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Network Working Group                                           S. SenumRequest for Comments: 1763                                     DigiBoardCategory: Standards Track                                     March 1995The PPP Banyan Vines Control Protocol (BVCP)Status of this Memo   This document specifies an Internet standards track protocol for the   Internet community, and requests discussion and suggestions for   improvements.  Please refer to the current edition of the "Internet   Official Protocol Standards" (STD 1) for the standardization state   and status of this protocol.  Distribution of this memo is unlimited.Abstract   The Point-to-Point Protocol (PPP) [1] provides a standard method for   transporting 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.   This document defines the Network Control Protocol for establishing   and configuring the Banyan VINES protocol over PPP.Table of Contents1.     Introduction ..........................................21.1       Specification of Requirements ...................21.2       Terminology .....................................32.     A PPP Network Control Protocol for VINES ..............32.1       Sending VINES Datagrams .........................42.2       General Considerations ..........................43.     BVCP Configuration Options ............................53.1       BV-NS-RTP-Link-Type .............................53.2       BV-FRP ..........................................63.3       BV-RTP ..........................................73.4       BV-Suppress-Broadcast ...........................8   SECURITY CONSIDERATIONS ......................................9   REFERENCES ...................................................9      ACKNOWLEDGEMENTS ..........................................9   CHAIR'S ADDRESS ..............................................10   AUTHOR'S ADDRESS .............................................10Senum                                                           [Page 1]

RFC 1763                        PPP BVCP                      March 19951.  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   BVCP packets to choose and configure the VINES network-layer   protocol.  Once BVCP has reached the Opened state, VINES datagrams   can be sent over the link.   The link will remain configured for communications until explicit LCP   or BVCP 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 must 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.Senum                                                           [Page 2]

RFC 1763                        PPP BVCP                      March 19951.2.  Terminology   This document frequently uses the following terms:   datagram  The unit of transmission in the network layer (such as IP).             A datagram may be encapsulated in one or more packets             passed to the data link layer.   frame     The unit of transmission at the data link layer.  A frame             may include a header and/or a trailer, along with some             number of units of data.   packet    The basic unit of encapsulation, which is passed across the             interface between the network layer and the data link             layer.  A packet is usually mapped to a frame; the             exceptions are when data link layer fragmentation is being             performed, or when multiple packets are incorporated into a             single frame.   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.2.  A PPP Network Control Protocol for VINES   The Banyan VINES Control Protocol (BVCP) is responsible for   configuring, enabling, and disabling the VINES protocol modules on   both ends of the point-to-point link.  BVCP uses the same packet   exchange mechanism as the Link Control Protocol.  BVCP packets may   not be exchanged until PPP has reached the Network-Layer Protocol   phase.  BVCP packets received before this phase is reached should be   silently discarded.   The Baynan VINES 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.Senum                                                           [Page 3]

RFC 1763                        PPP BVCP                      March 1995   Data Link Layer Protocol Field      Exactly one BVCP packet is encapsulated in the Information field      of a PPP Data Link Layer frame where the Protocol field indicates      type hex 8035 (Banyan VINES 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      BVCP 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      BVCP has a distinct set of Configuration Options.2.1.  Sending VINES Datagrams   Before any VINES datagrams may be communicated, PPP must reach the   Network-Layer Protocol phase, and the Banyan VINES Control Protocol   must reach the Opened state.   Exactly one VINES packet is encapsulated in the Information field of   a PPP Data Link Layer frame where the Protocol field indicates type   hex 0035 (Banyan VINES datagram).  The maximum length of a VINES   datagram transmitted over a PPP link is the same as the maximum   length of the Information field of a PPP data link layer frame.   The format of the Information field itself is the same as that   defined in [2].2.2.  General Considerations   VINES supports an Address Resolution Protocol, VINES ARP, primarily   used for address assignment.  Since this protocol is part of VINES   IP, it is fully supported over BVCP.  VINES also supports a data-link   Echo Protocol (VINES Echo), used to test connectivity to a VINES   Server in a LAN environment, which is not supported over BVCP.Senum                                                           [Page 4]

RFC 1763                        PPP BVCP                      March 19953.  BVCP Configuration Options   BVCP 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.   BVCP uses the same Configuration Option format defined for LCP [1],   with a separate set of Options.   Up-to-date values of the BVCP Option Type field are specified in the   most recent "Assigned Numbers" RFC [3].  Current values are assigned   as follows:      Value   Option        1     BV-NS-RTP-Link-Type        2     BV-FRP        3     BV-RTP        4     BV-Suppress-Broadcast   Note: A suggestion was made to combine the BV-NS-RTP-Link-Type option   and the BV-RTP option into a single option that could negotiate one   of four settings (S-RTP, NS-RTP-LAN, NS-RTP-WAN, NO-RTP).  This   suggestion has been rejected because VINES must already deal with a   mix of S-RTP and NS-RTP, and that pushing this information down to   the PPP layer is not desirable.3.1.  BV-NS-RTP-Link-Type   Description      This Configuration Option provides a way to negotiate the way the      Non-Sequenced Routing Update Protocol (NS-RTP) (pre-VINES 5.5,      i.e., 4.11 and 5.0) will run on the link.  NS-RTP handles updates      differently depending on whether the interface is a LAN type or a      WAN type.  For a LAN type, the full routing table is rebroadcast      every update interval (90 seconds).  For a WAN type, the full      routing table is only transmitted for the first 3 update intervals      after the link comes up.  After that only changes are transmitted      (for 5 update intervals).  Note that this has no effect if      Sequenced RTP (VINES 5.5) is being used.  More information on this      can be found in [2].      This option negotiates what an implementation is willing to      receive, and is negotiated separately per side of the PPP      connection.  The acceptance of this option (by the peer) indicates      that the peer will send NS-RTP updates as if the link was a LANSenum                                                           [Page 5]

RFC 1763                        PPP BVCP                      March 1995      type.  The rejection (or absence) of this option indicates that      the peer will send NS-RTP updates as if the link was a WAN type.      By default, NS-RTP updates are sent as if the link was a WAN type.   A summary of the BV-NS-RTP-Link-Type Configuration Option format is   shown below.  The fields are transmitted from left to right.       0                   1       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |     Type      |    Length     |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      Type         1      Length         23.2.  BV-FRP   Description      This Configuration Option provides a way to negotiate the use of      VINES Fragmentation Protocol (FRP).  This protocol is used to      allow fragmentation and reassembly of a VINES packet over the      link.  FRP prepends a two octet field to every packet going over      the link that contains a begin and end fragment information and a      sequence number.  With PPP's default MRU of 1500, FRP is not      normally needed, and no FRP header would be sent with the VINES      packet.  If a MRU of less than 1484 is negotiated, FRP will be      needed to send a full size VINES packet over the link.  More      information on this can be found in [2].      This option negotiates what an implementation is willing to      receive, and is negotiated separately per side of the PPP      connection.  The acceptance of this option (by the peer) indicates      that the peer will send VINES packets with a FRP header.  The      rejection (or absence) of this option indicates that the peer will      send VINES packets without a FRP header.      By default, VINES packets are sent without a FRP header.Senum                                                           [Page 6]

RFC 1763                        PPP BVCP                      March 1995   A summary of the BV-FRP Configuration Option format is shown below.   The fields are transmitted from left to right.       0                   1       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |     Type      |    Length     |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      Type         2      Length         23.3.  BV-RTP   Description      This Configuration Option provides a way to negotiate whether RTP      is used over the link.  If dial-up lines with static routes are      being used, the use of RTP may be totally suppressed to conserve      bandwidth on the link.      This option negotiates what an implementation is willing to      receive, and is negotiated separately per side of the PPP      connection.  The acceptance of this option (by the peer) indicates      that the peer will not send RTP packets.  The rejection (or      absence) of this option indicates that the peer will send any RTP      packets.      By default, RTP packets are sent over the link.Senum                                                           [Page 7]

RFC 1763                        PPP BVCP                      March 1995   A summary of the BV-RTP Configuration Option format is shown below.   The fields are transmitted from left to right.       0                   1       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |     Type      |    Length     |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      Type         3      Length         23.4.  BV-Suppress-Broadcast   Description      This Configuration Option provides a way to negotiate the sending      of VINES broadcast packets, i.e., packets with a destination VINES      network address of all ones.  This option only affects VINES      packets that are not of type VINES ARP or VINES RTP.  This option      can be used by a VINES Client to request that most of the      broadcast packets that would normally be sent to it by a VINES      Server be discarded, in order to conserve link bandwidth.  Most of      the broadcast packets sent by a VINES Server are not useful to a      VINES Client.      This option negotiates what an implementation is willing to      receive, and is negotiated separately per side of the PPP      connection.  The acceptance of this option (by the peer) indicates      that the peer MUST NOT send any VINES broadcast packets, other      than packets of type VINES ARP or VINES RTP.  The rejection (or      absence) of this option indicates that the peer will send all      VINES broadcast packets.      By default, all VINES broadcast packets are sent.Senum                                                           [Page 8]

RFC 1763                        PPP BVCP                      March 1995   A summary of the BV-Suppress-Broadcast Configuration Option format is   shown below.  The fields are transmitted from left to right.       0                   1       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |     Type      |    Length     |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      Type         4      Length         2Security Considerations   Security issues are not discussed in this memo.References   [1] Simpson, W., "The Point-to-Point Protocol (PPP)", STD 51,RFC1661, Daydreamer, July 1994.   [2] Banyan, "VINES Protocol Definition", June 1993, Order No.       003673.   [3] Reynolds, J., and J. Postel, "Assigned Numbers", STD 2,RFC 1700,       USC/Information Sciences Institute, October 1994.Acknowledgements   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).   In particular, Bill Simpson provided the boiler-plate used to create   this document.Senum                                                           [Page 9]

RFC 1763                        PPP BVCP                      March 1995Chair's Address   The working group can be contacted via the current chair:   Fred Baker   Cisco Systems   519 Lado Drive   Santa Barbara, California 93111   Phone: (805) 681-0115   EMail: fred@cisco.comAuthor's Address   Questions about this memo can also be directed to:   Steven J. Senum   DigiBoard   6400 Flying Cloud Drive   Eden Prairie, Minnesota 55344   Phone: (612) 943-9020   EMail: sjs@digibd.comSenum                                                          [Page 10]