An online reconfiguration method comprising communicating data transfer units (DTUs) using a subscriber line, monitoring the subscriber line for a line condition event, detecting the line condition event, wherein detecting the line condition event comprises determining whether the line condition triggers a threshold, sending an online reconfiguration request message that indicates a robust management channel (RMC) frame type in response to detecting the line condition event, wherein the RMC frame type is a normal RMC frame that comprises time marker information when the line condition event does not trigger the threshold, and wherein the RMC frame type is a special RMC frame that comprises time marker information when the line condition event triggers the threshold, receive an online reconfiguration response message that comprises the time marker information, and synchronizing a transition of one or more transmission parameters using the time marker information.