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Glossary
ASICs
application-specific integrated circuits: Used in layer-2 switches to
make filtering decisions. The ASIC looks in the filter table of MAC addresses
and determines which port the destination hardware address of a received
hardware address is destined for. The frame will be allowed to traverse only
that one segment. If the hardware address is unknown, the frame is for-
warded out all ports.
ASN.1
Abstract Syntax Notation One: An OSI language used to describe
types of data that is independent of computer structures and depicting
methods. Described by ISO International Standard 8824.
ASP
AppleTalk Session Protocol: A protocol employing ATP to establish,
maintain, and tear down sessions, as well as sequence requests.
See also: ATP.
AST
Automatic Spanning Tree: A function that supplies one path for span-
ning explorer frames traveling from one node in the network to another, sup-
porting the automatic resolution of spanning trees in SRB networks. AST is
based on the IEEE 802.1 standard.
See also: IEEE 802.1
and
SRB.
asynchronous transmission
Digital signals sent without precise timing,
usually with different frequencies and phase relationships. Asynchronous
transmissions generally enclose individual characters in control bits (called
start and stop bits) that show the beginning and end of each character.
Con-
trast with: isochronous transmission
and
synchronous transmission.
ATCP
AppleTalk Control Program: The protocol for establishing and con-
figuring AppleTalk over PPP, defined in RFC 1378.
See also: PPP.
ATDM
Asynchronous Time-Division Multiplexing: A technique for
sending information, it differs from normal TDM in that the time slots are
assigned when necessary rather than preassigned to certain transmitters.
Contrast with: FDM, statistical multiplexing,
and
TDM.
ATG
Address Translation Gateway: The mechanism within Cisco DECnet
routing software that enables routers to route multiple, independent DECnet
networks and to establish a user-designated address translation for chosen
nodes between networks.
ATM
Asynchronous Transfer Mode: The international standard, identified
by fixed-length 53-byte cells, for transmitting cells in multiple service sys-
tems, such as voice, video, or data. Transit delays are reduced because the
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