Patent ID: 8625987

Claim:
A method for monitoring a passive optical network, PON, having a tree-like structure with a main line and a plurality of branches, the method comprising: transmitting a wake-up signal from an optical line termination, OLT, arranged in the main line to a plurality of monitoring units arranged in the plurality of branches, the wake-up signal not addressing a specific one of the plurality of monitoring units and the wake-up signal configured to wake the plurality of monitoring units from a sleep mode; detecting the wake-up signal and listening to information requests from the OLT in the plurality of monitoring units during a listening time interval after the detection of the wake-up signal; transmitting, after a waiting time interval by the OLT after transmission of the wake-up signal and before any other transmission by the OLT, an information request to be received in the listening time interval from the OLT to the plurality of monitoring units; and receiving the information request in the plurality of monitoring units during the listening time interval, one of the plurality of monitoring units which is addressed by the information request transmitting a response message back to the OLT.