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Chapter 1. Understanding ISDN and the ISU 512e
the ISU 512e can create an aggregate bandwidth of up to 512 kbps
which can be used to backup a T1 circuit.
Since ISDN is a switched digital service, bandwidth can be established
and utilized on an as needed basis. Therefore, the ISU 512e is well suit-
ed for applications where a high bandwidth connection is needed to
support bursty or infrequent traffic like medical image or large file
transfer.
The ISU 512e supports synchronous data rates from 56 kbps to 512
kbps. At rates over 64 kbps, the ISU 512e supports BONDING Mode 1
and Multilink Point-to-Point Protocol (MLPPP) utilizing from one to
eight 64 kbps B channels. By supporting BONDING, the ISU 512e in-
teroperates with other BONDING-compatible inverse multiplexers
and ISDN terminal adapters. By supporting MLPPP, the ISU 512e in-
teroperates with MLPPP-compatible routers and bridges.
The ISU 512e can be configured and maintained, locally or remotely,
using a VT 100 terminal interface. For remote configuration, the unit
can be accessed over the ISDN line from another ISU 512e or over the
LAN via Telnet.
The front panel of the ISU 512e consists of a 2-line by 16-character
LCD, 7 LEDs, and a 16-button keypad. This allows for configuring, di-
aling, testing, and monitoring the unit without data terminal or test
equipment.
Dialing from the unit is accomplished by using the front panel, termi-
nal menu system, stored numbers, DTR assertion, or V.25 bis in-band
dialing. The EIA-366 parallel dial interface is available for applications
such as video-conferencing. The ISU 512e also supports dedicated
2B1Q services that allow data to be transferred at up to 512 kbps using
the BONDING Mode 1 Protocol. This provides a dedicated point-to-
point service (as in a limited distance modem or leased line applica-
tion) with no dialing necessary.
Figure 1-1 on page 1-3 illustrates the ISU 512e operation in various
switched network services and customer premises products.
1-2
ISU 512e User Manual
61203086L1-1
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