ConnectX-2 VPI and ConnectX-3 VPI

Does anyone know if these cards will connect together both the QSFP+ versions, and connect at the slower ConnectX-2 speeds via tcp/Ip?

Several different clients including win 10, esxi, freebsd and linux.

I currently have 2 ConnectX-2 cards but would prefer to buy the ConnectX-3 and wonder if I can use the ConnectX-2 cards in other servers, they are dual port.

Also for future I may get a switch for these, I got a switch capable of the 40gbe tcp/ip would it be backwards compatible with the 10gbe of the ConnectX-2 ?

Thanks in advance for any help.


There are breakout cables for qsfp+ To 4x SFP+ if that helps you.

@marelooke @nx2l i think remember either/both of you having connectx qsfp cards?

I do, but I actually use them for Infiniband.

I do know that not all of them support breakout. The older cards don’t support it card-side I’m pretty sure (adapter works for 2/3-Pro, can vouch for that as I own those models, but of course you’re leaving 30Gbit/s on the table that way). Some Infiniband switches with Ethernet support do support breakout, but that requires an Infiniband switch that supports Ethernet, which is an expensive license (could get really lucky and score one with a license already applied on, say, Ebay, of course)

If you run them in Ethernet mode they just work like any other Ethernet card.

Are you are asking whether connecting a ConnectX-2 with a QSFP+ cable to a 40Gbase Ethernet switch would work? I imagine the way to test this (without getting a switch) would be to direct-connect a 40Gbe capable ConnectX-model to a 10Gbe-only capable ConnectX-2 with a QSFP+ cable (all in Ethernet mode, of course). I would expect it to link up just fine at 10Gbe speeds, but never tested it.

Btw, note that, in case you were not aware, not all ConnectX-3 models can push 40Gbe, you need one of the FDR capable cards (QDR doesn’t have enough bandwidth for 40Gbe).

Also a note, Connect X2 cards are slowly losing support even in linux. I would not suggest getting anything older than x3 at this point unless its only to mess around and you wont ever need anything to actually run on it.

Some enterprise oriented distros might, but I rather doubt Linux (as in: the kernel) is dropping support for these anytime soon, unless they become a massive maintenance burden. They’re still perfectly usable, and quite popular, despite being “old”.

But indeed, something to be aware of when wanting to run enterprise distros at home, those often trim “unsupported” (by the vendor) hardware pretty aggressively.


Thanks all for the replies, yes my main question was would a 40gbe capable card connect at 10gbe with the older card and the same for a switch not using a breakout cable but the QSFP+ cables I already have.

For the ConnectX-3 card I was looking at the MCX354A-FCBT am I wrong in thinking that card can/does use a QSFP+ cable to connect?

Regarding using them in InfiniBand my knowledge of that is almost zero but my understanding is as one of my os’s is windows this wasn’t an option, if I am wrong in this please let me know as that would be great.

A big part of my thinking in going for the ConnectX-3 cards is they are now a lot cheaper than they were and they support pcie 3.0.

Thanks again for all the help

That’s an FDR capable card, so 40GbE should work according to the spec sheet. Just mentioned it because there are QDR ConnectX-3 variants too (like the MCX354A-QCBT) and those will only link at 10Gbit in Ethernet mode.

Brilliant, thanks for the confirmation, I was a little worried it was a different cable.

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