Internet DRAFT - draft-heinanen-ppp-subnet

draft-heinanen-ppp-subnet








Internet Engineering Task Force                            Juha Heinanen
INTERNET DRAFT                                             Telia Finland
Expires May 1999                                              Dave Allan
                                                         Nortel Networks
                                                              Arthur Lin
                                                         Shasta Networks
                                                              Paul Shieh
                                                        3Com Corporation
                                                           November 1998


    PPP Internet Protocol Control Protocol Extensions for IP Subnet
                   <draft-heinanen-ppp-subnet-00.txt>



Status of this Memo

   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
   and may be updated, replaced, or obsoleted by other documents at any
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   To learn the current status of any Internet-Draft, please check the
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   ftp.isi.edu (US West Coast).

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] by defining an IP Subnet configuration
   option.






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1. Motivation

   The IP-address configuration option [2] allows negotiation of a
   single IP address used on the local end of a PPP link.  It is
   adequate when the the local end is an IP host.  However, when the
   local end is an router, for example an ISDN or ADSL router providing
   IP connectivity for a home or small office LAN, then it should be
   possible to negotiate a whole IP subnet for the LAN rather than a
   single IP address for the local end of the link.

   This document defines an IP subnet configuration option that allows a
   router at the local end of an (unnumbered) PPP link to automatically
   negotiate an IP subnet for a LAN for which it provides IP
   connectivity via the PPP link.  Once the subnet has been negotiated,
   the router could allocate one (for example, the second) of the
   addresses of the subnet for its own address on the LAN.  The router
   could also implement a DHCP server for automatic configuration of IP
   information for the other devices on the LAN.

   The following section contains the formal definition of the IP Subnet
   configuration option.

2.  IP Subnet IPCP Configuration Option

   The IP Subnet configuration option, x (value to be assigned by IANA),
   is used to negotiate an IP subnet for a LAN attached to a router on
   the local end of an (unnumbered) PPP link.  The IP Subnet
   configuration option allows the sender of the Configure-Request to
   state the address and/or mask of the desired IP subnet or to request
   that the peer provides the information.  The peer MAY accept,
   provide, or deny the information by ACKing or NAKing the option.  The
   IP Subnet configuration option MAY be present in the Configure-Nak
   only if the option was present in the corresponding Configure-
   Request.  The IP Subnet configuration option MUST NOT be present in a
   Configure-Request if the IP-address configuration option is present.

   The format of the IP Subnet configuration option 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     |        Subnet Address
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
           Subnet Address (cont)      |     Mask      |    Padding    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type



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INTERNET DRAFT                                         November 12, 1998


      To be assigned.

   Length

      8

   Subnet Address

      The Subnet Address MUST be the first IP address in the desired IP
      subnet.  If all four octets of the Subnet Address are set to zero,
      it indicates a request for the peer to provide the Subnet Address
      information.

   Mask

      The Mask indicates the desired size of the IP subnet, i.e., how
      many most significant bits of the Subnet Address belong to the
      network part of the address.  The value of the Mask MUST be from 0
      to 32.  If the value of the Mask is 0, it indicates a request for
      the peer to provide the Mask information.  Mask value 32 denotes a
      single host address.

   Padding

      The Padding is used to make the length of the IP Subnet
      configuration option a multiple of four octets.  It MAY have any
      value.

   Default

      No IP subnet is assigned.

3. Security Considerations

   The remote end of the PPP link SHOULD verify that the local end is
   authorized to use the requested IP subnet information before ACKing
   the request.

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.






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INTERNET DRAFT                                         November 12, 1998


Author Information

   Juha Heinanen
   Telia Finland, Inc.
   Myyrmaentie 2
   01600 VANTAA
   Finland
   Email jh@telia.fi

   Dave Allan
   Nortel Networks
   P.O. Box 3511, Station 'C'
   Ottawa, Ontario
   CANADA, K2B 5P9
   dallan@nortelnetworks.com

   Arthur Lin
   Shasta Networks, Inc.
   249 Humboldt Court
   Sunnyvale, CA 94089-1300
   U.S.A
   alin@shastanets.com

   Paul Shieh
   3Com Corporation
   4 Technology Drive
   Westborough, MA 01581-1727
   U.S.A
   Paul_Shieh@ne.3com.com






















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