I recently purchased and am using two CRS328-24P-4S+RM switches. I had a heck of a time getting expected performance from five different S+RJ10 transceivers. I don't have 10G client devices on either end, but simply testing 1G performance very much depended on what transceiver was in what SFP port on either switch. I mapped all of the combinations and managed to get two SFPs on either switch, that when linked, would consistently provide 950Mbits (all I could push with existing clients). Other combinations saw between 750-850Mbits, which is really awkward for 10G ports. I'm not sure if there was any real negotiation happening between the S+RJ10s, or at least SwOS 2.7 wasn't showing anything except 10G (and link whether a cable was attached or not, also fun), so I assume 10G was active, and seeing >100Mbits at least means it wasn't at 100M.
In any case, while trying all the combinations of SFP ports and transceivers to figure out what was up with the throughput, it became very obvious if either side was using SFP3, no forwarding occurred. Because this happened on the same SFP port on two different devices, I somewhat assumed there was a software setting or configuration situation that was the culprit, or that there may be a legitimate, documented hardware limitation at play. I've found no mention of either thus far. However, I did notice there was one other post that mentioned having issues with SFP4, but only on one switch.
All five S+RJ10s were identified by SwOS 2.7 as available, showed 10G and link as normal, but they simply did not pass traffic. The same configuration was used on every other SFP port when testing throughput. Are my switches physically borked or do I need to shake the fairies out of SFP3?
Cheers,