draft-ietf-ipv6-ra-flags-option-01.txt   draft-ietf-ipv6-ra-flags-option-02.txt 
Network Working Group B. Haberman, Ed. Network Working Group B. Haberman, Ed.
Internet-Draft JHU APL Internet-Draft JHU APL
Intended status: Standards Track R. Hinden Intended status: Standards Track R. Hinden
Expires: December 23, 2007 Nokia Expires: March 16, 2008 Nokia
June 21, 2007 September 13, 2007
IPv6 Router Advertisement Flags Option IPv6 Router Advertisement Flags Option
draft-ietf-ipv6-ra-flags-option-01 draft-ietf-ipv6-ra-flags-option-02
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on December 23, 2007. This Internet-Draft will expire on March 16, 2008.
Copyright Notice Copyright Notice
Copyright (C) The IETF Trust (2007). Copyright (C) The IETF Trust (2007).
Abstract Abstract
The IPv6 Neighbor Discovery's Router Advertisement message contains The IPv6 Neighbor Discovery's Router Advertisement message contains
an 8-bit field reserved for single-bit flags. Several protocols have an 8-bit field reserved for single-bit flags. Several protocols have
reserved flags in this field and others are preparing to reserve a reserved flags in this field and others are preparing to reserve a
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+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|M|O|H|Prf|P|R|R| |M|O|H|Prf|P|R|R|
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 1: Router Advertisement Flags Figure 1: Router Advertisement Flags
o M - Managed Address Configuration Flag [1] o M - Managed Address Configuration Flag [1]
o O - Other Configuration Flag [1] o O - Other Configuration Flag [1]
o H - Mobile IPv6 Home Agent Flag [3] o H - Mobile IPv6 Home Agent Flag [4]
o Prf - Router Selection Preferences [4] o Prf - Router Selection Preferences [5]
o P - Neighbor Discovery Proxy Flag [5] o P - Neighbor Discovery Proxy Flag [6]
o R - Reserved o R - Reserved
With other protocols in the works (e.g., Detecting Network With other protocols in the works (e.g., Detecting Network
Attachment) that are wanting to use flags in the NDP messages, it is Attachment) that are wanting to use flags in the NDP messages, it is
necessary to define an expansion capability to support new features. necessary to define an expansion capability to support new features.
4. Flags Expansion Option 4. Flags Expansion Option
The Neighbor Discovery specification [1] contains the capability to The Neighbor Discovery specification [1] contains the capability to
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Bit fields available .. | Type | Length | Bit fields available ..
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
... for assignment | ... for assignment |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Router Advertisement Expanded Flags Option Figure 2: Router Advertisement Expanded Flags Option
o Type - TBD (to be assigned by IANA) o Type - TBD (to be assigned by IANA)
o Length = 1; The length MUST be checked when processing the option o Length - The length MUST be checked when processing the option in
in order to allow for future expansion of this option if the need order to allow for future expansion of this option. An
arises. 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 o Bits - allocated by IANA
The definition and usage of these bits is to be found in the document The definition and usage of these bits is to be found in the document
requesting their allocation. requesting their allocation.
During the construction/transmission, this option: During the construction/transmission, this option:
o MUST only occur in Router Advertisement messages o MUST only occur in Router Advertisement messages
o MUST be the first option immediately following the Router o MUST occur prior to any additional options associated with any
Advertisement message header flags set in this option
o MUST only occur once in the Router Advertisement message. o MUST only occur once in the Router Advertisement message
o MUST NOT be added to a Router Advertisement message if no flags in
the option are set
o MUST set all unused flags to zero.
Upon reception, a receiver processing NDP messages containing this Upon reception, a receiver processing NDP messages containing this
option: option:
o MUST ignore the option if it occurs in a message other than a o MUST ignore the option if it occurs in a message other than a
Router Advertisement Router Advertisement
o MUST ignore the option if it is not the first option in the Router
Advertisement
o MUST ignore all instances of the option except the first one o MUST ignore all instances of the option except the first one
encountered in the Router Advertisement message encountered in the Router Advertisement message
o MUST ignore the option if the Length is less than 1
o MUST ignore any unknown flag bits.
The bit fields within the option are numbered from left to right from The bit fields within the option are numbered from left to right from
8 to 55 and follow the numbering of the flag bits in the RA option 8 to 55 (starting as bit offset 16 in the option) and follow the
described in Figure 1. Flag bits 0 to 7 are found in the Router numbering of the flag bits in the RA option described in Figure 1.
Advertisement message header defined in [1] Flag bits 0 to 7 are found in the Router Advertisement message header
defined in [1]
5. IANA Considerations 5. IANA Considerations
The IANA is requested to define a new IPv6 Neighbor Discovery option The IANA is requested to define a new IPv6 Neighbor Discovery option
for the option defined in this document of the form: for the option defined in this document of the form:
+------+---------------------------+-----------+ +------+---------------------------+-----------+
| Type | Description | Reference | | Type | Description | Reference |
+------+---------------------------+-----------+ +------+---------------------------+-----------+
| TBA | RA Flags Extension Option | [RFCXXXX] | | TBA | RA Flags Extension Option | [RFCXXXX] |
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option and in the extension option defined in this document. It is option and in the extension option defined in this document. It is
suggested the new registry be added to the icmpv6-parameters as shown suggested the new registry be added to the icmpv6-parameters as shown
above. The format for the registry is: above. The format for the registry is:
+---------------+---------------------------------------+-----------+ +---------------+---------------------------------------+-----------+
| RA Option Bit | Description | Reference | | RA Option Bit | Description | Reference |
+---------------+---------------------------------------+-----------+ +---------------+---------------------------------------+-----------+
| 0 | M - Managed Address Configuration | [1] | | 0 | M - Managed Address Configuration | [1] |
| | Flag | | | | Flag | |
| 1 | O - Other Configuration Flag | [1] | | 1 | O - Other Configuration Flag | [1] |
| 2 | H - Mobile IPv6 Home Agent Flag | [3] | | 2 | H - Mobile IPv6 Home Agent Flag | [4] |
| 3 | Prf - Router Selection Preferences | [4] | | 3 | Prf - Router Selection Preferences | [5] |
| 4 | Prf - Router Selection Preferences | [4] | | 4 | Prf - Router Selection Preferences | [5] |
| 5 | P - Neighbor Discovery Proxy Flag | [5] | | 5 | P - Neighbor Discovery Proxy Flag | [6] |
| 6-53 | R - Reserved; Available for | | | 6-53 | R - Reserved; Available for | |
| | assignment | | | | assignment | |
| 54-55 | Private Experimentation | | | 54-55 | Private Experimentation | |
+---------------+---------------------------------------+-----------+ +---------------+---------------------------------------+-----------+
The assignment of new RA flags in the RA option header and for the The assignment of new RA flags in the RA option header and for the
bits defined in the RA extension option defined in this document bits defined in the RA extension option defined in this document
require standards action or IESG approval. require standards action or IESG approval[3].
6. Security Considerations 6. Security Considerations
This protocol shares the security issues of NDP that are documented This protocol shares the security issues of NDP that are documented
in the "Security Considerations" section of [1]. in the "Security Considerations" section of [1].
The inclusion of additional optional bit fields provides a potential The inclusion of additional optional bit fields provides a potential
covert channel useful for passing information. covert channel useful for passing information.
7. References 7. References
7.1. Normative References 7.1. Normative References
[1] Narten, T., Nordmark, E., and W. Simpson, "Neighbor Discovery [1] Narten, T., Nordmark, E., and W. Simpson, "Neighbor Discovery
for IP Version 6 (IPv6)", RFC 2461, December 1998. for IP Version 6 (IPv6)", RFC 2461, December 1998.
[2] Bradner, S., "Key words for use in RFCs to Indicate Requirement [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
[3] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
Considerations Section in RFCs", BCP 26, RFC 2434, October 1998.
7.2. Informative References 7.2. Informative References
[3] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in [4] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in
IPv6", RFC 3775, June 2004. IPv6", RFC 3775, June 2004.
[4] Draves, R. and D. Thaler, "Default Router Preferences and More- [5] Draves, R. and D. Thaler, "Default Router Preferences and More-
Specific Routes", RFC 4191, November 2005. Specific Routes", RFC 4191, November 2005.
[5] Thaler, D., Talwar, M., and C. Patel, "Neighbor Discovery [6] Thaler, D., Talwar, M., and C. Patel, "Neighbor Discovery
Proxies (ND Proxy)", RFC 4389, April 2006. Proxies (ND Proxy)", RFC 4389, April 2006.
Authors' Addresses Authors' Addresses
Brian Haberman (editor) Brian Haberman (editor)
Johns Hopkins University Applied Physics Lab Johns Hopkins University Applied Physics Lab
11100 Johns Hopkins Road 11100 Johns Hopkins Road
Laurel, MD 20723-6099 Laurel, MD 20723-6099
USA USA
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