Nortel Passport 15000 Hardware Description page 88

88 Chapter 3 Shelf assembly
241-1501-200 5.2S2
• support alarm, timing, and node addressing
A module is different from a card because it requires no software
configuration and has no connected signaling (traffic) cables. All modules are
installed at the rear of the shelf assembly. A fabric card is the only rear card
and the only card without signaling cables. Replacing a rear card or module
in a Passport 15000 or 20000 affects performance depending on whether it
has a redundant mate (backup). Each replacement procedure minimizes the
amount of time a card or module or a backup is out of service.
The software term shelf refers to the node rather than the shelf assembly. The
term shelf assembly refers to the hardware part of a shelf node that contains
the plug-in modules and processor cards.
These sections describe the hardware parts that constitute a single
Passport 15000 or 20000 shelf assembly:
• "Common backplane" (page 92)
• "Fabric cards" (page 94)
• "Power interface modules (PIMs)" (page 107)
• "Media access control (MAC) address module" (page 112)
• "Alarm/BITS module" (page 114)
• "Cooling units" (page 126)
The exterior parts of the shelf assembly are shown in the figures
• "A typical shelf assembly, front view" (page 89)
• "A shelf assembly of a Passport 15000 without fabrics, rear view"
(page 90)
• "A shelf assembly of a Passport 20000 with one fabric removed, rear
view" (page 91)
For information about installing or maintaining any of the shelf parts
described in this section, see 241-1501-240 Passport 15000, 20000 Hardware
Installation, Maintenance and Upgrade.