Network Working Group                                 F. L. Templin, Ed.
Internet-Draft                              Boeing Research & Technology
Intended status: Informational                               20 May 2024
Expires: 21 November 2024


                   IPv6 MANET Local Addresses (MLAs)
                       draft-templin-6man-mla-00

Abstract

   Mobile Ad-hoc NETworks (MANETs) present an interesting challenge for
   IPv6 addressing due to the indeterminant neighborhood properties of
   MANET interfaces.  MANET routers must assign an IPv6 address to each
   MANET interface that is both unique and routable within the MANET but
   must not be forwarded to other networks.  MANET routers must be able
   to assign self-generated addresses when there is no infrastructure
   present on the link that can delegate topology-relative IPv6
   addresses or prefixes.  This document therefore specifies a means for
   MANET routers to generate and assign MANET Local Addresses (MLAs).

Status of This Memo

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   extracted from this document must include Revised BSD License text as
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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  IPv6 MANET Local Addresses (MLAs) . . . . . . . . . . . . . .   3
   3.  Assigning IPv6 MLAs to an Interface . . . . . . . . . . . . .   5
   4.  Requirements  . . . . . . . . . . . . . . . . . . . . . . . .   5
   5.  Implementation Status . . . . . . . . . . . . . . . . . . . .   5
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Appendix A.  Change Log . . . . . . . . . . . . . . . . . . . . .   7
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   When two or more IPv6 [RFC8200] nodes come together within a common
   local operating region (e.g., during the formation of a Mobile Ad-hoc
   Network (MANET)), they must be able to assign unique local-use
   addresses and exchange IPv6 packets even if there is no operator
   infrastructure present.

   The key feature of these local-use IPv6 addresses is that they must
   be assured unique so that there is no chance of conflicting with an
   address assigned by another node.  There is no requirement that the
   addresses have topologically-oriented prefixes, since the (newly-
   formed) local network may not (yet) connect to any other
   Internetworking topologies.

   The local-use IPv6 addresses could then be used for continuous local-
   scoped communications and/or to bootstrap the assignment of
   topologically-oriented addresses under the IPv6 multi-addressing
   architecture [RFC4291].

   This document proposes a new unique local unicast address space known
   as MANET Local Addresses (MLAs).  MLAs are distinguished by a
   reserved IPv6 prefix "P" as defined in this document which is used in
   conjunction with the Universally Unique Interface IDentifier (UUID)
   [RFC9562] to form IPv6 addresses.






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2.  IPv6 MANET Local Addresses (MLAs)

   The IPv6 addressing architecture specified in [RFC4291] and [RFC4193]
   defines the supported IPv6 address unicast/multicast/anycast address
   forms with different scopes ranging from link-local to unique-local
   to global.  Unique-local and global-scoped unicast addresses are
   typically assigned through Stateless Address AutoConfiguration
   (SLAAC) [RFC4862] and/or the Dynamic Host Configuration Protocol for
   IPv6 (DHCPv6) [RFC8415], but these services require the presence of
   IPv6 network infrastructure which may not be immediately available in
   spontaneously-formed MANETs or other isolated local networks.

   A new IPv6 address type known as the DRIP Entity Tag (DET) (or,
   Hierarchical Host Identity Tag (HHIT)) [RFC9374] provides a well-
   structured address format with exceptional uniqueness properties.  A
   portion of the address includes the node's self-generated Overlay
   Routable Cryptographic Hash IDentifier (ORCHID) while the remainder
   of the address includes a well-formed IPv6 prefix plus bits
   corresponding to an attestation service that supports address proof-
   of-ownership.  Verification of the attestation aspect of the address
   requires access to network infrastructure, but this may not always be
   available.

   MANET interfaces have the interesting property that a MANET router R
   will often need to forward packets between MANET nodes A and B even
   though R uses the same interface in the inbound and outbound
   directions.  Since nodes A and B may not be able to communicate
   directly even though both can communicate directly with R, the link
   connectivity property is intransitive and the IPv6 Neighbor Discovery
   (ND) Redirect service cannot be used.  Conversely, R may need to
   forward packets between nodes A and B via different MANET interfaces
   within a single MANET that includes multiple partitions.  Due to
   these degenerate link properties, the use of IPv6 Link Local
   Addresses (LLAs) is also out of scope.

   This document therefore introduces a new fully-self-generated IPv6
   unicast address format known as the MANET Local Address (MLA) that
   can be used either instead of or in addition to a DET/HHIT and/or
   other IPv6 unicast address types (noting again that a single
   interface may have multiple IPv6 addresses [RFC4291]).  The address
   uses an n-bit IPv6 prefix "P" along with a (128-n)-bit interface
   identifier that includes the least-significant bits of a Universally
   Unique IDentifier (UUID) [RFC9562] as shown in Figure 1.

     |          n bits               |           128-n bits            |
     +-------------------------------+---------------------------------+
     |      IPv6 prefix ("P")        |           UUID Suffix           |
     +-------------------------------+---------------------------------+



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             Figure 1: IPv6 MANET Local Address (MLA) Format

   In this format, nodes can construct an MLA by first creating a self-
   generated UUID per [RFC9562] the writing the n bits of P over the n
   most significant bits of the UUID.  Due to the structure of the UUID
   which encodes a 4-bit Version code beginning at bit 48, n must be
   chosen to be no larger than 48, with the smallest value of n possible
   preferred in order to maintain maximum UUID resolution.  Several
   alternatives have been proposed for the selection of P, including
   1000::/4, 0f00::/8, a sub-prefix of 5f00::/8 and the ULA-C prefix
   fc00::/8 (see: [RFC4193]).  An example IPv6 MLA using the ULA-C
   prefix plus the UUIDv4 format is shown in Figure 2:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |1|1|1|1|1|1|0|0|                   random_a                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          random_a             |  ver  |       random_b        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |var|                       random_c                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                           random_c                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                   Figure 2: IPv6 MLA Example using ULA-C

   In this example, the node creates a 128-bit UUIDv4 per [RFC9562] then
   simply replaces the most significant 8 bits with the constant string
   '11111100' (0xfc); the resulting 128-bit MLA then has the format of
   an IPv6 address with an 8-bit prefix and 120-bit interface identifier
   as permitted by the IPv6 addressing architecture.  For example:

      fc84:6c29:de12:4b74:884e:9d2a:73fc:2d94::/8

   After a node creates an MLA, it can use the address within the
   context of spontaneously-organized local networks in which two or
   more nodes come together in the absence of supporting infrastructure
   and can still exchange IPv6 packets with little or no chance of
   address collisions.  The use could be limited to bootstrapping the
   assignment of topologically correct IPv6 addresses through other
   means mentioned earlier, or it could extend to longer term usage
   patterns such as sustained communications with single-hop neighbors
   on a local link or even between multi-hop peers within a MANET.

   Note: while the MLA example specified above is relative to UUIDv4,
   the same format can be applied also to all other UUID versions
   specified in [RFC9562], i.e. by replacing the most significant n bits



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   of the UUID with the n leading bits of P.  New UUID version types are
   therefore advised to provide compatibility for this construction
   method.

3.  Assigning IPv6 MLAs to an Interface

   IPv6 MLAs have no topological orientation and can therefore be
   assigned to any of a node's IPv6 interfaces.  The addresses may serve
   as a basis for multihop forwarding over a MANET interface and/or for
   local neighborhood discovery over other IPv6 interface types.  Due to
   their uniqueness properties, the node can assign an IPv6 MLA to an
   interface without invoking (pre-service) Duplicate Address Detection
   (DAD), however it should configure and assign a new IPv6 MLA if it
   later detects a duplicate through (in-service) DAD.

4.  Requirements

   IPv6 nodes MAY assign self-generated IPv6 MLAs to their interface
   connections to local networks (or MANETs).  If the node later becomes
   aware that the address is already in use by another node, it instead
   generates and assigns a new MLA.

   IPv6 routers MAY forward IPv6 packets with MLA source or destination
   addresses over multiple hops within the same local network (or
   MANET).

   IPv6 routers MUST NOT forward packets with MLA source or destination
   addresses to a link outside the packet's local network (or MANET) of
   origin.

   IPv6 routers MUST NOT advertise prefix P to in routing protocol
   exchanges with correspondents outside the local network (or MANET).
   For this reason, the ULA-C prefix has the advantage that it is
   already scoped for local use.

5.  Implementation Status

   In progress.

6.  IANA Considerations

   This document has no requirements for IANA.

7.  Security Considerations

   TBD.





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8.  Acknowledgements

   This work was inspired by continued investigations into 5G MANET
   operations in cooperation with the Virginia Tech National Security
   Institute (VTNSI).

   Emerging discussions on the IPv6 maintenance (6man) mailing list are
   expected to shape future versions of this document.  The author
   acknowledges all those whose useful comments have helped further the
   understanding of this proposal.

   Kyzer Davis (RFC9562 author) is acknowledged for his review and
   comments that helped shape the document.

   Honoring life, liberty and the pursuit of happiness.

9.  References

9.1.  Normative References

   [RFC4193]  Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
              Addresses", RFC 4193, DOI 10.17487/RFC4193, October 2005,
              <https://www.rfc-editor.org/info/rfc4193>.

   [RFC4291]  Hinden, R. and S. Deering, "IP Version 6 Addressing
              Architecture", RFC 4291, DOI 10.17487/RFC4291, February
              2006, <https://www.rfc-editor.org/info/rfc4291>.

   [RFC8200]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", STD 86, RFC 8200,
              DOI 10.17487/RFC8200, July 2017,
              <https://www.rfc-editor.org/info/rfc8200>.

   [RFC9562]  Davis, K., Peabody, B., and P. Leach, "Universally Unique
              IDentifiers (UUIDs)", RFC 9562, DOI 10.17487/RFC9562, May
              2024, <https://www.rfc-editor.org/info/rfc9562>.

9.2.  Informative References

   [RFC4862]  Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
              Address Autoconfiguration", RFC 4862,
              DOI 10.17487/RFC4862, September 2007,
              <https://www.rfc-editor.org/info/rfc4862>.








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   [RFC8415]  Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A.,
              Richardson, M., Jiang, S., Lemon, T., and T. Winters,
              "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)",
              RFC 8415, DOI 10.17487/RFC8415, November 2018,
              <https://www.rfc-editor.org/info/rfc8415>.

   [RFC9374]  Moskowitz, R., Card, S., Wiethuechter, A., and A. Gurtov,
              "DRIP Entity Tag (DET) for Unmanned Aircraft System Remote
              ID (UAS RID)", RFC 9374, DOI 10.17487/RFC9374, March 2023,
              <https://www.rfc-editor.org/info/rfc9374>.

Appendix A.  Change Log

   << RFC Editor - remove prior to publication >>

   Differences from earlier versions:

   *  First draft publication.

Author's Address

   Fred L. Templin (editor)
   Boeing Research & Technology
   P.O. Box 3707
   Seattle, WA 98124
   United States of America
   Email: fltemplin@acm.org
























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