AbstractThe European Union ACTS project SONATA will define and demonstrate a cswitchlessn all‐optical network to provide a future single‐layer, advanced transport architecture on a national scale. The single‐hop, shared‐access network employs time and wavelength agility (a WDMA/TDMA protocol), using fast tunable transmitters and receivers to route individual customer connections as well as bandwidth pipes through a single wavelength router (suitably replicated for resilience). No electronic switching nodes or cross‐connects (telephony, IP, ATM, SDH) are required within the transport network, nor optical cross‐connects (save the wavelength routing node), thus providing major transport architecture simplifications and hardware reductions. The network is scalable to 200 Tbit/s throughput over 1, 000 krn, connecting 20 million terminals operating at 622 Mbit/s over 50.000‐way split c