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Versions: 00 01 02 03                                                   
Network Working Group                                    F. Templin, Ed.
Internet-Draft                              Boeing Research & Technology
Intended status: Informational                          January 08, 2016
Expires: July 11, 2016


                       AERO Minimal Encapsulation
                      draft-templin-aeromin-03.txt

Abstract

   Asymmetric Extended Route Optimization (AERO) specifies both a
   control messaging and data packet forwarding facility for managing
   tunnels over an enterprise network or other Internetwork.  Although
   AERO can operate with any tunnel encapsulation format, the base
   document considers Generic UDP Encapsulation (GUE) as the default.
   This document presents minimal encapsulation formats for AERO using
   other encapsulation types.

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
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   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 July 11, 2016.

Copyright Notice

   Copyright (c) 2016 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
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   (http://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



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

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Minimal AERO Encapsulation  . . . . . . . . . . . . . . . . .   3
   3.  When to Insert an Encapsulation Fragment Header . . . . . . .   4
   4.  Considerations for Using Minimal Encapsulation  . . . . . . .   5
   5.  AERO Operation Over Native Links  . . . . . . . . . . . . . .   5
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   Asymmetric Extended Route Optimization (AERO) [I-D.templin-aerolink]
   specifies both a control messaging and data packet forwarding
   facility for forwarding Internet Protocol (IP) packets [RFC0791]
   [RFC2460] over an enterprise network or other Internetwork through a
   process known as tunneling.  Although AERO can operate with any
   tunnel encapsulation format, the base document specifies the
   insertion of a User Datagram Protocol (UDP) header [RFC0768] between
   the inner and outer IP headers per the Generic UDP Encapsulation
   (GUE) [I-D.ietf-nvo3-gue] specification.  This document presents
   minimal encapsulation formats for AERO using other encapsulation
   types.

   AERO can use common minimal encapsulations such as IP-in-IP
   [RFC2003][RFC2473][RFC4213], Generic Routing Encapsulation (GRE)
   [RFC2784][RFC2890] and others.  The encapsulation is therefore only
   differentiated from non-AERO tunnels through the application of AERO
   control messaging.

   In certain use cases, AERO minimal encapsulation formats may require
   encapsulation layer fragmentation in the same manner as for GUE
   fragmentation [I-D.herbert-gue-fragmentation] . For simple IP-in-IP
   encapsulation, an IPv6 fragment header is inserted directly between
   the inner and outer IP headers when needed, i.e., even if the outer
   header is IPv4.  The IPv6 Fragment Header is identified to the outer
   IP layer by its IP protocol number, and the Next Header field in the
   IPv6 Fragment Header identifies the inner IP header version.  For GRE
   encapsulation, a GRE fragment header is inserted within the GRE
   header [I-D.templin-intarea-grefrag].



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2.  Minimal AERO Encapsulation

   Figure 1 shows the AERO IP-in-IP minimal encapsulation format before
   any fragmentation is applied:

        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |     Outer IPv4 Header     |      |    Outer IPv6 Header      |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |IPv6 Frag Header (optional)|      |IPv6 Frag Header (optional)|
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |      Inner IP Header      |      |       Inner IP Header     |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |                           |      |                           |
        ~                           ~      ~                           ~
        ~    Inner Packet Body      ~      ~     Inner Packet Body     ~
        ~                           ~      ~                           ~
        |                           |      |                           |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+

        Minimal Encapsulation in IPv4      Minimal Encapsulation in IPv6


           Figure 1: Minimal Encapsulation Format using IP-in-IP

   GRE encapsulation can be used instead of simple IP-in-IP
   encapsulation when GRE facilities such as keys and checksums are
   desired.  In that case, AERO can include a GRE fragment header in the
   encapsulation [I-D.templin-intarea-grefrag] as shown in Figure 2:























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        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |        Outer IP Header        |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |          GRE Header           |
        | (with checksum, key, etc..)   |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        | GRE Fragment Header (optional)|
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |        Inner IP Header        |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |                               |
        ~                               ~
        ~      Inner Packet Body        ~
        ~                               ~
        |                               |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

         Minimal Encapsulation in GRE


                 Figure 2: Minimal Encapsulation Using GRE

3.  When to Insert an Encapsulation Fragment Header

   An encapsulation fragment header is inserted when the AERO tunnel
   ingress needs to apply fragmentation to accommodate packets that must
   be delivered without loss due to a size restriction.  Fragmentation
   is performed on the inner packet while encapsulating each inner
   packet fragment in identical outer IP and encapsulation layer
   headers.

   The fragment header can also be inserted in order to include a
   coherent Identification value with each packet, e.g., to aid in
   Duplicate Packet Detection (DPD).  In this way, network nodes can
   cache the Identification values of recently-seen packets and use the
   cached values to determine whether a newly-arrived packet is in fact
   a duplicate.  The Identification value within each packet could
   further provide a rough indicator of packet reordering, e.g., in
   cases when the tunnel egress wishes to discard packets that are
   grossly out of order.

   In some use cases, there may be operational assurance that no
   fragmentation of any kind will be necessary, or that only occasional
   large control messages will require fragmentation.  In that case, the
   encapsulation fragment header can be omitted and ordinary
   fragmentation of the outer IP protocol version can be applied when
   necessary.




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4.  Considerations for Using Minimal Encapsulation

   Minimal encapsulation is preferred in environments where GUE
   encapsulation would add unnecessary overhead.  For example, certain
   low-bandwidth wireless data links may benefit from a reduced
   encapsulation overhead.  This is not likely to be a prime
   consideration for many modern wireless data links nor for most modern
   wired-line data links.

   GUE encapsulation can traverse network paths that are inaccessible to
   minimal encapsulation, e.g., for crossing Network Address Translators
   (NATs).  More and more, network middleboxes are also being configured
   to discard packets that include anything other than a well-known IP
   protocol such as UDP and TCP.  It may therefore be necessary to
   determine the potential for middlebox filtering before enabling
   minimal encapsulation in a given environment.

5.  AERO Operation Over Native Links

   AERO can also operate over native links using no encapsulation at
   all.  In that case, AERO Clients can identify AERO Servers on the
   link through their link-layer addresses, and the AERO prefix
   delegation, mobility management, fault tolerance and route
   optimization facilities operate on the native link the same as over
   an NBMA tunnel overlay.

6.  IANA Considerations

   This document introduces no IANA considerations.

7.  Security Considerations

   Security considerations are discussed in the base AERO specification
   [I-D.templin-aerolink].

8.  Acknowledgements

   TBD

9.  References

9.1.  Normative References

   [RFC0768]  Postel, J., "User Datagram Protocol", STD 6, RFC 768,
              DOI 10.17487/RFC0768, August 1980,
              <http://www.rfc-editor.org/info/rfc768>.





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   [RFC0791]  Postel, J., "Internet Protocol", STD 5, RFC 791,
              DOI 10.17487/RFC0791, September 1981,
              <http://www.rfc-editor.org/info/rfc791>.

   [RFC2003]  Perkins, C., "IP Encapsulation within IP", RFC 2003,
              DOI 10.17487/RFC2003, October 1996,
              <http://www.rfc-editor.org/info/rfc2003>.

   [RFC2460]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
              December 1998, <http://www.rfc-editor.org/info/rfc2460>.

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

   [RFC2784]  Farinacci, D., Li, T., Hanks, S., Meyer, D., and P.
              Traina, "Generic Routing Encapsulation (GRE)", RFC 2784,
              DOI 10.17487/RFC2784, March 2000,
              <http://www.rfc-editor.org/info/rfc2784>.

   [RFC2890]  Dommety, G., "Key and Sequence Number Extensions to GRE",
              RFC 2890, DOI 10.17487/RFC2890, September 2000,
              <http://www.rfc-editor.org/info/rfc2890>.

   [RFC4213]  Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms
              for IPv6 Hosts and Routers", RFC 4213,
              DOI 10.17487/RFC4213, October 2005,
              <http://www.rfc-editor.org/info/rfc4213>.

9.2.  Informative References

   [I-D.herbert-gue-fragmentation]
              Herbert, T. and F. Templin, "Fragmentation option for
              Generic UDP Encapsulation", draft-herbert-gue-
              fragmentation-02 (work in progress), October 2015.

   [I-D.ietf-nvo3-gue]
              Herbert, T., Yong, L., and O. Zia, "Generic UDP
              Encapsulation", draft-ietf-nvo3-gue-02 (work in progress),
              December 2015.

   [I-D.templin-aerolink]
              Templin, F., "Asymmetric Extended Route Optimization
              (AERO)", draft-templin-aerolink-63 (work in progress),
              August 2015.





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   [I-D.templin-intarea-grefrag]
              Templin, F., "GRE Tunnel Fragmentation", draft-templin-
              intarea-grefrag-01 (work in progress), August 2015.

Author's Address

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

   Email: fltemplin@acm.org






































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