Method of optical data transmission, comprising - receiving a first optical time division multiplex signal containing header information frames at a first wavelength and second optical TDM signals containing data frames at respective second, different wavelengths, wherein furthermore said first wavelength is different to said second wavelengths, - terminating said optical TDM signals, - recovering from said second optical TDM signals respective synchronous TDM data signals (DS1, DS2, DS3), wherein said synchronous TDM data signals (DS1, DS2, DS3) contain data frames within synchronous time slots, - recovering from said first optical TDM signal a TDM header signal, containing header information frames within time slots associated with said time slots containing data frames of said synchronous TDM data signals (DS1, DS2, DS3), wherein a duration of said time slots containing said header information frames is equal to a duration of said time slots containing said data frames, - inserting at least one of said recovered data frames into at least one of generated new synchronous TDM data signals, using said header information frames, - generating a new TDM header signal, inserting into empty time slots of said generated new synchronous TDM data signals data frames containing dummy data, - inserting into time slots of said generated new TDM header signal header information frames, which indicate that the inserted data frames actually contain dummy data, - generating a new first optical TDM signal at said first wavelength using said generated new TDM header signal, - generating new second optical TDM signals at said respective second wavelengths, using said generated new TDM data signals, and - transmitting said new optical TDM signals. - receiving a first optical time division multiplex signal containing header information frames at a first wavelength and second optical TDM signals containing data frames at respective second, different wavelengths, wherein furthermore said first wavelength is different to said second wavelengths, - terminating said optical TDM signals, - recovering from said second optical TDM signals respective synchronous TDM data signals (DS1, DS2, DS3), wherein said synchronous TDM data signals (DS1, DS2, DS3) contain data frames within synchronous time slots, - recovering from said first optical TDM signal a TDM header signal, containing header information frames within time slots associated with said time slots containing data frames of said synchronous TDM data signals (DS1, DS2, DS3), wherein a duration of said time slots containing said header information frames is equal to a duration of said time slots containing said data frames, - inserting at least one of said recovered data frames into at least one of generated new synchronous TDM data signals, using said header information frames, - generating a new TDM header signal, inserting into empty time slots of said generated new synchronous TDM data signals data frames containing dummy data, - inserting into time slots of said generated new TDM header signal header information frames, which indicate that the inserted data frames actually contain dummy data, - generating a new first optical TDM signal at said first wavelength using said generated new TDM header signal, - generating new second optical TDM signals at said respective second wavelengths, using said generated new TDM data signals, and - transmitting said new optical TDM signals.