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Fans

The E320 router employs a bottom-to-top cooling system to keep the temperature of the modules and components within normal operating limits. Eight cooling fans are located in a tray at the top of the router. (See Figure 1 and Figure 2.) Air is pulled in from the front of the router at the bottom and is exhausted out the top.

The E120 router employs a right-to-left cooling system. Nine cooling fans are located in a tray at the left of the router. (See Figure 3.) Air is pulled in from the right of the router and is exhausted out the left.

The system monitors the temperature of each module. If the temperature of a module exceeds the maximum limit, the system immediately goes into thermal protection mode and the LMs and SFM modules are powered off. The system controllers remain active and respond on all management interfaces. All other modules remain in a power-off condition. The failure of any two components (fan or converter), or the absence of the fan tray, causes the chassis to enter thermal protection mode to prevent hardware damage. For information about troubleshooting high operating temperatures, see Troubleshooting.

The E320 fan tray has two primary converters that power four fans each. If a primary converter fails, a third redundant converter takes over. The E120 fan tray has dual converters that load share for redundancy. If one converter fails, the other redundant converter takes over. The system software reports an alarm if any of the fans or converters fail.

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