Nortel DMS-100 Series Maintenance Manual page 47

Ethernet The Ethernet interfaces at the 1-Meg Modem and the DBIC meet
standard ANSI/IEEE Standard 802.3 with one exception. The 1-Meg
Modem does not support the truncated binary exponential backoff algorithm
described in section 4.2.3.2.5 of the IEEE802.3 specification. This
exception allows the best use of the bandwidth on the link. This exception
also confirms a standard allocation between multiple users.
1-Meg Modem Service components
The following section describes some of the components in the 1-Meg
Modem Service.
xDSL line card The xDSL line card (xLC) provides full voice service and
high speed data communication with a subscriber's 1-Meg Modem.
The xLC has the following features:
located in a standard LCM line drawer with 1-Meg Modem Service
capability
provides standard voice service using the world line card (WLC)
provides xDSL modem function over loops up to 18,000 feet on 26
American wire gauge (AWG) wire and 24,000 feet on 24 AWG
rate-adaptable in both downstream (DS) and upstream (US) directions
QAM modulation in both DS and US directions
supports both narrowband and wideband DS spectra low and high
transmission levels
raw transport downstream data rates of 1280 kbit/s to 80 kbit/s
raw transport upstream transport data rates of 320 kbit/s to 40 kbit/s
provides an XLBUS interface to backplane
-48 V power to data part of card
self-identifying to DBIC on installation
out-of-service data loopback capability for OAM
low power design
occupies a two-slot form factor
The xLC terminates the subscriber's line and transmits the call to the DBIC
for multiplexing. The following figure illustrates the xLC in the 1-Meg
Modem Service.
DMS-100 Family RLCM Maintenance Manual XPM12 and up
Maintenance overview 1-31