Method and system for realizing timestamp synchronization of active and standby optical line terminals

Abstract

The invention discloses a method for realizing the timestamp synchronization of an active optical line terminal (OLT) and a standby OLT. The method comprises that: the active OLT synchronously transmits round trip time (RTT) values with all online optical network units (ONU) to the standby OLT; and the standby OLT selects a reference ONU, and sets a value of a local timestamp counter according to a timestamp in a multipoint control protocol (MPCP) frame and an RTT value of the active OLT with the reference ONU after receiving the MPCP frame of the reference ONU. The invention simultaneously discloses a system for realizing the timestamp synchronization of the active and standby OLTs. By the scheme provided by the invention, timestamp counters of the active and standby OLTs in an Ethernet passive optical network (EPON) backbone optical fiber protection system can be effectively synchronized, and the offline state of the ONU caused by timestamp drift in handover can be avoided, thereby ensuring that the handover can be finished quickly. Moreover, requirements on the ONUs are relatively lower, and compatibility with all conventional ONU equipment can be achieved.

Description

technical field [0001] The invention relates to optical link protection technology, in particular to a method and system for realizing time stamp synchronization of main and standby optical line terminals. Background technique [0002] Ethernet Passive Optical Network (EPON, Ethernet Passive Optical Network) is a new generation of broadband passive optical integrated access technology based on the IEEE802.3-2005 Section 5 standard. The system usually consists of an optical line terminal (OLT, Optical Line Terminal), the user-side optical network unit (ONU, Optical Network Unit) / optical network terminal (ONT, Optical Network Termination) and optical distribution network (ODN, Optical Distribution Network). ODN is composed of passive optical components such as single-mode optical fibers, optical splitters, and optical connectors, and provides optical transmission media for the physical connection between OLT and ONU. ODN is usually a point-to-multipoint structure, that is, on...

AI Technical Summary

Problems solved by technology

[0005] There is such a problem in the type b protection system: before the switchover, the time stamp counter of the ONU and the time stamp counter on the PON port of the main OLT of the OLT are kept in sync; If the difference between the time stamp in the frame and the local time stamp counter is too large, time stamp drift will occur, causing the ONU to go offline

But this feature reduces the sensitivity of the ONU to normal de-registration events

On the other hand, many ONU devices in the current network do not support the holdover function, and time stamp drift is still prone to occur during type b switching

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