    Network Working Group                                            S. Cobb
    Request for Comments: 1877                                     Microsoft
    Category: Informational                                    December 1995

             PPP Internet Protocol Control Protocol Extensions for
                             Name Server Addresses

    Status of this Memo

       This memo provides information for the Internet community.  This memo
       does not specify an Internet standard of any kind.  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 a family of Network
       Control Protocols (NCPs) for establishing and configuring different
       network-layer protocols.

       This document extends the NCP for establishing and configuring the
       Internet Protocol over PPP [2], defining the negotiation of primary
       and secondary Domain Name System (DNS) [3] and NetBIOS Name Server
       (NBNS) [4] addresses.

    Table of Contents

         1.     Additional IPCP Configuration options .................    1
            1.1         Primary DNS Server Address ....................    2
            1.2         Primary NBNS Server Address ...................    3
            1.3         Secondary DNS Server Address ..................    4
            1.4         Secondary NBNS Server Address .................    5
         REFRENCES ....................................................    6
         SECURITY CONSIDERATIONS ......................................    6
         CHAIR'S ADDRESS ..............................................    6
         AUTHOR'S ADDRESS .............................................    6

    1.  Additional IPCP Configuration Options

       The four name server address configuration options, 129 to 132,
       provide a method of obtaining the addresses of Domain Name System
       (DNS) servers and (NetBIOS Name Server (NBNS) nodes on the remote
       network.

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    RFC 1877                  PPP IPCP Extensions              December 1995

       Primary and secondary addresses are negotiated independently.  They
       serve identical purposes, except that when both are present an
       attempt SHOULD be made to resolve names using the primary address
       before using the secondary address.

       For implementational convenience, these options are designed to be
       identical in format and behavior to option 3 (IP-Address) which is
       already present in most IPCP implementations.

       Since the usefulness of name server address information is dependent
       on the topology of the remote network and local peer's application,
       it is suggested that these options not be included in the list of
       "IPCP Recommended Options".

    1.1.  Primary DNS Server Address

       Description

          This Configuration Option defines a method for negotiating with
          the remote peer the address of the primary DNS server to be used
          on the local end of the link.  If local peer requests an invalid
          server address (which it will typically do intentionally) the
          remote peer specifies the address by NAKing this option, and
          returning the IP address of a valid DNS server.

          By default, no primary DNS address is provided.

       A summary of the Primary DNS Address 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     |      Primary-DNS-Address
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          Primary-DNS-Address (cont)   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Type

          129

       Length

          6

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    RFC 1877                  PPP IPCP Extensions              December 1995

       Primary-DNS-Address

          The four octet Primary-DNS-Address is the address of the primary
          DNS server to be used by the local peer.  If all four octets are
          set to zero, it indicates an explicit request that the peer
          provide the address information in a Config-Nak packet.

       Default

          No address is provided.

    1.2.  Primary NBNS Server Address

       Description

          This Configuration Option defines a method for negotiating with
          the remote peer the address of the primary NBNS server to be used
          on the local end of the link.  If local peer requests an invalid
          server address (which it will typically do intentionally) the
          remote peer specifies the address by NAKing this option, and
          returning the IP address of a valid NBNS server.

          By default, no primary NBNS address is provided.

       A summary of the Primary NBNS Address 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     |      Primary-NBNS-Address
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          Primary-NBNS-Address (cont)  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Type

          130

       Length

          6

       Primary-NBNS-Address

          The four octet Primary-NBNS-Address is the address of the primary
          NBNS server to be used by the local peer.  If all four octets are
          set to zero, it indicates an explicit request that the peer

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          provide the address information in a Config-Nak packet.

       Default

          No address is provided.

    1.3.  Secondary DNS Server Address

       Description

          This Configuration Option defines a method for negotiating with
          the remote peer the address of the secondary DNS server to be used
          on the local end of the link.  If local peer requests an invalid
          server address (which it will typically do intentionally) the
          remote peer specifies the address by NAKing this option, and
          returning the IP address of a valid DNS server.

          By default, no secondary DNS address is provided.

       A summary of the Secondary DNS Address 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     |      Secondary-DNS-Address
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          Secondary-DNS-Address (cont) |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Type

          131

       Length

          6

       Secondary-DNS-Address

          The four octet Secondary-DNS-Address is the address of the primary
          NBNS server to be used by the local peer.  If all four octets are
          set to zero, it indicates an explicit request that the peer
          provide the address information in a Config-Nak packet.

       Default

          No address is provided.

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    1.4.  Secondary NBNS Server Address

       Description

          This Configuration Option defines a method for negotiating with
          the remote peer the address of the secondary NBNS server to be
          used on the local end of the link.  If local peer requests an
          invalid server address (which it will typically do intentionally)
          the remote peer specifies the address by NAKing this option, and
          returning the IP address of a valid NBNS server.

          By default, no secondary NBNS address is provided.

       A summary of the Secondary NBNS Address 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     |      Secondary-NBNS-Address
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            Secondary-NBNS-Address (cont) |
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

          Type

             132

          Length

             6

          Secondary-NBNS-Address

             The four octet Secondary-NBNS-Address is the address of the
             secondary NBNS server to be used by the local peer.  If all
             four octets are set to zero, it indicates an explicit request
             that the peer provide the address information in a Config-Nak
             packet.

          Default

             No address is provided.

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    RFC 1877                  PPP IPCP Extensions              December 1995

    References

       [1] Simpson, W., Editor, "The Point-to-Point Protocol (PPP)", STD 51,
           RFC 1661, Daydreamer, July 1994.

       [2] McGregor, G., "PPP Internet Control Protocol", RFC 1332, Merit,
           May 1992.

       [3] Auerbach, K., and A. Aggarwal, "Protocol Standard for a NetBIOS
           Service on a TCP/UDP Transport", STD 19, RFCs 1001 and 1002,
           March 1987.

       [4] Mockapetris, P., "Domain Names - Concepts and Facilities", STD
           13, RFC 1034, USC/Information Sciences Institute, November 1987.

       [5] Mockapetris, P., "Domain Names - Implementation and
           Specification", STD 13, RFC 1035, USC/Information Sciences
           Institute, November 1987.

    Security Considerations

       Security issues are not discussed in this memo.

    Chair's Address

       The working group can be contacted via the current chair:

          Fred Baker
          Cisco Systems
          519 Lado Drive
          Santa Barbara, California  93111

          EMail: fred@cisco.com

    Author's Address

       Questions about this memo can also be directed to:

          Steve Cobb
          Microsoft Corporation
          One Microsoft Way
          Redmond, WA  98052-6399

          Phone: (206) 882-8080

          EMail: stevec@microsoft.com

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