D
Glossary
B-22
Centillion 1200N ATM Switch User Manual
NTP 297-8103-903
Dijkstra's Algorithm
An algorithm that is sometimes used to calculate routes given a link and nodal state
topology database.
DIR
This is a field in an RM-cell which indicates the direction of the RM- cell with
respect to the data flow with which it is associated. The source sets DIR=0 and the
destination sets DIR=1.
Direct Set
A set of host interfaces which can establish direct layer two communications for
unicast (not needed in MPOA).
DLPI
UNIX International, Data Link Provider Interface (DLPI) Specification: Revision
2.0.0, OSI Work Group, August 1991.
DMA
Direct Memory Access: A fast method of moving data from a storage device or
LAN interface card directly to RAM which speeds processing.
Domain
Refer to Administrative Domain.
DS
Distributed Single Layer Test Method: An abstract test method in which the upper
tester is located within the system under test and the point of control and
observation (PCO) is located at the upper service boundary of the Implementation
Under Test (IUT) - for testing one protocol layer. Test events are specified in terms
of the abstract service primitives (ASP) at the upper tester above the IUT and ASPs
and/or protocol data units (PDU) at the lower tester PCO.
DS-0
Digital Signal, Level 0: The 64 kbps rate that is the basic building block for both
the North American and European digital hierarchies.
DS-1
Digital Signal, Level 1: The North American Digital Hierarchy signaling standard
for transmission at 1.544 Mbps. This standard supports 24 simultaneous DS-0
signals. The term is often used interchangeably with T1 carrier although DS-1
signals may be exchanged over other transmission systems.