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Chapter 1. Understanding ISDN and the ISU 2x64
61200051L1-1D ISU 2x64 Dual Port ISDN Service Unit User Manual
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The ISU 2x64 allows the user to migrate ISDN into existing net-
work services and data communications equipment. The ISU
2x64 interoperates with ISU 128s, Switched 56 DSUs, various
ISDN terminal adapters, and BONDING inverse multiplexers
(for example ASCEND®, PROMPTUS, and Teleos®). For
instance, in a video conferencing application, this compatibility
allows the ISU 2x64 to interoperate with networks utilizing two
Switched 56 DSUs.
The ISU 2x64 front panel accommodates a 2-line by 16-character
LCD display. Seven LED indicators monitor data flow and dis-
play the status of key DTE interface leads (see Table 1-A and Fig-
ure 1-2). A front panel keypad supports configuration, test
modes, test status, and dialing.
Table 1-A
DTE Indicators
Indicator Definition
RS Request to Send. Indicates the DTE is ready to
transmit.
CS Clear to Send. Indicates the ISU 2x64 is ready
to transmit.
TD Transmit Data. On when the DTE is transmitting
to the ISU 2x64.
RD Receive Data. On when the ISU 2x64 is receiv-
ing data from the far end.
CD Carrier Detect. On when the ISU 2x64 is con-
nected to a remote unit.
TR Data Terminal Ready from DTE. On when DTR is
active at DTE interface.
SR Data Set Ready.