The technique of wavelength division multiplexing (WDM) has paved the way for multi-terabit/s capacities in terrestrial optical networks. Recently, we conducted a laboratory experiment to emulate a terrestrial transmission of 6.3 Tbit/s capacity over a record 2700 km distance. After describing some of the specific features of optical terrestrial transmission, we discuss the various technologies possibly involved in such an emulator and discuss their implementation in actual systems, namely the modulation format, the optical amplifier scheme, the 40 Gbit/s electronics and the forward error-correcting codes.