Glossary
Issue 8.0 July 2002
GL-7
DRAM
Dynamic Random Access Memory — Semiconductor random-access memory that requires short
interval refreshing to retain its contents.
DS3
Digital Signal Level 3 (44.736 M/bs).
DS3 Interface Circuit Pack
The FT-2000 OC-48 Lightwave System DS3 Interface circuit pack interfaces with up to three bidi-
rectional DS3 signals.
DS-NE
Directory Service Network Element — The single reference point in a ring network. The Directory
Service Network Element stores the IDs of the other network elements in the ring and updates the
other network elements after configuration changes.
DSX
Digital Cross-Connect Panel — A panel designed to interconnect equipment that operates at a des-
ignated rate. For example, a DSX-3 interconnects equipment operating at the DS3 rate.
DTE
Data Terminating Equipment — The equipment that originates data for transmission and accepts
transmitted data.
Dual Ring Interworking
Dual Ring Interworking (DRI) is a configuration of two ring networks that share two common nodes.
DRI allows a circuit with one termination in one ring and one termination in another ring to survive a
loss-of-signal failure of the shared node that is currently carrying service for the circuit.
E
EC, EC-n
Electrical Carrier — The basic logical building block signal with a rate of 51.840 Mb/s for an EC-1
signal and a rate of n times 51.840 Mb/s for an EC-n signal.
EC-1
An STS-1 signal that has been shaped and encoded for transmission over electrical media. This
refers to the actual physical representation of an electrical signal with an EC-1 format at a manual
or electronic cross-connect interface. This signal is typically carried by coaxial cables from one
equipment location to another. The term EC-1 not only refers to the organization and data rate of a
signal but also to the voltage template the signal must conform to and the impedances for which the
voltage template is valid.
ECI
Equipment Catalog Item
EEPROM
Electrically Erasable Programmable Read-Only Memory — Readable memory that is nonvolatile in
nature, erased electrically, and programmed externally from the processor that uses it.
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