Nortel DMS-100 Series Maintenance Manual page 107

When both LCCs are active under normal conditions, LCC-0 connects
LCA-0, and LCC-1 connects LCA-1. The LCC-0 serves even numbered
PCM30 links (0, 2, and 4) from the PCM30 interface cards. The LCC-1
serves odd numbered PCM30 links (1, 3, and 5). The following diagram
describes how the LCCs configure in the PRLCM.
In one-to-one mapping of LCA primary ports with PCM30 links, all 32
channels of a PCM30 link come from one 32-channel DS30A port. Control
and signaling from the host requires additional channels. Intra- and
interspeech channels require additional channels.
The LCC accepts eight DS30A links from the LCA. The LCC allows these
links to provide the following:
message and speech paths to the host
connection to the RMM
link-sharing resources for each LCA
The LCC provides system clocks for the digroup controller card (DCC),
RMM, and LCM. The active units of the LCM cause the LCC-0 to become
frequency-locked to the primary PCM30 link. When both units of the LCM
are active, the LCC-1 clock locks to LCC-0. Both LCC clocks derive timing
from the same source. The source is the host line trunk controller (LTC).
The DS30A ports in the LCA are numbered 0 to 7. The following table lists
the functions of the DS30A ports.
LCA port assignments and use
Number Port type
0,1, 2 Primary
3, 4, 5 Image
DMS-100 Family RLCM Maintenance Manual XPM12 and up
Functions
Carries three message channels for the LCA shelf.
Message channels map onto channels 1, 2, and 3
of each of the two primary PCM30 links to the host
office. Channels that carry speech are mapped to
channels 4 through 24 of the primary PCM30 links.
These ports become active if the mate LCA and
LCC are inactive and takeover occurs. Port 3
takes over mate port 0 of the mate LCA. Port 4
takes over mate port 1 of the mate LCA. Port 5
takes over mate port 2 of the mate LCA. The
mapping of all channels on the PCM30 links
continues, and the active LCC takes control of all
PCM30 links.
—continued—
PRLCM overview 2-5