Network Working Group T J Dimitri Internet Draft Microsoft expires in six months October 1993 The PPP NetBIOS Frames Control Protocol (NBFCP) Status of this Memo This document is the product of the Point-to-Point Protocol Working Group of the Internet Engineering Task Force (IETF). Comments should be submitted to the ietf-ppp@ucdavis.edu mailing list. Distribution of this memo is unlimited. This document is an Internet Draft. Internet Drafts are working documents of the Internet Engineering Task Force (IETF), its Areas, and its Working Groups. Note that other groups may also distribute working documents as Internet Drafts. Internet Drafts are draft documents valid for a maximum of six months. Internet Drafts may be updated, replaced, or obsoleted by other documents at any time. It is not appropriate to use Internet Drafts as reference material or to cite them other than as a ``working draft'' or ``work in progress.'' Please check the 1id-abstracts.txt listing contained in the internet-drafts Shadow Directories on nic.ddn.mil, nnsc.nsf.net, nic.nordu.net, ftp.nisc.sri.com, or munnari.oz.au to learn the current status of any Internet Draft. Abstract The Point-to-Point Protocol (PPP) [1] provides a method for transmitting multi-protocol datagrams over point-to-point links. PPP defines an extensible Link Control Protocol, and proposes a family of Network Control Protocols for establishing and configuring different network-layer protocols. The NBF protocol was originally called the NetBEUI protocol and was used in versions of DOS and OS/2 LAN Manager. It is now used in Microsoft Windows NT and Microsoft Windows for Workgroups. This document defines the Network Control Protocol for establishing and configuring the NBF protocol over PPP. Dimitri expires in six months [Page i] DRAFT NBFCP October 1993 1. Introduction PPP has three main components: 1. A method for encapsulating multi-protocol datagrams. 2. A Link Control Protocol (LCP) for establishing, configuring, and testing the data-link connection. 3. A family of Network Control Protocols for establishing and configuring different network-layer protocols. 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). 1.1. Specification of Requirements In this document, several words are used to signify the requirements of the specification. These words are often capitalized. MUST This word, or the adjective "required", means that the definition is an absolute requirement of the specification. MUST NOT This phrase means that the definition is an absolute prohibition of the specification. SHOULD This word, or the adjective "recommended", means that there may exist valid reasons in particular circumstances to ignore this item, but the full implications should be understood and carefully weighed before choosing a different course. MAY This word, or the adjective "optional", means that this item is one of an allowed set of alternatives. An implementation which does not include this option MUST be prepared to interoperate with another implementation which does include the option. Dimitri expires in six months [Page 1] DRAFT NBFCP October 1993 1.2. Terminology This document frequently uses the following terms: peer The other end of the point-to-point link. silently discard This means the implementation discards the packet without further processing. The implementation SHOULD provide the capability of logging the error, including the contents of the silently discarded packet, and SHOULD record the event in a statistics counter. end-system A user's machine. It only sends packets to servers and other end-systems. It doesn't pass any packets through itself. router Allows packets to pass through, usually from one ethernet segment to another. Sometimes these are called "intermediate-systems". bridge Allows packets to pass through with the data field unmodified. Usually from one ethernet segment to another or from one ethernet segment to a token-ring segment. gateway Allows packets to be sent from one network protocol to the same or different network protocol. For example, NetBIOS packets from an NBF network to a TCP/IP network which has implemented RFC 1001 and RFC 1002. 2. A PPP Network Control Protocol for NBF 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 may not be exchanged until PPP has reached the Network-Layer Protocol phase. NBFCP packets received before this phase is reached should be silently discarded. The NBF Control Protocol is exactly the same as the Link Control Protocol [1] with the following exceptions: Frame Modifications The packet may utilize any modifications to the basic frame format which have been negotiated during the Link Establishment phase. Dimitri expires in six months [Page 2] DRAFT NBFCP October 1993 Data Link Layer Protocol Field Exactly one NBFCP packet is encapsulated in the Information field of a PPP Data Link Layer frame where the Protocol field indicates type hex 8039 (NBF Control Protocol). Code field Only Codes 1 through 7 (Configure-Request, Configure-Ack, Configure-Nak, Configure-Reject, Terminate-Request, Terminate-Ack and Code-Reject) are used. Other Codes should be treated as unrecognized and should result in Code-Rejects. Timeouts NBFCP packets may not be exchanged until PPP has reached the Network-Layer Protocol phase. An implementation should be prepared to wait for Authentication and Link Quality Determination to finish before timing out waiting for a Configure-Ack or other response. It is suggested that an implementation give up only after user intervention or a configurable amount of time. Configuration Option Types NBFCP has a distinct set of Configuration Options. 2.1. Sending NBF Datagrams 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. Unlesss otherwise negotiated, exactly one NBF packet is encapsulated in the Information field of a PPP Data Link Layer frame where the Protocol field indicates type hex 0039 (NBF datagram). An encapsulated NBF packet for PPP differs from the data field in DIX ethernet (RFC 894) because NBF packets do not contain the source, destination, or length fields in the datagram packet. Therefore, the encapsulated NBF packet contains two extra octets in the beginning of the PPP Information field. The most significant bit in the first octet indicates whether the frame is directed or multicast. The next 15 bits indicate the length of the rest of the NBF packet in the Information field. Dimitri expires in six months [Page 3] DRAFT NBFCP October 1993 A summary of the NBF default encapsulation format is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |x| Length | Data ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ x The x field is one bit and indentifies the type of NBF packet. The two values for this field are assigned as follows: 0 NBF directed packet. 1 NBF multicast packet (IEEE 6 octet addesss 03-00-00-00-00-01). Length The Length field is 15 bits and indicates the length of the Data field (excluding the two octets in the x and Length fields). The Length field is encoded with the most significant octet first. Octets outside the range of the Length field should be treated as Data Link Layer padding and should be ignored upon reception. When a packet is received with an invalid Length field, the packet is silently discarded. Data The Data field is zero or more octets as indicated by the Length field. The maximum length of an NBF datagram transmitted over a PPP link is the same as the maximum length of the Information field of a PPP data link layer frame. Since there is no standard method for fragmenting and reassembling NBF datagrams, PPP links supporting NBF MUST allow at least 578 (576 + 2 for length and type) octets in the information field of a data link layer frame. It is recommended that an implementation allow 1502 (1500 + 2) octets in the information field. Dimitri expires in six months [Page 4] DRAFT NBFCP October 1993 3. NBFCP Configuration Options NBFCP Configuration Options allow modifications to the standard characteristics of the network-layer protocol to be negotiated. If a Configuration Option is not included in a Configure-Request packet, the default value for that Configuration Option is assumed. NBFCP uses the same Configuration Option format defined for LCP [1], with a separate set of Options. Up-to-date values of the NBFCP Option Type field are specified in the most recent "Assigned Numbers" RFC [2]. Current values are assigned as follows: 1 Name-Projection 2 Peer-Information 3 Multicast-Filtering 3.1. Name-Projection Description This Configuration Option provides a method for the peer to provide the other peer of hte NetBIOS names on its network. The sender of the Configure-Request states which NetBIOS names should be added by the remote peer. More than one Name-Projection option MAY appear in a single Configure-Request. Implementations which do not attempt to add any NetBIOS names MUST Configure-Reject the Name-Projection Configuration Option. NetBIOS Gateway implementations which attempt to add NetBIOS names MUST respond with Configure-Ack even if no NetBIOS names were successfully added. The Configure-Ack packet MUST contain a zero in the Added field if the NetBIOS name was added successfully and MUST contain the appropriate non-zero return code if the NetBIOS name could not be successfully added. The implementation may choose to fail configuration if the complete list of NetBIOS names is not accepted. By failing, the implementation should terminate NBFCP by sending a Terminate-Request packet. Because adding NetBIOS names can take time and because PPP defaults the restart timer to 3 seconds, the restart timer SHOULD default to 10 seconds when configuring NetBIOS names. Dimitri expires in six months [Page 5] DRAFT NBFCP October 1993 A summary of the Name-Projection Configuration Option format is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | 1st NetBIOS-Name +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 1st NetBIOS-Name (cont.) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 1st NetBIOS-Name (cont.) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 1st NetBIOS-Name (cont.) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 1st NetBIOS-Name (cont.) | Added |2nd NetBIOS Name... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type 1 Length 2 + (Number of NetBIOS names * 17) NetBIOS-Names This group of zero or more sixteen octet NetBIOS-Name fields contains a list of all the NetBIOS names the peer wishes to add to the remote network if the packet is Configure-Request. If the packet is Configure-Reject, the peer does not support this configuration option and it can be assumed that no NetBIOS names were added. Because the length field is only one octet only 14 NetBIOS names can be added per Configure-Request packet. If more than 14 NetBIOS names should be added, more than one Name-Projection Request packet will have to be sent. Dimitri expires in six months [Page 6] DRAFT NBFCP October 1993 Added This is a one octet field which plays a dual role. The Added field in the Name-Projection Request packet contains the type of NetBIOS name added. A summary of name types is listed below. 01 Unique Name. 02 Group Name. If the packet is NOT a Configure-Request the Added field contains the NetBIOS return code for the NetBIOS Add Name or NetBIOS Add Group Name command as defined in the NetBIOS 3.0 specification [3]. A summary of common result codes is listed below in type hex. 0D Duplicate name in local name table. 0E Name table full. 15 Name not found or cannot specify "*" or null. 16 Name in use on remote NetBIOS. 19 Name conflict detected. 30 Name defined by another environment. 35 Required system resources exhausted. 3.2. Peer-Information Description This Configuration Option provides a way to obtain information about the peer providing the one side of the PPP connection. The nature of this option is advisory only. It is provided as a means of improving an end system's ability to provide information from peer to peer about one side of the PPP connection for User Interface or Logging purposes. Dimitri expires in six months [Page 7] DRAFT NBFCP October 1993 A summary of the Peer-Information Option format is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Peer-class | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Peer-version (major) | Peer-version (minor) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Peer-name +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Peer-name (cont.) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Peer-name (cont.) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Peer-name (cont.) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type 2 Length >=6 Peer-class The Peer-class field is two octets and indicates the class of the communication peer providing the one side of the PPP connection. This two octet quantity represents a 16 bit unsigned number sent with the most significant octet first. Dimitri expires in six months [Page 8] DRAFT NBFCP October 1993 Initial values are assigned as follows: Value Class 1 Microsoft PPP NetBIOS Gateway Dial-In Server. 2 Generic PPP NetBIOS Gateway Dial-In Server. 3 Microsoft PPP Local Access Only Server. 4 Generic PPP Local Access Only Server. 5 Reserved. 6 Generic PPP NBF bridge. 7 Microsoft PPP Client. 8 Generic PP Client. Peer-version The Peer-version field is four octets and indicates the version of the communication peer providing one side of the PPP connection. The first two octets are the major version number and the last two octets are the minor version number. The major and minor version represent a 16 bit unsigned number sent with the most significant octet first. Peer-name The 16-octet NetBIOS name of the peer. If the length field is 6, no peer name is provided. 3.3. Multicast-Filtering Description This Configuration Option provides a way to negotiate the use of the Multicast-Forward-Period and the Multicast-Priority. This Configuration Option provides a way to negotiate how to handle mulicast packets. It allows the sender of the Configure-Request to state the current handling of multicast packets. The peer can request parameters by NAKing the option, and returning valid Multicast-Filtering parameters. If negotiation about the remote Multicast-Filtering is required, and the peer did not provide the option in its Configure-Request, the option SHOULD be appended to a Configure-Nak. Dimitri expires in six months [Page 9] DRAFT NBFCP October 1993 By default, the peer is pre-configured to an administrator assigned Multicast-Forward-Period and Priority. A Multicast-Forward-Period specified as hex type FFFF in a Configure-Request shall be interpreted as requesting the remote peer to specify a value via Configure-Nak. A Multicast-Forward-Period value specified as hex type FFFF in Configure-Nak shall be interpreted as agreement that no value exists. A Multicast-Forward-Period of zero shall indicate that all multicast packets SHOULD be forwarded. An implementation which requires the Requested Multi-Filtering option SHOULD fail configuration if the remote peer fails to provide the requested value. Peers that rely on all multicast packets forwarded SHOULD request a Multicast-Forward-Period of zero and a Multicast-Priority of one by NAKing the Configure-Request option and appending the proper parameters to a Configure-Nak. A summary of the Multicast-Filtering Configuration Option format is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Multicast-Forward-Period | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Priority | +-+-+-+-+-+-+-+-+ Type 4 Length 6 Dimitri expires in six months [Page 10] DRAFT NBFCP October 1993 Multicast-Forward-Period The Multicast-Forward-Period field is two octets and indicates the maximum period in seconds at which multicast packets can be sent. The maximum value for this field is 60 (one minute). A value of zero indicates that there is no maximum period at which multicast packets can be sent. A value of hex type FFFF indicates that the Multicast-Forward-Period is unknown. This two octet quantity represents a 16 bit unsigned number sent with the most significant octet first. Priority The Priority field is two octets and indicates if multicast packets have priority over other packets when being sent. A value of 0 indicates that directed packets have priority. A value of 1 indicates that multicast packets have priority. Dimitri expires in six months [Page 11] DRAFT NBFCP October 1993 Security Considerations Security issues are not discussed in this memo. References [1] Simpson, W. A., "The Point-to-Point Protocol (PPP)", RFC 1331, May 1992. [2] Reynolds, J.K., Postel, J.B., "Assigned Numbers", RFC 1340, July 1992. [3] IBM Corp., "IBM Local Area Network Technical Reference", Third Edition, November 1988. Acknowledgments Some of the text in this document is taken from previous documents produced by the Point-to-Point Protocol Working Group of the Internet Engineering Task Force (IETF). This document is derivative of drafts written by the following people. Many thanks for their work, and for taking an initial stab at the protocol: TBA. Dimitri expires in six months [Page 12] DRAFT NBFCP October 1993 Chair's Address The working group can be contacted via the current chair: Fred Baker Advanced Computer Communications 315 Bollay Drive Santa Barbara, California, 93111 EMail: fbaker@acc.com Author's Address Questions about this memo can also be directed to: Thomas J. Dimitri Microsoft Corporation 1 Microsoft Way Redmond, WA 98052 EMail: tommyd@microsoft.com Dimitri expires in six months [Page 13] DRAFT NBFCP October 1993 Table of Contents 1. Introduction .......................................... 1 1.1 Specification of Requirements ................... 1 1.2 Terminology ..................................... 2 2. A PPP Network Control Protocol for NBF ................ 2 2.1 Sending NBF Datagrams ........................... 3 3. NBFCP Configuration Options ........................... 5 3.1 Name-Projection.................................. 5 3.2 Peer-Information................................. 7 3.3 Multicast-Filtering.............................. 9 SECURITY CONSIDERATIONS ...................................... 12 REFERENCES ................................................... 12 ACKNOWLEDGEMENTS ............................................. 12 CHAIR'S ADDRESS .............................................. 13 AUTHOR'S ADDRESS ............................................. 13