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Supervisory Port
Supervisory Terminal
Switched Network
Systems Network
Architecture (SNA)
T1
Telco
Terminal
Tie Line
Transmission
2047-Bit Test Pattern
USOC
Virtual Circuit
Voice-Grade Channel
Yellow Alarm Signal
GLOSSARY
An interface on the DataComm 551 to which the Supervisory terminal is con-
nected.
A terminal that provides software-control
maintenance for one or all DataComm 551s in a network.
Communications link for which the physical path, established by dialing, may
vary with each use (e.g., a dial-up telephone circuit).
In IBM networks, the layered logical structure, formats, protocols, and procedures
that govern information transmission.
AT&T term for a digital carrier facility used to transmit a DS-1 formatted digital
signal at 1.544 Mbps.
Telephone company.
A point in a network at which data can either enter or leave; a device, usually
equipped with a keyboard, often with a display, capable of sending and receiving
data over a communications link (IBM); generically the same as data terminal
equipment (DTE).
A leased or private line dedicated telephone circuit provided by common carriers
that links two points together without using the switched telephone network.
The dispatching of a signal, message, or other form of intelligence by wire, radio,
telegraphy, telephony, facsimile, or other means (ISO); a series of characters,
messages or blocks, including control information and user data; the signaling
of data over communications channels.
An irregular, quasi-random pattern of 2,047 bits used to test and measure network
jitter.
The Universal Service Order Code (USOC) is accepted telecommunications indus-
try code for identifying servicing arrangements provided by telephone companies,
and is used to identify the standard jack required for the equipment.
A connection established between a channel from the calling DTE and a channel
to the called DTE before any data packets may be sent. May be a Switched Virtual
Circuit (SVC) or a Permanent Virtual Circuit (PVC).
A telecommunications circuit used primarily for speech transmission but suitable
for the transmission of analog or digital data or facsimile; typically supporting a
frequency range of 300 to 3,400 Hz; also voice band.
A Yellow alarm signal is a remotely detected failure. A Yellow alarm is trans-
mitted as a specific bit pattern contained in the data stream when using D4 fram-
ing, or in the data link when using ESF framing. In response to receiving a
Yellow alarm from one side, the CSU transmits a Yellow alarm to the other side
in the proper format (D4 or ESF).
B-9
of
configuration,
diagnostics,
and
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