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rfc:rfc1763

Network Working Group S. Senum Request for Comments: 1763 DigiBoard Category: Standards Track March 1995

            The 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 Contents

 1.     Introduction ..........................................    2
    1.1       Specification of Requirements ...................    2
    1.2       Terminology .....................................    3
 2.     A PPP Network Control Protocol for VINES ..............    3
    2.1       Sending VINES Datagrams .........................    4
    2.2       General Considerations ..........................    4
 3.     BVCP Configuration Options ............................    5
    3.1       BV-NS-RTP-Link-Type .............................    5
    3.2       BV-FRP ..........................................    6
    3.3       BV-RTP ..........................................    7
    3.4       BV-Suppress-Broadcast ...........................    8
 SECURITY CONSIDERATIONS ......................................    9
 REFERENCES ...................................................    9
    ACKNOWLEDGEMENTS ..........................................    9
 CHAIR'S ADDRESS ..............................................   10
 AUTHOR'S ADDRESS .............................................   10

Senum [Page 1] RFC 1763 PPP BVCP March 1995

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
 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 1995

1.2. 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 1995

3. 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 LAN

Senum [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
       2

3.2. 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
       2

3.3. 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
       2

3.4. 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
       2

Security Considerations

 Security issues are not discussed in this memo.

References

 [1] Simpson, W., "The Point-to-Point Protocol (PPP)", STD 51, RFC
     1661, 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 1995

Chair'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.com

Author'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.com

Senum [Page 10]

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