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Installation Planning
2-33000-A2-GA31-80 December 1994
One COMSPHERE 72-inch cabinet can accommodate
up to six COMSPHERE 3000 Series Carriers. A cabinet
does not need to be fully populated with carriers, however.
There are several general rules to follow during
installation of the carrier.
1. If installing multiple carriers, install the lower one
first, and if installing a full cabinet of carriers,
install the carriers from the bottom of the cabinet
and work up. This provides the following:
a. Proper alignment for subsequent carriers.
b. Easier carrier installation since they can be
placed in the mounting and lowered onto the
mounting screws.
c. Easier connection of the DTE interface.
d. Proper cabinet balance. Bottom-up installation
keeps the cabinet from becoming top heavy.
2. You must mount carriers when they are empty.
If a carrier is installed in an EIA standard 23-inch
(wide) cabinet, however, the mounting brackets on the
carrier must be reversed before the carrier is mounted.
Carriers can be installed in either EIA standard 19- or
23-inch (wide) cabinets.
Models 3551, 3611, and 3616 DSUs and Models 3811
and 3911 dial/ lease modems within the COMSPHERE
3000 Series Carrier(s) can be managed from an SDCP, a
Network Management System (NMS), or both.
Remember that the Models 3551, 3611, and 3616 DSUs
and Models 3811 and 3911 dial/lease modems are
managed by the 6700 or 6800 Series NMS. A
COMSPHERE 3000 Series Carrier cannot be connected to
both a 6700 Series NMS and a 6800 Series NMS at the
same time.
The location of the SDCP within the cabinet should be
determined ahead of time. It should be installed at a
convenient level, usually at eye-level. In a fully
configured cabinet, this would be the fourth or fifth carrier
from the bottom. Note that the Model 3511 DSUs are not
capable of being managed by an SDCP.
The alarm output connection is closed, activating the
customer-supplied alarm, when any DSU or Model 3811
or 3911 dial/lease modem in the carrier has an alarm
condition that lights the red Alrm LED of the DSU or
modem. For information on how to connect the alarm
output, see the Alarm Output Connection section in
Chapter 3.
Up to eight carriers can be controlled by an SDCP, but
there must be a Shared Diagnostic Unit (SDU) installed in
each carrier. (Slot 0 in each carrier is reserved for the
SDU.) The SDU provides the interface that connects the
SDCP to other carriers. Cabling is required that daisy
chains these interfaces together.
If the units in the carriers are to be managed from an
NMS, an SDU is required in all carriers. Up to eight
carriers can be daisy chained together.
Cooling requirements should be given consideration.
Depending upon the number of units in the carrier and
how they are equipped, a fan module may be
recommended. Table 3-1 in Chapter 3 will help you
determine whether or not you need additional cooling for
your carrier.
Two 50-pin connectors (P21 and P22) at the rear of the
carrier, each serving eight slots, provide the digital
interface for DSUs and the analog leased-line interface for
dial/lease modems. DSUs and dial/lease modems can be
placed in the same carrier, but they should be grouped
together, (e.g., eight DSUs with a digital interface and
eight dial/lease modems with an analog leased-line
interface).