within the Data Link layer of the OSI model. LLC frames carry user
information between the nodes on a network and define the transmis-
sion of a frame between two stations. These standards are common
across the various lower level standards within the Data Link and the
Physical layers.

802.3 IEEE

◆

Standards that govern the use of the CSMA/CD (Car-

rier Sense Multiple Access/Collision Detection) network access
method used by Ethernet networks.

802.5 IEEE

◆

Standards that govern the use of the token ring indicator

and frame priority.

Adapter

◆

A device, usually a user interface card, that physically

connects an end station to the network medium (for example, twisted
pair, coaxial, fiber).

Advanced Program-to-Program Communication

◆

See APPC.

AIS (Alarm Indication Signal)

◆

PRI alarm, also known as Keep

Alive or Blue signal.

AMI (Alternate Mark Inversion)

◆

A method of digitally encoding

data as electrical signals on a link.

ANSI (American National Standards Institute)

◆

An organization

which coordinates, develops, and publishes standards used in the
United States.

APPC

◆

Advanced Program-to-Program Communications.The gen-

eral facility characterizing the LU 6.2 architecture and its various
implementations in products. 2. Sometimes used to refer to the LU 6.2
architecture and its product implementations as a whole, or to an LU
6.2 product feature in particular, such as an APPC application pro-
gramming interface.