Juniper CBL-M40-PWR-AU 사용자 설명서
Troubleshoot the Cooling System
197
Chapter 17
Troubleshoot the Cooling System
The router’s cooling system comprises two separate subsystems:
Upper and lower impeller assemblies—Cool the Packet Forwarding Engine components
(backplane, SCB, FPCs, and PICs). The lower impeller assembly is located behind the
craft interface at the front the chassis (see Figure 1), and the upper assembly is located
above the fan tray at the rear of the chassis (see Figure 2). Each assembly houses two
impellers for redundancy. The assemblies are not interchangeable.
craft interface at the front the chassis (see Figure 1), and the upper assembly is located
above the fan tray at the rear of the chassis (see Figure 2). Each assembly houses two
impellers for redundancy. The assemblies are not interchangeable.
Fan tray—Cools the Routing Engine and backplane. The tray houses three fans for
redundancy and is located above the Routing Engine at the upper rear of the chassis (see
Figure 2).
Figure 2).
The cooling system draws in room air through the air intake vent located at the front of the
chassis below the craft interface. After entering the chassis, the air stream separates into
separate flows for the front and rear subsystems, and the temperature of each flow is
monitored independently. For a graphic depiction of the airflow, see Figure 10.
chassis below the craft interface. After entering the chassis, the air stream separates into
separate flows for the front and rear subsystems, and the temperature of each flow is
monitored independently. For a graphic depiction of the airflow, see Figure 10.
For the cooling system to function properly, the clearance around the chassis must be
sufficient for unobstructed airflow. See “Clearance Requirements for Airflow and Hardware
Maintenance” on page 42.
sufficient for unobstructed airflow. See “Clearance Requirements for Airflow and Hardware
Maintenance” on page 42.
During normal operation, the impellers and fans in the fan tray function at less than full
speed. Sensors on the backplane and router components constantly monitor their
temperature, and the speed of the fans and impellers is adjusted as necessary. If the router
temperature exceeds the acceptable maximum, the JUNOS software shuts down the router
by turning off the power supplies.
speed. Sensors on the backplane and router components constantly monitor their
temperature, and the speed of the fans and impellers is adjusted as necessary. If the router
temperature exceeds the acceptable maximum, the JUNOS software shuts down the router
by turning off the power supplies.
To troubleshoot the cooling subsystems, follow these procedures: