Patent ID: 7254337

Claim:
A multiple span optical communication system comprising: at least one optical add/drop multiplexing (OADM) node operable to receive at least a first input band comprising a first plurality of signal wavelengths, at least a second input band comprising a second plurality of signal wavelengths, and at least one signal wavelength that is designated as a first guard-channel, wherein the first guard-channel is substantially free from being an information bearing channel, wherein each of the first plurality of signal wavelengths of the first input band is different than each of the second plurality of signal wavelengths of the second input band, wherein each of the first plurality of wavelengths and each of the second plurality of wavelengths received by the OADM is designated as an information bearing channel, and wherein the first guard-channel received by the OADM separates the first input band from the second input band, the at least one OADM further operable to communicate at least one output band and at least another signal wavelength that is designated as a second guard-channel that separates the at least one output band from other output bands, wherein the second guard-channel is substantially free from being an information bearing channel; wherein at least one signal wavelength of the second plurality of signal wavelengths received by the OADM is designated as the second guard-channel communicated from the OADM, and wherein the at least one signal wavelength of the first guard-channel received by the OADM is designated as an information bearing channel in the at least one output band communicated from the OADM.