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EX4650 Cooling System

 

The cooling system in an EX4650 switch consists of five fan modules and each power supply has its own fans. The switch can be set up to work in one of two airflow directions depending on the fan modules and power supplies installed in the switch.

  • Back-to-front airflow (air enters through the back of the switch), indicated by the label AIR IN (AFI)

  • Front-to-back (air exhausts through the back of the switch), indicated by the label AIR OUT (AFO)

Caution

Do not mix AFI and AFO fans and power supplies in the same chassis.

Fan Modules

The fan modules in EX4650 switches are hot-insertable and hot-removable FRUs. These fan modules are designed for one of the two available airflow directions (Airflow In or Airflow Out). The fan modules are also color-coded to indicate the airflow direction. The fan modules are installed in the fan module slots between the management panel and the power supplies.

Figure 1 shows the EX4650 fan module.

Figure 1: EX4650 Fan Module
EX4650 Fan Module

The five fan modules are numbered 0 through 4 counting from left to right. Each fan module slot has a fan icon and an LED next to it.

You must remove only one fan module at a time for replacement from the rear panel of the chassis. The switch continues to operate for a limited period of time (30 seconds) during the replacement of the fan module without thermal shutdown.

Note

All the five fan modules must be installed for optimal functioning of the switch.

The fan modules are available in four models that have different airflow directions—back-to-front (air enters through the back of the switch), indicated by the label AFI and azure blue color, and front-to-back (air exhausts through the back of the switch), indicated by label AFO and gold color. Table 1 lists the available fan module models and the direction of airflow in them.

Table 1: Fan Modules in EX4650 Switches

Fan Module

Label on the Fan Module

Color of the Fan Module

Direction of Airflow in the Fan Module

Power Supplies

EX4650-FANAFO

AFO

Juniper Gold

Front-to-back—air intake to cool the chassis is through the vents on the front panel of the chassis, and hot air exhausts through the vents on the rear panel of the chassis.

You must install only power supplies that have AIR OUT(AFO) labels in switches that have fan modules with AIR OUT labels.

EX4650-FANAFI

AFI

Juniper Azure Blue

Back-to-front—air intake to cool the chassis is through the vents on the rear panel of the chassis, and hot air exhausts through the vents on the front panel of the chassis.

You must install only power supplies that have AIR IN(AFI) labels in switches that have fan modules with AIR IN labels.

Airflow Direction in EX4650 Switch Models

Table 2 shows the direction of airflow in EX4650 switch models as shipped.

Table 2: Airflow Direction in EX4650 Switch Models

Model Number

Fan Modules and Power Supply

Direction of Airflow

EX4650-48Y-AFO

The switch ships with five fan modules and two AC power supplies, each with a label AIR OUT (AFO).

Front-to-back—that is, air intake to cool the chassis is through the vents on the front panel of the chassis and hot air exhausts through the vents on the rear panel of the chassis.

EX4650-48Y-AFI

The switch ships with five fan modules and two AC power supplies, each with a label AIR IN (AFI).

Back-to-front—that is, air intake to cool the chassis is through the vents on the rear panel of the chassis and hot air exhausts through the vents on the front panel of the chassis.

EX4650-48Y-DC-AFO

The switch ships with five fan modules and two DC power supplies, each with a label AIR OUT (AFO).

Front-to-back—that is, air intake to cool the chassis is through the vents on the front panel of the chassis and hot air exhausts through the vents on the rear panel of the chassis.

EX4650-48Y-DC-AFI

The switch ships with five fan modules and two DC power supplies, each with a label AIR IN (AFI).

Back-to-front—that is, air intake to cool the chassis is through the vents on the rear panel of the chassis and hot air exhausts through the vents on the front panel of the chassis.

Caution

Do not mix:

  • Do not mix:

    • AC and DC power supplies in the same chassis.

    • Power supplies with different airflow labels (AFI and AFO) in the same chassis.

    • Power supplies and fan modules with different airflow labels (AFI) and (AFO)) in the same chassis.

Front-to-Back Airflow

In the EX4650 switch models that have front-to-back airflow, the air intake to cool the chassis is through the vents on the front panel of the switch and hot air exhausts through the vents on the rear panel (See Figure 2).

Figure 2: Front-to-Back Airflow Through EX4650 Switch Chassis
Front-to-Back Airflow Through EX4650
Switch Chassis

You must install only power supplies that have AIR OUT (AFO) labels in switches that have fan modules with AIR OUT (AFO) labels.

Back-to-Front Airflow

In the EX4650 switch models that have back-to-front airflow, the air intake to cool the chassis is through the vents on the rear panel and hot air exhausts through the vents on the front panel of the switch. See Figure 3.

Figure 3: Back-to-Front Airflow Through EX4650 Switch Chassis
Back-to-Front Airflow Through EX4650
Switch Chassis

You must install only power supplies that have AIR IN (AFI) labels in switches in which the fan modules have AIR IN (AFI) labels.

Do Not Mix AIR IN (AFI) and AIR OUT (AFO) Components in the Switch

Do not mix power supplies and fan modules with different airflow labels (AIR IN (AFI) and AIR OUT (AFO)) in the same chassis. If the fan modules have AIR IN (AFI) labels, the power supplies must also have AIR IN (AFI) labels; if the fan modules have AIR OUT (AFO) labels, the power supplies must also have AIR OUT (AFO) labels.

The labels on the power supplies and fan modules should match the labels on the switch chassis.

Mixing components with AIR IN (AFI) and AIR OUT (AFO) labels in the same chassis hampers the performance of the cooling system of the switch and leads to overheating of the chassis.

Caution

The system raises an alarm if a fan module fails or if the ambient temperature inside the chassis rises above the acceptable range. If the temperature inside the chassis rises above the threshold temperature, the system shuts down automatically.

Positioning the Switch

In front-to-back airflow, indicated by the label AIR OUT (AFO) on the fan modules and power supplies, hot air exhausts through the vents on the rear panel of the switch. In back-to-front airflow, indicated by the label AIR IN (AFI) on the fan modules and power supplies, hot air exhausts through the vents on the front panel of the switch.

In data center deployments, position the switch in such a manner that the AIR IN (AFI) labels on switch components are next to the cold aisle, and AIR OUT (AFO) labels on switch components are next to the hot aisle.

Fan Module Status

Each fan module in the switch has a status LED next to the fan module slot on the rear panel of the chassis, which indicated the fan module status.Table 3 describes the status LED on the fan module in an EX4650 switch.

Table 3: Fan Module Status LED

LED

Color

State

Description

Status

Green

On steadily

The fan module is functioning normally.

Amber

Blinking

An error has been detected in the fan module. Replace the fan module as soon as possible. Either the fan has failed or it is seated incorrectly. To maintain proper airflow through the chassis, leave the fan module installed in the chassis until you are ready to replace it.

Under normal operating conditions, the fan modules operate at a moderate speed. Temperature sensors in the chassis monitor the temperature within the chassis.

The system raises an alarm if a fan module fails or if the ambient temperature inside the chassis rises above the acceptable range. If the temperature inside the chassis rises above the threshold temperature, the system shuts down automatically.