Page 299 - Optical Switching And Networking Handbook

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284 Glossary

Optical Carrier Level N (OC-N) The optical equivalent of an
STS-N signal.

Opaque optical networks The current vision of the optical net-
work whereby conversions from the optical to the electrical and
back to the optical domain are required periodically. Such opti-
cal/electrical/optical conversions are required in order to retime
the signal in the digital domain, clean up signal impairments,
enable fault isolation, and provide performance monitoring (par-
ticularly of signal bit error rate). Today’s optical networks take
advantage of SONET/SDH frame structure for B1 byte parity
checks, BER monitoring, and J0 byte path trace at a minimum.
Opaque network elements will occur as gateways along extended
backbones to limit the accumulation of analog signal impair-
ments and enable performance monitoring and fault isolation.
Optical Add/Drop Multiplexer (OADM) Also called a Wave-
length Add/Drop Multiplexer (WADM). An optical network ele-
ment that lets specific channels of a multi-channel optical
transmission system be dropped and/or added without affecting
the through signals (the signals that are to be transported
through the network node).
Optical amplifier A device that increases the optical signal
strength without an optical-to-electrical-to-optical conversion
process.
Optical carrier (OC) A designation used as a prefix denoting
the optical carrier level of SONET data standards. OC-1/STS-1,
OC-3/STS-3, OC-12, OC-48, and OC-192 denote transmission
standards for fiber-optic data transmissions in SONET and
frames at data rates of 51.84 Mbps, 155.52 Mbps, 622.08 Mbps,
2.48832 Gbps, and 9.95 Gbps, respectively. See SONET and STS.
Optical carrier (OC-x) This is a base unit found in the SONET
hierarchy; the “x” represents increments of 51.84 Mbps (so OC-1
is 51.84 Mbps, OC-3 is 155 Mbps, and OC-12 is 622 Mbps). See
Synchronous Optical Network.
Optical cross-connect (OXC or OCS) An optical network
element that provides for incoming optical signals to be switched
to any one of a number of outputs. Some OXCs connect fibers