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Network Working Group                                          J. MannerRequest for Comments: 5350                                           TKKUpdates:2113,3175                                          A. McDonaldCategory: Standards Track                                   Siemens/Roke                                                          September 2008IANA Considerations for the IPv4 and IPv6 Router Alert OptionsStatus 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.Copyright Notice   Copyright (C) The IETF Trust (2008).Abstract   This document updates the IANA allocation rules and registry of IPv4   and IPv6 Router Alert Option Values.Table of Contents1. Introduction ....................................................22. Use of the Router Alert Option Value Field ......................23. IANA Considerations .............................................43.1. IANA Considerations for IPv4 Router Alert Option Values ....43.2. IANA Considerations for IPv6 Router Alert Option Values ....54. Security Considerations .........................................55. Acknowledgements ................................................66. References ......................................................66.1. Normative References .......................................66.2. Informative References .....................................6Manner & McDonald           Standards Track                     [Page 1]

RFC 5350          IANA Considerations for Router Alert    September 20081.  Introduction   The IP Router Alert Option is defined for IPv4 in [RFC2113].  A   similar IPv6 option is defined in [RFC2711].  When one of these   options is present in an IP datagram, it indicates that the contents   of the datagram may be interesting to routers.  The Router Alert   Option (RAO) is used by protocols such as the Resource Reservation   Protocol (RSVP) [RFC2205] and IGMP [RFC3376].   Both the IPv4 and IPv6 options contain a two-octet Value field to   carry extra information.  This information can be used, for example,   by routers to determine whether or not the packet should be more   closely examined by them.   There can be up to 65536 values for the RAO.  Yet, currently there is   only a registry for IPv6 values.  No registry or allocation policies   are defined for IPv4.   This document updates the IANA registry for managing IPv4 and IPv6   Router Alert Option Values, and removes one existing IPv6 Router   Alert Option Value.2.  Use of the Router Alert Option Value Field   One difference between the specifications for the IPv4 and IPv6   Router Alert Options is the way values for the Value field are   managed.  In [RFC2113], the IPv4 Router Alert Option Value field has   the value 0 assigned to "Router shall examine packet".  All other   values (1-65535) are reserved.  Neither a management mechanism (e.g.,   an IANA registry) nor an allocation policy are provided for the IPv4   RAO values.   The IPv6 Router Alert Option has an IANA-managed registry   [IANA-IPv6RAO] containing allocations for the Value field.   In [RFC3175], the IPv4 Router Alert Option Value is described as a   parameter that provides "additional information" to the router in   making its interception decision, rather than as a registry managed   by IANA.  As such, this aggregation mechanism makes use of the Value   field to carry the reservation aggregation level.  For the IPv6   option, IANA has assigned a set of 32 values to indicate reservation   levels.  However, since other registrations have already been made in   that registry, these values are from 3-35 (which is actually a set of   33 values).   Although it might have been desirable to have the same values used in   both the IPv4 and IPv6 registries, the initial allocations in   [RFC2711] and the aggregation-level allocations in [RFC3175] haveManner & McDonald           Standards Track                     [Page 2]

RFC 5350          IANA Considerations for Router Alert    September 2008   made this impossible.  The following table shows the allocations in   the IPv6 registry and the values used in the IPv4 registry, where the   latter have been deduced from [RFC2113] and [RFC3175] with the   assumption that the number of aggregation levels can be limited to 32   as in the IPv6 case.  Entries for values 6 to 31 have been elided for   brevity.   +----------+-------------------------+------------------------------+   | Value    | IPv4 RAO Meaning        | IPv6 RAO Meaning             |   +----------+-------------------------+------------------------------+   | 0        | Router shall examine    | Datagram contains a          |   |          | packet [RFC2113]        | Multicast Listener Discovery |   |          | [RFC2205] [RFC3376]     | message [RFC2711] [RFC2710]  |   |          | [RFC4286]               | [RFC4286]                    |   | 1        | Aggregated Reservation  | Datagram contains RSVP       |   |          | Nesting Level 1         | message [RFC2711] [RFC2205]  |   |          | [RFC3175]               |                              |   | 2        | Aggregated Reservation  | Datagram contains an Active  |   |          | Nesting Level 2         | Networks message [RFC2711]   |   |          | [RFC3175]               | [Schwartz2000]               |   | 3        | Aggregated Reservation  | Aggregated Reservation       |   |          | Nesting Level 3         | Nesting Level 0 [RFC3175](*) |   |          | [RFC3175]               |                              |   | 4        | Aggregated Reservation  | Aggregated Reservation       |   |          | Nesting Level 4         | Nesting Level 1 [RFC3175]    |   |          | [RFC3175]               |                              |   | 5        | Aggregated Reservation  | Aggregated Reservation       |   |          | Nesting Level 5         | Nesting Level 2 [RFC3175]    |   |          | [RFC3175]               |                              |   | ...      | ...                     | ...                          |   | 32       | Aggregated Reservation  | Aggregated Reservation       |   |          | Nesting Level 32        | Nesting Level 29 [RFC3175]   |   |          | [RFC3175]               |                              |   | 33       | Reserved                | Aggregated Reservation       |   |          |                         | Nesting Level 30 [RFC3175]   |   | 34       | Reserved                | Aggregated Reservation       |   |          |                         | Nesting Level 31 [RFC3175]   |   | 35       | Reserved                | Aggregated Reservation       |   |          |                         | Nesting Level 32(*)          |   |          |                         | [RFC3175]                    |   | 36-65534 | Reserved                | Reserved to IANA for future  |   |          |                         | assignment                   |   | 65535    | Reserved                | Reserved [IANA-IPv6RAO]      |   +----------+-------------------------+------------------------------+   Note (*): The entry in the above table for the IPv6 RAO Value of 35   (Aggregated Reservation Nesting Level 32) has been marked due to an   inconsistency in the text of [RFC3175], and is consequently reflectedManner & McDonald           Standards Track                     [Page 3]

RFC 5350          IANA Considerations for Router Alert    September 2008   in the IANA registry.  In that document, the values 3-35 (i.e., 33   values) are defined for nesting levels 0-31 (i.e., 32 levels).   Similarly, value 3 is a duplicate, because aggregation level 0 means   end-to-end signaling, and this already has an IPv6 RAO value "1"   assigned.   Also note that nesting levels begin at 1 for IPv4 (described inSection 1.4.9 of [RFC3175]) and 0 for IPv6 (allocated inSection 6 of   [RFC3175]).Section 3.2 of this document redefines these so that for IPv6, value   3 is no longer used and values 4-35 represent levels 1-32.  This   removes the above inconsistencies.3.  IANA Considerations   This section contains the new procedures for managing IPv4 Router   Alert Option Values.  IANA has created a registry for IPv4 Router   Alert Option Values (described inSection 3.1) and has updated the   IPv6 Router Alert Option Values (described inSection 3.2).   IP Router Alert Option Values are currently managed separately for   IPv4 and IPv6.  This document does not change this, as there is   little value in forcing the two registries to be aligned.3.1.  IANA Considerations for IPv4 Router Alert Option Values   The Value field, as specified in [RFC2113], is two octets in length.   The Value field is registered and maintained by IANA.  The initial   contents of this registry are:   +-------------+--------------------------------------+-----------+   | Value       | Description                          | Reference |   +-------------+--------------------------------------+-----------+   | 0           | Router shall examine packet          | [RFC2113] |   | 1-32        | Aggregated Reservation Nesting Level | [RFC3175] |   | 33-65502    | Available for assignment by the IANA |           |   | 65503-65534 | Available for experimental use       |           |   | 65535       | Reserved                             |           |   +-------------+--------------------------------------+-----------+   New values are to be assigned via IETF Review as defined in   [RFC5226].Manner & McDonald           Standards Track                     [Page 4]

RFC 5350          IANA Considerations for Router Alert    September 20083.2.  IANA Considerations for IPv6 Router Alert Option Values   The registry for IPv6 Router Alert Option Values continues to be   maintained as specified in [RFC2711].  In addition, the following   value has been removed from the IANA registry and reserved for   possible future use (not to be allocated currently).  The reason is   that it is a duplicate value; aggregation level 0 means end-to-end   signaling, and this already has an IPv6 RAO value "1" assigned.   +-------+--------------------------+-----------+   | Value | Description              | Reference |   +-------+--------------------------+-----------+   | 3     | RSVP Aggregation level 0 | [RFC3175] |   +-------+--------------------------+-----------+   The following IPv6 RAO values are available for experimental use:   +-------------+------------------+-----------+   | Value       | Description      | Reference |   +-------------+------------------+-----------+   | 65503-65534 | Experimental use |           |   +-------------+------------------+-----------+4.  Security Considerations   Since this document is only concerned with the IANA management of the   IPv4 and IPv6 Router Alert Option Values registry, it raises no new   security issues beyond those identified in [RFC2113] and [RFC2711].   Yet, as discussed inRFC 4727 [RFC4727], production networks do not   necessarily support the use of experimental code points in IP option   headers.  The network scope of support for experimental values should   be evaluated carefully before deploying any experimental RAO value   across extended network domains, such as the public Internet.  The   potential to disrupt the stable operation of the network hosting the   experiment through the use of unsupported experimental code points is   a serious consideration when planning an experiment using such code   points.   When experimental RAO values are deployed within an administratively   self-contained network domain, the network administrators should   ensure that each value is used consistently to avoid interference   between experiments.  When experimental values are used in traffic   that crosses multiple administrative domains, the experimenters   should assume that there is a risk that the same values will be used   simultaneously by other experiments, and thus that there is aManner & McDonald           Standards Track                     [Page 5]

RFC 5350          IANA Considerations for Router Alert    September 2008   possibility that the experiments will interfere.  Particular   attention should be given to security threats that such interference   might create.5.  Acknowledgements   Thanks to Robert Hancock, Martin Stiemerling, Alan Ford, and Francois   Le Faucheur for their helpful comments on this document.6.   References6.1.   Normative References   [RFC2113]        Katz, D., "IP Router Alert Option",RFC 2113,                    February 1997.   [RFC2711]        Partridge, C. and A. Jackson, "IPv6 Router Alert                    Option",RFC 2711, October 1999.   [RFC3175]        Baker, F., Iturralde, C., Le Faucheur, F., and B.                    Davie, "Aggregation of RSVP for IPv4 and IPv6                    Reservations",RFC 3175, September 2001.   [RFC5226]        Narten, T. and H. Alvestrand, "Guidelines for                    Writing an IANA Considerations Section in RFCs",BCP26,RFC 5226, May 2008.6.2.  Informative References   [IANA-IPv6RAO]  "IANA Registry for Internet Protocol version 6 (IPv6)                    Router Alert Option Values", <http://www.iana.org>.   [RFC2205]        Braden, R., Ed., Zhang, L., Berson, S., Herzog, S.,                    and S. Jamin, "Resource ReSerVation Protocol (RSVP)                    -- Version 1 Functional Specification",RFC 2205,                    September 1997.   [RFC2710]        Deering, S., Fenner, W., and B. Haberman, "Multicast                    Listener Discovery (MLD) for IPv6",RFC 2710,                    October 1999.   [RFC3376]        Cain, B., Deering, S., Kouvelas, I., Fenner, B., and                    A. Thyagarajan, "Internet Group Management Protocol,                    Version 3",RFC 3376, October 2002.   [RFC4286]        Haberman, B. and J. Martin, "Multicast Router                    Discovery",RFC 4286, December 2005.Manner & McDonald           Standards Track                     [Page 6]

RFC 5350          IANA Considerations for Router Alert    September 2008   [RFC4727]        Fenner, B., "Experimental Values In IPv4, IPv6,                    ICMPv4, ICMPv6, UDP, and TCP Headers",RFC 4727,                    November 2006.   [Schwartz2000]   Schwartz, B., Jackson, A., Strayer, W., Zhou, W.,                    Rockwell, D., and C. Partridge, "Smart Packets:                    Applying Active Networks to Network Management", ACM                    Transactions on Computer Systems (TOCS), Volume 18,                    Issue 1, February 2000.Authors' Addresses   Jukka Manner   Department of Communications and Networking (Comnet)   Helsinki University of Technology (TKK)   P.O. Box 3000   Espoo  FIN-02015 TKK   Finland   Phone: +358 9 451 2481   EMail: jukka.manner@tkk.fi   Andrew McDonald   Roke Manor Research Ltd (a Siemens company)   Old Salisbury Lane   Romsey, Hampshire  SO51 0ZN   United Kingdom   EMail: andrew.mcdonald@roke.co.ukManner & McDonald           Standards Track                     [Page 7]

RFC 5350          IANA Considerations for Router Alert    September 2008Full Copyright Statement   Copyright (C) The IETF Trust (2008).   This document is subject to the rights, licenses and restrictions   contained inBCP 78, and except as set forth therein, the authors   retain all their rights.   This document and the information contained herein are provided on an   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND   THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS   OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF   THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.Intellectual Property   The IETF takes no position regarding the validity or scope of any   Intellectual Property Rights or other rights that might be claimed to   pertain to the implementation or use of the technology described in   this document or the extent to which any license under such rights   might or might not be available; nor does it represent that it has   made any independent effort to identify any such rights.  Information   on the procedures with respect to rights in RFC documents can be   found inBCP 78 andBCP 79.   Copies of IPR disclosures made to the IETF Secretariat and any   assurances of licenses to be made available, or the result of an   attempt made to obtain a general license or permission for the use of   such proprietary rights by implementers or users of this   specification can be obtained from the IETF on-line IPR repository athttp://www.ietf.org/ipr.   The IETF invites any interested party to bring to its attention any   copyrights, patents or patent applications, or other proprietary   rights that may cover technology that may be required to implement   this standard.  Please address the information to the IETF at   ietf-ipr@ietf.org.Manner & McDonald           Standards Track                     [Page 8]