SONET/SDH

Basis is een "optical carrier" van 51,84 Mbps

OC3/STM-1: 155 Mbps

OC12/STM-4: 622 Mbps

OC48/STM-16: 2488 Mbps

OC192/STM-64: 9952 Mbps (129000 DS0s!)

c is “concatenated”: OC3c = 155, OC3 = 3 x 51