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QFX5100 Cooling System

 

Cooling System and Airflow in a QFX5100 Device

The cooling system in an QFX5100 device consists of fan modules and a single fan in each power supply. The number of fan modules vary depending whether the size of the switch is 1 U or 2 U high. All switches can be set up to work in one of two airflow directions:

  • Airflow In–Air comes into the switch through the vents in the field-replaceable units (FRUs)

  • Airflow Out–Air comes into the switch through the vents in the port panel.

Caution

Airflow In and Airflow Out fans and power supplies cannot be mixed in the same chassis.

Fan Modules

The fan modules in QFX5100 devices are hot-insertable and hot-removable field-replaceable units (FRUs). These fan modules are designed for one of the two available airflow directions (Airflow In or Airflow Out). Some fan modules are also color-coded for the airflow direction as well. The fan modules are installed in the fan module slots on the management panel of the switch next to the power supplies.

Both the 1 U and 2 U versions of QFX5100 fan modules have a similar design with different dimensions. The 1 U QFX5100 devices have 5 fan modules numbered 0 through 4 from left to right, where the 2 U, QFX5100-96S device, has 3 fan modules numbered 0 through 2. On all QFX5100 devices, each fan module slot has a fan icon next to it.

Figure 1 shows the 1 U fan module and Figure 2 shows the 2 U fan module.

Figure 1: 1 U Fan Module Used in QFX5100 Switches
1 U Fan Module Used in
QFX5100 Switches
Figure 2: 2 U Fan Module Used in QFX5100-96S Switches
2 U Fan Module Used
in QFX5100-96S Switches

You remove and replace a fan module from the FRU end 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 fan modules must be installed for optimal operation of the switch.

The fan modules are available in two product SKUs that have different airflow directions—FRU-to-port airflow, indicated on some units by the azure blue color or a label. FRU-to-port airflow versions of the fan module that have labels are marked AIR IN . Likewise, port-to-FRU airflow is indicated by either a gold color or the label AIR OUT . On legacy switches or switches with LCDs, this airflow is also called front-to-back and back-to-front. Table 1 lists the available fan module product SKUs and the direction of airflow in them:

Table 1: Fan Modules in QFX5100 Switches

Fan Module

Product SKUs

Airflow Diagram

Label on the Fan Module

Color of Fan Module

Direction of Airflow in the Fan Module

Power Supplies

QFX5100-FAN-AFI

QFX5100-24Q

QFX5100-48S

QFX5100-48SH

QFX5100-48T

QFX5100-48TH

Figure 3

AIR IN

Juniper Azure Blue

FRU-to-port, that is, air comes in from the end of the switch with the fans; air exhausts from the switch end with ports (also known as back-to-front airflow).

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

QFX5100-96S-FANAFI

QFX5100-96S

Figure 4

QFX5100-FAN-AFO

QFX5100-24Q

QFX5100-48S

QFX5100-48SH

QFX5100-48T

QFX5100-48TH

Figure 5

AIR OUT

Juniper Gold

Port-to-FRU, that is, air comes in through vents on the end with ports; air exhausts out the end with the fans (also known as front-to-back airflow).

You must install only power supplies that have AIR OUT labels in switches in which the fan modules have AIR OUT labels.

QFX5100-96S-FANAFO

QFX5100-96S

Figure 6

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

Figure 3: Air In Airflow Through 1 U QFX5100 Switch Chassis
Air In Airflow Through 1 U
QFX5100 Switch Chassis
Figure 4: Air In Airflow Through 2 U QFX5100 Switch Chassis
Air In Airflow Through 2 U
QFX5100 Switch Chassis
Figure 5: Air Out Airflow Through 1 U QFX5100 Switch Chassis
Air Out Airflow Through 1 U
QFX5100 Switch Chassis
Figure 6: Air Out Airflow Through 2 U QFX5100 Switch Chassis
Air Out Airflow Through 2 U
QFX5100 Switch Chassis

Do Not Install Components with Different Airflow or Wattage in the Switch

Do not mix power supplies with different airflow. If the power supplies are color-coded, ensure they are either all azure blue for airflow in models or all gold for airflow out models. If the power supplies are not color-coded but have a label, ensure that the chassis is either using all airflow in ( AFI ) or all airflow out (AFO). Likewise, ensure that all fan modules have the same airflow and match the airflow of the power supplies. Fan modules are also either color-coded azure blue for airflow in or gold for airflow out. If the fan module has a label instead of being color-coded, ensure that labels (AIR IN and AIR OUT ) are not mixed. If the fan modules have AIR IN labels, the power supplies must also have AIR IN labels; if the fan modules have AIR OUT labels, the power supplies must also have AIR OUT labels.

Mixing components with different airflows 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.

Do not mix fan modules with different wattage. Only use the replacement fan modules that are designed for use with your product number. See Table 1 for the correct part number for your QFX5100 device.

Caution

Do not mix AC and DC power supplies in the same chassis.

However if you need to convert a QFX5100 device to have a different airflow, you can change the airflow pattern. To convert an AIR IN product SKU to an AIR OUT product SKU or an AIR OUT product SKU to a AIR IN product SKU, you must replace all of the fans and power supplies at one time to use the new direction. The system raises an alarm when the system is converted, which is normal.

Fan Module Status

You can check the status of fan modules through the show system alarms command or by looking at the LEDs next to each fan module.

Each switch has a Status LED (labeled ST) for each fan module on the left side of the corresponding fan module slot. It indicates the status of all the fan modules. Table 2 describes the Status LED on the fan module in a QFX5100 device.

Table 2: Fan Module LED

LED State

Description

Solid Green

The individual fan module is present. After the hardware senses the fan module, software ensures the airflow is consistent with the other fan modules and that it is functioning correctly.

Blinking Amber

Indicates one of the following:

  • The fan module is not present.

  • The fan module is not functioning normally.

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.

Fan Module LED on a QFX5100 Device

Figure 7 shows the location of the LED next to the fan module.

Figure 7: Fan Module LED in a QFX5100 Switch
Fan Module LED in a
QFX5100 Switch
  1
Fan LED
 

Table 3 describes the function of the fan tray LED.

Table 3: Fan Tray LED in a QFX5100 Switch

Name

Color

State

Description

Fan

Green

On steadily

The fan module is operating normally. The system has verified that the module is engaged, that the airflow is in the correct direction, and that the fan is operating correctly.

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.

Clearance Requirements for Airflow and Hardware Maintenance for a QFX5100 Device

When planning the site for installing a QFX5100 device, you must allow sufficient clearance around the installed chassis (see Figure 8).

Figure 8: Clearance Requirements for Airflow and Hardware Maintenance for a QFX5100 Device
Clearance Requirements for Airflow and Hardware Maintenance
for a QFX5100 Device
  • For the cooling system to function properly, the airflow around the chassis must be unrestricted. See Cooling System and Airflow in a QFX5100 Device for more information about the airflow through the chassis.

  • If you are mounting a QFX5100 device in a rack or cabinet with other equipment, ensure that the exhaust from other equipment does not blow into the intake vents of the chassis.

  • Leave at least 24 in. (61 cm) both in front of and behind the QFX5100 device. For service personnel to remove and install hardware components, you must leave adequate space at the front and back of the switch. NEBS GR-63 recommends that you allow at least 30 in. (76.2 cm) in front of the rack or cabinet and 24 in. (61 cm) behind the rack or cabinet.