CoAP Simple Congestion Control/Advanced
draft-ietf-core-cocoa-02

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Last updated 2017-11-16 (latest revision 2017-10-30)
Replaces draft-bormann-core-cocoa
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CoRE Working Group                                            C. Bormann
Internet-Draft                                   Universitaet Bremen TZI
Intended status: Informational                                A. Betzler
Expires: May 3, 2018                                      Fundacio i2CAT
                                                                C. Gomez
                                                             I. Demirkol
                     Universitat Politecnica de Catalunya/Fundacio i2CAT
                                                        October 30, 2017

                CoAP Simple Congestion Control/Advanced
                        draft-ietf-core-cocoa-02

Abstract

   The CoAP protocol needs to be implemented in such a way that it does
   not cause persistent congestion on the network it uses.  The CoRE
   CoAP specification defines basic behavior that exhibits low risk of
   congestion with minimal implementation requirements.  It also leaves
   room for combining the base specification with advanced congestion
   control mechanisms with higher performance.

   This specification defines more advanced, but still simple CoRE
   Congestion Control mechanisms, called CoCoA.  The core of these
   mechanisms is a Retransmission TimeOut (RTO) algorithm that makes use
   of Round-Trip Time (RTT) estimates, in contrast with how the RTO is
   determined as per the base CoAP specification (RFC 7252).  The
   mechanisms defined in this document have relatively low complexity,
   yet they improve the default CoAP RTO algorithm.  The design of the
   mechanisms in this specification has made use of input from
   simulations and experiments in real networks.

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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   This Internet-Draft will expire on May 3, 2018.

Bormann, et al.            Expires May 3, 2018                  [Page 1]
Internet-Draft              CoAP Simple CoCoA               October 2017

Copyright Notice

   Copyright (c) 2017 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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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Context . . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Area of Applicability . . . . . . . . . . . . . . . . . . . .   4
   4.  Advanced CoAP Congestion Control: RTO Estimation  . . . . . .   5
     4.1.  Blind RTO Estimate  . . . . . . . . . . . . . . . . . . .   6
     4.2.  Measured RTO Estimate . . . . . . . . . . . . . . . . . .   6
       4.2.1.  Differences with the algorithm of RFC 6298  . . . . .   7
       4.2.2.  Discussion  . . . . . . . . . . . . . . . . . . . . .   7
     4.3.  Lifetime, Aging . . . . . . . . . . . . . . . . . . . . .   8
   5.  Advanced CoAP Congestion Control: Non-Confirmables  . . . . .   8
     5.1.  Discussion  . . . . . . . . . . . . . . . . . . . . . . .   9
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  10
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  10
   Appendix A.  Supporting evidence  . . . . . . . . . . . . . . . .  11
     A.1.  Older versions of the draft and improvement . . . . . . .  12
     A.2.  References  . . . . . . . . . . . . . . . . . . . . . . .  12
   Appendix B.  Pseudocode . . . . . . . . . . . . . . . . . . . . .  13
     B.1.  Updating the RTO estimator  . . . . . . . . . . . . . . .  13
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