I've got two CRS518-16XS-2XQ switches. I've added a FS QSFP-LX4-40G (QSFP+ fibre) transceiver to each and connected them up with a 2m OM3 patch lead for testing. Auto negotiation wouldn't work, but setting them to 40G full duplex worked. I've assigned an IP address to each interface. I've set the FEC Mode to fec91 as that gives me 0% packet loss.
The SFP tab says that the SM Link Length is 2.000km. I think that might be hard coded into the SFP module though.
I've run a speed test between the two and I currently get 178Mbps up and down on UDP with the CPU load maxing out at 100% with 0% packet loss. The speed worries me as that's far lower than the 40Gbps I'm expecting.
Is this expected behaviour, or is that a bit lower than expected?
I want to setup a PC bandwidth test between the two, but I don't have any SFP28 enabled servers at the moment.
EDIT: Forgot to mention both switches are running routeros 7.7