Cisco XR 12406 - Manual (Page 55)

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Cisco XR 12406 Router Installation Guide
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Chapter 1 Cisco XR 12406 Router Overview
Line Cards
The two LEDs on the blower module provide a visual indication of blower module
status. Both LEDs are visible on the blower module from the rear of the chassis.
• OK—Left LED; Green. When on, this LED indicates that the blower module
is operating normally. This LED should come on as soon as the blower
module is installed and receives power from the backplane connector.
• Fail—Right LED; Red. The red LED should remain off during normal
operation. If the red LED is on, the system has detected a fan failure or other
fault in the blower module. Replace the existing blower module with a spare.
Chassis Backplane and Maintenance Bus
All of the card cages for the Cisco XR 12406 Router are tied together electrically
through a passive system backplane in the back of the chassis. Nearly all of the
wiring and circuitry in the chassis is contained within or connected to the chassis
backplane. The chassis backplane distributes DC power to all of the cards in the
chassis as well as the blower module, and provides the physical communication
pathway between cards, both for network data and system communication across
the internal system maintenance bus (MBus).
The maintenance bus and MBus modules manage the maintenance functions of
the system. The MBus is integrated into the backplane and consists of two
separate buses, providing MBus redundancy.
Both MBus networks are linked to all the following items:
• Route processor and line cards
• CSCs, SFCs, and alarm cards
• Power modules
• Blower module
The MBus module located on each component communicates over the MBus and
is powered by DC voltage directly from the alarm card. The MBus performs the
functions of power-up/down control for each component, component (device)
discovery, code download, diagnostics, and environmental monitoring and
alarms.