Nortel DMS-100 Series Maintenance Manual page 155

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One-to-one mapping of LCA primary ports with PCM30 links means that all

24 channels of a PCM30 link come out of one 32-channel DS30A port. Extra

channels are used for control and signaling, from the host, and for intra- and

interspeech channels.

The LCC accepts eight DS30A links from its LCA. Through the LCC, these

links provide the following:

message and speech paths to the host

connection to the RMM

link-sharing resources for each LCA

The LCC also provides system clocks for the digroup controller card (DCC),

RMM, and LCM. When both units of the LCM are active, LCC-0 is

frequency-locked to its primary PCM30 link, and the LCC-1 clock is locked to

LCC-0. Thus, both LCC clocks derive their timing from the same source,

which is the host line trunk controller (LTC).

The DS30A ports in the LCA are numbered 0 to 7. Their functions are listed

in the following table.

Table 3-1 LCA port assignments and use (Sheet 1 of 2)

Carries three message channels for the LCA shelf.

Message channels are mapped onto channels 1, 2,

and 3 of each of the two primary PCM30 links to the

host office. Other channels, carrying speech, are

mapped onto channels 4 through 24 of the primary

PCM30 links.

Normally inactive, these ports become active if the

mate LCA and LCC are inactive and takeover

occurs. Port 3 takes over mate port 0, port 4 takes

over mate port 1, and port 5 takes over mate port 2

of the mate LCA. The mapping of all channels onto

the PCM30 links is maintained, and the active LCC

takes control of all PCM30 links.

DMS-100 Family OPM Maintenance Manual XPM14 and up

PRLCM overview 3-5

Troubleshooting