Lucent Technologies PortMaster - Manual (Page 320)

Glossary
Glossary-10 PortMaster Configuration Guide
digital service unit
See DSU.
direct memory access
See DMA.
DLCI
Data link connection identifier. A unique number that represents a particular permanent
virtual circuit (PVC) on a particular physical segment of the Frame Relay network. As the
frame is passed through each switch, the DLCI is remapped automatically by the switch as
necessary.
DMA
Direct memory access. Transfer of data from a peripheral device, such as a hard disk drive,
into a computer memory without mediation by a microprocessor.
DNS
Domain Name System. The system used on the Internet for translating the names of
network hosts into IP addresses.
DRAM
Dynamic random access memory. A type of semiconductor random access memory
(RAM) that stores information in integrated circuits containing capacitors.
DSR
Data Set Ready. The circuit that is activated when data communications equipment
(DCE) is powered up and ready for use. See also DCE.
DSU
Digital service unit or data service unit. An ancillary device needed to adapt the physical
interface on a data terminal equipment (DTE) device—such as a V.35 interface on a
port—to a transmission facility—such as leased line or a Frame Relay switch. If the DTE
lacks complete digital line interface capability, the DSU can be located with the channel
service unit (CSU) on the customer’s site and known as a CSU/DSU. See also CSU.