Patent ID: 6868232

Claim:
In an optical network comprising an optical splitter connected to (1) a working optical subscriber unit (OSU) of a working circuit via a working optical fiber, (2) a protection OSU of a protection circuit via a protection optical fiber, and (3) one or more optical network terminals (ONTs), a method for enabling fast protection switching from the working OSU to the protection OSU, comprising the steps of: (a) synchronizing the working and protection OSUs; (b) initiating a cell delineation procedure at the protection OSU during normal, non-ranging operations of the working OSU to enable the protection OSU to correctly delineate upstream cells; (c) measuring arrival times of corresponding upstream cells at both the working and protection OSUs; and (d) generating a propagation delay value based on the arrival times for use by the protection OSU for communications with the one or more ONTs if and when protection switching is implemented upon detection of a failure in the working circuit, wherein the optical network further comprises: one or more additional working OSUs, each connected via an additional working optical fiber to an additional optical splitter, which is further connected to one or more additional ONTs; and an optical switch connected to each of the optical splitters via a protection optical fiber and to the protection OSU, wherein the optical switch is controlled to sequentially connect the protection OSU to each of the optical splitters to implement steps (a) through (d) to generate a different propagation delay value for each working OSU for use by the protection OSU in ranging the one or more ONTs corresponding to a particular working OSU if and when protection switching is implemented upon detection of a failure in the working circuit corresponding to the particular working OSU.