SMB2 is the new default protocol for sharing files in OS X Mavericks. SMB2 is superfast, increases security, and improves Windows compatibility.
[…] SMB2 is automatically used to share files between two Mac computers running OS X Mavericks, or when a Windows client running Vista, Windows 7, or Windows 8 connects to your Mac. OS X Mavericks maintains support for AFP and SMB network file-sharing protocols, automatically selecting the appropriate protocol as needed.
AFP will still be used in OS X for Time Machine backups and existing network resources but I’m wondering if a future update to OS X will remove any need for AFP to be a requirement in Time Machine.
Time Machine currently only supports AFP share points but can be used on other protocols such as SMB/CIFS by enabling the TMShowUnsupportedNetworkVolumes flag within the preference file.