Cisco Systems Cisco 12816 Manuale Utente

Cool air is circulated through the router chassis by two blower modules. The 
blower modules maintain acceptable operating temperatures for the internal 
components by drawing in cool air through the air filter in front of the switch 
fabric card cage (middle), and circulating the air through both card cages 
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Each power supply is also equipped with a fan that draws cooler air into the front 
of the power supply and forces warmer air out of the back of the chassis.

When selecting a site to install the router, observe the following guidelines:

Dust free area—The site should be as dust free as possible. Dusty 
environments can clog the air filter or power supply intake vents, reducing the 
cooling air flow through the router. Clogged filters and vents can cause an 
overtemperature condition in the router.

Unrestricted air flow—Allow sufficient air flow by maintaining a minimum 
of 6 inches (15.24 cm) of clearance at both the inlet and exhaust openings on 
the chassis and the power modules. If the air flow is blocked or restricted, or 
if the inlet air is too warm, an overtemperature condition can occur within the 
router. Under extreme conditions, the environmental monitoring system will 
power off the router to protect the components.