Juniper EX4300 Series

The labels on the power supplies and fan modules should match the labels on the switch chassis.
Mixing components with AIR IN (AFI) and AIR OUT (AFO) labels in the same chassis hampers the
performance of the cooling system of the switch and leads to overheang of the chassis.
CAUTION: The system raises an alarm if a fan module fails or if the ambient
temperature inside the chassis rises above the acceptable range. If the temperature
inside the chassis rises above the threshold temperature, the system shuts down
automacally.
Posioning the Switch
In front-to-back airow, indicated by the label AIR OUT (AFO) on the fan modules and power supplies,
hot air exhausts through the vents on the rear panel of the switch. In back-to-front airow, indicated by
the label AIR IN (AFI) on the fan modules and power supplies, hot air exhausts through the vents on the
front panel of the switch.
In data center deployments, posion the switch in such a manner that the AIR IN (AFI) labels on switch
components are next to the cold aisle, and AIR OUT (AFO) labels on switch components are next to the
hot aisle.
Fan Module Status
Each switch has a status LED for each fan module next to the fan module slot on the rear panel of the
chassis. The Status LED indicates the status of the fan module. Table 29 on page 89 describes the
Status LED on the fan module in an EX4300 switch.
Table 29: Fan Module Status LED
LED State Descripon
Status Green The fan module is funconing normally.
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