I’m trying to bring 56GigE to fly. Switch is an SX1700, adapters are MCX313A-BCCT, cables FDR rated MC2207130-002 and recognized as 56GigE capable cables. Even then, the switch and ethtool on the installed Linux (RHEL 6.6 with drivers out of Mellanox OFED 2.4-1.0.0 and stock Ubuntu 14.04) are reporting 40GigE.
netperf shows the same speed between two nodes with FDR rated cables as two nodes with QDR rated cabling.
Screenshot from the Switch management GUI:
Is there any additional requirement to get 56GigE instead of 40GigE?
Thanks for your feedback!