OC-n / OC-xxx indicates Optical Carrier signals which are
carried over a SONET (Synchronous Optical Network) fiber optical
network. The numbers after OC indicate various levels or data rates
in the SONET hierarchy. Hierarchy goes like OC-1, OC3, OC-12,
OC-24, OC-48, OC-96, OC-192 and OC-768 OC-1 is a SONET line with
transmission speeds of 51.84 Mbit/s. OC-192 has a speed of 9953.28
Mbit/s (almost 10Gbps, so also called SONET 10G). You can get more
details in SONET literature. - Neeraj Sharma