Product Overview 1-15
Overview of the Cisco 12008
Redundant (1+1) modeIn this configuration, two power supplies are installed in the
power supply bays, sharing the load current to provide required DC operating voltages
to the backplane. If one of the units fails, the surviving power supply takes over to
maintain normal system operations.
The online insertion and removal (OIR) capability of the router enables you to add or
remove a redundant power supply without introducing noise in the DC operating
voltages being supplied to the backplane.

Features of the Power Supplies

The AC-input and DC-input power supplies incorporate the following features:
Onboard maintenance bus (MBus) moduleThe MBus module on the power s upply is
a microprocessor-based subassembly that links the power supply to the routers
environmental monitoring system.
The environmental monitoring system includes identical MBus modules on all of the
router circuit boards, including the RP. This system enables you to perform router
functions and to respond to alarm conditions (such as overtemperature or overvoltage
conditions).
An alarm condition in the router causes the MBus module on the CSC to illuminate an
appropriate LED on the card faceplate, providing a visible notification of the alarm
condition.
Blind mating connector at the back of the unitSupplies DC operating voltages to the
backplane for distribution to the routers electronic and electrical components.
OIR capabilityEnables a second AC-input power supply to be installed in or removed
from the router without disrupting normal system operations.
Temperature sensorMeasures the ambient air temperature of the power supply.