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Network Working Group                                       B. Carpenter
Internet-Draft                                         Univ. of Auckland
Intended status: Informational                                  S. Jiang
Expires: December 13, 2018                  Huawei Technologies Co., Ltd
                                                           June 11, 2018

                 Limited Domains and Internet Protocols


   There is a noticeable trend towards network requirements, behaviours
   and semantics that are specific to a limited region of the Internet
   and a particular set of requirements.  Policies, default parameters,
   the options supported, the style of network management and security
   requirements may vary.  This document reviews examples of such
   limited domains and emerging solutions.  It shows the needs for a
   precise definition of a limited domain boundary and for a
   corresponding protocol to allow nodes to discover where such a
   boundary exists.

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
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   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 December 13, 2018.

Copyright Notice

   Copyright (c) 2018 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

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

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Examples of Limited Domain Requirements . . . . . . . . . . .   3
   3.  Examples of Limited Domain Solutions  . . . . . . . . . . . .   5
   4.  Common Aspects of Limited Domains . . . . . . . . . . . . . .   7
   5.  The Need to Define a Limited Domain Boundary  . . . . . . . .   8
   6.  Defining Protocol Scope . . . . . . . . . . . . . . . . . . .   8
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   10. Informative References  . . . . . . . . . . . . . . . . . . .   8
   Appendix A.  Change log [RFC Editor: Please remove] . . . . . . .  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   As the Internet continues to grow and diversify, with a realistic
   prospect of tens of billions of nodes being connected directly and
   indirectly, there is a noticeable trend towards local requirements,
   behaviours and semantics.  The word "local" should be understood in a
   special sense, however.  In some cases it may refer to geographical
   and physical locality - all the nodes in a single building, on a
   single campus, or in a given vehicle.  In other cases it may refer to
   a defined set of users or nodes distributed over a much wider area,
   but drawn together by a single virtual network over the Internet, or
   a single physical network running partially in parallel with the
   Internet.  We expand on these possibilities below.  To capture the
   topic, this document refers to such networks as "limited domains".

   The phrase "Balkanization of the Internet" has often been used to
   criticise mechanisms that block the free flow of information across
   the network.  That is not the topic of this document, which does not
   discuss filtering mechanisms and does not apply to protocols that are
   designed for use across the whole Internet.

   The requirements of limited domains will be different in different
   scenarios.  Policies, default parameters, and the options supported
   may vary.  Also, the style of network management may vary, between a
   completely unmanaged network, one with fully autonomic management,
   one with traditional central management, and mixtures of the above.

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   Finally, the requirements and solutions for security and privacy may

   This documents analyses and discusses some of the consequences of
   this trend, and how it impacts the idea of universal interoperability
   in the Internet.  In particular, we challenge the notion that all
   Internet standards must be universal in scope and applicability.  To
   the contrary, we assert that some standards need to be specifically
   limited in their applicability.  This requires that the concepts of a
   limited domain, and of its boundary, need to be formalised.

   NOTE: This document is incomplete.  Comments on the following two
   sections are invited before we complete the later sections.

2.  Examples of Limited Domain Requirements

   This section describes various examples where limited domain
   requirements can be identified.  It is of course not a complete list.

   NOTE: The authors welcome more suggestions and references for this

   1.   A home network.  It will be unmanaged, constructed by a non-
        specialist, and will possibly include wiring errors such as
        physical loops.  It must work with devices "out of the box" as
        shipped by their manufacturers and must create adequate security
        by default.  Remote access may be required.  The requirements
        and applicable principles are summarised in [RFC7368].

   2.   A small office network.  This is very similar to a home network,
        since whoever is in charge will probably have little or no
        specialist knowledge, but may have differing security and
        privacy requirements.  Remote access may be required.

   3.   A vehicle network.  This will be designed by the vehicle
        manufacturer but may include devices added by the vehicle's
        owner or operator.  Parts of the network will have demanding
        performance and reliability requirements with implications for
        human safety.  Remote access may be required to certain
        functions, but absolutely forbidden for others.  Communication
        with other vehicles, roadside infrastructure, and external data
        sources will be required.  See
        [I-D.ietf-ipwave-vehicular-networking] for a survey of use

   4.   A building services network.  This will be designed specifically
        for a particular building, but using standard components.
        Additional devices may need to be added at any time.  Parts of

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        the network may have demanding reliability requirements with
        implications for human safety.  Remote access may be required to
        certain functions, but absolutely forbidden for others.
        [I-D.martocci-6lowapp-building-applications] (need current

   5.   Supervisory Control And Data Acquisition (SCADA) networks in
        general, which will exhibit widely differing requirements,
        including tough real-time performance targets, of which building
        networks are a simple example.  See for example

   6.   The three preceding cases will all include sensors, but some
        networks may be specifically limited to sensors and the
        collection and processing of sensor data.  They may be in remote
        or technically challenging locations and installed by non-

   7.   "Traditional" enterprise and campus networks, which may be
        spread over many kilometres and over multiple separate sites.

   8.   Data centres and hosting centres, or distributed services acting
        as such centres.  These will have high performance, security and
        privacy requirements and will typically include large numbers of
        independent "tenant" networks overlaid on shared infrastructure.

   9.   Content Delivery Networks, comprising distributed data centres
        and the paths between them, spanning thousands of kilometres.

   10.  Internet of Things (IoT) networks.  While this term is very
        flexible and covers many innovative types of network, it seems
        reasonable to assert that many IoT edge networks will in fact
        have special requirements and protocols that are useful only
        within a specific domain, and that these protocols cannot, and
        for security reasons should not, run over the Internet as a

   Two other concepts, while not tied to specific network types, also
   strongly depend on the concept of limited domains:

   1.  Intent Based Networking.  In this concept, a network domain is
       configured and managed in accordance with an abstract policy
       known as "Intent", to ensure that the network performs as
       required [I-D.moulchan-nmrg-network-intent-concepts].  Whatever
       technologies are used to support this, they will be applied
       within the domain boundary.

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   2.  Network Slicing.  A network slice is a virtual network that
       consists of a managed set of resources carved off from a larger
       network [I-D.geng-netslices-architecture].  Whatever technologies
       are used to support slicing, they will require a clear definition
       of the boundary of a given slice.

   While it is clearly desirable to use common solutions, and therefore
   common standards, wherever possible, it is increasingly difficult to
   do so while satisfying the widely varying requirements outlined
   above.  However, there is a tendency when new protocols and protocol
   extensions are proposed to always ask the question "How will this
   work across the open Internet?"  This document suggests that this is
   not always the right question.  There are protocols and extensions
   that are not intended to work across the open Internet.  On the
   contrary, their requirements and semantics are specifically limited
   (in the sense defined above).

   A common argument is that if a protocol is intended for limited use,
   the chances are very high that it will in fact be used (or misused)
   in other scenarios including the so-called open Internet.  This is
   undoubtedly true and means that limited use is not an excuse for bad
   design or poor security.  In fact, a limited use requirement
   potentially adds complexity to both the protocol and its security
   design, as discussed later.

   Nevertheless, because of the diversity of limited environments with
   specific requirements that is now emerging, specific standards will
   necessarily emerge.  There will be attempts to capture each market
   sector, but the market will demand standardised limited solutions.
   However, the "open Internet" must remain as the universal method of
   interconnection.  Reconciling these two aspects is a major challenge.

3.  Examples of Limited Domain Solutions

   This section lists various examples of specific limited domain
   solutions that have been proposed or defined.  It intentionally does
   not include Layer 2 technology solutions, which are by definition
   defined for limited domains.

   NOTE: Please suggest additional items for this list.

   1.  Differentiated Services.  This mechanism [RFC2474] allows a
       network to assign locally significant values to the 6-bit
       Differentiated Services Code Point field in any IP packet.
       Although there are some recommended codepoint values for specific
       per-hop queue management behaviours, these are specifically
       intended to be domain-specific codepoints with traffic being
       classified, conditioned and re-marked at domain boundaries

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       (unless there is an inter-domain agreement that makes re-marking

   2.  Network function virtualisation.  As described in
       [I-D.irtf-nfvrg-gaps-network-virtualization], this general
       concept is an open research topic, in which virtual network
       functions are orchestrated as part of a distributed system.
       Inevitably such orchestration applies to an administrative domain
       of some kind, even though cross-domain orchestration is also a
       research area.

   3.  Service Function Chaining (SFC).  This technique [RFC7665]
       assumes that services within a network are constructed as
       sequences of individual functions within a specific SFC-enabled
       domain.  As that RFC states: "Specific features may need to be
       enforced at the boundaries of an SFC-enabled domain, for example
       to avoid leaking SFC information".  A Network Service Header
       (NSH) [RFC8300] is used to encapsulate packets flowing through
       the service function chain: "The intended scope of the NSH is for
       use within a single provider's operational domain."

   4.  Data Centre Network Virtualization Overlays.  A common
       requirement in data centres that host many tenants (clients) is
       to provide each one with a secure private network, all running
       over the same physical infrastructure.  [RFC8151] describes
       various use cases for this, and specifications are under
       development.  These include use cases in which the tenant network
       is physically split over several data centres, but which must
       appear to the user as a single secure domain.

   5.  Segment Routing.  This is a technique which "steers a packet
       through an ordered list of instructions, called segments"
       [I-D.ietf-spring-segment-routing].  The semantics of these
       instructions are explicitly local to a segment routing domain or
       even to a single node.  Technically, these segments or
       instructions are represented as an MPLS label or an IPv6 address,
       which clearly adds a semantic interpretation to them within the

   6.  Autonomic Networking.  As explained in
       [I-D.ietf-anima-reference-model], an autonomic network is also a
       security domain within which an autonomic control plane
       [I-D.ietf-anima-autonomic-control-plane] is used by service
       agents.  These service agents manage technical objectives, which
       may be locally defined, subject to domain-wide policy.  Thus the
       domain boundary is important for both security and protocol

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   7.  Homenet.  As shown in [RFC7368], a home networking domain has
       specific protocol needs that differ from those in an enterprise
       network or the Internet as a whole.  These include the Home
       Network Control Protocol (HNCP) [RFC7788] and a naming and
       discovery solution [I-D.ietf-homenet-simple-naming].

   8.  Creative uses of IPv6 features.  As IPv6 enters more general use,
       engineers notice that it has much more flexibility than IPv4.
       Innovative suggestions have been made for:

       *  The flow label, e.g.  [RFC6294],

       *  Extension headers, e.g. for segment routing

       *  Meaningful address bits, e.g.  [I-D.jiang-semantic-prefix].
          Also, segment routing uses IPv6 addresses as segment
          identifiers with specific local meanings

       All of these suggestions are only viable within a specified
       domain.  The case of the extension header is particularly
       interesting, since its existence has been a major "selling point"
       for IPv6, but it is notorious that new extension headers are
       virtually impossible to deploy across the whole Internet
       [RFC7045], [RFC7872].  It is worth noting that extension header
       filtering is considered as an important security issue
       [I-D.ietf-opsec-ipv6-eh-filtering].  There is considerable
       appetite among vendors or operators to have flexibility in
       defining extension headers for use in limited or specialised
       domains, e.g.  [I-D.voyer-6man-extension-header-insertion] and

   9.  Deterministic Networking (DetNet).  The Deterministic Networking
       Architecture [I-D.ietf-detnet-architecture] and encapsulation
       [I-D.ietf-detnet-dp-sol] aim to support flows with extremely low
       data loss rates and bounded latency, but only within a part of
       the network that is "DetNet aware".  Thus, as for differentiated
       services above, the concept of a domain is fundamental.

4.  Common Aspects of Limited Domains

   This section derives common aspects of limited domains from the
   examples above.


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5.  The Need to Define a Limited Domain Boundary

   This section justifies the need for a precise definition of a limited
   domain boundary and for a corresponding protocol to allow nodes to
   discover where such a boundary exists.


6.  Defining Protocol Scope

   This section suggests that protocols or protocol extensions should,
   when appropriate, be standardised to interoperate only within a
   Limited Domain Boundary.  Such protocols are not required to operate
   across the Internet as a whole.


7.  Security Considerations

   Clearly, the boundary of a limited domain will almost always also act
   as a security boundary.  In particular, it will serve as a trust
   boundary, and as a boundary of authority for defining capabilities.
   Within the boundary, limited-domain protocols or protocol features
   will be useful, but they will be meaningless if they enter or leave
   the domain.

   The security model for a limited-scope protocol must allow for the
   boundary, and in particular for a trust model that changes at the
   boundary.  Typically, credentials will need to be signed by a domain-
   specific authority.

8.  IANA Considerations

   This document makes no request of the IANA.

9.  Acknowledgements

   Useful comments were received from ...

10.  Informative References

   [BIGIP]    Li, R., "HUAWEI - Big IP Initiative.", 2018,

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              Fioccola, G., Velde, G., Cociglio, M., and P. Muley, "IPv6
              Performance Measurement with Alternate Marking Method",
              draft-fioccola-v6ops-ipv6-alt-mark-01 (work in progress),
              June 2018.

              67, 4., Dong, J., Bryant, S., kiran.makhijani@huawei.com,
              k., Galis, A., Foy, X., and S. Kuklinski, "Network Slicing
              Architecture", draft-geng-netslices-architecture-02 (work
              in progress), July 2017.

              Previdi, S., Filsfils, C., Leddy, J., Matsushima, S., and
              d. daniel.voyer@bell.ca, "IPv6 Segment Routing Header
              (SRH)", draft-ietf-6man-segment-routing-header-13 (work in
              progress), May 2018.

              Eckert, T., Behringer, M., and S. Bjarnason, "An Autonomic
              Control Plane (ACP)", draft-ietf-anima-autonomic-control-
              plane-16 (work in progress), June 2018.

              Behringer, M., Carpenter, B., Eckert, T., Ciavaglia, L.,
              and J. Nobre, "A Reference Model for Autonomic
              Networking", draft-ietf-anima-reference-model-06 (work in
              progress), February 2018.

              Finn, N., Thubert, P., Varga, B., and J. Farkas,
              "Deterministic Networking Architecture", draft-ietf-
              detnet-architecture-05 (work in progress), May 2018.

              Korhonen, J., Andersson, L., Jiang, Y., Finn, N., Varga,
              B., Farkas, J., Bernardos, C., Mizrahi, T., and L. Berger,
              "DetNet Data Plane Encapsulation", draft-ietf-detnet-dp-
              sol-04 (work in progress), March 2018.

              Grossman, E., "Deterministic Networking Use Cases", draft-
              ietf-detnet-use-cases-16 (work in progress), May 2018.

              Lemon, T., Migault, D., and S. Cheshire, "Simple Homenet
              Naming and Service Discovery Architecture", draft-ietf-
              homenet-simple-naming-01 (work in progress), March 2018.

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              Jeong, J., "IP-based Vehicular Networking: Use Cases,
              Survey and Problem Statement", draft-ietf-ipwave-
              vehicular-networking-02 (work in progress), March 2018.

              Gont, F. and W. LIU, "Recommendations on the Filtering of
              IPv6 Packets Containing IPv6 Extension Headers", draft-
              ietf-opsec-ipv6-eh-filtering-05 (work in progress), March

              Filsfils, C., Previdi, S., Ginsberg, L., Decraene, B.,
              Litkowski, S., and R. Shakir, "Segment Routing
              Architecture", draft-ietf-spring-segment-routing-15 (work
              in progress), January 2018.

              Bernardos, C., Rahman, A., Zuniga, J., Contreras, L.,
              Aranda, P., and P. Lynch, "Network Virtualization Research
              Challenges", draft-irtf-nfvrg-gaps-network-
              virtualization-09 (work in progress), February 2018.

              Jiang, S., Qiong, Q., Farrer, I., Bo, Y., and T. Yang,
              "Analysis of Semantic Embedded IPv6 Address Schemas",
              draft-jiang-semantic-prefix-06 (work in progress), July

              Martocci, J., Schoofs, A., and P. Stok, "Commercial
              Building Applications Requirements", draft-martocci-
              6lowapp-building-applications-01 (work in progress), July

              Sivakumar, K. and M. Chandramouli, "Concepts of Network
              Intent", draft-moulchan-nmrg-network-intent-concepts-00
              (work in progress), October 2017.

              daniel.voyer@bell.ca, d., Leddy, J., Filsfils, C., Dukes,
              D., Previdi, S., and S. Matsushima, "Insertion of IPv6
              Segment Routing Headers in a Controlled Domain", draft-
              voyer-6man-extension-header-insertion-03 (work in
              progress), May 2018.

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   [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,

   [RFC6294]  Hu, Q. and B. Carpenter, "Survey of Proposed Use Cases for
              the IPv6 Flow Label", RFC 6294, DOI 10.17487/RFC6294, June
              2011, <https://www.rfc-editor.org/info/rfc6294>.

   [RFC7045]  Carpenter, B. and S. Jiang, "Transmission and Processing
              of IPv6 Extension Headers", RFC 7045,
              DOI 10.17487/RFC7045, December 2013,

   [RFC7368]  Chown, T., Ed., Arkko, J., Brandt, A., Troan, O., and J.
              Weil, "IPv6 Home Networking Architecture Principles",
              RFC 7368, DOI 10.17487/RFC7368, October 2014,

   [RFC7665]  Halpern, J., Ed. and C. Pignataro, Ed., "Service Function
              Chaining (SFC) Architecture", RFC 7665,
              DOI 10.17487/RFC7665, October 2015,

   [RFC7788]  Stenberg, M., Barth, S., and P. Pfister, "Home Networking
              Control Protocol", RFC 7788, DOI 10.17487/RFC7788, April
              2016, <https://www.rfc-editor.org/info/rfc7788>.

   [RFC7872]  Gont, F., Linkova, J., Chown, T., and W. Liu,
              "Observations on the Dropping of Packets with IPv6
              Extension Headers in the Real World", RFC 7872,
              DOI 10.17487/RFC7872, June 2016,

   [RFC8151]  Yong, L., Dunbar, L., Toy, M., Isaac, A., and V. Manral,
              "Use Cases for Data Center Network Virtualization Overlay
              Networks", RFC 8151, DOI 10.17487/RFC8151, May 2017,

   [RFC8300]  Quinn, P., Ed., Elzur, U., Ed., and C. Pignataro, Ed.,
              "Network Service Header (NSH)", RFC 8300,
              DOI 10.17487/RFC8300, January 2018,

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Appendix A.  Change log [RFC Editor: Please remove]

   draft-carpenter-limited-domains, 2018-06-11:

   Initial version

Authors' Addresses

   Brian Carpenter
   Department of Computer Science
   University of Auckland
   PB 92019
   Auckland  1142
   New Zealand

   Email: brian.e.carpenter@gmail.com

   Sheng Jiang
   Huawei Technologies Co., Ltd
   Q14, Huawei Campus, No.156 Beiqing Road
   Hai-Dian District, Beijing, 100095
   P.R. China

   Email: jiangsheng@huawei.com

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