The Open Systems Interconnection (OSI) Reference Model is traditionally used as a general purpose reference for describing protocols and comparing protocols. It is assumed that the reader is familiar with the OSI model; there are of course numerous resources on the WEB that explain the OSI model. The diagrams below attempt to show the components of the NetBIOS protocols and higher level protocols such as SMB in relation to the OSI Reference Model. Because the protocols were not developed specifically to comply with the OSI model any mapping is only approximate and intended as a guide. When protocols (such as NetBIOS) are encapsulated within other protocols (such as TCP/IP or IPX) it is particularly difficult to map these to a reference model, thus the diagrams below are intended to help show the relationships between the protocols rather than provide a definitive mapping to the OSI model.

NetBIOS is often described as a session layer protocol but in the IEEE 802.2 implementation there are no transport or datagram delivery protocols between the session layer and the datalink layer. While there is a datagram protocol, this is used exclusively for datagrams and not as a foundation for higher layer protocols. 7 Application e.g. Browser Service 6 Presentation Higher level protocols e.g. SMB / CIFS 5 Session   Session Management Protocol 4 Transport 3 Network User Datagram Protocol, Name Management Protocol, NetBIOS Diagnostic and Monitoring Protocol 2 Datalink IEEE 802.2 IEEE 802.3 / IEEE 802.5 etc 1 Physical Token Ring / Ethernet etc

NetBIOS over TCP/IP is described in RFC 1001 and RFC 1002. Note that when higher level protocols such as SMB or CIFS are implemented over TCP/IP they are in fact implemented over NetBIOS over TCP/IP. 7 Application e.g. Browser Service 6 Presentation Higher level protocols e.g. SMB / CIFS 5 Session Name Service datagram service Session Service 4 Transport UDP TCP 3 Network IP 2 Datalink e.g. IEEE 802.2 e.g. Ethernet II etc IEEE 802.3 / IEEE 802.5 etc 1 Physical Token Ring / Ethernet etc

NetBIOS over IPX uses IPX packets to provide the underlying delivery mechanism for the NetBIOS protocols. 7 Application e.g. Browser Service 6 Presentation Higher level protocols e.g. SMB / CIFS 5 Session   Session Management Protocol 4 Transport 3 Network User Datagram Protocol, Name Management Protocol, NetBIOS Diagnostic and Monitoring Protocol IPX 2 Datalink e.g. IEEE 802.2 e.g. Ethernet II etc IEEE 802.3 / IEEE 802.5 etc 1 Physical Token Ring / Ethernet etc

The latest version of CIFS can run directly over TCP/IP. 7 Application CIFS 6 Presentation5 Session 4 Transport UDP TCP 3 Network IP 2 Datalink e.g. IEEE 802.2 e.g. Ethernet II etc IEEE 802.3 / IEEE 802.5 etc 1 Physical Token Ring / Ethernet etc