Open Systems Interconnection (OSI) Reference Model
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.
NBF on 802.2 networks
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.
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
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
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.
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
NetBIOS over IPX uses IPX packets to provide the underlying delivery
mechanism for the NetBIOS protocols.
NetBIOS over IPX
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
CIFS over TCP/IP
The latest version of CIFS can run directly over TCP/IP.
CIFS over TCP/IP
7 Application
CIFS
6 Presentation
5 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