A method, in a communications controller, for wavelength control of a first and second channel, said first and second channel being bidirectional and adjacent to one another in a single fiber in a Dense Wavelength Division Multiplexing, DWDM, based system, the method comprising: receiving, from a receiver of the first channel, a current bit error rate of the first channel; receiving, from a receiver of the second channel, a current bit error rate of the second channel; characterized in that the method further comprises: comparing the current bit error rate of the first channel with a previous bit error rate of the first channel, said previous bit error rate of the first channel being determined at an earlier time as said current bit error rate of the first channel; comparing the current bit error rate of the second channel with a previous bit error rate of the second channel, said previous bit error rate of the second channel being determined at an earlier time as said current bit error rate of the second channel; identifying if said comparing (14, 16) is equivalent to one of three predetermined profiles, said predetermined profiles being said current bit error rate for the first channel is greater than said first previous bit error rate of the first channel, said current bit error rate of the second channel is greater than said previous bit error rate of the second channel, or said current bit error rate of the first and second channel is greater than said previous bit error rate of the first and second channel, respectively; and sending, to transmitter(s) (209, 213) of at least one of the first and second channel, a set of wavelength tuning instructions to tune a center wavelength of at least one of the first and second channel based on the identified predetermined profile, wherein each of the three predetermined profiles comprises a respective set of wavelength tuning instructions. receiving, from a receiver of the first channel, a current bit error rate of the first channel; receiving, from a receiver of the second channel, a current bit error rate of the second channel; characterized in that the method further comprises: comparing the current bit error rate of the first channel with a previous bit error rate of the first channel, said previous bit error rate of the first channel being determined at an earlier time as said current bit error rate of the first channel; comparing the current bit error rate of the second channel with a previous bit error rate of the second channel, said previous bit error rate of the second channel being determined at an earlier time as said current bit error rate of the second channel; identifying if said comparing (14, 16) is equivalent to one of three predetermined profiles, said predetermined profiles being said current bit error rate for the first channel is greater than said first previous bit error rate of the first channel, said current bit error rate of the second channel is greater than said previous bit error rate of the second channel, or said current bit error rate of the first and second channel is greater than said previous bit error rate of the first and second channel, respectively; and sending, to transmitter(s) (209, 213) of at least one of the first and second channel, a set of wavelength tuning instructions to tune a center wavelength of at least one of the first and second channel based on the identified predetermined profile, wherein each of the three predetermined profiles comprises a respective set of wavelength tuning instructions. comparing the current bit error rate of the first channel with a previous bit error rate of the first channel, said previous bit error rate of the first channel being determined at an earlier time as said current bit error rate of the first channel; comparing the current bit error rate of the second channel with a previous bit error rate of the second channel, said previous bit error rate of the second channel being determined at an earlier time as said current bit error rate of the second channel; identifying if said comparing (14, 16) is equivalent to one of three predetermined profiles, said predetermined profiles being said current bit error rate for the first channel is greater than said first previous bit error rate of the first channel, said current bit error rate of the second channel is greater than said previous bit error rate of the second channel, or said current bit error rate of the first and second channel is greater than said previous bit error rate of the first and second channel, respectively; and sending, to transmitter(s) (209, 213) of at least one of the first and second channel, a set of wavelength tuning instructions to tune a center wavelength of at least one of the first and second channel based on the identified predetermined profile, wherein each of the three predetermined profiles comprises a respective set of wavelength tuning instructions.