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IPv6 MANET Local Addressing

Document Type Active Internet-Draft (individual)
Author Fred Templin
Last updated 2024-06-05
Replaces draft-templin-6man-ula-uuid
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Network Working Group                                 F. L. Templin, Ed.
Internet-Draft                              Boeing Research & Technology
Updates: rfc3879, rfc4007, rfc4291, rfc5889,                 5 June 2024
         rfc6724 (if approved)                                          
Intended status: Standards Track                                        
Expires: 7 December 2024

                      IPv6 MANET Local Addressing


   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 to their MANET interfaces when
   there is no infrastructure present that can coordinate topology-
   relative IPv6 addresses or prefixes.  This document therefore
   specifies a means for MANET routers to generate and assign address
   types useful for MANET local communications.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 7 December 2024.

Copyright Notice

   Copyright (c) 2024 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  IPv6 MANET Local Addressing . . . . . . . . . . . . . . . . .   3
   3.  Assigning MANET Local Addresses to an Interface . . . . . . .   5
   4.  Reclaiming fec0::/10  . . . . . . . . . . . . . . . . . . . .   6
   5.  Obtaining and Assigning IPv6 GUAs/ULAs  . . . . . . . . . . .   6
   6.  Address Selection . . . . . . . . . . . . . . . . . . . . . .   8
   7.  Requirements  . . . . . . . . . . . . . . . . . . . . . . . .   8
   8.  Implementation Status . . . . . . . . . . . . . . . . . . . .   9
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   10. Security Considerations . . . . . . . . . . . . . . . . . . .   9
   11. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     12.1.  Normative References . . . . . . . . . . . . . . . . . .  10
     12.2.  Informative References . . . . . . . . . . . . . . . . .  10
   Appendix A.  Change Log . . . . . . . . . . . . . . . . . . . . .  12
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  12

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 addresses,
   discover multihop routes and exchange IPv6 packets with local network
   peers over their MANET interfaces even if there is no operator
   infrastructure present.

   MANETs include routers that configure interfaces to links with
   undetermined connectivity, in particular where the transitive
   property of connectivity for traditional shared links is not assured.
   MANET routers must nonetheless assign and use IPv6 addresses that are
   unique within the MANET.  This is true even for nodes that configure
   multiple interface connections to the same MANET as a multilink
   routing domain.

   Section 6 of the "IP Addressing Model in Ad Hoc Networks" [RFC5889]
   states that: "an IP address configured on this (MANET) interface
   should be unique, at least within the routing domain" and: "no on-

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   link subnet prefix is configured on this (MANET) interface".  The
   section then continues to explain why IPv6 Link-Local Addresses
   (LLAs) are of limited utility on links with undetermined
   connectivity, to the point that they cannot be used exclusively
   within multilink routing domains.

   [RFC5889] suggests that global [RFC4291] (aka "GUA") and unique-local
   [RFC4193] (aka "ULA") addresses are MANET addressing candidates.
   However, provisioning of unique GUAs and ULAs must be coordinated
   either through administrative actions or through an automated address
   delegation service that all MANET routers can access.  This document
   asserts that new forms of self-generated and unique MANET local IPv6
   addresses are needed.

   The key feature of these MANET local 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 MANET local IPv6 addresses could then be used for continuous
   local communications and/or to coordinate topologically-oriented
   addresses for assignment on other interfaces.  This would also
   manifest a new "MANET local" scope for the IPv6 scoped addressing
   architecture [RFC4007] with scope greater than link-local but lesser
   than global/unique-local unicast.

   This document proposes a new unique local unicast address space known
   as "MANET-Local Addresses (MLAs)".  MLAs use the formerly-deprecated
   IPv6 site-local prefix fec0::10 according to the address generation
   procedures specified in this document.  The document further
   discusses the utility of the Hierarchical Host Identity Tag (HHIT)
   specified in [RFC9374] for MANET local addressing purposes.

2.  IPv6 MANET Local Addressing

   The IPv6 addressing architecture specified in [RFC4007], [RFC4193]
   and [RFC4291] defines the supported IPv6 unicast/multicast/anycast
   address forms with various scopes including link-local, site-local
   and others.  Unique-local and global unicast addresses are typically
   obtained 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.

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   A new IPv6 address type known as the Hierarchical Host Identity Tag
   (HHIT) (aka DRIP Entity Tag (DET)) [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.  Hence, a fully self-generated MLA may be necessary in
   environments where an HHIT cannot be used.

   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 can both 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 distinct links/regions.
   Due to these indeterminant (multi-)link properties, exclusive use of
   IPv6 Link Local Addresses (LLAs) is also out of scope.

   This document therefore introduces the MLA as a new fully self-
   generated IPv6 unicast address type that can be used either instead
   of or in addition to other IPv6 unicast address types.  MLAs use the
   formerly-deprecated Site-Local IPv6 Address prefix fec0::10 according
   to the modified format shown in Figure 1:

     | 10 bits  |1|       53 bits         |         64 bits            |
     |1111111011|L|      subnet ID        |       interface ID         |

             Figure 1: IPv6 MANET Local Address (MLA) Format

   The node sets the first 10 bits of the MLA to the constant string
   '1111111011' then sets the 11th bit (i.e., the "(L)ocal" bit) to 1.
   The node next sets subnet ID to a 53 bit random value calculated the
   same as specified in Section 3.2.1 of [RFC4193] for the Unique Local
   Address Global ID.

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   The node finally generates and assigns a semantically opaque
   interface ID based on this self-generated prefix as specified in
   [RFC7217]; the resulting 128-bit MLA then has the proper format of an
   IPv6 address with a 64-bit "prefix" followed by a 64-bit interface
   identifier as required by the IPv6 addressing architecture.  For


   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: the above MLA generation procedures apply when the L bit is set
   to 1; MLA generation procedures for L=0 may be specified by future

3.  Assigning MANET Local Addresses to an Interface

   IPv6 MLAs and HHITS have no topological orientation and can therefore
   be assigned to any of a node's MANET interfaces with a /128 prefix
   length (i.e., as a singleton address).  The node can then begin to
   use MLAs or HHITs as the source/destination addresses of IPv6 packets
   that are forwarded over the interface within a local routing region.
   The node can assign the same MLA or HHIT to multiple interfaces all
   members of the same MANET, but must assign a different MLA or HHIT to
   the interfaces of each interface set connected to different MANETs.

   MLAs and HHITs may then 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 or HHIT to an interface without invoking (pre-
   service) Duplicate Address Detection (DAD), however it should
   deprecate an address if it detects a duplicate through (in-service)

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4.  Reclaiming fec0::/10

   Returning to a debate from more than 20 years ago, this document now
   proposes to reclaim the deprecated prefix "fec0::/10" for use as the
   MLA top-level prefix.  [RFC3879] documents the reasons for
   deprecation including the assertion that "Site is an Ill-Defined
   Concept".  However, the concept of a MANET is a logical one based on
   (multihop) connectivity and not necessarily one constrained by
   physical boundaries.

   For example, a MANET router may connect to multiple distinct MANETs
   with a first set of interfaces connected to MANET "A", a second set
   of interfaces connected to MANET "B", etc.  According to the scoped
   IPv6 addressing architecture, the router would assign a separate MLA
   for each interface set A, B, etc. and maintain separate MANET routing
   protocol instances for each set.  MLAs A, B, etc.  then become the
   router IDs for the separate routing protocol instances, but the MANET
   router may elect to redistribute discovered MLA routes between the
   instances.  The uniqueness properties of MLAs and HHITs therefore
   transcends logical MANET boundaries but without "leaking" into
   external networks.

   The MLA prefix (formerly known as "Site-Local") has the distinct
   advantage that it is reserved and available for reclamation by a
   future standards track publication, for which this document
   qualifies.  Upon publication as a standards track RFC, the RFC Editor
   is instructed to update [RFC3879], [RFC4007], [RFC4291] and [RFC5889]
   to reflect this new use for "fec0::/10".

5.  Obtaining and Assigning IPv6 GUAs/ULAs

   MANET routers assign MLAs and/or HHITs to their MANET interfaces for
   use only within the scope of their locally connected MANETs.  The
   MLAs and HHITs are carried in MANET routing protocol control messages
   and can also appear as the source and destination addresses for IPv6
   packets forwarded within the locally connected MANETs.  MLAs and
   HHITs cannot appear in the source or destination addresses for IPv6
   packets forwarded beyond the locally connected MANETs, however, where
   an IPv6 Globally-Unique (GUA) and possibly also a companion Unique-
   Local (ULA) address is necessary.

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   In order to support global-scope communications, each MANET router is
   required to obtain an IPv6 GUA through a border router/proxy that
   connects the MANET to the global IPv6 Internet.  Since the proxy may
   be multiple MANET hops away, however, the MANET router configures and
   engages an Overlay Multilink Network (OMNI) Interface as specified in
   [I-D.templin-6man-omni3].  The MANET router assigns the GUA to the
   OMNI interface which forwards original packets by inserting an IPv6
   encapsulation header that uses MLAs or HHITs as the source/
   destination addresses while the original packet uses GUAs.

   The proxy may be configured as an IPv6-to-IPv6 Network Prefix
   Translation (NPTv6) gateway that connects the rest of the MANET to
   the outside Internet.  In that case, the proxy supplies each MANET
   router with a ULA internally and maintains a 1:1 relationship between
   the ULA on the "inside" and a GUA on the "outside" as discussed in
   [I-D.bctb-6man-rfc6296-bis].  Each MANET router will then assign the
   ULA to its OMNI interface which encapsulates each original packet in
   an IPv6 header that uses MLAs or HHITs as the encapsulation source/
   destination addresses while the original packet uses ULAs/GUAs.  The
   NPTv6 gateway will then statelessly translate each ULA into its
   corresponding GUA (and vice versa) for packets that transit the

   The proxy delegates a ULA and its companion Provider-Aggregated (PA)
   GUA for each MANET router which assigns them according to either the
   "ULA+PA" or "ULA-Only" connected network models
   [I-D.ietf-v6ops-ula-usage-considerations].  If the MANET router
   employs the "ULA+PA" model, it can assign both the ULA and GUA to the
   OMNI interface.  The MANET router can then use the ULA for local-
   scoped communications with peers inside the MANET and the GUA for
   global-scoped communications with external peers via the proxy as a
   "NPTv6 pass-through".  MANET routers can then select address pair
   combinations according to IPv6 default address selection rules

   After receiving a ULA plus PA GUA delegation, MANET routers that
   require Provider-Independent (PI) GUAs can use the OMNI interface in
   conjunction with the Automatic Extended Route Optimization (AERO)
   global distributed mobility management service
   [I-D.templin-6man-aero3] to request and maintain IPv6 and/or IPv4 PI
   prefixes from the mobility service.  The MANET router can then sub-
   delegate GUAs from the PI prefixes to its attached downstream local
   networks which may in turn engage an arbitrarily large IPv6 and/or
   IPv4 "Internet of Things".

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6.  Address Selection

   "Default Address Selection for Internet Protocol Version 6 (IPv6)"
   [RFC6724] provides a policy table that specifies precedence values
   and preferred source prefixes for destination prefixes.  "Preference
   for IPv6 ULAs over IPv4 addresses in RFC6724"
   [I-D.ietf-6man-rfc6724-update] updates the policy table entries for
   ULAs, IPv4 addresses and the 6to4 prefix (2002::/16).

   This document proposes a further update to the policy table for IPv6
   MLAs (prefix fec0::/10) and HHITs (prefix 2001:30::/28).  The
   proposed updates appear in the table below:

 draft-ietf-6man-rfc6724-update                           Updated
Prefix        Precedence Label        Prefix        Precedence Label
::1/128               50     0        ::1/128               50     0
::/0                  40     1        ::/0                  40     1
::ffff:0:0/96         20     4        ::ffff:0:0/96         20     4
2002::/16              5     2        2002::/16              5     2
2001::/32              5     5        2001::/32              5     5
fc00::/7              30    13        fc00::/7              30    13
::/96                  1     3        ::/96                  1     3
fec0::/10              1    11        fec0::/10              3    11 (*)
3ffe::/16              1    12        3ffe::/16              1    12
                                      2001:30::/28           4    14 (*)
(*) value(s) changed in update

       Figure 2: Policy Table Update for MANET Local Addresses

   With the proposed updates, IPv6 HHITs now appear as a lesser
   precedence than IPv6 GUAs, IPv6 ULAs and IPv4 addresses but as a
   greater precedence than IPv6 MLAs.  IPv6 MLAs now appear as a greater
   precedence than deprecated IPv6 prefixes but a lesser precedence than
   all other address types.

7.  Requirements

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

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

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

   IPv6 routers MUST NOT advertise the prefix fec0::/10 (or any IPv6
   prefixes reserved for HHITs) in routing protocol exchanges with
   correspondents outside the local network (or MANET).

   The default behavior of exterior routing protocol sessions between
   administrative routing regions must be to ignore receipt of and not
   advertise prefixes in the fee0::/11 block.

   At the present time, AAAA and PTR records for MLAs in the fee0::/11
   block are not recommended to be installed in the global DNS.

8.  Implementation Status

   In progress.

9.  IANA Considerations

   [RFC3879] instructed IANA to mark the fec0::/10 prefix as
   "deprecated", and as such it does not appear in the IANA IPv6
   Special-Purpose Address Registry.

   Upon publication, IANA is instructed to add the prefix fec0::/10 to
   the 'iana-ipv6-special-registry' registry with the name "MANET-Local
   Unicast" and with RFC set to "[RFCXXXX]" (i.e., this document).

10.  Security Considerations

   IPv6 MLAs include very large uniquely-assigned bit strings in both
   the prefix and interface identifier components.  With the random
   prefix generation procedures specified in [RFC4193] and the
   semantically opaque interface identifier generation procedures
   specified in [RFC7217] the only apparent opportunity for address
   duplication would be through either intentional or unintentional
   misconfiguration.  A node that generates an MLA and assigns it to an
   interface should therefore be prepared to deprecate the MLA and
   generate/assign a new one if it detects a legitimate duplicate.

11.  Acknowledgements

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

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

   Honoring life, liberty and the pursuit of happiness.

12.  References

12.1.  Normative References

   [RFC4007]  Deering, S., Haberman, B., Jinmei, T., Nordmark, E., and
              B. Zill, "IPv6 Scoped Address Architecture", RFC 4007,
              DOI 10.17487/RFC4007, March 2005,

   [RFC4193]  Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
              Addresses", RFC 4193, DOI 10.17487/RFC4193, October 2005,

   [RFC4291]  Hinden, R. and S. Deering, "IP Version 6 Addressing
              Architecture", RFC 4291, DOI 10.17487/RFC4291, February
              2006, <>.

   [RFC5889]  Baccelli, E., Ed. and M. Townsley, Ed., "IP Addressing
              Model in Ad Hoc Networks", RFC 5889, DOI 10.17487/RFC5889,
              September 2010, <>.

   [RFC6724]  Thaler, D., Ed., Draves, R., Matsumoto, A., and T. Chown,
              "Default Address Selection for Internet Protocol Version 6
              (IPv6)", RFC 6724, DOI 10.17487/RFC6724, September 2012,

   [RFC7217]  Gont, F., "A Method for Generating Semantically Opaque
              Interface Identifiers with IPv6 Stateless Address
              Autoconfiguration (SLAAC)", RFC 7217,
              DOI 10.17487/RFC7217, April 2014,

   [RFC8200]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", STD 86, RFC 8200,
              DOI 10.17487/RFC8200, July 2017,

12.2.  Informative References

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              Cullen, M., Baker, F., Trøan, O., and N. Buraglio, "RFC
              6296bis IPv6-to-IPv6 Network Prefix Translation", Work in
              Progress, Internet-Draft, draft-bctb-6man-rfc6296-bis-02,
              26 January 2024, <

              Buraglio, N., Chown, T., and J. Duncan, "Preference for
              IPv6 ULAs over IPv4 addresses in RFC6724", Work in
              Progress, Internet-Draft, draft-ietf-6man-rfc6724-update-
              08, 9 April 2024, <

              Jiang, S., Liu, B., and N. Buraglio, "Considerations For
              Using Unique Local Addresses", Work in Progress, Internet-
              Draft, draft-ietf-v6ops-ula-usage-considerations-04, 17
              May 2024, <

              Templin, F., "Automatic Extended Route Optimization
              (AERO)", Work in Progress, Internet-Draft, draft-templin-
              6man-aero3-04, 22 May 2024,

              Templin, F., "Transmission of IP Packets over Overlay
              Multilink Network (OMNI) Interfaces", Work in Progress,
              Internet-Draft, draft-templin-6man-omni3-05, 3 June 2024,

   [RFC3879]  Huitema, C. and B. Carpenter, "Deprecating Site Local
              Addresses", RFC 3879, DOI 10.17487/RFC3879, September
              2004, <>.

   [RFC4862]  Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
              Address Autoconfiguration", RFC 4862,
              DOI 10.17487/RFC4862, September 2007,

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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,

   [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,

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

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