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Versions: 00                                                            
TODO Working Group                                           C. Gündoğan
Internet-Draft                                               HAW Hamburg
Intended status: Informational                                 C. Amsüss
Expires: 26 August 2021
                                                             TC. Schmidt
                                                             HAW Hamburg
                                                            M. Waehlisch
                                                    link-lab & FU Berlin
                                                        22 February 2021


               A Data-centric Deployment Option for CoAP
                     draft-gundogan-core-icncoap-00

Abstract

   The information-centric networking (ICN) paradigm offers replication
   of autonomously verifiable content throughout a network, in which
   content is bound to names instead of hosts.  This has proven
   beneficial in particular for the constrained IoT.  Several
   approaches, the most prominent of which being Content-Centric
   Networking (CCNx) and Named-Data Networking (NDN), propose access to
   named content directly on the network layer.  Independently, the CoRe
   WG developed mechanisms that support autonomous content processing,
   on-path caching, and content object security using CoAP proxies and
   OSCORE.

   This document describes a data-centric deployment option using
   standard CoAP features to replicate information-centric properties
   and benefits to the host-centric IoT world.

Discussion Venues

   This note is to be removed before publishing as an RFC.

   Discussion of this document takes place on the Constrained RESTful
   Environments Working Group mailing list (core@ietf.org), which is
   archived at https://mailarchive.ietf.org/arch/browse/core/.

   Source for this draft and an issue tracker can be found at
   https://github.com/inetrg/draft-core-icncoap.

Status of This Memo

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





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Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  Data-centric Deployment Option for CoAP . . . . . . . . . . .   3
     3.1.  Stateful Forwarding . . . . . . . . . . . . . . . . . . .   3
     3.2.  Content Caching . . . . . . . . . . . . . . . . . . . . .   4
     3.3.  Corrective Actions  . . . . . . . . . . . . . . . . . . .   4
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6










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1.  Introduction

   Information-Centric Networking (ICN) introduced the idea to turn
   named content objects into first class citizens of the Internet
   ecosystem.  This paradigm gave rise to (i) a decoupling of content
   from hosts and the ability of ubiquitous content caching without
   content delivery networks (CDNs), and (ii) serverless routing on
   names without the DNS infrastructure; (iii) Named Data Networking
   (NDN) additionally abandoned network endpoint addresses in favor of a
   stateful forwarding fabric.  These properties enable an asynchronous,
   hop-wise content fetching, which prevents forwarding of unsolicited
   data.  The latter significantly reduces the attack surface of
   (Distributed) Denial-of-Service (DDoS).

   All three constituents make ICN appealing to the (constrained)
   Internet of Things (IoT) as infrastructural burdens and common DDoS
   threats stand in the way of a lean and efficient inter-networking for
   embedded devices.  Early experimental work [NDN-IOT] shows that NDN
   can successfully operate on very constrained nodes with noticeable
   resource savings compared to IP.  In addition, short-term in-network
   caching proved valuable for increasing reliability in low-power lossy
   networks with nodes frequently at sleep as common at the IoT edge.

   The deployment option described in this document replicates these
   information-centric properties using standard CoAP features.  Recent
   experimental evaluations [OBJECTSEC][ICN-COAP] in a testbed with real
   IoT hardware demonstrate promising results.

2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  Data-centric Deployment Option for CoAP

3.1.  Stateful Forwarding

   In the data-centric deployment, all IoT devices act as CoAP proxies
   with enabled caching functionality.  A forwarding information base
   (FIB) on the application-layer describes a mapping of resource names
   to next-hop CoAP proxies.  This mapping list is compiled statically,
   or is dynamically discovered in the network; future document
   iterations will further elaborate on this topic.





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   Within the IoT stub network, requests traverse multiple proxies,
   install forwarding state, and build return paths for corresponding
   responses.  The use of IPv6 link-local addresses between each proxy
   hop is encouraged for a better 6LoWPAN compressibility.  Responses
   return on symmetrical request paths, which consequently consumes
   existing forwarding state.

3.2.  Content Caching

   A deployment of proxy nodes on each hop enables a hop-wise caching
   just as performed by CCNx [RFC8569] and NDN.  Responses replicate on
   a request path following a cache decision and cache replacement
   strategy.  A simple and lightweight approach is to _cache everywhere_
   and replace _least recently used_ (LRU) content.

   OSCORE enables content object security for CoAP and allows for
   transmitting autonomously verifiable content similar to CCNx and NDN.
   Further details on cachable OSCORE messages is recorded in
   [I-D.draft-amsuess-core-cachable-oscore-00].

3.3.  Corrective Actions

   In contrast to end-to-end retransmissions for standard CoAP
   deployments, the data-centric setup performs hop-wise retransmissions
   in the event of message timeouts.  Confirmable messages arm message
   timers on each proxy node.

   Figure 1 illustrates the default retransmission behavior: each
   subsequent packet traverses the full request path to recover a lost
   message.

            Initial request:

            ,-------,  Request   ,-------,  Request   ,-------,
            |client |------------|router |----------->|server |
            |       |  x---------|       |------------|       |
            '-------'  Response  '-------'  Response  '-------'



            Request retransmission:

            ,-------,  Request   ,-------,  Request   ,-------,
            |client |------------|router |----------->|server |
            |       |<-----------|       |------------|       |
            '-------'  Response  '-------'  Response  '-------'

               Figure 1: End-to-end recovery of lost packets.



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   Figure 2 demonstrates the shortening of request paths for subsequent
   request retransmissions due to the on-path caching functionality.

            Initial request:

            ,-------,  Request   ,-------,  Request   ,-------,
            | Proxy |----------->| Proxy |----------->| Proxy |
            |(cache)|  x---------|(cache)|<-----------|(cache)|
            '-------'  Response  '-------'  Response  '-------'



            Request retransmission:

            ,-------,  Request   ,-------,            ,-------,
            | Proxy |----------->| Proxy |            | Proxy |
            |(cache)|<-----------|(cache)|            |(cache)|
            '-------'  Response  '-------'            '-------'

     Figure 2: Hop-wise recovery of lost packets with on-path caching.

   Proxy nodes aggregate requests and suppress the forwarding procedure,
   if they already maintain an on-going request with the same cache key.

4.  Security Considerations

   TODO Security

5.  IANA Considerations

   This document has no IANA actions.

6.  References

6.1.  Normative References

   [I-D.draft-amsuess-core-cachable-oscore-00]
              Amsuess, C. and M. Tiloca, "Cachable OSCORE", Work in
              Progress, Internet-Draft, draft-amsuess-core-cachable-
              oscore-00, 13 July 2020, <http://www.ietf.org/internet-
              drafts/draft-amsuess-core-cachable-oscore-00.txt>.

   [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>.





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   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

6.2.  Informative References

   [ICN-COAP] Gündoğan, C., Amsüss, C., Schmidt, TC., and M. Waehlisch,
              "Toward a RESTful Information-Centric Web of Things: A
              Deeper Look at Data Orientation in CoAP", Proceedings
              of 7th ACM ICN, DOI 10.1145/3405656.3418718, 2020,
              <https://dl.acm.org/doi/10.1145/3405656.3418718>.

   [NDN-IOT]  Gündoğan, C., Kietzmann, P., Lenders, M., Petersen, H.,
              Schmidt, TC., and M. Waehlisch, "NDN, CoAP, and MQTT: a
              comparative measurement study in the IoT", Proceedings
              of 5th ACM ICN, DOI 10.1145/3267955.3267967, 2018,
              <https://dl.acm.org/doi/10.1145/3267955.3267967>.

   [OBJECTSEC]
              Gündoğan, C., Amsüss, C., Schmidt, TC., and M. Waehlisch,
              "IoT Content Object Security with OSCORE and NDN: A First
              Experimental Comparison", Proceedings of 19th IFIP
              Networking, 2020,
              <https://ieeexplore.ieee.org/document/9142731>.

   [RFC8569]  Mosko, M., Solis, I., and C. Wood, "Content-Centric
              Networking (CCNx) Semantics", RFC 8569,
              DOI 10.17487/RFC8569, July 2019,
              <https://www.rfc-editor.org/info/rfc8569>.

Acknowledgments

   TODO acknowledge.

Authors' Addresses

   Cenk Gündoğan
   HAW Hamburg

   Email: cenk.guendogan@haw-hamburg.de


   Christian Amsüss

   Email: christian@amsuess.com






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   Thomas C. Schmidt
   HAW Hamburg

   Email: t.schmidt@haw-hamburg.de


   Matthias Waehlisch
   link-lab & FU Berlin

   Email: m.waehlisch@haw-hamburg.de









































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