Expand all | Collapse all

QFX3500 airflow qustion

Jump to Best Answer
  • 1.  QFX3500 airflow qustion

    Posted 06-16-2020 07:50


    We have some qfx3500 that their airflow are front to back so the cool air is entering from front of the chassis and exit from back of the chassis which 48x 10g is located, so my question is when hot air exit from 48x 10g port side, it does not cause warm/hot air cause failure for fibers or optics?

    because we have cold coridor and hot coridor and then the cold air enter from front and exit from back, i am curoius if fibers or optics fail due to warm/hot air ,

    THank you.

  • 2.  RE: QFX3500 airflow qustion
    Best Answer

    Posted 06-16-2020 09:00

    Hello blackmetal, 


    To answer your question, I think you have a AFI system (FRU-to-port airflow) and I would say the cooling system and airflow mechanism is designed in such a way that it doesn't heat up the optics/fiber and since the system has fans and sensors installed, the speed of fans spinning is varied based on the heat producted or the inputs from sensors within



    The chassis includes a fan speed-control system. Under normal operating conditions, fans operate at reduced speed to reduce noise and power consumption and the temperature sensors in the chassis monitor the temperature within the chassis. The system raises an alarm if a fan fails or if the temperature inside the chassis rises above permitted levels. If the temperature inside the chassis rises above the threshold, the device shuts down automatically.

    You can see the status of fans and the temperature remotely through the CLI by issuing the operational mode command show chassis environment.


    Also, you could mount it on a cabinet and prevent any overheating by ensuring sufficient ventilation.

    Refer Page 37 and 60 of this document for details: QFX 3500 Hardware Guide 


    Hope this helps. Smiley Happy


    Please mark "Accept as solution" if this answers your query. 


    Kudos are appreciated too! 



    Sharat Ainapur


  • 3.  RE: QFX3500 airflow qustion

    Posted 06-16-2020 10:07

    OK, so for sure i can use 48x 10g with no worry about heating optics?

  • 4.  RE: QFX3500 airflow qustion

    Posted 06-16-2020 10:44

    Hi Black Metal,


    No, you should not worry about the optics over heating due to the airflow,, if notice any abnormal heat environment ashould be check, but there is still that a hardware problem may be causing it.




  • 5.  RE: QFX3500 airflow qustion

    Posted 06-16-2020 10:51



    You should be save to use the 48X10G ports regardless the direction of the airflow. 


    There is inbuild chassis temperature sensor in the box, which will control the fan speed to control the temperature within the operational range. 


    Normal Operation temperature range is from 0C to 40C, temperature could temperatally goes up to 70C. 


    (Details could be found here :https://www.juniper.net/documentation/en_US/release-independent/junos/information-products/pathway-pages/hardware/qfx-series/qfx3500.pdf)


    Normal operation temperature for the 10G SFP is between 0C to 70C. 


    (You could check the details for supported SFP in herehttps://apps.juniper.net/hct/model/?cat=Transceivers&component=EX-SFP-10GE-SR&prd=QFX3500&tab=oView)


    So the chassis temperature will not be a limitation for the SFP. 


    Hope this answers your question.