Patent ID: 7233738

Claim:
A protection switching system for use in a wavelength division multiplexing (WDM) optical communications system comprising a plurality of service wavelength processing device transmitters for transmitting optical signals at respective wavelengths, a plurality of service wavelength processing device receivers for receiving said optical signals at said respective wavelengths, and at least one service transmission line coupled between said service wavelength processing device transmitters and said service wavelength processing device receivers for carrying said optical signals, said protection switching system comprising: at least one spare wavelength processing device transmitter for transmitting an optical signal at a spare wavelength separate from said wavelengths of said optical signals transmitted by said service wavelength processing device transmitters, and wherein said spare wavelength processing device transmitter is configured to replace one of said service wavelength processing device transmitters; at least one spare wavelength processing device receiver for receiving an optical signal, wherein said spare wavelength processing device receiver is configured to replace one of said service wavelength processing device receivers, and wherein said spare wavelength processing device receiver is configured to monitor optical signals having any one of said wavelengths when said spare wavelength processing device receiver is not being used to replace one of said service wavelength processing device receivers; at least one spare transmission line coupled between said wavelength processing device transmitters and said wavelength processing device receivers for carrying said optical signals; and wavelength selection equipment for selectively routing said optical signals on either said service transmission line or said spare transmission line to either said service wavelength processing device receivers or said spare wavelength processing device receiver and for selecting one of said wavelengths to be sent to said spare wavelength processing device receiver, wherein said wavelength selection equipment is configured to sequentially provide each of said wavelengths of said optical signals on either said spare transmission line or said service transmission line to said spare wavelength processing device receiver for monitoring by said spare wavelength processing device receiver when said spare wavelength processing device receiver is not being used to replace one of said service wavelength processing device receivers.