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Glossary

alignment error

An error occurring in Ethernet networks, in which a

received frame has extra bits; that is, a number not divisible by eight. Align-
ment errors are generally the result of frame damage caused by collisions.

all-routes explorer packet

An explorer packet that can move across an

entire SRB network, tracing all possible paths to a given destination. Also
known as an all-rings explorer packet.

See also: explorer packet, local

explorer packet,

and

spanning explorer packet.

Amplitude modulation: A modulation method that represents infor-

mation by varying the amplitude of the carrier signal.

See also: modulation.

AMI

Alternate Mark Inversion: A line-code type on T-1 and E-1 circuits

that shows zeros as "01" during each bit cell, and ones as "11" or "00," alter-
nately, during each bit cell. The sending device must maintain ones density in
AMI but not independently of the data stream. Also known as binary-coded,
alternate mark inversion.

Contrast with: B8ZS. See also: ones density.

amplitude

An analog or digital waveform's highest value.

analog transmission

Signal messaging whereby information is repre-

sented by various combinations of signal amplitude, frequency, and phase.

ANSI

American National Standards Institute: The organization of corpo-

rate, government, and other volunteer members that coordinates standards-
related activities, approves U.S. national standards, and develops U.S. posi-
tions in international standards organizations. ANSI assists in the creation of
international and U.S. standards in disciplines such as communications, net-
working, and a variety of technical fields. It publishes over 13,000 stan-
dards, for engineered products and technologies ranging from screw threads
to networking protocols. ANSI is a member of the IEC and ISO.

anycast

An ATM address that can be shared by more than one end system,

allowing requests to be routed to a node that provides a particular service.

AppleTalk

Currently in two versions, the group of communication proto-

cols designed by Apple Computer for use in Macintosh environments. The
earlier Phase 1 protocols support one physical network with only one net-
work number that resides in one zone. The later Phase 2 protocols support
more than one logical network on a single physical network, allowing net-
works to exist in more than one zone.

See also: zone.

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