Splitting Mellanox ConnectX-4 interface using breakout cables

[Matt Joras]

On Sep 13, 2017 6:43 AM, "David Horn" <dhorn2000 at gmail.com> wrote:

I was under the impression that these Mellanox 40G->4x10G breakout cables
were for the Mellanox switch side (not Mellanox NIC) to provide more
flexible utilization options for the switch.  I have never heard of doing
this from the 40G NIC (on any OS).

Please reply if you have seen this working on *any* OS from the Mellanox
40G NIC, as I am curious as well and have a both ConnectX-3 and -4 HW.

-Dave

On Wed, Sep 13, 2017 at 7:00 AM, Andrey V. Elsukov <bu7cher at yandex.ru>
wrote:

> Hi All,
>
> we are wondering, is it possible to use such configuration under
> FreeBSD? I.e. split one mce interface 40G => 4x10G or 100G => 4x25G?
>
> --
> WBR, Andrey V. Elsukov
>
>



I was also under the impression that they were exclusively used on the
switch for Mellanox. Mellanox's documentation seems to back this up:

"Important: The 40GbE split options is supported only on Mellanox
switches and not supported on Mellanox adapters (e.g. ConnectX-3) when
equipped with 40GbE ports. In case you wish to limit the 40GbE port on
the adapter to 10GbE you can use QSA or similar 40GbE-10GbE cables
(Refer to Mellanox.com - here)" [1]

That doesn't mention their newer NICs, however, though I don't see a
mention of the feature on their product sheets.

Matt

[1] https://community.mellanox.com/docs/DOC-1450