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QFX5120 Cooling System

The cooling system in QFX5120 switches consists of fan modules and built-in fans in the power supplies. The airflow direction depends on the fan modules and power supplies installed in the switch. You can order a QFX5120 switch that supports front-to-back airflow (air enters through the front of the switch) or back-to-front airflow (air enters through the back of the switch).

The fan modules are hot-removable and hot-insertable field-replaceable units (FRUs) installed in the rear panel of the switch: You can remove and replace them without powering off the switch or disrupting switch functions.

Fan Modules for QFX5120 Switches

We ship QFX5120-32C switches with six fan modules (5+1 redundancy) preinstalled in the rear panel. We ship QFX5120-48T, QFX5120-48Y, and QFX5120-48YM switches with five fan modules (4+1 redundancy) preinstalled in the rear panel.

The fan modules are available in two models that have different airflow directions:

  • Front-to-back (cold air enters through the front of the switch and hot air exhausts through the back of the switch), indicated by the label F2B and red handle in QFX5120-32C switches and by the label AIR OUT and Juniper Gold handle in QFX5120-48T, QFX5120-48Y, and QFX5120-48YM switches.

  • Back-to-front (cold air enters through the back of the switch and hot air exhausts through the front), indicated by the label B2F and blue handle in QFX5120-32C switches and by the label AIR IN and Juniper Azure Blue handle in QFX5120-48T, QFX5120-48Y, and QFX5120-48YM switches.

Figure 1 shows the fan module for QFX5120-32C switches.

Figure 1: Fan Module for QFX5120-32C SwitchesFan Module for QFX5120-32C Switches

The fan module slots on the switch chassis are numbered 0 through 5 from left to right and have an arrow-shaped LED each next to them.

Figure 2 shows the fan module for QFX5120-48T, QFX5120-48Y, and QFX5120-48YM switches.

Figure 2: Fan Module for QFX5120-48T, QFX5120-48Y, and QFX5120-48YM SwitchesFan Module for QFX5120-48T, QFX5120-48Y, and QFX5120-48YM Switches

The fan module slots on the switch chassis are numbered 0 through 4 from left to right and have a fan icon and a round LED each next to them.

Note:

You must install all the fan modules for optimal functioning of the switch.

If the switch is operational while you are replacing fan modules, you must remove only one fan module at a time. The switch continues to operate for 30 seconds without thermal shutdown while you are replacing a fan module.

QFX5120 Models and Airflow Direction

Table 1 shows the airflow direction in QFX5120 switch models.

Table 1: Airflow Direction in QFX5120 Switch Models

Model Number

 Fan Model Number

Fan Modules and Power Supplies

Direction of Airflow in the Fan Modules and Power Supplies

QFX5120-32C-AFO

 QFX520048Y-FAN-AO

We ship the switch with six fan modules (with front-to-back airflow, indicated by the label F2B and a red handle) and two AC power supplies (with a red ejector lever).

Front-to-back—Cold 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.

QFX5120-32C-AFI

 QFX520048Y-FAN-AI

We ship the switch with six fan modules (with front-to-back airflow, indicated by the label B2F and a blue handle) and two AC power supplies (with a blue ejector lever).

Back-to-front—Cold 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.

QFX5120-32C-DC-AFO

 QFX520048Y-FAN-AO

We ship the switch with six fan modules (with front-to-back airflow, indicated by the label F2B and a red handle) and two DC power supplies (with a red ejector lever).

Front-to-back—Cold 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.

QFX5120-32C-DC-AFI

 QFX520048Y-FAN-AI

We ship the switch with six fan modules (with front-to-back airflow, indicated by the label B2F and a blue handle) and two DC power supplies (with a blue ejector lever).

Back-to-front—Cold 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.

QFX5120-48T-AFO

 QFX5110-FANAFO

We ship the switch with five fan modules (with the label AIR OUT) and two AC power supplies (with a Juniper Gold handle).

Front-to-back—Cold 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.

QFX5120-48T-AFI

 QFX5110-FANAFI

We ship the switch with five fan modules (with the label AIR IN) and two AC power supplies (with a Juniper Azure Blue handle).

Back-to-front—Cold 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.

QFX5120-48T-DC-AFO

 QFX5110-FANAFO

We ship the switch with five fan modules (with the label AIR OUT) and two DC power supplies (with a Juniper Gold handle).

Front-to-back—Cold 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.

QFX5120-48T-DC-AFI

 QFX5110-FANAFI

We ship the switch with five fan modules (with the label AIR IN) and two DC power supplies (with a Juniper Azure Blue handle).

Back-to-front—Cold 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.

QFX5120-48Y-AFO2

 QFX5110-FANAFO

We ship the switch with five fan modules (with the label AIR OUT) and two AC power supplies (with a Juniper Gold handle).

Front-to-back—Cold 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.

QFX5120-48Y-AFI2

 QFX5110-FANAFI

We ship the switch with five fan modules (with the label AIR IN) and two AC power supplies (with a Juniper Azure Blue handle).

Back-to-front—Cold 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.

QFX5120-48Y-DC-AFO2

 QFX5110-FANAFO

We ship the switch with five fan modules (with the label AIR OUT) and two DC power supplies (with a Juniper Gold handle).

Front-to-back—Cold 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.

QFX5120-48Y-DC-AFI2

 QFX5110-FANAFI

We ship the switch with five fan modules (with the label AIR IN) and two DC power supplies (with a Juniper Azure Blue handle).

Back-to-front—Cold 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.

QFX5120-48YM-AFO

 QFX5110-FANAFO

We ship the switch with five fan modules (with the label AIR OUT) and two AC power supplies (with a Juniper Gold handle).

Front-to-back—Cold 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.

QFX5120-48YM-AFI

 QFX5110-FANAFI

We ship the switch with five fan modules (with the label AIR IN) and two AC power supplies (with a Juniper Azure Blue handle).

Back-to-front—Cold 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.

QFX5120-48YM-DC-AO

 QFX5110-FANAFO

We ship the switch with five fan modules (with the label AIR OUT) and two DC power supplies (with a Juniper Gold handle).

Front-to-back—Cold 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.

QFX5120-48YM-DC-AI

 QFX5110-FANAFI

We ship the switch with five fan modules (with the label AIR IN) and two DC power supplies (with a Juniper Azure Blue handle).

Back-to-front—Cold 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:

  • Power supplies with different airflow directions in the same chassis.

  • Fan modules with different airflow directions in the same chassis.

  • Power supplies and fan modules with different airflow directions in the same chassis.

Mixing components with different airflow directions in the same chassis hampers the performance of the cooling system of the switch and leads to overheating of the chassis.

If you install power supplies or fan modules with different airflow directions, Junos OS raises an alarm.

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

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

QFX5120 Models with Front-to-Back Airflow

In the QFX5120 switch models that have front-to-back airflow, the cold 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.

Figure 3 shows the front-to-back airflow through the QFX5120-32C switch chassis.

Figure 3: Front-to-Back Airflow Through the QFX5120-32C Switch ChassisFront-to-Back Airflow Through the QFX5120-32C Switch Chassis

Figure 4 shows the front-to-back airflow through the QFX5120-48T switch chassis.

Figure 4: Front-to-Back Airflow Through the QFX5120-48T Switch ChassisFront-to-Back Airflow Through the QFX5120-48T Switch Chassis

Figure 5 shows the front-to-back airflow through the QFX5120-48Y switch chassis.

Figure 5: Front-to-Back Airflow Through the QFX5120-48Y Switch ChassisFront-to-Back Airflow Through the QFX5120-48Y Switch Chassis

Figure 6 shows the front-to-back airflow through the QFX5120-48YM switch chassis.

Figure 6: Front-to-Back Airflow Through the QFX5120-48YM Switch ChassisFront-to-Back Airflow Through the QFX5120-48YM Switch Chassis

QFX5120 Models with Back-to-Front Airflow

In the QFX5120 switch models that have back-to-front airflow, the cold 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.

Figure 7 shows the back-to-front airflow through the QFX5120-32C switch chassis.

Figure 7: Back-to-Front Airflow Through the QFX5120-32C Switch ChassisBack-to-Front Airflow Through the QFX5120-32C Switch Chassis

Figure 8 shows the back-to-front airflow through the QFX5120-48T switch chassis.

Figure 8: Back-to-Front Airflow Through the QFX5120-48T Switch ChassisBack-to-Front Airflow Through the QFX5120-48T Switch Chassis

Figure 9 shows the back-to-front airflow through the QFX5120-48Y switch chassis.

Figure 9: Back-to-Front Airflow Through the QFX5120-48Y Switch ChassisBack-to-Front Airflow Through the QFX5120-48Y Switch Chassis

Figure 10 shows the back-to-front airflow through the QFX5120-48YM switch chassis.

Figure 10: Back-to-Front Airflow Through the QFX5120-48YM Switch ChassisBack-to-Front Airflow Through the QFX5120-48YM Switch Chassis

How to Position the Switch

In front-to-back airflow, hot air exhausts through the vents on the rear panel of the switch. In back-to-front airflow, 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 F2B labels on the fan modules for QFX5120-32C switches and the AIR OUT labels on the fan modules for QFX5120-48T, QFX5120-48Y, and QFX5120-48YM switches are facing the hot aisle (see Figure 11).

    Figure 11: Deployment of Switches with Front-to-Back Airflow Through the QFX5120 Switch ChassisDeployment of Switches with Front-to-Back Airflow Through the QFX5120 Switch Chassis

  • The B2F labels on the fan modules for QFX5120-32C switches and the AIR IN labels on the fan modules for QFX5120-48T, QFX5120-48Y, and QFX5120-48YM switches are facing the cold aisle (see Figure 12).

    Figure 12: Deployment of Switches with Back-to-Front Airflow Through the QFX5120 Switch ChassisDeployment of Switches with Back-to-Front Airflow Through the QFX5120 Switch Chassis

QFX5120 Fan Module Status

There is a status LED for each fan module on QFX5120 switches, next to the fan module slot on the rear panel of the chassis, indicating the status of the fan module. Table 2 describes the fan module LED.

Table 2: Fan Module Status LED

LED

Color

State

Description

Status

Green

On steadily

The switch has verified that the fan module is engaged, that the airflow is in the correct direction, and that the fan module is functioning normally.

  • QFX5120-32C—Red

  • QFX5120-48T, QFX5120-48Y, and QFX5120-48YM—Amber

Blinking

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