System and method for synchronizing GPON OLT and previous-level clock in ToD service scene

Abstract

The invention discloses a system and method for synchronizing a GPON OLT and a previous-level clock in a ToD service scene, relating to the field of optical fibre access networks. When the system and the previous-level clock are synchronous, a clock module is synchronous with a clock source of the GPON OLT; the previous-level clock respectively sends a 1PPS clock signal to the clock module and a ToD signal to the GPON OLT; the clock module performs synchronous calibration of a second counter and a nanosecond counter according to the 1PPS clock signal; after simultaneously detecting a sampling signal and a GPON frame starting time signal sent by the GPON OLT, the clock module records the starting time of a GPON downlink super-frame to be sampled; and the GPON OLT reads the starting time of a current GPON downlink super-frame from the clock module. The system disclosed by the invention can be precisely synchronous with the previous-level clock; the sending time corresponding to the starting bit of a specific GPON downlink super-frame can be precisely obtained; furthermore, the upgrading cost of the GPON OLT can be reduced; and the system and the method are applied to popularization.

Description

technical field [0001] The present invention relates to the field of optical fiber access network, in particular to a 1588 (precise clock synchronization protocol standard for network measurement and control system) ToD (Timeoftheday, Ethernet message, which contains 1PPS rising edge and can be converted into year, month, day, hour and minute A system and method for synchronizing GPONOLT and a superior clock in a business scenario. Background technique [0002] The GPON (Gigabit-Capable Passive Optical Network, Gigabit-Capable Passive Optical Network) system plays the role of transparently transmitting the clock signal in the 1588 network. GPONOLT (optical line terminal, optical line terminal) needs to transparently transmit the clock signal and correct the forwarding delay of the signal. GPONOLT itself does not process the 1588 protocol message. ITU-TG.984.3AMD2 (supplementary standard for GPON transmission and convergence layer) defines a method for synchronizing time in ...

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Problems solved by technology

[0003] However, although GPONOLT has an electronic clock with a fixed frequency provided by a crystal oscillator, the electronic clock cannot be synchronized with the upper-level clock, that is, the above-mentioned precise clock synchronized with the upper-level clock node does not actually exist in GPONOLT

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