Patent ID: 6848053

Claim:
An optical network unit coupled to an optical access network system, which receives a data stream and dechurns information contained in the received data stream by using a churning key, comprising: (a) churning parameter memory means for storing churning parameters that indicate which logical connections are churned or not churned, comprising: (a1) first memory means, initially assigned an active role, for storing the churning parameters that are currently used, and (a2) second memory means, initially assigned a backup role, for storing newly updated churning parameters, wherein said first memory means and second memory means are controlled so that the active and backup roles will alternate with each other at every churning key updating time point at which an updated churning key becomes effective; and (b) data dechurning means for receiving a data stream consisting of a plurality of frames and dechurning churned information contained in the data stream according to the churning parameters stored in said first or second memory means currently playing the active role, the churning parameters being activated at the beginning of a frame subsequent to the churning key updating time point said first memory means is assigned the backup role, and said second memory means is assigned the active role as a result of said alternating of the active and backup roles at the churning key updating time point; and said churning parameter memory means performs a copying process to copy the stored churning parameters from said second memory means to said first memory means, and wherein said churning parameter memory means saves a new churning parameter into said first memory means after the copying process is finished, when the new churning parameter is received during the copying process.