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Aruba 8320/8400X fans airflow direction

AFAIK both Aruba 8320/8400X provide Fan(s) working with the Front-to-Back airflow direction rule.

Given that I'm not able to understand if there are specific Fan(s) Hardware designs restrictions on both platforms with regards to expected airflow...I've this question: Will airflow's direction management (Front-to-Back versus Back-to-Front) be ever supported through Software (supposing it is yet by Hardware) on these platforms as it happens on most HPE FlexFabric switch series?

We try to get an strict and common Hot/Cold airflow separation on each DC Rack we have but our Aruba 8320 pair (ToR), sharing the same Rack with SAN Storages/Switches designed to run with Back-to-Front airflow direction, is causing a weak undesired local airflow loop.

Up to now that is not worrying us too much - top Aruba 8320 internal temperatures are below 36°C despite its inlet air temperature isn't 16°C as it should be due to the airflow local loop (that's the supposed fresh inlet air temperature on the Rack backside) - it's just annoying since neighbour switches are capable of running colder by just respecting the set airflow direction.

As you can image...we can't simply reverse the Aruba 8320 mounting direction inside the Rack since FO cables arrive all at Rack backside (which is the frontside of all Switches).
MVP Expert

Re: Aruba 8320/8400X fans airflow direction

WRT Aruba 8320: looking at Sunon Fan [*] assemblies supported on similar switching platform Accton AS5712-54x [**] and, provided that each Fan Assembly owns a fans pair which is suppling an IR E/R direction signal (0=Front-to-Back versus 1=Back-to-Front) acting as input for the Altera EPM570 MAX II CPLD mainboard IC, I suspect that Air Flow's direction in this particular platform is something that can't be simply driven by (ArubaOS-CX or whatever) OS (hope to be wrong here)...instead it depends strictly on how fans pair are mechanically mounted inside their Fan Assembly...and so the only way for each Fan Assembly to provide an inverted air flow is (a) use [***] a proper Back-to-Front Air-Flow direction Fan Assembly (AFAIK no HPE/Aruba SKU is available at present time) or (b) try an hack (I've read somewhere that someone really did that on a Aruba 8400X...) and manually invert Fans mounting sense inside each Fan Assembly (given that Fan Assembly frame lets us to do it, mechanically speaking).

Clearly option (b) is not something I feel to suggest here...just a for say.

[*] Aruba 8320 uses fIve of those ones with the description "Aruba X721 Front-to-Back fan" (HPE/Aruba SKU JL481A).

[**] Sunon Front-to-Back PF40561BX-Q020-S99 with Red hand and Sunon Back-to-Front PF40561BX-Q010-S99 with Blue hand.

[***] provided that that SKU is going to be marketed by HPE/Aruba.

Re: Aruba 8320/8400X fans airflow direction

Hello Davide,

Before getting back with an informative answer, let me clarify something about your statement:

"supported through Software (supposing it is yet by Hardware) on these platforms as it happens on most HPE FlexFabric switch series?"


With 5900/5930/5940 you have to select a B2F or a F2B FAN tray. You can not tune the rotation by software (even if you have to

set the proper direction in CLI to be compliant to installed hardware).


MVP Expert

Re: Aruba 8320/8400X fans airflow direction

Hello Vincent, you're correct.


I tend to be too indulgent (or too optimistic) with HPE FlexFabric's features&capabilities.


So, yes, HPE FlexFabric switch series need correct Fan Trays SKUs to be installed (Front-to-Back or Back-to-Front, mix is supported)...nevertheless there is a Comware command (fan preferred air-flow) used to reconciliate/reconfigure air flows directions with preferred ones, if I'm not mistaken...I should have clarified I was referring about that.

Aruba Employee

Re: Aruba 8320/8400X fans airflow direction

The older Comware fantrays were not colour coded, and it was not always clear whether a fantray was FB or BF (the airflow direction arrow and the P/N help if you can read them!) That command is purely a verification to make sure that mismatched trays were not installed (potentially messing up airflows, and perhaps feeding hot air back into the switch).

Richard Litchfield, HPE Aruba
Consulting System Engineer
Network Ambassador
MVP Expert

Re: Aruba 8320/8400X fans airflow direction

Thanks! that's OK (sorry for confusion), nevertheless my question for Aruba 8320/8400X is still valid...

Re: Aruba 8320/8400X fans airflow direction

And after checking, there is no such developpment plan for 8400 and 8320. Thanks anyhow for great ideas and comments.

MVP Expert

Re: Aruba 8320/8400X fans airflow direction

The solution is use 8325 :-) there is a model with Fan Front to Back and another for Back to Front !

PowerArubaSW: Powershell Module to use Aruba Switch API for Vlan, VlanPorts, LACP, LLDP... More info

PowerArubaCP: Powershell Module to use ClearPass API (create NAD, Guest...) More info

PowerArubaCX: Powershell Module to use ArubaCX API (get interface/vlan/ports info)

PowerArubaIAP: Powershell Module to use Aruba Instant AP

ACMP 6.4 / ACMX #107 / ACCP 6.5
MVP Expert

Re: Aruba 8320/8400X fans airflow direction

Gosh...would be nice!

The Aruba 8325 has Front-to-Back and Back-to-Front on both Power Supply Modules and Fan Modules...but I don't think they're exchangeable with Aruba 8320...and I really can't exchange a pair of Aruba 8320 for a pair of Aruba 8325...at least until Aruba will knock the door to leave my company a Xmas present! in ant case we are pretty much tied to (a lot of) 10Gbps NICs...so Aruba 8320 fits the bill.

MVP Expert

Re: Aruba 8320/8400X fans airflow direction

Hi Vincent,


months have passed and I already know that, probably, the answer you gave me was (and still it is) definitive...nevertheless looking at Edgecore offering (note the blue Fans B2F):



I still don't understand why Aruba wasn't able to provide Back-to-Front (Power-to-Port) Power Supply modules and Fans for its Aruba 8320...it would be an appreciated addition especially for users that deployed Aruba 8320 in a Campus/DC IT room where the cold/hot air isles are well separated.  

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