Internet Engineering Task Force (IETF)                          O. Troan
Request for Comments: 8425                                 Cisco Systems
Updates: 4861                                                  July 2018
Category: Standards Track
ISSN: 2070-1721

IANA Considerations for IPv6 Neighbor Discovery
Prefix Information Option Flags

Abstract

   The Prefix Information Option (PIO) in the IPv6 Neighbor Discovery
   Router Advertisement message defines an 8-bit flag field; this field
   has two flags defined, and the remaining 6 bits are reserved
   (Reserved1).  RFC 6275 defines a flag from this field without
   creating an IANA registry or updating RFC 4861.  The purpose of this
   document is to create an IANA registry for the PIO flags.  This
   document updates RFC 4861.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8425.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Current Prefix Information Option Flags . . . . . . . . . . .   2
   3.  Updates to RFC 4861 . . . . . . . . . . . . . . . . . . . . .   3
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   6.  Normative References  . . . . . . . . . . . . . . . . . . . .   4
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   4

1. Introduction

   The Prefix Information Option (PIO) in the IPv6 Neighbor Discovery
   Router Advertisement message defines an 8-bit flag field; this field
   has two flags defined and the remaining 6 bits are reserved
   (Reserved1).  RFC 6275 defines a flag from this field without
   creating an IANA registry or updating RFC 4861.  The purpose of this
   document is to create a new registry for the PIO flags.

2. Current Prefix Information Option Flags

   Currently, the Neighbor Discovery Protocol Prefix Information Option
   [RFC4861] contains the following one-bit flags defined in published
   RFCs:

                               0 1 2 3 4 5 6 7
                              +-+-+-+-+-+-+-+-+
                              |L|A|R|Reserved1|
                              +-+-+-+-+-+-+-+-+

                            Figure 1: PIO Flags

      L - On-link Flag [RFC4861]

      A - Autonomous Address Configuration Flag [RFC4861]

      R - Router Address Flag [RFC6275]

      Reserved1 - Reserved

3. Updates to RFC 4861

   This document updates Section 4.6.2 "Prefix Information" of [RFC4861]
   to point to the IANA registry that is created in this document (see
   Section 4).

   Specifically, the current list of flags in the Prefix Information
   Option can be found in the "IPv6 Neighbor Discovery Prefix
   Information Option Flags" registry.

4. IANA Considerations

   IANA has created a new registry for IPv6 Neighbor Discovery Prefix
   Information Option flags.  This registry includes the current flags
   in the PIO.  The initial contents of the registry are as follows:

       +----------------+---------------------------------+-----------+
       | PIO Option Bit | Description                     | Reference |
       +----------------+---------------------------------+-----------+
       | 0              | L - On-link Flag                | [RFC4861] |
       | 1              | A - Autonomous Address          | [RFC4861] |
       |                |     Configuration Flag          |           |
       | 2              | R - Router Address Flag         | [RFC6275] |
       | 3-7            | Reserved                        |           |
       +----------------+---------------------------------+-----------+

     Figure 2: IPv6 Neighbor Discovery Prefix Information Option Flags

   The assignment of new flags in the PIO option header requires
   Standards Action [RFC8126].

   The registry for these flags is available at
   <http://www.iana.org/assignments/icmpv6-parameters>.

5. Security Considerations

This document has no security considerations.

6. Normative References

   [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>.

   [RFC6275]  Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility
              Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July
              2011, <https://www.rfc-editor.org/info/rfc6275>.

   [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>.

Author's Address

   Ole Troan
   Cisco Systems
   Philip Pedersens vei 1
   Lysaker  1366
   Norway

   Email: ot@cisco.com