IPv6 Router Advertisement Flags Option
RFC 5075

 
Document Type RFC - Proposed Standard (November 2007; Errata)
Obsoleted by RFC 5175
Last updated 2013-03-02
Replaces draft-haberman-ipv6-ra-flags-option
Stream IETF
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Stream WG state (None)
Consensus Unknown
Document shepherd No shepherd assigned
IESG IESG state RFC 5075 (Proposed Standard)
Telechat date
Responsible AD Jari Arkko
Send notices to ipv6-chairs@ietf.org,draft-ietf-ipv6-ra-flags-option@ietf.org
Network Working Group                                   B. Haberman, Ed.
Request for Comments: 5075                                       JHU APL
Category: Standards Track                                      R. Hinden
                                                                   Nokia
                                                           November 2007

                 IPv6 Router Advertisement Flags Option

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Abstract

   The IPv6 Neighbor Discovery's Router Advertisement message contains
   an 8-bit field reserved for single-bit flags.  Several protocols have
   reserved flags in this field and others are preparing to reserve a
   sufficient number of flags to exhaust the field.  This document
   defines an option to the Router Advertisement message that expands
   the available number of flag bits available.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 2
   3.  Current Router Advertisement Flags  . . . . . . . . . . . . . . 2
   4.  Flags Expansion Option  . . . . . . . . . . . . . . . . . . . . 3
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
   6.  Security Considerations . . . . . . . . . . . . . . . . . . . . 5
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 5
     7.1.  Normative References  . . . . . . . . . . . . . . . . . . . 5
     7.2.  Informative References  . . . . . . . . . . . . . . . . . . 6

Haberman & Hinden           Standards Track                     [Page 1]
RFC 5075                 IPv6 RA Flags Options             November 2007

1.  Introduction

   The IPv6 Neighbor Discovery Protocol's (NDP) [RFC4861] Router
   Advertisement message contains an 8-bit field reserved for single-bit
   flags.  Several protocols have reserved flags in this field and
   others are preparing to reserve a sufficient number of flags to
   exhaust the field.

   This document defines an option for the Router Advertisement message
   that expands the available number of flag bits by adding an
   additional 48 flag bits to NDP messages.

2.  Terminology

   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].

3.  Current Router Advertisement Flags

   Currently, the NDP Router Advertisement message contains the
   following one-bit flags defined in published RFCs:

    0 1 2 3 4 5 6 7
   +-+-+-+-+-+-+-+-+
   |M|O|H|Prf|P|R|R|
   +-+-+-+-+-+-+-+-+

                   Figure 1: Router Advertisement Flags

   o  M - Managed Address Configuration Flag [RFC4861]

   o  O - Other Configuration Flag [RFC4861]

   o  H - Mobile IPv6 Home Agent Flag [RFC3775]

   o  Prf - Router Selection Preferences [RFC4191]

   o  P - Neighbor Discovery Proxy Flag [RFC4389]

   o  R - Reserved

   With other protocols in the works (e.g., Detecting Network
   Attachment) that want to use flags in the NDP messages, it is
   necessary to define an expansion capability to support new features.

Haberman & Hinden           Standards Track                     [Page 2]
RFC 5075                 IPv6 RA Flags Options             November 2007

4.  Flags Expansion Option

   The Neighbor Discovery specification [RFC4861] contains the
   capability to define NDP options.  The following (Figure 2) is the
   definition of the Expanded Flags Option (EFO) for NDP Router
   Advertisement messages.

    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     |         Bit fields available ..
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ... for assignment                                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

           Figure 2: Router Advertisement Expanded Flags Option

   o  Type - TBD (to be assigned by IANA)

   o  Length - The length MUST be checked when processing the option in
      order to allow for future expansion of this option.  An
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