Infiniband QDR vs FDR

[aarcane]

So I know Infiniband QDR is 40Gbps with 8/10 encoding and FDR is 56 Gbps with 64/66 encoding, but one question I can never find answered anywhere is as follows:
Can an infinband QDR card connect to an infinband FDR switch with reduced throughput compared to the rest of the network? Can an infiniband FDR card function in QDR mode if connected to a QDR switch?

I ask because I'm shopping around, and some of the hardware I'm looking at only supports QDR mezzanine cards, but most of the components for a full FDR network are widely available, and I would prefer FDR if the few QDR components could work with it, but I'll settle for either going full FDR if that's not possible and skipping the QDR only devices, or settling for QDR only and stick to QDR switches and cards if I need to. One of the two settles.

 

[i386]

Infiniband should be backwards compatible with lower speeds, connecting qdr nics to an fdr switch should work.

 

[necr]

QDR/FDR mix works great(not in the chassis though, especially true for SMC. Midplane is not a tested and certified cable), but I’d recommend to not add EDR to the mix. Seen some issues with QDR/EDR already. Current technology is HDR, EDR will be retired next, FDR is nearing EoL, be prepared to throw out all those chassis soon.