The Universal IPv6 Configuration Option (experiment)
draft-troan-6man-universal-ra-option-02

Versions: 00 01 02                                                      
Network Working Group                                           O. Troan
Internet-Draft                                                     cisco
Intended status: Standards Track                            2 April 2020
Expires: 4 October 2020


          The Universal IPv6 Configuration Option (experiment)
                draft-troan-6man-universal-ra-option-02

Abstract

   One of the original intentions for the IPv6 host configuration, was
   to configure the network-layer parameters only with IPv6 ND, and use
   service discovery for other configuration information.  Unfortunately
   that hasn't panned out quite as planned, and we are in a situation
   where all kinds of configuration options are added to RAs and DHCP.
   This document proposes a new universal option for RA and DHCP in a
   self-describing data format, with the list of elements maintained in
   an IANA registry, with greatly relaxed rules for registration.

Status of This Memo

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   This Internet-Draft will expire on 4 October 2020.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
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   This document is subject to BCP 78 and the IETF Trust's Legal
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   Please review these documents carefully, as they describe your rights
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   as described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  The Experiment  . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  The Universal IPv6 Configuration option . . . . . . . . . . .   3
   5.  Implementation Guidance . . . . . . . . . . . . . . . . . . .   4
   6.  Implementation Status . . . . . . . . . . . . . . . . . . . .   5
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
     8.1.  Initial objects in the registry . . . . . . . . . . . . .   5
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   This document proposes a new universal option for the Router
   Advertisement IPv6 ND message [RFC4861] and DHCPv6 [RFC8415].  It's
   purpose is to use the RA or DHCP message as an opaque carrier for
   configuration information between an agent on a router or DHCP server
   and host / host application.

   DHCP is suited to give per-client configuration information, while
   the RA mechanism advertises configuration information to all hosts on
   the link.  There is a long running history of "conflict" between the
   two.  The arguments go; there is less fate-sharing in DHCP, DHCP
   doesn't deal with multiple sources of information, or make it more
   difficult to change information independent of the lifetimes, RA
   cannot be used to configure different information to different
   clients and so on.  And of course some options are only available in
   RAs and some options are only available in DHCP.

   While this proposal does not resolve the DHCP vs RA debate, it
   proposes an experimental solution to the problem of a very slow
   process of standardizing new options, and the IETF spending an
   inordinate amount of time arguing over new configuration options.

2.  Conventions

   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 RFC 2119 [RFC2119].






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3.  The Experiment

   This document specifies a new "self-describing" universal
   configuration option.  Currently new configuration option requires
   "standards action".  The purpose of the experiment is two-fold.  What
   are the implications of an opaque configuration option that should
   not require any code changes for new elements within the option?  And
   what happens when change control is relaxed?  The proposal is that no
   IETF document is required.  The configuration option is described
   directly in the universal configuration IANA registry.

   Duration of experiment: 2 years.

   How to evaluate success?  How many new options have been defined.
   Did expert review suffice to stop "harmful" options?  Were any of the
   options implemented and deployed?  On a successful experiment, the
   time limit of the registry will be removed and it's experimental
   status will be removed.  If the experiment is deemed a failure, then
   the registry will be removed.

4.  The Universal IPv6 Configuration option

   The option data is described using the schema language CDDL
   [RFC8610], encoded in CBOR [RFC7049].

        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     |   Data ...
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


            Figure 1: Universal IPv6 Configuration Option Format

   Fields:

   Type        42 for Universal IPv6 Configuration Option

   Length      The length of the option (including the type and length
               fields) in units of 8 octets.

   Data        CBOR encoded data.

   Padding     Option zero-padded to nearest 8-octet boundary

   Example:





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   {
       "ietf": {
           "dns": {
               "dnssl": [
                   "example.com"
               ],
               "rdnss": [
                   "2001:db8::1",
                   "2001:db8::2"
               ]
           },
           "nat64": {
               "prefix": "64:ff9b::/96"
           }
           "rio": {
               "routes": [
                   "rio_routes": {
                       "prefix": "::/0",
                       "next-hop": "fe80::1"
                   }
               ]
           }
       }
   }

                                  Figure 2

   The universal IPv6 Configuration option MUST be small enough to fit
   within a single IPv6 ND or DHCPv6 packet.  It then follows that a
   single element in the dictionary cannot be larger than what fits
   within a single option.  Different elements can be split across
   multiple universal configuration options (in separate ND RA packets).

   All IANA registered elements are under the "ietf" key in the
   dictionary.  Private configuration information can be included in the
   option using different keys.

5.  Implementation Guidance

   The purpose of this option is to allow users to use the RA or DHCP as
   an opaque carrier for configuration information without requiring
   code changes in the option carrying infrastructure.

   On the router or DHCP server side there should be an API allowing a
   user to add an element, e.g. a JSON object [RFC8259] or a pre-encoded
   CBOR string to RAs sent on a given interface or to DHCP messages sent
   to a client.




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   On the host side, an API should be available allowing applications to
   subscribe to received configuration elements.  It should be possible
   to subscribe to configuration object by dictionary key.

   The contents of any elements that are not recognized, either in whole
   or in part, by the receiving host MUST be ignored and the remainder
   of option's contents processed as normal.

6.  Implementation Status

   The Universal IPv6 configuration option sending side is implemented
   in VPP (https://wiki.fd.io/view/VPP).

   The implementation is a prototype released under Apache license and
   available at: https://github.com/vpp-dev/vpp/
   commit/156db316565e77de30890f6e9b2630bd97b0d61d.

7.  Security Considerations

   Unless there is a security relationship between the host and the
   router (e.g.  SEND), and even then, the consumer of configuration
   information can put no trust in the information received.

8.  IANA Considerations

   IANA is requested to add a new registry for the Universal IPv6
   Configuration option.  The registry should be named "IPv6 ND RA
   Universal option (experimental)".  Changes and additions to the
   registry require expert review [RFC8126].

   The schema field follows the CDDL schema definition in [RFC8610].

   The IANA is requested to add the universal option to the "IPv6
   Neighbor Discovery Option Formats" registry with the value of 42.

   The IANA is requested to add the universal option to the "Dynamic
   Host Configuration Protocol for IPv6 (DHCPv6) Option Codes" registry.

8.1.  Initial objects in the registry

   The PVD [I-D.ietf-intarea-provisioning-domains] elements (and PIO,
   RIO [RFC4191]) are included to provide an alternative representation
   for the proposed new options in that draft.








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      +-------------------------------------------------+-----------+
      | CDDL Description                                | Reference |
      +---------------+---------------------------------+-----------+
      | ietf = {                                        |           |
      |   ? dns : dns                                   |           |
      |   ? nat64: nat64                                |           |
      |   ? ipv6-only: bool                             |           |
      |   ? pvd : pvd                                   |           |
      |   ? mtu : uint .size 4                          |           |
      |   ? rio : rio                                   |           |
      | }                                               |           |
      |                                                 |           |
      | pio = {                                         | [RFC4861] |
      |   prefix : tstr                                 |           |
      |   ? preferred-lifetime : uint                   |           |
      |   ? valid-lifetime : uint                       |           |
      |   ? a-flag : bool                               |           |
      |   ? l-flag : bool                               |           |
      | }                                               |           |
      |                                                 |           |
      | rio_route = {                                   | [RFC4191] |
      |   prefix : tstr                                 |           |
      |   ? preference : (0..3)                         |           |
      |   ? lifetime : uint                             |           |
      |   ? mtu : uint .size 4                          | [this]    |
      |   ? nexthop: tstr                               |           |
      | }                                               |           |
      | rio = {                                         |           |
      |   routes : [+ rio_route]                        |           |
      | }                                               |           |
      |                                                 |           |
      | dns = {                                         | [RFC8106] |
      |  dnssl : [* tstr]                               |           |
      |  rdnss : ipv6-addresses : [* tstr]              |           |
      |  ? lifetime : uint                              |           |
      | }                                               |           |
      |                                                 |           |
      | nat64 = {                                       | [RFC7050] |
      |   prefix : tstr                                 |           |
      | }                                               |           |
      | ipv6-only : bool                                | [v6only]  |
      |                                                 |           |
      | pvd = {                                         | [pvd]     |
      |   fqdn : tstr                                   |           |
      |   uri : tstr                                    |           |
      |   ? dns : dns                                   |           |
      |   ? nat64: nat64                                |           |
      |   ? pio : pio                                   |           |



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      |   ? rio : rio                                   |           |
      | }                                               |           |
      +---------------+---------------------------------+-----------+


                                  Figure 3

9.  References

   [I-D.ietf-intarea-provisioning-domains]
              Pfister, P., Vyncke, E., Pauly, T., Schinazi, D., and W.
              Shao, "Discovering Provisioning Domain Names and Data",
              Work in Progress, Internet-Draft, draft-ietf-intarea-
              provisioning-domains-11, 31 January 2020,
              <https://tools.ietf.org/html/draft-ietf-intarea-
              provisioning-domains-11>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC4191]  Draves, R. and D. Thaler, "Default Router Preferences and
              More-Specific Routes", RFC 4191, DOI 10.17487/RFC4191,
              November 2005, <https://www.rfc-editor.org/info/rfc4191>.

   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
              "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
              DOI 10.17487/RFC4861, September 2007,
              <https://www.rfc-editor.org/info/rfc4861>.

   [RFC7049]  Bormann, C. and P. Hoffman, "Concise Binary Object
              Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
              October 2013, <https://www.rfc-editor.org/info/rfc7049>.

   [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
              Writing an IANA Considerations Section in RFCs", BCP 26,
              RFC 8126, DOI 10.17487/RFC8126, June 2017,
              <https://www.rfc-editor.org/info/rfc8126>.

   [RFC8259]  Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
              Interchange Format", STD 90, RFC 8259,
              DOI 10.17487/RFC8259, December 2017,
              <https://www.rfc-editor.org/info/rfc8259>.

   [RFC8415]  Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A.,
              Richardson, M., Jiang, S., Lemon, T., and T. Winters,
              "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)",



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              RFC 8415, DOI 10.17487/RFC8415, November 2018,
              <https://www.rfc-editor.org/info/rfc8415>.

   [RFC8610]  Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
              Definition Language (CDDL): A Notational Convention to
              Express Concise Binary Object Representation (CBOR) and
              JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
              June 2019, <https://www.rfc-editor.org/info/rfc8610>.

Author's Address

   Ole Troan
   cisco
   Philip Pedersens vei 1
   1366 Lysaker
   Norway

   Email: ot@cisco.com

































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