiving an optical signal from an optical line terminal (OLT);
• recovering a frequency-reference signal from the received optical signal;
• receiving phase information associated with a phase-reference signal from an Operation Administration Management (OAM) message broadcast by the OLT, the OAM message including a count number indicating a Multipoint Control Protocol (MPCP) time corresponding to the phase-reference signal;
• synchronizing a phase of the recovered frequency-reference signal to a phase of the phase-reference signal based on the received phase information;
• and
• generating an output based on the recovered frequency-reference signal.