Isdn Network Extension Card - Vocality V100 Technical Manual

3.4.13 ISDN Network Extension Card

The ISDN Network Extension Card (VI68706) allows a local 2B+D Basic Rate Interface
(BRI) to be presented at a remote location via the V100 network. At the local end, the
card is plugged into the terrestrial ISDN network as a standard terminal device (TE
mode) and at the remote location, the ISDN interface is presented by the card to look
like the ISDN network (NT mode). The cards then operate together by converting the
data at the ISDN BRI (two B channels and one D-channel) into a synchronous bitstream, which is
transmitted over dedicated bandwidth between the two V100 units and then reconverting the
synchronous bitstream back into an ISDN BRI.
Each B-channel requires 64Kbps of bandwidth and in the V100 implementation, just 9.6Kbps of bandwidth
is required for the D-channel protocol. The minimum advisable link bandwidth is therefore obtained from
the following equation:
Link Bandwidth >= (64000*Number of bearers needed + 9600)/0.875
So if only one bearer will be used, a minimum link bandwidth of 84800bps is needed, or if both will be
used, 157600bps. A typical application could be to extend analogue voice and ISDN bearer services over a
satellite link to a remote destination, allowing a videoconferencing terminal to be connected at the same
time as voice and data:
V100 Versatile Multiplexer Technical Manual Version 2.2
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