Cisco cBR Series Hardware Installation Manual page 48

Cooling System of the Cisco cBR Chassis
All the remaining fans are capable of changing to full speed operation to compensate for the failed fan or
module.
Warning Ensure that all Fan Module bays have functioning Fan Modules. If a Fan Module is removed, replace it with
a functioning Fan Module within one minute of the removal in order to avoid critical thermal alarms relating
to overheating of individual components.
Table 25: Physical Specifications of the Fan Module
Unit
Depth
Width
Height
Weight
The faceplate of the Fan Module has the following LEDs:
LED
STATUS 1
STATUS 2
RPLC
Cooling System of the Cisco cBR Chassis
The Fan Modules in the Cisco cBR chassis are controlled by the Supervisor Card. Until the Supervisor Card
boots up, the fans spin at default speed of 11000 RPM. After Supervisor Card boot-up, the Supervisor Card
controls the fan speeds, based on the temperature of the air entering the chassis and the barometric pressure
reported by the sensors in the Fan Modules.
Failure Responses and Fan Speed Variations
The fan module will change speed based on the following conditions:
• When communication with the Supervisor Card is lost, both the fans in the Fan Module are set the 11,000
• If a fan is considered to have failed if it operates at +/- 1000rpm from the set point. All fans are elevated
Cisco Converged Broadband Routers Hardware Installation Guide
40
RPM default speed mode until communication is established. If the fans were running above 11,000
RPM default when communication was lost, the fans continue to operate at the elevated speeds until they
are power cycled.
in speed based on facility air inlet temperature to the Supervisor Card as safety measure, by a temperature
sensor on the Supervisor Card. The front panel LED of the Fan Module indicates an amber color LED.
If there is an indication of a fan failure the Supervisor Card sets all the fan modules to a higher RPM
value based on the inlet temperature on the Supervisor Card. The Supervisor Card sets the following
values:
What is a Cisco cBR Series Converged Broadband Router
Value
8.40 in (21.34 cm)
5.20 in (13.20 cm)
3.50 in (8.89 cm)
4 lbs (1.81 kg)
Description
Status of the rear fan that faces inside the chassis.
Status of the front fan that faces outside the chassis.
Failure and replacement status of the Fan Module.