Cooling System Components

The cooling system has the following components. Except as noted, they are hot-removable and hot-insertable, as described in Field-Replaceable Units (FRUs).

• Air intake vent and air filter—Provide an opening for room air to enter the router. They are located at the bottom of the chassis front, below the craft interface, as shown in Figure 1. The air filter prevents dust and other particles from entering the cooling system. For replacement instructions, see Maintain and Replace the Air Filter. 
  
  

  Do not remove the air filter for more than a minute or so while the router is operating. The fans and impellers are powerful enough to draw in foreign material, such as bits of wire, through the unfiltered air intake, which could damage router components.

  
  
• Upper and lower impeller assemblies—Cool the Packet Forwarding Engine components (backplane, SCB, FPCs, and PICs). The lower impeller assembly is located behind the craft interface at the front the chassis, and the upper assembly is located above the fan tray at the rear of the chassis. Each assembly houses two impellers for redundancy. The assemblies are not interchangeable. For replacement instructions, see Replace the Lower Impeller Assembly and Replace the Upper Impeller Assembly.
• Fan tray—Cools the Routing Engine and backplane. The tray houses three fans for redundancy and is located above the Routing Engine at the upper rear of the chassis (see Figure 2). For replacement instructions, see Maintain and Replace the Fan Tray.
• Power supply integrated fan—Cools the power supply. It is not field-replaceable.