NBFCP, PPP NetBIOS Frames Control Protocol

Description Glossary RFCs Publications Obsolete RFCs


Protocol suite: PPP.
Protocol type:PPP network control protocol.
PPP protocol:0x803F.
MIME subtype:
Working groups: pppext, Point-to-Point Protocol Extensions.
Links: PPP Assigned numbers.

The NBFCP protocol is used for establishing and configuring the NetBIOS Frames Protocol over a PPP link.

RFC 2097:

NBFCP is only applicable for an end system to connect to a peer system or the LAN that peer system is connected to. It is not applicable for connecting two LANs together due to NetBIOS name limitations and NetBIOS name defense mechanisms.

In order to establish communications over a point-to-point link, each end of the PPP link must first send LCP packets to configure and test the data link. After the link has been established and optional facilities have been negotiated as needed by the LCP, PPP must send NBFCP packets to choose and configure the NBF network-layer protocol. Once NBFCP has reached the Opened state, NBF datagrams can be sent over the link.

The link will remain configured for communications until explicit LCP or NBFCP packets close the link down, or until some external event occurs (an inactivity timer expires or network administrator intervention).

The NBF Control Protocol (NBFCP) is responsible for configuring, enabling, and disabling the NBF protocol modules on both ends of the point-to-point link. NBFCP uses the same packet exchange mechanism as the Link Control Protocol. NBFCP packets MUST NOT be exchanged until PPP has reached the Network-Layer Protocol phase. NBFCP packets received before this phase is reached should be silently discarded.

Before any NBF packets may be communicated, PPP must reach the Network-Layer Protocol phase, and the NBF Control Protocol must reach the Opened state.

PPP header NBFCP header Data :::

NBFCP header:

00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Code Identifier Length
Data :::

Code. 8 bits.
Specifies the function to be performed.

0 Vendor Specific. RFC 2153
1 Configure-Request. 
3 Configure-Nak.  
4 Configure-Reject.  
5 Terminate-Request.  
6 Terminate-Ack.  
7 Code-Reject.  

Identifier. 8 bits.
Used to match requests and replies.

Length. 16 bits.
Size of the packet including the header.

Data. Variable length.
Zero or more bytes of data as indicated by the Length field. This field may contain one or more Options.

NBFCP Configuration Options.

00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15
Option Length
Data :::

Option. 8 bits.

12 +Name-Projection.
2 Peer-Information.

Length. 8 bits.

Data. Variable length.



[RFC 2097] The PPP NetBIOS Frames Control Protocol (NBFCP).


Obsolete RFCs:

Description Glossary RFCs Publications Obsolete RFCs