Interphase Tech iSPAN - Manual (Page 228)

208 Interphase Corporation
RS-232 ◆ Universally accepted Electronics Industries Association
standard that defines the signals between data terminal equipment and
data communications equipment. Uses a 25-pin connector; theoreti-
cally limited to distances of 50 feet; functionally identical to standards
V.24/V.28.
RS-422 ◆ Electronics Industries Association standard for balanced
transmission at distances greater than 50 feet. Compatible with V.11.
RTS (Request To Send) ◆ RS-232 (V.24) control signal, sent from
the data terminal equipment to the data communications equipment on
pin 4. Indicates that the DTE has data to transmit. (See
RS-232 .)
Rx ◆ Abbreviation meaning receive, receiver, or reception.
SAP ◆ Service Access Point
SAPI (Service Access Point Identifier) ◆ Part of the address in an
ISDN signalling frame. Identifies the service that the signalling frame
is intended for.
SDLC ◆ See Synchronous Data Link Control (SDLC) .
Serial Transmission ◆ Technique in which each bit of information is
sent sequentially on a single channel. Serial transmission is the normal
mode for data communications. Contrast with parallel transmission.
SDU (Service Data Unit) ◆ User data passed through a SAP between
the layers of the OSI or a similar model.
Signalling ◆ An ATM connection procedure that dynamically imple-
ments explicit routes through switches to establish a communication
link with another station on the network.
S Interface ◆ The interface point between an ISDN device and the
user premises network termination.
SDLC ◆ See Synchronous Data Link Control.
SNA ◆ IBM’s Systems Network Architecture. The part of a user-
application network that conforms to the formats and protocols of Sys-
tems Network Architecture. It enables reliable transfer of data among
users and provides protocols for controlling the resources of various
network configurations. The SNA network consists of Network Acces-
sible Units (NAUs), boundary function, gateway function, and inter-
mediate session routing function components, and the transport
network.
SNMP (Simple Network Management Protocol) ◆ A high-level, stan-
dards-based protocol for network management, usually used in TCP/
IP networks. An SNMP manager controls and measures the activities