Can a SFP+ optic plug into a SFP slot and will it function? Yes, a SFP+ optics can be physically plug into a SFP slot. SonicOS will treat the SFP+ optic as a 1GE SFP optic.
Can a SFP optic plug into a SFP+ slot and will it function? Newer appliances (NSA 3650-NSA6650, SM 9x50) do support SFP modules in SFP+ ports. SonicOS will detect them and limit speed appropriately if it found SFP module in SFP+ port.
In SonicOS for SFP 1G Optical module in SFP+ Ports, to make it compatible with Third Party switches, a user is allowed the ability to select between “AutoNeg” or “1G” speed selection to link UP properly (ensure the selection setting are the same at both ends.)
Logging Feature : Details can be found in the INVESTIGATE
Logs
Event Logs when the SFP are Connected and Disconnected to the system.