- AAL
- Adjacent
Binder
- ADSL
- ALARM
Circuits
- ASCII
-
Ayschronous Interface
- ATM
- ATU-C
- ATU-R
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AAL - ATM Adaptation Layer -
Standard of protocols that adapt user traffic into
ATM cell format. AAL is sub-divided into Convergence Sublayer (CS) and
the Segmentation and Reassembly (SAR) Sublayer. 4 types of these layers
support the various AAL service classes.
- AAL1 - AAL type 1
- Protocol standard for the transport of time-dependent Constant Bit
Rate (CBR) traffic (i.e. audio and video) and the emulation of TDM-based
circuits (i.e. DS1, E1). Timing information exchanged between the
source and the destination. AAL1 supports
QoS
Class A.
AAL2 - AAL type 2
- Protocol standard for supporting time-dependent slow or Variable
Bit Rate (VBR-RT) connection-oriented traffic (e.g. packetized and
compressed audio and video). Timing information is required to be
exchanged between the source and the destination. AAL2 supports
QoS
Class B.
AAL 3/4 - AAL type 3 and 4
- Protocol standard for supporting both connectionless and
connection-oriented Variable Bit Rate (VBR-NRT) traffic. AAL3
supports
QoS class C while AAL4
supports QoS
class D. They are currently combined into one type. AAL3/4 also
performs resequencing and cell identification operations. AAL3/4
services are suitable for supporting interworking with Frame Relay,
SMDS and X.25.
AAL5 - AAL type 5
- Protocol standard for supporting
connection-oriented Variable Bit Rate (VBR-NRT) data traffic and
signaling messages. AAL5 supports
QoS
Class X. AAL5 services are suitable for supporting interworking with
most data networking protocols, such as Frame Relay, SMDS, Ethernet
and IP.
Adjacent Binder
-- Refers to the groups of twisted pairs
of copper wires within a protected coating. A binder could contain
several sub-'binders' of wires. An adjacent binder refers to the
'binder' that is physically next to another 'binder'. See:
unbundling
ADSL(Asymmetric Digital
Subscriber Line) -- A method for moving
data from client (home or business) to the Telco's CO over regular
copper phone lines. An ADSL circuit must be configured to connect two
specific locations (point to point). In that regard, ADSL is similar to
leased line modems. It is important to note that ADSL and normal " POTS"
are allowed to CO-exist simultaneously over the same copper pair in most
instances. Speeds
vary significantly by distance, cable noise, modulation type (DMT
or CAP)
and manufacturer. Downstream speeds vary from 128Kbps to 8Mbps. There
are some discussion of 50Meg via
VDSL (Loosely related) Some supporters of ADSL
and RADSL
have a claimed (not necessarily founded) range of downstream speeds
depending on distance:
Up to: 18,000 feet 1.544 Mbps
16,000 feet 2.048 Mbps
12,000 feet 6.312 Mbps
9,000 feet 8.448 Mbps
ALARM CIRCUITS --
ASCII (American Standard
Code for Information Interchange) --
Worldwide standard for the code numbers used by computers to represent
all the upper and lower-case Latin letters, numbers, punctuation, etc.
There are 128 standard ASCII codes, each of which can be represented by
a 7 digit binary number: 0000000 through 1111111.
Asynchronous
Interface -In serial data transmission
interfaces, refers to the data that does not require an associate clock
on another pin to indicate the voltage levels on the send and received
data pins. Asynchronous data requires a start and stop bit to frame each
data character. Asynchronous interfaces are the popular method of data
in and out of Personal Computers.
RS232 and
V.24 /
V.28
are a popular Asynchronous serial Interface but also can be a
Synchronous Interface by adding the clocking pins.
ATM (Asynchronous Transfer
Mode) -- A method of communication which
can be used for both LAN and WAN technologies. Today, in many instances,
separate networks are used to carry voice, data and video
information-mostly because these traffic types have different
characteristics. For instance, data traffic tends to be in random block
lengths at intermittent periods - not needing to communicate for an
extended period of time and then needing to communicate large quantities
of information as fast as possible. Voice and video, on the other hand,
require more consistency in the amount of information required-but are
very sensitive to when, and the order the information arrives.
Theoretically with ATM, separate networks will not be required. .ATM
uses fixed length packets or cells. ATM is the only standards based
technology, which has been designed to accommodate the simultaneous
transmission of data, voice and video. ATM is the emerging standard
for communications. This is possible because ATM is available at various
speeds from Megabits to Gigabit speeds. ( www.atmforum.com)
See: Frame Relay
ATU-C (ADSL Transceiver Unit
- Central office)
ATU-R (ADSL Transceiver Unit
- Remote) - Originally conceived by the
ADSL Forum as the designation for "ADSL-CO" equipment and "ADSL-Remote"
equipment. The CO is the chassis mount side and the R is the customer
premsis(CPE) side. More recently, with the invent of several forms of
xDSL equipment, the ATU-C/R designation is a generally accepted term for
other types of DSL services including
RADSL,
SDSL,
HDSL,
HDSL2
and even IDSL.
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