Juniper EX4400 - Fan Modules

The cooling system in an EX4400 switch consists of two fan modules for the chassis and a single built-in
fan in each power supply. The airow direcon depends on the fan modules and power supplies
installed in the switch. You can order an EX4400 switch that supports front-to-back (air enters through
the front panel of the switch) or back-to-front airow (air enters through the rear panel of the switch).
Fan Modules
The fan modules are hot-removable and hot-insertable eld-replaceable units (FRUs) installed in the rear
panel of the switch: You can remove and replace them without powering o the switch or disrupng
switch funcons.
We ship EX4400 switches with two fan modules (1+1 redundancy) preinstalled in the rear panel of the
switch. The fan module slots are numbered 0 and 1, and each slot has a fan icon next to it.
The fan modules are available in two models that have dierent airow direcons:
• Front-to-back (cold air enters through the vents on the front panel of the switch and hot air exhausts
through the vents on the rear panel), indicated by the AIR OUT label and the Juniper Gold handle.
• Back-to-front (cold air enters through the vents on the rear panel of the switch and hot air exhausts
through the vents on the front panel), indicated by the AIR IN label and the Juniper Azure Blue
handle.
Figure 59 on page 79 shows the fan module used in an EX4400 switch.
Figure 59: Fan Module Used in an EX4400 Switch
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