LPWAN Static Context Header Compression (SCHC) for CoAP
draft-ietf-lpwan-coap-static-context-hc-02

Document Type Active Internet-Draft (lpwan WG)
Last updated 2017-09-06
Replaces draft-toutain-lpwan-coap-static-context-hc
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lpwan Working Group                                          A. Minaburo
Internet-Draft                                                    Acklio
Intended status: Informational                                L. Toutain
Expires: March 10, 2018          Institut MINES TELECOM ; IMT Atlantique
                                                      September 06, 2017

        LPWAN Static Context Header Compression (SCHC) for CoAP
               draft-ietf-lpwan-coap-static-context-hc-02

Abstract

   This draft defines the way SCHC header compression can be applied to
   CoAP headers.  CoAP header structure differs from IPv6 and UDP
   protocols since the CoAP Header is flexible header with a variable
   number of options themself of a variable length.  Another important
   difference is the asymmetry in the header information used for
   request and response messages.  This draft takes into account the
   fact that a thing can play the role of a CoAP client, a CoAP client
   or both roles.

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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   This Internet-Draft will expire on March 10, 2018.

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

Minaburo & Toutain       Expires March 10, 2018                 [Page 1]
Internet-Draft           LPWAN CoAP compression           September 2017

   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  CoAP Compressing  . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Compression of CoAP header fields . . . . . . . . . . . . . .   4
     3.1.  CoAP version field (2 bits) . . . . . . . . . . . . . . .   4
     3.2.  CoAP type field . . . . . . . . . . . . . . . . . . . . .   5
     3.3.  CoAP token length field . . . . . . . . . . . . . . . . .   5
     3.4.  CoAP code field . . . . . . . . . . . . . . . . . . . . .   6
     3.5.  CoAP Message ID field . . . . . . . . . . . . . . . . . .   8
     3.6.  CoAP Token field  . . . . . . . . . . . . . . . . . . . .   9
   4.  CoAP options  . . . . . . . . . . . . . . . . . . . . . . . .   9
     4.1.  CoAP option Content-format field. . . . . . . . . . . . .   9
     4.2.  CoAP option Accept field  . . . . . . . . . . . . . . . .  10
     4.3.  CoAP option Max-Age field, CoAP option Uri-Host and Uri-
           Port fields . . . . . . . . . . . . . . . . . . . . . . .  11
   5.  CoAP option Uri-Path and Uri-Query fields . . . . . . . . . .  11
     5.1.  CoAP option Proxy-URI and Proxy-Scheme fields . . . . . .  12
     5.2.  CoAP option ETag, If-Match, If-None-Match, Location-Path
           and Location-Query fields . . . . . . . . . . . . . . . .  13
   6.  Other RFCs  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     6.1.  Block . . . . . . . . . . . . . . . . . . . . . . . . . .  13
     6.2.  Observe . . . . . . . . . . . . . . . . . . . . . . . . .  13
     6.3.  No-Response . . . . . . . . . . . . . . . . . . . . . . .  13
   7.  Protocol analysis . . . . . . . . . . . . . . . . . . . . . .  13
   8.  Examples of CoAP header compression . . . . . . . . . . . . .  14
     8.1.  Mandatory header with CON message . . . . . . . . . . . .  14
     8.2.  Complete exchange . . . . . . . . . . . . . . . . . . . .  16
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .  17
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  18

1.  Introduction

   CoAP [rfc7252] is an implementation of the REST architecture for
   constrained devices.  Gateway between CoAP and HTTP can be easily
   built since both protocols uses the same address space (URL), caching
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