Server Message Block (SMB), also known as CIFS (Common Internet File System) is the file sharing protocol used by default on Windows based computers. Windows includes an SMB client component (Client for Microsoft Windows) and an SMB server component (File and Printer Sharing for Microsoft Windows).
SMB in Windows Server 2008 and Windows Vista support the new SMB version 2.0 that has been redesigned for today’s networking environments (wireless, possible high loss, timeouts, high latency, …) and for the needs of the next generation of file servers (EFS over the wire, Offline Files and Folders enhancements, …).
Machines running Windows Server 2008 and Windows Vista support both SMB v1.0 and SMB v2.0. However SMB 2.0 can only be used if both client and server support it!! So, the SMB protocol revision to be used for file operations is decided during the negotiation phase.
A Vista client advertises to the server that it can understand the new SMB 2.0 protocol. If the server (Windows Server 2008 or otherwise) understands SMB 2.0, then SMB 2.0 is chosen for subsequent communication, otherwise they fall back to SMB 1.0.
This preserves “downwards” compatibility so that deploying Vista clients or Windows Server 2008 servers should be simple and straightforward. The following list below describes what protocol will be used when communicating between different types of client and servers.
# Vista client <> Vista client or Windows Server 2008 – SMB 2.0
# Non-Vista client <> Vista client or Windows Server 2008 – SMB 1.0
# Vista client <> Non-Vista client or Non-Windows Server 2008 – SMB 1.0
# Non-Vista client <> Non-Vista client or Non-Windows Server 2008 – SMB 1.0
For an overview of the impact on network throughput, have to look at the white paper of a third-party benchmark study done by The Tolly Group which compares network throughput and time-to-completion of several tasks when using Windows XP, Windows Vista, Windows Server 2003 and Windows Server 2008 .