Glossary
Glossary-3
Glossary of TermsA
AAL
ATM Adaptation Layer. One of
the three layers of the ATM
protocol reference model. It
translates incomin g data into
ATM cell payloads and
translates outgoing cells into a
format readable by the higher
layers. Five AALs have been
defined: AAL1 and 2 handle
traffic like voice and video
which is sensitive to
transmission delays, while AAL
3, 4, and 5 pertain to data
communications through the
segmentation and reassembly of
packets.
Analog
A representation of an object
that resembles the original.
Analog devices monitor
conditions, such as moveme n t,
temperature, and sound, and
convert them into analogous
electronic or mechanical
patterns. For example,
telephones turn voice vibrations
into electrical vibrations of the
same shape. Analog implies
continuous operation.
ANSI
American National Standards
Institute. The coordinating body
for voluntary standards gr oups
within the United States. ANSI
is a member of the International
Organization for
Standardization (ISO).
API
Applications Programming
Interface. A method of allowing
an application to interact
directly with certain functions of
an operating system or with
another application.
ARP (ATM)
Address Resolution Protocol. A
protocol that dynamically maps
between various types of
addresses (IP addresses to T oken
Ring addresses for instance) on a
local area network.
ASIC
Application Specific Integrated
Circuit. An integ rated circ uit
designed solely for a specific
function.
ATM
Asynchronous Transfer Mode. A
form of data tran smission based
on fixed-length packets, called
cells, that can carry data, voice,
and video at high speeds. This
technology is designed to
combine the benefits of
switching technology (constant
transmission delay, guaranteed
capacity) with those of packet
switching (flexibility, efficiency
for intermittent traffic). ATM is
defined by ITU-T specifications.
ATM Layer
A service-independent layer that
sits on top of the PHY Layer. The
ATM layer receives the 48-byte
SAR-PDU from the AAL La y e r,