Network Working Group                                        S. Krishnan
Internet-Draft                                                  Ericsson
Intended status: Standards Track                         August 23, 2007
Expires: February 24, 2008


                Neighbor Discovery Information over DHCP
                    draft-krishnan-dhc-ndc-option-00

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Copyright Notice

   Copyright (C) The IETF Trust (2007).














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Abstract

   Neighbor discovery options, in addition to being used for Neighbor
   Discovery, are used to convey some forms of network configuration
   information to the hosts attached to a network.  Some centrally
   managed networks, that do not wish to configure their routers to
   advertise these pieces of information, might use a DHCP server to
   configure there parameters.  This document defines a generic DHCP
   option for carrying these parameters.


Table of Contents

   1.  Requirements notation  . . . . . . . . . . . . . . . . . . . .  3
   2.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Applicability  . . . . . . . . . . . . . . . . . . . . . . . .  5
   4.  Operation  . . . . . . . . . . . . . . . . . . . . . . . . . .  6
   5.  Neighbor Discovery Container(NDC) Option . . . . . . . . . . .  7
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  9
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   8.  Normative References . . . . . . . . . . . . . . . . . . . . . 11
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 12
   Intellectual Property and Copyright Statements . . . . . . . . . . 13




























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1.  Requirements notation

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].














































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2.  Introduction

   Router Advertisements (RAs) as defined in [RFC2461] are used to
   deliver configuration information that is common to several nodes in
   the same network.  The router advertisements are usually multicasted
   to all nodes in a given network in order to be scalable.  The
   configuration information is contained in Neigbor Discovery (ND)
   options.  DHCP [RFC3315] is used for delivering addressing
   information and other related configuration information to single
   clients when they request it.  Since there are two mechanisms for
   delivering configuration information to a given node, configuration
   parameters need to be defined under two varying option formats.  This
   leads to duplication of work needed to standardize these options and
   additional implementation complexity on hosts in order to process
   these option variants.  In order to prevent this duplication, this
   document proposes a DHCP option that can be used to directly carry
   any neighbor discovery option.


































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3.  Applicability

   It is possible to carry any neighbor discovery option using the NDC
   option.  This does not always make sense since there are neigbor
   discovery options that are not related to configuration.  The NDC
   option SHOULD NOT be used to carry neighbor discovery options that
   are not related to configuration. e.g.  Source Link-layer Address,
   Target Link-layer Address etc.











































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4.  Operation

   After a DHCP client receives a message that contains a NDC option it
   needs to verify if the NDC option length is at least 8 octets.  If it
   is not, the client MUST NOT process the NDC option any further and
   SHOULD log an error message locally.  Otherwise it needs to process
   the embedded Neighbor Discovery options one at a time as it would if
   it had received them through a Router Advertisement.  It is entirely
   possible that the code for processing these options is shared between
   the RA based delivery and DHCP based delivery of these options.









































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5.  Neighbor Discovery Container(NDC) Option

   The DHCP NDC option is used to carry complete neighbor discovery
   options.  There can be more than one neighbor discovery option that
   is contained in a NDC.  The number of contained options is not
   explicitly mentioned in the NDC.  The receiving node needs to process
   all the contained options

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |          OPTION_NDC           |        Option Length          |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  OPT1_Type    | OPT1_Length   |                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               |
       |                                                               |
       |                          OPT1_Data                            |
       .                                                               .
       .                                                               .
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  OPTn_Type    | OPTn_Length   |                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               |
       |                                                               |
       |                          OPTn_Data                            |
       .                                                               .
       .                                                               .
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       OPTION_NDC

          DHCP Option code allocated for the NDC option. To be
          allocated by IANA out of the dhcpv6 parameters for option
          codes.

       Option Length

          Length of the NDC option in octets not including the Option
          Code and the Option Length fields. i.e. Combined length of
          the included neighbor discovery options.

       OPT1_Type

          The neighbor discovery option type of the first included
          option.

       OPT1_Length



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          The length of the first included option (including the
          OPT1_Type and OPT1_Length fields) in units of 8 octets. The
          value 0 is invalid.

       OPT1_Data

          The data field of the first included neighbor discovery
          option. The contents of this field are determined by the type
          of the option.

       OPTn_Type

          The neighbor discovery option type of the nth included option.

       OPTn_Length

          The length of the nth included option (including the OPT1_Type
          and OPT1_Length fields) in units of 8 octets. The value 0 is
          invalid.

       OPTn_Data

          The data field of the nth included neighbor discovery option.
          The contents of this field are determined by the type of the
          option.


                           Figure 1: NDC layout























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6.  IANA Considerations

   This document defines a new DHCPv6 option code for carrying neighbor
   discovery options.  IANA is requested to assign the following new
   DHCPv6 Option Code in the registry maintained at

   http://www.iana.org/assignments/dhcpv6-parameters:

   OPTION_NDC










































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7.  Security Considerations

   The mechanism described in this document provides a method by which
   one or more neighbor discovery options can be carried using DHCP
   messages.  The DHCP messages containing the NDC option may be
   intercepted, modified or replayed in order to communicate false
   configuration data to the client hosts.  In order to prevent these
   kinds of attacks, it is recommended that authenticated DHCP [RFC3118]
   be used.










































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8.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2461]  Narten, T., Nordmark, E., and W. Simpson, "Neighbor
              Discovery for IP Version 6 (IPv6)", RFC 2461,
              December 1998.

   [RFC3118]  Droms, R. and W. Arbaugh, "Authentication for DHCP
              Messages", RFC 3118, June 2001.

   [RFC3315]  Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
              and M. Carney, "Dynamic Host Configuration Protocol for
              IPv6 (DHCPv6)", RFC 3315, July 2003.




































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Author's Address

   Suresh Krishnan
   Ericsson
   8400 Decarie Blvd.
   Town of Mount Royal, QC
   Canada

   Phone: +1 514 345 7900 x42871
   Email: suresh.krishnan@ericsson.com









































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