Airflow Direction In The Ex8208 Switch Chassis - Juniper EX8208 Hardware Manual

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Airflow Direction in the EX8208 Switch Chassis

The air intake to cool the chassis 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 tray. Hot air exhausts from the left side of the
chassis. See Figure 9 on page 55.
Figure 9: Airflow Through the EX8208 Switch Chassis
The Switch Fabric and Routing Engine (SRE) module monitors the temperature of switch components.
Under normal operating conditions, the fans in the fan tray run at less than full speed. The fans are controlled
by two fan tray controllers. The fans are numbered 1 through 12. Fans 1 through 6 are controlled by the
first fan tray controller. Fans 7 through 12 are controlled by the second fan tray controller. If one fan tray
controller fails, the other fan tray controller keeps half the fans working. This allows the switch to continue
to operate normally as long as the remaining fans cool the chassis sufficiently.
If a fan fails or the ambient temperature rises above the threshold 113°F (45°C), the speed of the remaining
fans is automatically adjusted to keep the temperature within the acceptable range, 32°F (0°C) through
104°F (40°C).
The fan tray continues 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.