AT&T 7200 series, 7500 series, 7100 series, 2500 series, 7400 series, 7300 series manual Sdlc

GLOSSARY GL-21

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route advance	A telecommunications routine that routes outgoing calls over alternate
	trunk groups when the first-choice trunk group is busy.
RS-232	A physical interface specified by the EIA. RS-232 transmits and receives
	asynchronous data at speeds of up to 19.2 kbps over cable distances of up
	to 50 feet.
S-channel data	The transmission of data over an S-channel using the digital
transmission	communications protocol (DCP).
SDLC	See Synchronous Data Link Control.
serial data transmission	An operation whereby data is transmitted or processed sequentially, one
	bit after another.
signaling system number	The standard being developed by the CCITT to provide interoffice
7	signaling — for example, signaling from a central office (CO) to a toll
	office, a toll office to a toll office, and a toll office to a CO. When
	implemented, signaling system 7 will replace common-channel interoffice
	signaling (CCIS). See also common channel interoffice signaling and Q
	recommendations.
simplex data link	Electronic equipment that permits automatic transmission of digital
	information in only one direction. See also duplex data link.
SMT	See system management terminal.
SNA	See Systems Network Architecture.
software	A set of computer instructions designed to perform one or more tasks.
Software-Defined	An AT&T private networking service created by specialized software
Network (SDN)	within the public network. SDN is designed to carry voice and data traffic
	between customer locations as well as to off-network locations, and offers
	a pricing structure based on communications usage, distance, and access-
	line charges.
Star-Based Local Area	See StarLAN.
Network (StarLAN)
StarLAN	A 1 or 10-Mbps local area network (LAN) linking intelligent workstations,
	asynchronous terminals, printers, modems, and host computers. StarLAN
	functions as a standalone PC network in small offices, departments, and
	workgroups, and can accommodate any size business that needs, for
	example, to share files and printers, and exchange electronic mail. See
	also network-access unit.
statistical multiplexing	A form of time division multiplexing (TDM) that uses a microprocessor
	control unit to dynamically allocate available bandwidth.