In Mac OS X 10.9 Apple is introducing support for SMBv2. They are also making SMB the standard protocol for Mac to Mac and Mac to Windows file transfers. AFP is being deprecated and will only be used when transferring files between clients 10.8 and below.  Mac OS X 10.0 to 10.6 used the open source Samba package for SMB support Mac OS X 10.7 Apple started using their own SMB stack called SMBX  SMBv2 should support nearly line speed speed compared with 50-60% with SMBv1  More information is available here:  [URL]  AFP548 – SMB2 & You: Saying Goodbye to AFP in OS X Mavericks
What versions of SMB does Apple Mac OS X support?
FAQ: What versions of SMB does Apple Mac OS X support?