{PDF} SAS Protocol Layer – 5 (SPL-5 r06) T10 Technical Committee

This standard defines the three transport protocols that use the SAS interconnect (see SAS-4):
a) Serial SCSI Protocol (SSP): a mapping of SCSI supporting multiple initiators and multiple targets;
b) Serial ATA Tunneled Protocol (STP): a mapping of Serial ATA expanded to support multiple initiators
and multiple targets; and
c) Serial Management Protocol (SMP): a management protocol.