Early versions of NetBEUI used a 1- byte (8-character binary) number with a maximum decimal value of 254 to identify NetBIOS sessions. Session numbers were assigned per computer. That is, a computer using NetBEUI could support a maximum of 254 network connections.
NBF is not constrained by the session limitation of earlier versions of NetBEUI. NBF uses the TDI and a TDI 32-bit handle composed of the session number and the network address of the remote computer. This allows a virtually limitless range of unique numbers that can be used to uniquely identify sessions.
Using NBF, it is possible for a Windows NT Server with a single network adapter card to support simultaneous sessions that exceed the previous NetBEUI session limit of 256. For example, a Windows NT Server running NBF with a single network adapter card is able to support sessions with more than 1,000 clients.
The following figure illustrates the differences between NBF and other non-Windows implementations of NetBEUI.
Figure 13.4 Comparison between NetBEUI and Windows NT NBF Session Limits