CoAP (Constrained Application Protocol) over TCP, TLS, and WebSockets
draft-ietf-core-coap-tcp-tls-10

Document Type Active Internet-Draft (core WG)
Last updated 2017-10-30
Replaces draft-tschofenig-core-coap-tcp-tls, draft-bormann-core-block-bert, draft-bormann-core-coap-sig, draft-savolainen-core-coap-websockets
Stream IETF
Intended RFC status Proposed Standard
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Stream WG state Submitted to IESG for Publication (wg milestone: Oct 2016 - CoAP over TCP, TLS, ... )
Document shepherd Jaime Jimenez
Shepherd write-up Show (last changed 2017-03-21)
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CORE                                                          C. Bormann
Internet-Draft                                   Universitaet Bremen TZI
Updates: 7641, 7959 (if approved)                               S. Lemay
Intended status: Standards Track                      Zebra Technologies
Expires: May 3, 2018                                       H. Tschofenig
                                                                ARM Ltd.
                                                               K. Hartke
                                                 Universitaet Bremen TZI
                                                           B. Silverajan
                                        Tampere University of Technology
                                                          B. Raymor, Ed.
                                                               Microsoft
                                                        October 30, 2017

 CoAP (Constrained Application Protocol) over TCP, TLS, and WebSockets
                  draft-ietf-core-coap-tcp-tls-10

Abstract

   The Constrained Application Protocol (CoAP), although inspired by
   HTTP, was designed to use UDP instead of TCP.  The message layer of
   the CoAP over UDP protocol includes support for reliable delivery,
   simple congestion control, and flow control.

   Some environments benefit from the availability of CoAP carried over
   reliable transports such as TCP or TLS.  This document outlines the
   changes required to use CoAP over TCP, TLS, and WebSockets
   transports.  It also formally updates RFC 7641 for use with these
   transports and RFC 7959 to enable the use of larger messages over a
   reliable transport.

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
   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 May 3, 2018.

Bormann, et al.            Expires May 3, 2018                  [Page 1]
Internet-Draft   TCP/TLS/WebSockets Transports for CoAP     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
   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
   carefully, as they describe your rights and restrictions with respect
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   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  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Conventions and Terminology . . . . . . . . . . . . . . . . .   6
   3.  CoAP over TCP . . . . . . . . . . . . . . . . . . . . . . . .   7
     3.1.  Messaging Model . . . . . . . . . . . . . . . . . . . . .   7
     3.2.  Message Format  . . . . . . . . . . . . . . . . . . . . .   8
     3.3.  Message Transmission  . . . . . . . . . . . . . . . . . .  10
     3.4.  Connection Health . . . . . . . . . . . . . . . . . . . .  11
   4.  CoAP over WebSockets  . . . . . . . . . . . . . . . . . . . .  11
     4.1.  Opening Handshake . . . . . . . . . . . . . . . . . . . .  13
     4.2.  Message Format  . . . . . . . . . . . . . . . . . . . . .  14
     4.3.  Message Transmission  . . . . . . . . . . . . . . . . . .  15
     4.4.  Connection Health . . . . . . . . . . . . . . . . . . . .  15
   5.  Signaling . . . . . . . . . . . . . . . . . . . . . . . . . .  15
     5.1.  Signaling Codes . . . . . . . . . . . . . . . . . . . . .  16
     5.2.  Signaling Option Numbers  . . . . . . . . . . . . . . . .  16
     5.3.  Capabilities and Settings Messages (CSM)  . . . . . . . .  16
     5.4.  Ping and Pong Messages  . . . . . . . . . . . . . . . . .  18
     5.5.  Release Messages  . . . . . . . . . . . . . . . . . . . .  20
     5.6.  Abort Messages  . . . . . . . . . . . . . . . . . . . . .  21
     5.7.  Signaling examples  . . . . . . . . . . . . . . . . . . .  22
   6.  Block-wise Transfer and Reliable Transports . . . . . . . . .  22
     6.1.  Example: GET with BERT Blocks . . . . . . . . . . . . . .  24
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