Glossary-2
analog loopback
A diagnostic test that forms the loop at the data communications equipment's
telephone line interface, returning transmitted signals to their source.
Annex D
A common management protocol used for frame relay.
AppleTalk
Allows LAN networking among Macintosh computers. All Macintoshes have
a LocalTalk port, running AppleTalk over a 230 kbit serial line. AppleTalk
also runs over Ethernet (EtherTalk) and Token Ring (TokenTalk) network
media.
ARQ, automatic request for retransmission
An error control method in which the receiving device informs the
transmitting device which transmission blocks were received successfully.
The transmitting device retransmits any blocks not successfully received.
ASCII, American Standard Code for Information Interchange
A 7bitplusparity character set or code established by the American
National Standards Institute (ANSI) to achieve compatibility between data
services.
async
Short for asynchronous that describes the method of transmission for data.
See
asynchronous transmission.
asynchronous transmission
A method of sending data in which the interval between characters may be of
unequal length. The characters transmitted include a start bit and one or
more stop bits, which define the beginning and ending of the character. No
timing signals need to be sent.
ATM, asynchronous transfer mode
Method of data transmission using cell relay, supporting speeds up to 2.2
gigabits/second, and capable of carrying voice and LAN traffic.
attenuation
Deterioration of a signal's strength as it passes through a transmission
medium; generally attenuation increases with both frequency and cable
length. The signal level decreases. Attenuation is measured in terms of
decibels. Contrast with gain.