Webster's New World Telecom Dictionary
Chapter One
A
A (Ampere) See ampere.
AAL (ATM Adaptation Layer) In the ATM reference model, a layer that comprises two sublayers. The
Convergence Sublayer (CS) functions are determined by the specifics of the service class supported by that
particular AAL. The Segmentation and Reassembly (SAR) sublayer functions to segment the user data into
payloads for insertion into cells, on the transmit side. On the receive side, the SAR extracts the payload
from the cells and reassembles the data into the information stream as originally transmitted. There exist
defined AAL Types 1, 2, 3/4, and 5, each of which supports a specific class of traffic. See also ATM, ATM
reference model, CS, and SAR.
AAL1 (ATM Adaptation Layer Type 1) Supports Class A traffic, which is connection-oriented constant
bit rate (CBR) traffic timed between the source and the sink. Such traffic is stream-oriented and
intolerant of latency. Isochronous traffic such as digitally encoded, uncompressed voice is supported via
AAL 1, which essentially supports the emulation of a T/E-carrier ... read full excerpt from Webster's New World Telecom Dictionary ebook
