Since the ConnectX-3 is PCIe Gen3 x 8, my understanding from some back of the envelope figuring is that it is not able to saturate/handle both ports at full rate. (i.e. the bus max is going to be 985MB/s * 8 lanes * 8 bits or approximately 63 mbit/s or so vs 80 mbit/s for both ports). Is this correct? Are the two ports primary intended for failover or less than full simultaneous usage?
I notice some of the ConnectX-4s come in Gen3 x 16 so I assume this is a better choice if you want both ports running at full rate, but the ConnectX-4 advertises QSFP28. Am I correct that QSFP28 and QSFP+ are the same physical form-factor? The ConnectX-4 w/ its QSFP28 port should still be able to successfully connect to a 40G QSFP+ switch via a QSFP+ DAC, right?
I notice some of the ConnectX-4s come in Gen3 x 16 so I assume this is a better choice if you want both ports running at full rate, but the ConnectX-4 advertises QSFP28. Am I correct that QSFP28 and QSFP+ are the same physical form-factor? The ConnectX-4 w/ its QSFP28 port should still be able to successfully connect to a 40G QSFP+ switch via a QSFP+ DAC, right?