Network Working Group                                        A. McDonald
Internet-Draft                                              Siemens/Roke
Updates: RFC2113, RFC2711                                      J. Manner
(if approved)                                                        TKK
Intended status: Standards Track                       February 25, 2008
Expires: August 28, 2008


     IANA Considerations for the IPv4 and IPv6 Router Alert Option
                   draft-manner-router-alert-iana-02

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Copyright Notice

   Copyright (C) The IETF Trust (2008).

Abstract

   This document provides new instructions to IANA on the allocation of
   IPv4 and IPv6 Router Alert Option Values.







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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Use of the Router Alert Option Value Field  . . . . . . . . . . 3
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
     3.1.  IANA Considerations for IPv4 Router Alert Option Values . . 5
     3.2.  IANA Considerations for IPv6 Router Alert Option Values . . 5
   4.  Security Considerations . . . . . . . . . . . . . . . . . . . . 6
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 6
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 6
     6.1.  Normative References  . . . . . . . . . . . . . . . . . . . 6
     6.2.  Informative References  . . . . . . . . . . . . . . . . . . 6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 7
   Intellectual Property and Copyright Statements  . . . . . . . . . . 8





































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1.  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 RSVP [RFC2205] and IGMP
   [RFC3376].

   Both the IPv4 and IPv6 option 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 repository for IPv6 values.  No repository or allocation
   policies are defined for IPv4.

   This document proposes the creation of a new IANA registry for
   managing IPv4 Router Alert Option Values.  In conjunction with this,
   it also proposes an update to the way in which IPv6 Router Alert
   Option Values are assigned in the existing IANA registry, and
   proposes small changes to the current allocations.


2.  Use of the Router Alert Option Value Field

   One difference betwen the specifications for the IPv4 and IPv6 Router
   Alert Options is the way in which 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.  No mechanism is provided for the
   allocation of these values by IANA.

   The IPv6 Router Alert Option has an IANA managed registry
   [IANA-IPv6RAO] containing allocations for the value field.  All
   values in this registry are assigned by IETF consensus.

   In [RFC3175] the IPv4 Router Alert Option Value is described as a
   parameter which 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, this document requests a set of 32 values to be assigned by
   IANA for indicating reservation levels.  However, since other
   registrations had already been made in that registry these values are
   from 3-35 (which is actually a set of 33 values).




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   Although it would be desirable to have the same values being used in
   both the IPv4 and IPv6 registries, the initial allocations in
   [RFC2711] and the aggregation level allocations in [RFC3175] have
   made this impossible.  The following table shows the allocations in
   the IPv6 registry and 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  |
   |          |                         | use                          |
   | 65535    | Reserved                | Reserved [IANA-IPv6RAO]      |
   +----------+-------------------------+------------------------------+




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   The entry in the above table for the IPv6 RAO Value of 35 (Aggregated
   Reservation Nesting Level 32) 2 has been marked with a question mark
   due to an inconsistency in the text of [RFC3175], which is
   consequently reflected 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).

   It is unclear why nesting levels begin at 1 for IPv4 (described in
   section 1.4.9 of [RFC3175]) and 0 for IPv6 (allocated in section 6 of
   [RFC3175]).


3.  IANA Considerations

   This section contains the proposed new procedures for managing Router
   Alert Option Values.  This requires the creation of a registry for
   IPv4 Router Alert Option Values (described in Section 3.1) and
   changes to the way in which IPv6 Router Alert Option Values are
   managed (described in Section 3.2).

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    | Reserved to IANA for future use      |           |
    | 65503-65534 | Reserved for experimental use        |           |
    | 65535       | Reserved                             |           |
    +-------------+--------------------------------------+-----------+

   New values are to be assigned via IETF Consensus as defined in
   [RFC2434].

3.2.  IANA Considerations for IPv6 Router Alert Option Values

   The registry for IPv6 Router Alert Option Values should continue to
   be maintained as specified in [RFC2711].

   In addition, the following value should be 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, aggreagation
   level 0 means end-to-end signaling, and this already has an IPv6 RAO



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   value "1" assigned.

   3: "RSVP Aggregation level 0"

   The following IPv6 RAO values should be reserved for experimental
   use:

   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].


5.  Acknowledgements

   Thanks to Robert Hancock, Martin Stiemerling, Alan Ford and Francois
   Le Faucher for their helpful comments on this document.


6.  References

6.1.  Normative References

   [RFC2113]  Katz, D., "IP Router Alert Option", RFC 2113,
              February 1997.

   [RFC2434]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 2434,
              October 1998.

   [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.

 6.2.   Informative References

    [IANA-IPv6RAO]
               "IANA Registry for Internet Protocol version 6 (IPv6)
              Router Alert Option Values" .

              <http://www.iana.org/assignments/ipv6-routeralert-values>



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   [RFC2205]  Braden, B., 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.

   [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

   Andrew McDonald
   Roke Manor Research Ltd (a Siemens company)
   Old Salisbury Lane
   Romsey, Hampshire  SO51 0ZN
   United Kingdom

   Email: andrew.mcdonald@roke.co.uk


   Jukka Manner
   Helsinki University of Technology (TKK)
   P.O. Box 3000
   Espoo  FIN-02015 TKK
   Finland

   Phone: +358 9 451 2481
   Email: jukka.manner@tkk.fi









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