Cooling System and Airflow in an EX8216 Switch

The cooling system in an EX8216 switch consists of two fan trays. Each fan tray has nine fans and two fan tray controllers. The fan trays are hot-insertable and hot-removable field-replaceable units (FRUs).

Both fan trays install vertically on the front of the chassis, one on the top left and the other on the bottom left. Each fan tray has a handle on the front faceplate that facilitates handling of the fan tray. See Figure 1.

Figure 1: Fan Tray for an EX8216 Switch

The top and bottom fan trays are identical and interchangeable. Both fan trays can be removed and replaced from the front of the chassis. The switch continues to operate for a limited time (2 minutes) after a fan tray has been removed.

Caution: You must replace the fan tray within 2 minutes of removing it.

The switch has side-to-side airflow in the front of the chassis. The air intake to cool the chassis from the midplane out to the chassis front is located on the right side of the chassis. Air is pulled into the chassis and is pushed thorough the line card cage towards the fan trays. Hot air exhausts from the left side of the chassis. See the front view in Figure 2 for this airflow.

Figure 2: Airflow Through the EX8216 Switch Chassis

The air intake to cool the power supplies is located in the front of each power supply unit. The exhaust for the hot air collected from the power supplies is located on the rear of the chassis at the bottom. See the side view in Figure 2 for this airflow.

Cooling for the rear of the chassis and the Switch Fabric (SF) modules is done with front-to-side airflow. The air intake to cool the chassis from the midplane to the chassis rear is located on the front of the chassis, just below the slots for the power supplies. Air is pulled in from the chassis front towards the chassis rear and then pulled to the top of the chassis by the top fan tray. The hot air is then forced to turn left and exhausts from the left side of the chassis. See Figure 3 for this airflow.

Figure 3: Airflow for the EX8216 Switch Chassis Rear

Note: Do not block the air intake below the power supply slots.

The Routing Engine (RE) module monitors the temperature of switch components. Under normal operating conditions, the fans in the fan trays run at less than full speed. Each fan tray has two fan tray controllers.

In each fan tray, the fans are numbered 1 through 9. Fans 1 through 5 are controlled by the first fan tray controller. Fans 6 through 9 are controlled by the second fan tray controller. If one fan tray controller fails, the other fan tray controller keeps the remaining fans in the fan tray working. This allows the switch to continue to operate normally as long as the remaining working fans cool the chassis sufficiently.

If the ambient temperature rises above the threshold 113°F (45°C), the speed of the working fans is automatically adjusted to keep the temperature within the acceptable range, 32°F (0°C) through 104°F (40°C).

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 fans and the chassis temperature from the Environment Status option in the Status menu on the LCD panel. See LCD Panel in an EX8200 Switch.

You cannot replace a single fan. 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.