Optical network node for an optical ring network, comprising - a first optical interface, operable to receive a plurality of optical time division multiplexed signals carrying respective optical data packet sequences via respective synchronous time slot sequences, wherein said optical TDM signals have different respective wavelengths, - a receiver, operable to detect an optical data packet at a detected wavelength within a time slot, - a control unit, operable to receive control information indicating for each optical data packet of said same time slot a respective destination node, and furthermore operable to control said receiver in dependence on said control information for detecting said optical data packet at said detected wavelength within said same time slot characterized in that, said control unit is furthermore operable to modify at least two of said optical TDM signals within said same time slot, by controlling - a first optical gate to terminate a first optical data packet at a first wavelength, - a first tunable laser (TLTX) to generate a new optical data packet (DP11') comprising transmission data at said first wavelength, - a second optical gate to terminate a second optical data packet at a second wavelength, which is different from said first wavelength, - a second tunable laser (TLTXD) to generate a new optical data packet (DP31') comprising dummy data at said second wavelength, wherein said detected wavelength is equal to said first wavelength or equal to said second wavelength, and wherein said node comprises furthermore a second optical interface, operable to transmit the modified optical TDM signals. - a first optical interface, operable to receive a plurality of optical time division multiplexed signals carrying respective optical data packet sequences via respective synchronous time slot sequences, wherein said optical TDM signals have different respective wavelengths, - a receiver, operable to detect an optical data packet at a detected wavelength within a time slot, - a control unit, operable to receive control information indicating for each optical data packet of said same time slot a respective destination node, and furthermore operable to control said receiver in dependence on said control information for detecting said optical data packet at said detected wavelength within said same time slot characterized in that, said control unit is furthermore operable to modify at least two of said optical TDM signals within said same time slot, by controlling - a first optical gate to terminate a first optical data packet at a first wavelength, - a first tunable laser (TLTX) to generate a new optical data packet (DP11') comprising transmission data at said first wavelength, - a second optical gate to terminate a second optical data packet at a second wavelength, which is different from said first wavelength, - a second tunable laser (TLTXD) to generate a new optical data packet (DP31') comprising dummy data at said second wavelength, - a first optical gate to terminate a first optical data packet at a first wavelength, - a first tunable laser (TLTX) to generate a new optical data packet (DP11') comprising transmission data at said first wavelength, - a second optical gate to terminate a second optical data packet at a second wavelength, which is different from said first wavelength, - a second tunable laser (TLTXD) to generate a new optical data packet (DP31') comprising dummy data at said second wavelength,