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.
Table 1. NBF on 802.2 networks
|7 Application||e.g. Browser Service|
|6 Presentation||Higher level protocols e.g. SMB / CIFS|
|5 Session||Session Management Protocol|
|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|