Cooling System and Airflow in a QFX3008-I Interconnect Device

 

The cooling system in a QFX3008-I Interconnect device consists of ten fan trays and nine air filters. The fan trays and air filters are hot-insertable and hot-removable field-replaceable units (FRUs).

Eight fan trays install vertically on the front sides of the chassis, one fan tray installs directly below the front card cage, and one in the rear of the chassis at the top. See Figure 1 and Figure 2.

Figure 1: Location of Bottom and Side Fan Trays
Location of Bottom and
Side Fan Trays
Figure 2: Location of Top Fan Tray
Location of Top Fan
Tray

The chassis continues to operate for a limited time (2 minutes) after a fan tray has been removed.

Caution

You must replace a fan tray within 2 minutes of removing it.

The chassis has front-to-back airflow. The air intake to cool the front card cage and power supplies is located on the front bottom of the chassis. Cool air is pulled into the chassis and is pushed through the front card cage toward the rear fan tray. Hot air exhausts from the upper rear of the chassis. See the side view in Figure 3 for this airflow.

The same air intake directs cool air to the power supplies and wiring trays. The hot air passes through the power supplies and wiring trays and exhausts on the rear of the chassis at the bottom. See the side view in Figure 3 for this airflow.

Figure 3: Airflow Through the Front Card Cage and Powerhouse
Airflow Through the Front
Card Cage and Powerhouse

Cooling for the rear card cage is also front to back. The air intake to cool the rear card cage is located on the front sides of the chassis. Cool air is pulled in through the side fan trays. The hot air exhausts through the rear card cage. See Figure 4 for this airflow.

Figure 4: Airflow Through the Rear Card Cage
Airflow Through the Rear
Card Cage
Note

Do not block the air intake at the bottom front of the chassis, or the side fan trays.

The Control Board monitors the temperature of device components. Under normal operating conditions, the fans in the fan trays run at less than full speed.

If the chassis temperature rises above the acceptable threshold the speed of the working fans is automatically adjusted to keep the temperature within the acceptable range. If the ambient maximum temperature specification (104° F or 40° C) is exceeded and the system cannot be adequately cooled, the device shuts down within 4 minutes of the alarm being generated if the problem is not fixed.

The fan trays continue to operate indefinitely and provide sufficient cooling even when a single fan fails, provided the room temperature is within the operating range. You can check the status of the fan trays on the front panel display. See Chassis Status LEDs on a QFX3008-I Interconnect Device.

You cannot replace a single fan in a fan tray. If one or more fans fail, you must replace the entire fan tray.

Warning

There is no fan guard on the fans. Be careful to keep your fingers clear of moving fan blades when you are removing the fan trays.