Patent ID: 6771908
Filing Date: 2004-08-03
Classification: H04B,H04J,H04Q

Abstract:
In an optical network comprising an optical splitter connected to (1) a working optical subscriber unit (OSU) of a working circuit, (2) a protection OSU of a protection circuit, and (3) one or more optical network terminals (ONTs), wherein at least one ONT comprises (i) a working line termination (LT) unit of the working circuit and connected to the optical splitter via a working optical fiber and (ii) a protection LT unit of the protection circuit and connected to the optical splitter via a protection optical fiber, a method for enabling fast protection switching from the working circuit to the protection circuit, comprising the steps of:(a) synchronizing the working and protection LT units of the at least one ONT; (b) measuring arrival times of corresponding downstream cells at both the working and protection LT units of the at least one ONT; (c) transmitting information related to the arrival times from the at least one ONT to the protection OSU; and (d) generating at least one propagation delay value based on the transmitted information for use by the protection OSU for communications with the at least one ONT if and when protection switching is implemented upon detection of a failure in the working circuit.