IPv6 Router Advertisement Flags Option
RFC 5075
Document | Type |
RFC - Proposed Standard
(November 2007; Errata)
Obsoleted by RFC 5175
|
|
---|---|---|---|
Authors | Bob Hinden , Brian Haberman | ||
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.Show full document text