A set of optical network elements connected by optical fiber links, able to provide functionality of transport, multiplexing, switching, management, supervision and survivability of optical channels carrying client signals. The OTN was created to combine the benefits of SONET/SDH technology with the bandwidth expansion capabilities offered by dense wavelength-division multiplexing (DWDM) technology. It is no longer only used in core networks to transport high-speed rates (10/40/100 Gbit/s), it is now used in edge networks too.