CoAP Simple Congestion Control/Advanced
draft-ietf-core-cocoa-03

Document Type Active Internet-Draft (core WG)
Last updated 2018-02-21
Replaces draft-bormann-core-cocoa
Stream IETF
Intended RFC status Informational
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Stream WG state Submitted to IESG for Publication
Document shepherd Jaime Jimenez
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CoRE Working Group                                            C. Bormann
Internet-Draft                                   Universitaet Bremen TZI
Intended status: Informational                                A. Betzler
Expires: August 25, 2018                                  Fundacio i2CAT
                                                                C. Gomez
                                                             I. Demirkol
                     Universitat Politecnica de Catalunya/Fundacio i2CAT
                                                       February 21, 2018

                CoAP Simple Congestion Control/Advanced
                        draft-ietf-core-cocoa-03

Abstract

   CoAP, the Constrained Application 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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Bormann, et al.          Expires August 25, 2018                [Page 1]
Internet-Draft              CoAP Simple CoCoA              February 2018

   This Internet-Draft will expire on August 25, 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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   described in the Simplified BSD License.

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.  Measurement-based 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  . . . . .   9
     5.1.  Discussion  . . . . . . . . . . . . . . . . . . . . . . .   9
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  10
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  11
   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
     B.2.  RTO aging . . . . . . . . . . . . . . . . . . . . . . . .  14
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