Unless connected by optical fibre links, it shall not be OTN. Mere functionality of switching, management, supervision shall not make it OTN, unless the signals are carried through optical fibre.OverviewAn optical transport network (OTN) is a digital wrapper that encapsulates frames of data, to allow multiple data sources to be sent on the same channel. This creates an optical for each client signal. At a very high level, the typical signals processed by OTN equipment at the Optical Channel layer are: • SONET/SDH• Ethernet/FibreChannel• Packets.