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EX9253 Cooling System

The cooling system in an EX9253 switch consists of four fan trays and an air filter unit. The cooling system components work together to keep all switch components within the acceptable temperature range.

Fan Tray

The fan tray is a hot-insertable and hot-removable field-replaceable unit (FRU) and contains two counter-rotating fans (see Figure 1 and Figure 2). The fan trays install vertically in the rear of the switch.

Figure 1: Fan TrayFan Tray
Figure 2: Faceplate of the Fan TrayFaceplate of the Fan Tray
  1
Captive screw
  3
Status LED
  2
Latch
 

The fan trays and power supplies are hot-removable and hot-insertable field-replaceable units installed in the rear panel of the switch. You can replace them without powering off the switch or disrupting switch functions. In a switch powered by AC power supplies, a minimum of two high line power supplies or three low line must be installed in the switch for non-redundant operation. To ensure proper operation of the switch, you must install a replacement power supply shortly after removing a power supply from the chassis. To maintain proper cooling, you must install a replacement fan tray or a blank panel in the fan tray slot shortly after removing a fan tray from the chassis.

The switch monitors the temperature of switch components. Under normal operating conditions, the fans in the fan trays run at less than full speed. If a fan fails or the ambient temperature rises above a threshold, the speed of the remaining fans is automatically adjusted to keep the temperature within the acceptable range. If the ambient maximum temperature specification is exceeded and the system cannot be adequately cooled, the Routing Engine shuts down the line card that cannot be cooled adequately is disabled. If the fire threshold temperature is exceeded, the Routing Engine shuts down the system by disabling output power from each power supply. You cannot replace a single fan. If one or more fans fail, you must replace the entire fan tray.

Air Filter Unit

The air filter unit has three parts–the outer filter cover, the air filter, and the inner cage that form the body (see Figure 3). The air filter is in between the outer filter cover and the inner cage. The air filter unit is mounted on the cable management brackets, and are held tightly by captive screws.

Figure 3: Air Filter UnitAir Filter Unit
  1
Outer filter cover
  3
Inner cage
  2
Air filter
 

Fan Tray Status LEDs

The LEDs indicating the state of the fan trays are located adjacent to the fan tray slots on the rear panel of the chassis (see Figure 4 and Table 1).

Figure 4: Fan Tray Status LEDsFan Tray Status LEDs
  1
Captive screw
  3
Status LED
  2
Latch
 

Table 1 describes the behavior of the fan tray LEDs.

Table 1: Fan Tray LED

Color

State

Description

Green

Blinking

Fan tray hardware initialization is complete and software initialization is pending.

On steadily

Fan tray software initialization is complete and the fan is functioning normally.

Red

On steadily

The fan tray is faulty and not functioning normally.

Cooling System in the Power Supplies

The power supplies are self-cooling and are installed in the rear panel of the switch. The exhaust for the power supplies are also located on the rear of the chassis.

Airflow Direction in the EX9253 Switch Chassis

The switch has front-to-back (AIR OUT) airflow (see Figure 5). The air intake to cool the chassis is located on the front of the chassis. Air is pulled through the chassis toward the fan tray, where it is exhausted out through the rear of the chassis. The air intake to cool the power supplies is also located in the front of the chassis.

Figure 5: Airflow Through the EX9253 Switch ChassisAirflow Through the EX9253 Switch Chassis