Cooling System

The cooling system includes several fan trays that draw room air into the chassis to keep its internal temperature below a maximum acceptable level. The cooling subsystems have redundant components, which are controlled by the SSB. If a fan fails, the remaining fans provide sufficient cooling for the unit indefinitely.

The router cooling system consists of the following components:

• Three front fan trays—Cool the FPCs and the SSB. The fan trays are located on the left front side of the chassis, as shown in Figure 1. Each tray houses three fans.
• Routing Engine fan tray—Cools the Routing Engines. The fan tray is located behind the Routing Engine panel, as shown in Figure 2. It houses two fans.
• Power supply integrated fan—Cools each power supply. It is built into the supply.

All cooling components are hot-removable and hot-insertable, as described in Field-Replaceable Units (FRUs). For instructions on replacing cooling system components, see Replacing Cooling System Components.

Caution: Do not remove a fan tray for more than a few minutes while the router is operating. The fans are powerful enough to draw in foreign material, such as bits of wire, into the chassis, which could damage router components.

The four fan trays plug directly into the router midplane and work together to provide side-to-side cooling, as shown in Figure 19.

Figure 19: Airflow Through the Chassis