Architecture of NBF

NBF is a transport driver that is composed of the following layers:

• LLC802.2 Protocol
  LLC802.2 Protocol (LLC) corresponds to the Open Systems Interconnection (OSI) Data Link layer. It performs code, address, control frame flow, and provides connection-oriented and connectionless communications.

• NetBIOS Frame Format Protocol
  NetBIOS Frame Format Protocol (NBFP) corresponds to the OSI Transport layer. It performs session establishment, multiplexing, and termination. It also performs message segmentation, delimiting, assembly, and acknowledgment.

Figure 16.1 compares the OSI model to the NBF architecture.

Figure 16.1 OSI Model and NBF Architecture

NBFP connects with TDI, which provides a common interface to multiple transport driver protocols, while the LLC component connects to the Network Driver Interface Specification (NDIS), which in turn provides the interface to the network adapter. Since NBF is not a routable protocol, it does not have a component that corresponds to the OSI model Network layer.

Note

In Token Ring networks, NetBEUI uses IBM Token Ring source routing to perform Network layer functions. Token Ring source routing conforms to the Institute of Electrical and Electronics Engineers (IEEE) 802.5 standard and corresponds to the OSI Physical layer, not the OSI Network layer.