Patent ID: 6968131

Claim:
A method of determining topology of an optical WDM (wavelength division multiplex) network in which optical signals comprising a plurality of WDM optical channels are communicated, comprising the steps of: modulating each optical channel with a respective signal comprising a channel identity; detecting the channel identities of all of the optical channels in an optical signal at each of a plurality of points in the network to produce a channel list for each of said points; identifying matched pairs of channel lists to determine optical paths of the network between pairs of said points; wherein the step of detecting channel identities comprises detecting the channel identities of all of the optical channels in an optical signal at a multiplex port of each of a plurality of optical band filters to produce a respective channel list M, and determining a channel list T for a through port of the respective optical band filter, the channel list T comprising channels of the list M which are not within a pass band of the filter.