IPv6 Router Advertisement Flags Option
RFC 5075
| Document | Type |
RFC - Proposed Standard
(November 2007; Errata)
Obsoleted by RFC 5175
|
|
|---|---|---|---|
| Last updated | 2020-01-21 | ||
| Replaces | draft-haberman-ipv6-ra-flags-option | ||
| Stream | IETF | ||
| Formats | plain text html pdf htmlized with errata bibtex | ||
| Reviews | |||
| Stream | WG state | (None) | |
| Document shepherd | No shepherd assigned | ||
| IESG | IESG state | RFC 5075 (Proposed Standard) | |
| Consensus Boilerplate | Unknown | ||
| Telechat date | |||
| Responsible AD | Jari Arkko | ||
| Send notices to | (None) | ||
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
implementation of this specification MUST set the Length to 1,
MUST ignore any unrecognized data, and MUST be able to recognize
the specific length in order to skip over unrecognized bits.
o Bits - allocated by IANA
The definition and usage of these bits is to be found in the document
requesting their allocation.
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