Cooling System And Fans - Foundry Networks FES2402 Installation Manual

Product Overview
equally distributed (within a certain percentage depending on power load or power supply type) between both
power supplies. The power supplies provide power to both the system and POE components. Therefore, a power
supply failure can affect the operation of the entire device and not just POE ports.
NOTE: If a switch has 48 ports and two power supplies, and the POE ports are consuming more than 480 watts
of power, a single power supply failure will cause both power supplies to shut down.
If a power supply fails and the system is left with less than the minimum required power, the remaining power
supply will go into overload. Several things can happen with a power supply failure in a FastIron POE switch. The
output voltage of the remaining good power supply will likely drop as it tries unsuccessfully to generate more
power than it is capable of. The system will react to a drop in voltage by increasing the current draw. POE ports
will start to shut down due to over-current protection or under-voltage protection, whichever occurs first. There is
no particular order in which the POE ports will shut down, as this will occur in hardware and not in software.
After a power loss, if the system is left with less than the minimum number of power supplies required for normal
operation, the system will be left in an unknown state. At this point, manual recovery is required (i.e. restore power
and power cycle the switch).

Cooling System and Fans

This section describes the fans in the FastIron compact switches.
FES Fans
The FES cooling fans cool the CPU, main memory, and voltage regulators. The fans use either a push or pull
configuration to move the air from the left side of the device to the right side of the device.
The fans in the FES operate at a steady speed, and do not support multiple fan speeds.
FastIron X Series Fans
The FastIron X Series cooling fans cool the CPU, main memory, and voltage regulators. The fans use either a
push or pull configuration to move the air from the left side of the device to the right side of the device.
The fans in the 24-port FastIron X Series switches operate at a single speed and do not support multiple fan
speeds.
The fans in the 48-port FastIron X Series switches include two three-speed fans that operate at low speed, then
adjust based on the ambient temperature and configured or default temperature thresholds. Both fans operate
simultaneously at the same speed. If one fan fails, it does not affect the operation of the other fan.
The fans can operate at speeds of low, medium, and high. The system uses a fan speed switch and a default or
configured temperature threshold associated with it to determine at which speed the fan should operate. If
desired, you can change the settings of the temperature thresholds associated with fan speed switches. For more
information, see "Managing Temperature Settings and Fan Speed on FastIron X Series Compact Switches" on
page 5-3.
December 2008 © 2008 Foundry Networks, Inc. 2 - 21