Cisco XR 12406 - Manual (Page 135)

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Cisco XR 12406 Router Installation Guide
OL-13831-01
Chapter 4 Troubleshooting the Installation
Problem-Solving with Subsystems
For troubleshooting purposes, the Cisco XR 12406 router consist of the following
subsystems:
• Power subsystem—Includes the following components:
– AC-input or DC-input power distribution unit (PDU)
– AC or DC power entry modules (PEMs). The Cisco XR 12406 router can
be configured for source AC or source DC power (you can not mix AC
and DC power).
– Chassis backplane power distribution. The –48 VDC power from the
power supplies is transferred to the chassis backplane, which distributes
–48 VDC power to the cards in the card cages through the backplane
connectors. The blower module receives power from the chassis
backplane and passes MBus data back to the chassis backplane through
a PDU connector.
DC-to-DC converters on the two alarm cards convert –48 VDC to
+5 VDC and put it back on the chassis backplane, where it is picked up
to power the MBus modules on other cards and the blower module.
– DC-to-DC converters. Each card in the router is equipped with DC-to-DC
converters. These converters are controlled by the MBus module on each
card. The DC-to-DC converters take –48 VDC and convert it into the
voltages required by the card circuitry.
• Processor subsystem—Includes the RP, up to five line cards (when no
optional, redundant RP is installed) and two alarm cards. The RP downloads
a copy of the Cisco XR IOS image to each line card processor. The system
uses alphanumeric LED displays to display status and error messages, which
can help in troubleshooting.
• Cooling subsystem—Consists of the blower module, which circulates air
through the card cages to cool the cards, and the fan in each of the power
modules, which circulates cooling air through the power module bays.
Caution Replace the blower module within 2 minutes of removing it from the
chassis or the router will go into a critical failure mode and shutdown
due to an overtemp condition.