Specifications

Glossary
GL-4
Cisco ONS 15454 Troubleshooting and Maintenance Guide
November 2001
D
DCC
Data Communications Channel. Used to transport information about operation, administration, maintenance, and provisioning
(OAM&P) over a SONET interface. DCC can be located in section DCC (SDCC) or line overhead (LDCC.)
Demultiplex
To separate multiple multiplexed input streams from a common physical signal back into multiple output streams. See also
Multiplexing.
DSX
Digital Signal Cross-connect frame. A manual bay or panel where different electrical signals are wired. A DSX permits
cross-connections by patch cords and plugs.
DWDM
Dense Wave Division Multiplexing. A technology that increases the information carrying capacity of existing fiber optic
infrastructure by transmitting and receiving data on different light wavelengths. Many of these wavelengths can be combined
on a single strand of fiber.
E
EDFA
Erbium Doped Fiber Amplifier. A type of fiber optical amplifier that transmits a light signal through a section of erbium-doped
fiber and amplifies the signal with a laser pump diode. EDFA is used in transmitter booster amplifiers, in-line repeating
amplifiers, and in receiver preamplifiers.
EIA
Electrical Interface Assemblies. Provides connection points for the ONS 15454 and DS-1, DS-3, or EC-1 units.
EMI
Electromagnetic Interference. Interference by electromagnetic signals that can cause reduced data integrity and increased error
rates on transmission channels.
Envelope
The part of messaging that varies in composition from one transmittal step to another. It identifies the message originator and
potential recipients, documents its past, directs its subsequent movement by the Message Transfer System (MTS), and
characterizes its content.
EOW
Express Orderwire. A permanently connected voice circuit between selected stations for technical control purposes.
Ethernet switch
An Ethernet data switch. Ethernet switches provide the capability to increase the aggregate LAN bandwidth by allowing
simultaneous switching of packets between switch ports. Ethernet switches subdivide previously-shared LAN segments into
multiple networks with fewer stations per network.