Patent ID: 7587139

Claim:
In an optical network, a method for operating a node comprising an optical add/drop multiplexer (OADM) in said network, said method comprising: receiving at the node an indicator of input ASE power comprising an estimate of total input ASE power over total input power from a previous node in line; generating an indicator of output ASE power comprising an estimate of total output ASE power over total output power, wherein said generating comprises: measuring total input power; estimating absolute ASE input power by multiplying said indicator of input ASE power by total input power; estimating absolute output power by multiplying absolute ASE input power by loss associated with said OADM for channels that pass through the OADM; and estimating said indicator of output ASE power by dividing absolute ASE output power by total output power; and transmitting said indicator of output ASE power to a next node in line.