In many cases, the SFP+ port accepts SFP optics, but the speed will be down to 1G instead of 10G. However, SFP+ optics cannot be plugged into the SFP port, because SFP+ does not support speed under 1G. In addition, almost all SFP+ ports on Cisco switches can support SFPs, but many SFP+ ports of Brocade switch only support SFP+ optics.