Xlc And Loop; 1-Meg Modem - Nortel DMS-100 Series Maintenance Manual

XLBUS
The DBIC uses a point-to-point connection to each line card to exchange voice
and data with the xLCs. The extended LBUS (XLBUS) is bidirectional with a
total capacity of approximately 1.5 Mbit/s for data traffic. Upstream data,
downstream data, and control data share this capacity. The XLBUS carries
user data, synchronization and xLC control and status information. The control
data carried over the XLBUS allows the DBIC processor to access registers in
the xLC. User frames passed by the XLBUS have special Start Of Frame
(SOF) and End Of Frame (EOF) control bytes.

xLC and loop

The xLC and subscriber loop use the following protocols.
XDLC
The user data in the xLC is encapsulated into the XDLC protocol, which is
based on HDLC.
XLINK
The XLINK frame has a fixed length for robust framing.
XLOOP
The XLOOP includes the details that relate to the modulation used to carry
data over the copper loop. In the downstream direction,
256/64/16/4-quadrature amplitude modulation (QAM) can be used over
narrowband or wideband spectrums providing 1280, 960, 640, 320, 240, 160
or 80 kbit/s of raw data throughput. In the upstream direction,
256/64/16/4-QAM are also used providing 320, 240, 160, 120, 80 or 40 kbit/s
of raw data throughput.

1-Meg Modem

The Ethernet interface at the 1-Meg Modem provides a half-duplex 10BaseT
or 100BaseT connection. The interface does not filter local traffic and passes
all traffic upstream. Only one Ethernet device can connect to the 1-Meg
Modem.
Signaling for the Star Remote System 3-15
DMS-100 Family NA100 Star Remote System XPM15 and up