[Docs] [txt|pdf] [Tracker] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21

Network Working Group                                    F. Templin, Ed.
Internet-Draft                              Boeing Research & Technology
Intended status: Standards Track                               A. Whyman
Expires: February 7, 2020                MWA Ltd c/o Inmarsat Global Ltd
                                                          August 6, 2019


   Transmission of IPv6 Packets over Aeronautical ("aero") Interfaces
                draft-templin-atn-aero-interface-05.txt

Abstract

   Mobile nodes (e.g., aircraft of various configurations) communicate
   with networked correspondents over multiple access network data links
   and configure mobile routers to connect their on-board networks.
   Mobile nodes connect to access networks using either the classic or
   mobility service-enabled link model.  This document specifies the
   transmission of IPv6 packets over aeronautical ("aero") interfaces.

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 https://datatracker.ietf.org/drafts/current/.

   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 February 7, 2020.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/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 Simplified BSD License text as described in Section 4.e of



Templin & Whyman        Expires February 7, 2020                [Page 1]


Internet-Draft          IPv6 over AERO Interfaces            August 2019


   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Requirements  . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Aeronautical ("aero") Interface Model . . . . . . . . . . . .   4
   5.  Maximum Transmission Unit . . . . . . . . . . . . . . . . . .   6
   6.  Frame Format  . . . . . . . . . . . . . . . . . . . . . . . .   6
   7.  Link-Local Addresses  . . . . . . . . . . . . . . . . . . . .   6
   8.  Address Mapping - Unicast . . . . . . . . . . . . . . . . . .   8
   9.  Address Mapping - Multicast . . . . . . . . . . . . . . . . .  11
   10. Address Mapping for IPv6 Neighbor Discovery Messages  . . . .  11
   11. Conceptual Sending Algorithm  . . . . . . . . . . . . . . . .  12
     11.1.  Multiple Aero Interfaces . . . . . . . . . . . . . . . .  13
   12. Router Discovery and Prefix Assertion . . . . . . . . . . . .  13
   13. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  16
   14. Security Considerations . . . . . . . . . . . . . . . . . . .  16
   15. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  16
   16. References  . . . . . . . . . . . . . . . . . . . . . . . . .  17
     16.1.  Normative References . . . . . . . . . . . . . . . . . .  17
     16.2.  Informative References . . . . . . . . . . . . . . . . .  18
   Appendix A.  Aero Option Extensions for Special-Purpose Links . .  19
   Appendix B.  Prefix Length Considerations . . . . . . . . . . . .  20
   Appendix C.  Change Log . . . . . . . . . . . . . . . . . . . . .  20
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  22

1.  Introduction

   Mobile Nodes (MNs) such as aircraft of various configurations may
   have multiple data links for communicating with networked
   correspondents.  These data links often have differing performance,
   cost and availability characteristics that can change dynamically
   according to mobility patterns, flight phases, proximity to
   infrastructure, etc.

   Each MN receives an IPv6 Mobile Network Prefix (MNP) that can be used
   by on-board networks regardless of the access network data links
   selected for data transport.  The MN performs router discovery the
   same as for customer edge routers [RFC7084], and acts as a mobile
   router on behalf of its on-board networks.  The MN connects to access
   networks using either the classic [RFC4861] or Mobility Service (MS)-
   enabled link model.

   In the classic model, all IPv6 Neighbor Discovery (IPv6 ND) messaging
   is directly over native access network interfaces managed according



Templin & Whyman        Expires February 7, 2020                [Page 2]


Internet-Draft          IPv6 over AERO Interfaces            August 2019


   to the weak end system model.  The MN discovers neighbors on the link
   through link-scoped multicast and/or unicast transmissions that map
   to their corresponding link layer addresses per standard address
   resolution / mapping procedures.  The MN then coordinates with
   mobility agents located in the larger Internetwork beyond the first-
   hop access links according the on-board mobility function.  This
   arrangement requires the MN to engage in active mobility messaging on
   its own behalf and with no assistance from the access network.

   In the MS-enabled model, a virtual interface (termed the "aero
   interface") is configured as a thin layer over the underlying access
   network interfaces.  The aero interface is therefore the only
   interface abstraction exposed to the IPv6 layer and behaves according
   to the Non-Broadcast, Multiple Access (NBMA) interface principle,
   while underlying access network interfaces appear as link layer
   communication channels in the architecture.  The aero interface
   connects to a virtual overlay cloud service known as the "aero link".

   Each aero link has one or more associated Mobility Service Prefixes
   (MSPs) that identify the link.  An MSP is an aggregated IPv6 prefix
   from which aero link MNPs are derived.  If the MN connects to
   multiple aero links, then it configures a separate aero interface for
   each link.

   The aero interface interacts with the ground-domain MS through IPv6
   ND control message exchanges [RFC4861].  The MS tracks MN movements
   and represents their MNPs in a global routing or mapping system.

   The aero interface provides a traffic engineering nexus for guiding
   inbound and outbound traffic to the correct underlying interface(s).
   The IPv6 layer sees the aero interface as a point of connection to
   the aero link; if there are multiple aero links (i.e., multiple
   MS's), the IPv6 layer will see multiple aero interfaces.

   This document specifies the transmission of IPv6 packets [RFC8200]
   and MN/MS control messaging over aeronautical ("aero") interfaces in
   the MS-enabled link model, but also includes all necessary details
   for MN operation in the classic link model.

2.  Terminology

   The terminology in the normative references applies; especially, the
   terms "link" and "interface" are the same as defined in the IPv6
   [RFC8200] and IPv6 Neighbor Discovery (ND) [RFC4861] specifications.

   The following terms are defined within the scope of this document:

   Access Network (ANET)



Templin & Whyman        Expires February 7, 2020                [Page 3]


Internet-Draft          IPv6 over AERO Interfaces            August 2019


      a data link service network (e.g., an aviation radio access
      network, satellite service provider network, cellular operator
      network, etc.) protected by physical and/or link layer security.
      Each ANET connects to outside Internetworks via border security
      devices such as proxys, firewalls, packet filtering gateways, etc.

   ANET interface
      a node's attachment to a link in an ANET.

   Internetwork (INET)
      a connected network region with a coherent IP addressing plan that
      provides transit forwarding services for ANET mobile nodes and
      INET correspondents.  Examples include private enterprise
      networks, aviation networks and the global public Internet itself.

   INET interface
      a node's attachment to a link in an INET.

   aero link
      a virtual overlay cloud service configured over one or more INETs
      and their connected ANETs.  An aero link may comprise multiple
      segments joined by bridges the same as for any link; the
      addressing plans in each segment may be mutually exclusive and
      managed by different administrative entities.

   aero interface
      a node's attachment to an aero link, and configured over one or
      more underlying ANET/INET interfaces.

   aero address
      an IPv6 link-local address constructed as specified in Section 7,
      and assigned to an aero interface.

3.  Requirements

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].  Lower case
   uses of these words are not to be interpreted as carrying RFC2119
   significance.

4.  Aeronautical ("aero") Interface Model

   An aero interface is a MN virtual interface configured over one or
   more ANET interfaces, which may be physical (e.g., an aeronautical
   radio link) or virtual (e.g., an Internet or higher-layer "tunnel").
   The MN coordinates with the MS through IPv6 ND message exchanges.




Templin & Whyman        Expires February 7, 2020                [Page 4]


Internet-Draft          IPv6 over AERO Interfaces            August 2019


   The aero interface architectural layering model is the same as in
   [RFC7847], and augmented as shown in Figure 1.  The IPv6 layer
   therefore sees the aero interface as a single network layer interface
   with multiple underlying ANET interfaces that appear as link layer
   communication channels in the architecture.

                                     +----------------------------+
                                     |          TCP/UDP           |
              Session-to-IP    +---->|                            |
              Address Binding  |     +----------------------------+
                               +---->|            IPv6            |
              IP Address       +---->|                            |
              Binding          |     +----------------------------+
                               +---->|       aero Interface       |
              Logical-to-      +---->|       (aero address)       |
              Physical         |     +----------------------------+
              Interface        +---->|  L2  |  L2  |       |  L2  |
              Binding                |(IF#1)|(IF#2)| ..... |(IF#n)|
                                     +------+------+       +------+
                                     |  L1  |  L1  |       |  L1  |
                                     |      |      |       |      |
                                     +------+------+       +------+

           Figure 1: Aero Interface Architectural Layering Model

   The aero virtual interface model gives rise to a number of
   opportunities:

   o  since aero interface link-local addresses are uniquely derived
      from an MNP (see: Section 7, no Duplicate Address Detection (DAD)
      messaging is necessary over the aero interface.

   o  ANET interfaces can remain unnumbered in environments where
      communications are coordinated entirely over the aero interface.

   o  as ANET interface properties change (e.g., link quality, cost,
      availability, etc.), any active ANET interface can be used to
      update the profiles of multiple additional ANET interfaces in a
      single message.  This allows for timely adaptation and service
      continuity under dynamically changing conditions.

   o  coordinating ANET interfaces in this way allows them to be
      represented in a unified MS profile with provisions for mobility
      and multilink operations.

   o  exposing a single virtual interface abstraction to the IPv6 layer
      allows for traffic engineering (including QoS based link
      selection, packet replication, load balancing, etc.) at the link



Templin & Whyman        Expires February 7, 2020                [Page 5]


Internet-Draft          IPv6 over AERO Interfaces            August 2019


      layer while still permitting queuing at the IPv6 layer based on,
      e.g., traffic class, flow label, etc.

   o  the IPv6 layer sees the aero interface as a point of connection to
      the aero link; if there are multiple aero links (i.e., multiple
      MS's), the IPv6 layer will see multiple aero interfaces.

   Other opportunities are discussed in [RFC7847].

5.  Maximum Transmission Unit

   The aero interface and all underlying ANET interfaces MUST configure
   an MTU of at least 1280 bytes as required for all IPv6 interfaces
   [RFC8200].  The aero interface SHOULD configure an MTU based on the
   largest MTU among all ANET interfaces.  If the aero interface
   receives a IPv6 ND Router Advertisement (RA) message with an MTU
   option, it configures this new value regardless of any ANET interface
   MTUs.

   The aero interface can return internally-generated ICMPv6 "Packet Too
   Big" messages for packets that fit within the aero interface MTU but
   are too large for the selected underlying ANET interface.  This
   ensures that the MTU is adaptive and reflects the ANET interface used
   for a given data flow.

   Underlying ANET interfaces can employ link-layer fragmentation at a
   layer below IPv6 so that packets as large as the aero interface MTU
   can be accommodated.  This ensures that no packets are lost due to a
   size restriction in either the uplink or downlink direction.

6.  Frame Format

   The aero interface transmits IPv6 packets according to the native
   frame format of each underlying ANET interface.  For example, for
   Ethernet-compatible interfaces the frame format is specified in
   [RFC2464], for aeronautical radio interfaces the frame format is
   specified in standards such as ICAO Doc 9776 (VDL Mode 2 Technical
   Manual), for tunnels over IPv6 the frame format is exactly as
   specified in [RFC2473], etc.

7.  Link-Local Addresses

   A MN "aero address" is an IPv6 link-local address with an interface
   identifier based on its assigned MNP.  MN aero addresses begin with
   the prefix fe80::/64 followed by a 64-bit prefix taken from the MNP
   (see: Appendix B).  For example, for the MNP:

      2001:db8:1000:2000::/56



Templin & Whyman        Expires February 7, 2020                [Page 6]


Internet-Draft          IPv6 over AERO Interfaces            August 2019


   the corresponding aero addresses are:

      fe80::2001:db8:1000:2000

      fe80::2001:db8:1000:2001

      fe80::2001:db8:1000:2002

      ... etc. ...

      fe80::2001:db8:1000:20ff

   When the MN configures aero addresses from its MNP, it assigns them
   to each ANET interface (and also to the Aero interface in the MS-
   enabled model).  The lowest-numbered aero address serves as the
   "base" address (for example, for the MNP 2001:db8:1000:2000::/56 the
   base aero address is fe80::2001:db8:1000:2000).  The MN uses the base
   aero address for IPv6 ND messaging, but accepts packets destined to
   all aero addresses equally (i.e., the same as for any multi-addressed
   IPv6 interface).

   In the MS-enabled link model, MS endpoint (MSE) aero addresses are
   allocated from the range fe80::/96, and MUST be managed for
   uniqueness by the collective aero link administrative authorities.
   The lower 32 bits of the address includes a unique integer value,
   e.g., fe80::1, fe80::2, fe80::3, etc.  The address fe80:: is reserved
   as the IPv6 link-local Subnet Router Anycast address [RFC4291], and
   the address fe80::ffff:ffff is reserved as the MSE discovery address;
   hence, these values are not available for general assignment.

   In the classic link model, ANET link devices number their interface
   from the range fe80::/96 the same as above except that these
   addresses need not be managed for uniqueness outside of the local
   ANET link.  It is therefore possible that different ANET links could
   reuse numbers from the fe80::/96 space since the addresses are link-
   scope only.

   In a mixed model, both the classic and MS-enabled numbering schemes
   can be used without conflict within the same ANET, as the two
   services would be conducted as ships in the night.  A mix of MNs
   operating according to classic and MS-enabled models could then
   operate within the same ANETs without interference.

   Since MN aero addresses are guaranteed unique by the nature of the
   unique MNP delegation, aero interfaces set the autoconfiguration
   variable DupAddrDetectTransmits to 0 [RFC4862].





Templin & Whyman        Expires February 7, 2020                [Page 7]


Internet-Draft          IPv6 over AERO Interfaces            August 2019


8.  Address Mapping - Unicast

   Aero interfaces maintain a neighbor cache for tracking per-neighbor
   state the same as for any IPv6 interface and use the link-local
   address format specified in Section 7.  IPv6 Neighbor Discovery (ND)
   [RFC4861] messages on aero interfaces use the native Source/Target
   Link-Layer Address Option (S/TLLAO) formats of the underlying ANET
   interfaces (e.g., for Ethernet the S/TLLAO is specified in
   [RFC2464]).

   MNs such as aircraft typically have many wireless data link types
   (e.g. satellite-based, cellular, terrestrial, air-to-air directional,
   etc.) with diverse performance, cost and availability properties.
   The aero interface would therefore appear to have multiple link layer
   connections, and may include information for multiple ANET interfaces
   in a single message exchange.

   Aero interfaces use a new IPv6 ND options called the "Aero
   Registration (AR)" option (type TBD).  MNs include the AR option in
   Router Solicitation (RS) and/or unsolicited Neighbor Advertisement
   (uNA) messages to request registration/deregistration, and the MS
   includes the AR option in Router Advertisement (RA) messages to
   acknowledge the MN's registration/deregistration.

   MNs send RS/uNA messages that include AR options formatted as shown
   in Figure 2:

























Templin & Whyman        Expires February 7, 2020                [Page 8]


Internet-Draft          IPv6 over AERO Interfaces            August 2019


        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |      Type     |     Length    | Prefix Length |R|  Reserved   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                             Nonce                             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |           ifIndex [1]         |P00|P01|P02|P03|P04|P05|P06|P07|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |P08|P09|P10|P11|P12|P13|P14|P15|P16|P17|P18|P19|P20|P21|P22|P23|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |P24|P25|P26|P27|P28|P29|P30|P31|P32|P33|P34|P35|P36|P37|P38|P39|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |P40|P41|P42|P43|P44|P45|P46|P47|P48|P49|P50|P51|P52|P53|P54|P55|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |P56|P57|P58|P59|P60|P61|P62|P63|           ifIndex [2]         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       ...
       ...                             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       ...                             |           ifIndex [N]         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
               ... (0 - 6 octets of trailing zero padding) ...

     Figure 2: Aero Registration (AR) Option Format in RS/uNA Messages

   In this format:

   o  Type is set to TBD.

   o  Length is set to the value (2.25*N + 1), where N is the number of
      ifIndex tuples.  Length is incremented to the next highest integer




Templin & Whyman        Expires February 7, 2020                [Page 9]


Internet-Draft          IPv6 over AERO Interfaces            August 2019


      value, and 0-6 octets of trailing zero padding are added to the
      end of the option to produce an integral number of 8-octet units.

   o  Prefix Length is set to the length of the MNP embedded in the MN's
      aero address.

   o  R is set to '1' to request registration or set to '0' to request
      de-registration.

   o  Reserved is set to the value '0' on transmission.

   o  Nonce is set to a (pseudo)-random 32-bit value selected by the MN,
      and used to correlate received confirmations.

   o  A list of N (ifIndex[i], P[i])-tuples are included as follows:

      *  ifIndex[i] [RFC2863] is set to a 16-bit integer value
         corresponding to a specific underlying ANET interface.  The
         first ifIndex MUST correspond to the ANET interface over which
         the message is sent.  Once the MN has assigned an ifIndex to an
         ANET interface, the assignment MUST remain unchanged until the
         MN disables the interface.  MNs MUST number each ifIndex with a
         value between '1' and '0xffff'.

      *  P[i] is a per-ifIndex set of Preferences that correspond to the
         64 Differentiated Service Code Point (DSCP) values [RFC2474]
         pertaining to the ANET interface.  Each (P00 - P63) field is
         set to the value '0' ("disabled"), '1' ("low"), '2' ("medium")
         or '3' ("high") to indicate a QoS preference level for ANET
         interface selection purposes.

   The MS sends corresponding RA messages with AR options formatted as
   shown in Figure 3:

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |      Type     |   Length = 2  | Prefix Length |R|  Reserved   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                             Nonce                             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Prefix Lifetime                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                            Reserved                           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Figure 3: Aero Registration (AR) Option Format in RA messages




Templin & Whyman        Expires February 7, 2020               [Page 10]


Internet-Draft          IPv6 over AERO Interfaces            August 2019


   In this format:

   o  Type is set to TBD.

   o  Length is set to the constant value '2' (i.e., 2 units of 8
      octets).

   o  Prefix Length is set to the length included in the AR option of
      the RS message that triggered the RA response.

   o  R is set to '1' to confirm registration or set to '0' to release/
      decline registration.

   o  Reserved is set to the value '0' on transmission.

   o  Nonce echoes the 32 bit value received in the AR option of the
      corresponding RS message.

   o  Prefix Lifetime is set to the time in seconds that the MSE will
      maintain the Prefix registration.

9.  Address Mapping - Multicast

   The multicast address mapping of the native underlying ANET interface
   applies.  The mobile router on board the aircraft also serves as an
   IGMP/MLD Proxy for its EUNs and/or hosted applications per [RFC4605]
   while using the link layer address of the router as the link layer
   address for all multicast packets.

10.  Address Mapping for IPv6 Neighbor Discovery Messages

   As discussed in [RFC4861], IPv6 ND messages may be sent to either a
   multicast or unicast link-scoped IPv6 destination address.  For aero
   interfaces in the MS-enabled model, however, IPv6 ND messaging must
   be coordinated between the MN and MS only without invoking other
   nodes on the ANET.

   For this reason, each ANET link type is required to reserve a fixed
   unicast link-layer address ("MSADDR") for the purpose of supporting
   MN/MS IPv6 ND messaging the same as in [RFC6543].  For Ethernet-
   compatible ANETs, this specification reserves one Ethernet unicast
   address 00-00-5E-00-52-14.  For non-Ethernet ANETs, MSADDR is
   reserved per the assigned numbers authority for the ANET addressing
   space.

   MNs operating according to the MS-enabled model map all IPv6 ND
   messages they send (i.e., both multicast and unicast) to MSADDR
   instead of to an ordinary unicast or multicast link-layer address.



Templin & Whyman        Expires February 7, 2020               [Page 11]


Internet-Draft          IPv6 over AERO Interfaces            August 2019


   In this way, all of the MN's IPv6 ND messages will be received by MS
   devices that are configured to accept packets destined to MSADDR
   (i.e., a point-to-point neighbor model).  Note that multiple MS
   devices on the link could be configured to accept packets destinted
   to MSADDR.  Though out of scope for this document, such an
   arrangement could provide basis for virtual router redundancy.

   Therefore, ANET MS devices MUST accept and process packets destined
   to MSADDR, while all other devices MUST NOT process packets destined
   to MSADDR.  In this arrangement MNs operating according to the MS-
   enabled model have assurance that their IPv6 ND messages will be
   handled only by the MS, and will not corrupt the neighbor caches of
   classic devices and/or MNs on the link.  This model has a well-
   established operational experience in Proxy Mobile IPv6 (PMIP)
   [RFC5213].

11.  Conceptual Sending Algorithm

   The MN's IPv6 layer selects the outbound aero interface according to
   standard IPv6 requirements.  The aero interface maintains default
   routes and neighbor cache entries for MSEs, and may also include
   additional neighbor cache entries created through other means (e.g.,
   Address Resolution, static configuration, etc.).

   When the MN sends packets, it may receive a Redirect message the same
   as for any IPv6 interface.  When the MN uses Address Resolution, the
   aero interface forwards NS messages to an MSE (see: Section 12) which
   acts as a link-layer forwarding agent according to the NBMA link
   model.  The resulting NA message will provide link-layer address
   information for the neighbor.  When Neighbor Unreachability Detection
   is used, the NS/NA exchange confirms reachability the same as for any
   IPv6 interface.

   After a packet enters the aero interface, an outbound ANET interface
   is selected based on traffic engineering information such as DSCP,
   application port number, cost, performance, etc.  Aero interface
   traffic engineering could also be configured to perform replication
   across multiple ANET interfaces for increased reliability at the
   expense of packet duplication.

   When a target neighbor has multiple link-layer addresses (each with a
   different traffic engineering profile), the aero interface selects
   ANET interfaces and neighbor link-layer addresses according to both
   its own outbound preferences and the inbound preferences of the
   target neighbor.






Templin & Whyman        Expires February 7, 2020               [Page 12]


Internet-Draft          IPv6 over AERO Interfaces            August 2019


11.1.  Multiple Aero Interfaces

   MNs may associate with multiple MS instances concurrently.  Each MS
   instance represents a distinct aero link distinguished by its
   associated MSPs.  The MN configures a separate aero interface for
   each link so that multiple interfaces (e.g., aero0, aero1, aero2,
   etc.) are exposed to the IPv6 layer.

   Depending on local policy and configuration, an MN may choose between
   alternative active aero interfaces using a packet's DSCP, routing
   information or static configuration.  In particular, the MN can add
   the MSPs received in Prefix Information Options (PIOs) [RFC4861]
   [RFC8028] as guidance for aero interface selection based on per-
   packet source addresses.

   Each aero interface can be configured over the same or different sets
   of ANET interfaces.  Each ANET distinguishes between the different
   aero links based on the MSPs represented in per-packet IPv6
   addresses.

   Multiple distinct aero links can therefore be used to support fault
   tolerance, load balancing, reliability, etc.  The architectural model
   parallels Layer 2 Virtual Local Area Networks (VLANs), where the MSPs
   serve as (virtual) VLAN tags.

12.  Router Discovery and Prefix Assertion

   ANET access routers accept packets destined to the link-local Subnet
   Router Anycast Address (fe80::).  ANET access routers that support
   the classic link model configure link-local addresses that are
   guaranteed not to conflict with MN link-local addresses as discussed
   in Section 7.  ANET access routers that support the MS-enabled model
   configure the link-layer address MSADDR (see: Section 10) and act as
   proxies for all MSEs from the range fe80::1 through fe80::ffff:fffe.

   MNs that support the classic model perform ordinary RS/RA exchanges
   over each ANET the same as for ordinary IPv6 links.  ANET access
   routers send RAs with an IPv6 link-local source address from the
   range fe80::1 through fe80::ffff:fffe that is guaranteed not to
   conflict with the MN's aero address nor the address of any other
   routers on the link.  The MNs are then responsible for coordinating
   their ANET interfaces on their own behalf and for coordinating with
   any INET-based mobility agents.  No further support from the ANET is
   needed.

   MNs that support the MS-enabled model instead interface with the MS
   via RS/RA message exchanges that include AR options.  For each ANET
   interface, the MN sends initial RS messages with AR options with



Templin & Whyman        Expires February 7, 2020               [Page 13]


Internet-Draft          IPv6 over AERO Interfaces            August 2019


   link-layer address set to MSADDR and with network-layer address set
   to a specific MSE address (or to fe80::ffff:ffff to request the ANET
   to select an MSE).  The ANET access router receives the RS messages
   and contacts the corresponding MSE.  When the MSE responds, the ANET
   access router returns RA messages with AR options and with any
   information for the link that would normally be delivered in a
   solicited RA message.

   MNs configure aero interfaces that observe the properties discussed
   in the previous section.  The aero interface and its underlying
   interfaces are said to be in either the "UP" or "DOWN" state
   according to administrative actions in conjunction with the interface
   connectivity status.  An aero interface transitions to UP or DOWN
   through administrative action and/or through state transitions of the
   underlying interfaces.  When a first underlying interface transitions
   to UP, the aero interface also transitions to UP.  When all
   underlying interfaces transition to DOWN, the aero interface also
   transitions to DOWN.

   When an aero interface transitions to UP, the MN sends initial RS
   messages to register its MNP and an initial set of underlying ANET
   interfaces that are also UP.  The MN sends additional RS messages to
   refresh lifetimes and to register/deregister underlying ANET
   interfaces as they transition to UP or DOWN.

   MS-enabled ANET access routers send RA messages with configuration
   information in response to a MN's RS messages.  The RA includes a
   Router Lifetime value and PIOs with (A; L=0) that include MSPs for
   the link.  The configuration information may also include Route
   Information Options (RIO) options [RFC4191] with more-specific
   routes, and an MTU option that specifies the maximum acceptable
   packet size for the link.  The ANET access router sends immediate
   unicast RA responses without delay; therefore, the
   'MAX_RA_DELAY_TIME' and 'MIN_DELAY_BETWEEN_RAS' constants for
   multicast RAs do not apply.  The ANET access router MAY send periodic
   and/or event-driven unsolicited RA messages, but is not required to
   do so for unicast advertisements [RFC4861].

   The MN sends RS messages from within the aero interface while using
   an UP underlying ANET interface as the outbound interface.  Each RS
   message is formatted as though it originated from the IPv6 layer, but
   the process is coordinated wholly from within the aero interface and
   is therefore opaque to the IPv6 layer.  The MN sends initial RS
   messages over an UP underlying interface with its aero address as the
   source and the address of an MSE as the destination.  The RS messages
   include AR options with a valid Prefix Length as well as ifIndex and
   P(i) values appropriate for underlying ANET interfaces.  The MS-




Templin & Whyman        Expires February 7, 2020               [Page 14]


Internet-Draft          IPv6 over AERO Interfaces            August 2019


   enabled ANET access router processes RS message and forwards the
   information in the AR option to the MSE.

   When the MSE processes the AR information, if the prefix registration
   was accepted the MSE injects the MNP into the routing/mapping system
   then caches the new Prefix Length, MNP, ifIndex and P(i) values.  The
   MSE then returns a non-zero Prefix Lifetime if the prefix assertion
   was acceptable; otherwise, with a zero Prefix Lifetime.  The ANET
   access router then returns an RA message to the MN.

   When the MN receives the RA message, it creates a default route with
   next hop address set to the MSE found in the RA source address and
   with link-layer address set to MSADDR.  The ANET access router will
   then forward packets acting as a proxy between the MN and the actual
   MSE.

   The MN then manages its underlying ANET interfaces according to their
   states as follows:

   o  When an underlying ANET interface transitions to UP, the MN sends
      an RS over the ANET interface with an AR option.  The AR option
      contains a first ifIndex-tuple with values appropriate for this
      ANET interface, and may contain additional ifIndex-tuples
      appropriate for other ANET interfaces.

   o  When an underlying ANET interface transitions to DOWN, the MN
      sends an RS/uNA message over any UP ANET interface with an AR
      option containing an ifIndex-tuple for the DOWN ANET interface
      with all P(i) values set to '0'.  The MN sends an RS when an
      acknowledgement is required, or an uNA when reliability is not
      thought to be a concern (e.g., if redundant transmissions are sent
      on multiple ANET interfaces).

   o  When a MN wishes to release from the current MSE, it sends an RS
      message over any UP ANET interface with an AR option with R set to
      0.  The corresponding MSE then withdraws the MNP from the routing/
      mapping system and returns an RA message with an AR option with
      Prefix Lifetime set to 0.

   o  When all of a MNs underlying interfaces have transitioned to DOWN,
      the MSE withdraws the MNP the same as if it had received a message
      with an AR option with R set to 0.

   The MN is responsible for retrying each RS exchange up to
   MAX_RTR_SOLICITATIONS times separated by RTR_SOLICITATION_INTERVAL
   seconds until an RA is received.  If no RA is received over multiple
   UP ANET interfaces, the MN declares this MSE unreachable and tries a
   different MSE.



Templin & Whyman        Expires February 7, 2020               [Page 15]


Internet-Draft          IPv6 over AERO Interfaces            August 2019


   The IPv6 layer sees the aero interface as an ordinary IPv6 interface.
   Therefore, when the IPv6 layer sends an RS message the aero interface
   returns an internally-generated RA message as though the message
   originated from an IPv6 router.  The internally-generated RA message
   contains configuration information (such as Router Lifetime, MTU,
   etc.) that is consistent with the information received from the RAs
   generated by the MS.

   Whether the aero interface IPv6 ND messaging process is initiated
   from the receipt of an RS message from the IPv6 layer is an
   implementation matter.  Some implementations may elect to defer the
   IPv6 ND messaging process until an RS is received from the IPv6
   layer, while others may elect to initiate the process independently
   of any IPv6 layer messaging.

13.  IANA Considerations

   The IANA is instructed to allocate an official number from the IPv6
   Neighbor Discovery Option Formats registry for the Aero Registration
   (TBD) option.  Implementations set TBD to 253 as an interim value
   [RFC4727].

   The IANA is instructed to allocate one Ethernet unicast address,
   00-00-5E-00-52-14 [RFC5214] in the registry "IANA Ethernet Address
   Block - Unicast Use".

14.  Security Considerations

   Security considerations are the same as defined for the specific
   access network interface types, and readers are referred to the
   appropriate interface specifications.

   IPv6 and IPv6 ND security considerations also apply, and are
   specified in the normative references.

15.  Acknowledgements

   This document was prepared per the consensus decision at the 8th
   Conference of the International Civil Aviation Organization (ICAO)
   Working Group-I Mobility Subgroup on March 22, 2019.  Attendees and
   contributors included: Guray Acar, Danny Bharj, Francois D'Humieres,
   Pavel Drasil, Nikos Fistas, Giovanni Garofolo, Vaughn Maiolla, Tom
   McParland, Victor Moreno, Madhu Niraula, Brent Phillips, Liviu
   Popescu, Jacky Pouzet, Aloke Roy, Greg Saccone, Robert Segers,
   Stephane Tamalet, Fred Templin, Bela Varkonyi, Tony Whyman, and
   Dongsong Zeng.





Templin & Whyman        Expires February 7, 2020               [Page 16]


Internet-Draft          IPv6 over AERO Interfaces            August 2019


   The following individuals are acknowledged for their useful comments:
   Pavel Drasil, Zdenek Jaron, Madhu Niraula.

   .

16.  References

16.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC2474]  Nichols, K., Blake, S., Baker, F., and D. Black,
              "Definition of the Differentiated Services Field (DS
              Field) in the IPv4 and IPv6 Headers", RFC 2474,
              DOI 10.17487/RFC2474, December 1998,
              <https://www.rfc-editor.org/info/rfc2474>.

   [RFC4191]  Draves, R. and D. Thaler, "Default Router Preferences and
              More-Specific Routes", RFC 4191, DOI 10.17487/RFC4191,
              November 2005, <https://www.rfc-editor.org/info/rfc4191>.

   [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>.

   [RFC4727]  Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4,
              ICMPv6, UDP, and TCP Headers", RFC 4727,
              DOI 10.17487/RFC4727, November 2006,
              <https://www.rfc-editor.org/info/rfc4727>.

   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
              "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
              DOI 10.17487/RFC4861, September 2007,
              <https://www.rfc-editor.org/info/rfc4861>.

   [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>.

   [RFC8028]  Baker, F. and B. Carpenter, "First-Hop Router Selection by
              Hosts in a Multi-Prefix Network", RFC 8028,
              DOI 10.17487/RFC8028, November 2016,
              <https://www.rfc-editor.org/info/rfc8028>.




Templin & Whyman        Expires February 7, 2020               [Page 17]


Internet-Draft          IPv6 over AERO Interfaces            August 2019


   [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>.

16.2.  Informative References

   [RFC2464]  Crawford, M., "Transmission of IPv6 Packets over Ethernet
              Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998,
              <https://www.rfc-editor.org/info/rfc2464>.

   [RFC2473]  Conta, A. and S. Deering, "Generic Packet Tunneling in
              IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473,
              December 1998, <https://www.rfc-editor.org/info/rfc2473>.

   [RFC2863]  McCloghrie, K. and F. Kastenholz, "The Interfaces Group
              MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000,
              <https://www.rfc-editor.org/info/rfc2863>.

   [RFC4605]  Fenner, B., He, H., Haberman, B., and H. Sandick,
              "Internet Group Management Protocol (IGMP) / Multicast
              Listener Discovery (MLD)-Based Multicast Forwarding
              ("IGMP/MLD Proxying")", RFC 4605, DOI 10.17487/RFC4605,
              August 2006, <https://www.rfc-editor.org/info/rfc4605>.

   [RFC5213]  Gundavelli, S., Ed., Leung, K., Devarapalli, V.,
              Chowdhury, K., and B. Patil, "Proxy Mobile IPv6",
              RFC 5213, DOI 10.17487/RFC5213, August 2008,
              <https://www.rfc-editor.org/info/rfc5213>.

   [RFC5214]  Templin, F., Gleeson, T., and D. Thaler, "Intra-Site
              Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214,
              DOI 10.17487/RFC5214, March 2008,
              <https://www.rfc-editor.org/info/rfc5214>.

   [RFC6543]  Gundavelli, S., "Reserved IPv6 Interface Identifier for
              Proxy Mobile IPv6", RFC 6543, DOI 10.17487/RFC6543, May
              2012, <https://www.rfc-editor.org/info/rfc6543>.

   [RFC7084]  Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic
              Requirements for IPv6 Customer Edge Routers", RFC 7084,
              DOI 10.17487/RFC7084, November 2013,
              <https://www.rfc-editor.org/info/rfc7084>.








Templin & Whyman        Expires February 7, 2020               [Page 18]


Internet-Draft          IPv6 over AERO Interfaces            August 2019


   [RFC7421]  Carpenter, B., Ed., Chown, T., Gont, F., Jiang, S.,
              Petrescu, A., and A. Yourtchenko, "Analysis of the 64-bit
              Boundary in IPv6 Addressing", RFC 7421,
              DOI 10.17487/RFC7421, January 2015,
              <https://www.rfc-editor.org/info/rfc7421>.

   [RFC7847]  Melia, T., Ed. and S. Gundavelli, Ed., "Logical-Interface
              Support for IP Hosts with Multi-Access Support", RFC 7847,
              DOI 10.17487/RFC7847, May 2016,
              <https://www.rfc-editor.org/info/rfc7847>.

Appendix A.  Aero Option Extensions for Special-Purpose Links

   The aero option format specified in Section 8 includes a Length value
   of 3 (i.e., 3 units of 8 octets).  However, special-purpose aero
   links may extend the basic format to include additional fields and a
   Length value larger than 3.

   For example, adaptation of the aero interface to the Aeronautical
   Telecommunications Network with Internet Protocol Services (ATN/IPS)
   includes link selection preferences based on transport port numbers
   in addition to the existing DSCP-based preferences.  ATN/IPS nodes
   maintain a map of transport port numbers to 64 possible preference
   fields, e.g., TCP port 22 maps to preference field 8, TCP port 443
   maps to preference field 20, UDP port 8060 maps to preference field
   34, etc.  The extended aero option format for ATN/IPS is shown in
   Figure 4, where the Length value is 7 and the 'Q(i)' fields provide
   link preferences for the corresponding transport port number.























Templin & Whyman        Expires February 7, 2020               [Page 19]


Internet-Draft          IPv6 over AERO Interfaces            August 2019


        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |      Type     |   Length = 5  | Prefix Length |S|R|D| Reserved|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |            ifIndex            |           Reserved            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |P00|P01|P02|P03|P04|P05|P06|P07|P08|P09|P10|P11|P12|P13|P14|P15|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |P16|P17|P18|P19|P20|P21|P22|P23|P24|P25|P26|P27|P28|P29|P30|P31|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |P32|P33|P34|P35|P36|P37|P38|P39|P40|P41|P42|P43|P44|P45|P46|P47|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |P48|P49|P50|P51|P52|P53|P54|P55|P56|P57|P58|P59|P60|P61|P62|P63|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |Q00|Q01|Q02|Q03|Q04|Q05|Q06|Q07|Q08|Q09|Q10|Q11|Q12|Q13|Q14|Q15|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |Q16|Q17|Q18|Q19|Q20|Q21|Q22|Q23|Q24|Q25|Q26|Q27|Q28|Q29|Q30|Q31|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |Q32|Q33|Q34|Q35|Q36|Q37|Q38|Q39|Q40|Q41|Q42|Q43|Q44|Q45|Q46|Q47|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |Q48|Q49|Q50|Q51|Q52|Q53|Q54|Q55|Q56|Q57|Q58|Q59|Q60|Q61|Q62|Q63|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 4: ATN/IPS Extended Aero Option Format

Appendix B.  Prefix Length Considerations

   The IPv6 addressing architecture [RFC4291] reserves the prefix ::/8;
   this assures that MNPs will not begin with ::32 so that MN and MS
   aero addresses cannot overlap.  Additionally, this specification
   currently observes the 64-bit boundary in IPv6 addresses [RFC7421].

   MN aero addresses insert the most-significant 64 MNP bits into the
   least-significant 64 bits of the prefix fe80::/64, however [RFC4291]
   defines the link-local prefix as fe80::/10 meaning "fe80" followed by
   54 unused bits followed by the least-significant 64 bits of the
   address.  Future versions of this specification may adapt the 54
   unused bits for extended coding of MNP prefixes of /65 or longer (up
   to /118).

Appendix C.  Change Log

   << RFC Editor - remove prior to publication >>

   Differences from draft-templin-atn-aero-interface-04 to draft-
   templin-atn-aero-interface-05:




Templin & Whyman        Expires February 7, 2020               [Page 20]


Internet-Draft          IPv6 over AERO Interfaces            August 2019


   o  Introduced RFC6543 precedent for focusing IPv6 ND messaging to a
      reserved unicast link-layer address

   o  Introduced new IPv6 ND option for Aero Registration

   o  Specification of MN-to-MSE message exchanges via the ANET access
      router as a proxy

   o  IANA Considerations updated to include registration requests and
      set interim RFC4727 option type value.

   Differences from draft-templin-atn-aero-interface-03 to draft-
   templin-atn-aero-interface-04:

   o  Removed MNP from aero option format - we already have RIOs and
      PIOs, and so do not need another option type to include a Prefix.

   o  Clarified that the RA message response must include an aero option
      to indicate to the MN that the ANET provides a MS.

   o  MTU interactions with link adaptation clarified.

   Differences from draft-templin-atn-aero-interface-02 to draft-
   templin-atn-aero-interface-03:

   o  Sections re-arranged to match RFC4861 structure.

   o  Multiple aero interfaces

   o  Conceptual sending algorithm

   Differences from draft-templin-atn-aero-interface-01 to draft-
   templin-atn-aero-interface-02:

   o  Removed discussion of encapsulation (out of scope)

   o  Simplified MTU section

   o  Changed to use a new IPv6 ND option (the "aero option") instead of
      S/TLLAO

   o  Explained the nature of the interaction between the mobility
      management service and the air interface

   Differences from draft-templin-atn-aero-interface-00 to draft-
   templin-atn-aero-interface-01:





Templin & Whyman        Expires February 7, 2020               [Page 21]


Internet-Draft          IPv6 over AERO Interfaces            August 2019


   o  Updates based on list review comments on IETF 'atn' list from
      4/29/2019 through 5/7/2019 (issue tracker established)

   o  added list of opportunities afforded by the single virtual link
      model

   o  added discussion of encapsulation considerations to Section 6

   o  noted that DupAddrDetectTransmits is set to 0

   o  removed discussion of IPv6 ND options for prefix assertions.  The
      aero address already includes the MNP, and there are many good
      reasons for it to continue to do so.  Therefore, also including
      the MNP in an IPv6 ND option would be redundant.

   o  Significant re-work of "Router Discovery" section.

   o  New Appendix B on Prefix Length considerations

   First draft version (draft-templin-atn-aero-interface-00):

   o  Draft based on consensus decision of ICAO Working Group I Mobility
      Subgroup March 22, 2019.

Authors' Addresses

   Fred L. Templin (editor)
   Boeing Research & Technology
   P.O. Box 3707
   Seattle, WA  98124
   USA

   Email: fltemplin@acm.org


   Tony Whyman
   MWA Ltd c/o Inmarsat Global Ltd
   99 City Road
   London  EC1Y 1AX
   England

   Email: tony.whyman@mccallumwhyman.com









Templin & Whyman        Expires February 7, 2020               [Page 22]


Html markup produced by rfcmarkup 1.129d, available from https://tools.ietf.org/tools/rfcmarkup/