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

security and increase the configuration work for the transport network.
However, this setup can be acceptable in a campus environment. The
maximum transfer unit (MTU) size for the 1-Meg Modem Service is 1500
bytes, the same size that is defined in the ANSI 802.3 standard.
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-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.
DMS-100 Family RLCM Maintenance Manual XPM12 and up
Signaling for RLCM 4-9