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Trend
Aurora Plus
User Guide
1-14 429850
In Basic Rate the D channel carries control and signalling
data at 16kbps. It may also be used for X.25, the Packet
mode service.
Basic Rate access to the ISDN
The diagram below illustrates Basic Rate ISDN operation.
In this illustration, a 4 wire interface consisting of a transmit
and receive pair (known as the ‘S/T interface’), is connected
to the NT1. The S/T interface is terminated at the NT1 and
the distant end, on both the transmit and receive pairs.
Connection to the interface is usually made via 8-pin plugs
which conform to ISO Specification 8877. Over this
interface pass the 2B+D channels.
Point-to-Point and Point-to-Multipoint links
The layer 2 of a S/T interface can operate in either
Point-to-Point (PP) or Point-to-Multipoint (PMP) mode.
• On a PP link, only one TE may be connected at the end of up
to 1km of cable.
• On a PMP link, up to 8 terminals can be connected in
parallel along the bus. The length of the bus is limited to
about 200m, depending on the cable.
Chap01.P65 30/04/01, 16:26 14