LPWAN Static Context Header Compression (SCHC) for CoAP
draft-ietf-lpwan-coap-static-context-hc-09

Document Type Active Internet-Draft (lpwan WG)
Last updated 2019-07-06
Replaces draft-toutain-lpwan-coap-static-context-hc
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lpwan Working Group                                          A. Minaburo
Internet-Draft                                                    Acklio
Intended status: Standards Track                              L. Toutain
Expires: January 7, 2020          Institut MINES TELECOM; IMT Atlantique
                                                            R. Andreasen
                                             Universidad de Buenos Aires
                                                           July 06, 2019

        LPWAN Static Context Header Compression (SCHC) for CoAP
               draft-ietf-lpwan-coap-static-context-hc-09

Abstract

   This draft defines the way SCHC header compression can be applied to
   CoAP headers.  The CoAP header structure differs from IPv6 and UDP
   protocols since CoAP uses a flexible header with a variable number of
   options, themselves of variable length.  The CoAP protocol is
   asymmetric in its message format: the format of the packet header in
   the request messages is different from that in the response messages.
   Most of the compression mechanisms have been introduced in
   [I-D.ietf-lpwan-ipv6-static-context-hc], this document explains how
   to use the SCHC compression for CoAP.

Status of This Memo

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   Copyright (c) 2019 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

Minaburo, et al.         Expires January 7, 2020                [Page 1]
Internet-Draft           LPWAN CoAP compression                July 2019

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  SCHC Compression Process  . . . . . . . . . . . . . . . . . .   3
   3.  CoAP Compression with SCHC  . . . . . . . . . . . . . . . . .   4
   4.  Compression of CoAP header fields . . . . . . . . . . . . . .   6
     4.1.  CoAP version field  . . . . . . . . . . . . . . . . . . .   6
     4.2.  CoAP type field . . . . . . . . . . . . . . . . . . . . .   6
     4.3.  CoAP code field . . . . . . . . . . . . . . . . . . . . .   6
     4.4.  CoAP Message ID field . . . . . . . . . . . . . . . . . .   6
     4.5.  CoAP Token fields . . . . . . . . . . . . . . . . . . . .   7
   5.  CoAP options  . . . . . . . . . . . . . . . . . . . . . . . .   7
     5.1.  CoAP Content and Accept options.  . . . . . . . . . . . .   7
     5.2.  CoAP option Max-Age, Uri-Host and Uri-Port fields . . . .   7
     5.3.  CoAP option Uri-Path and Uri-Query fields . . . . . . . .   8
       5.3.1.  Variable length Uri-Path and Uri-Query  . . . . . . .   8
       5.3.2.  Variable number of path or query elements . . . . . .   9
     5.4.  CoAP option Size1, Size2, Proxy-URI and Proxy-Scheme
           fields  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     5.5.  CoAP option ETag, If-Match, If-None-Match, Location-Path
           and Location-Query fields . . . . . . . . . . . . . . . .   9
   6.  Other RFCs  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     6.1.  Block . . . . . . . . . . . . . . . . . . . . . . . . . .   9
     6.2.  Observe . . . . . . . . . . . . . . . . . . . . . . . . .  10
     6.3.  No-Response . . . . . . . . . . . . . . . . . . . . . . .  10
     6.4.  OSCORE  . . . . . . . . . . . . . . . . . . . . . . . . .  10
   7.  Examples of CoAP header compression . . . . . . . . . . . . .  11
     7.1.  Mandatory header with CON message . . . . . . . . . . . .  11
     7.2.  OSCORE Compression  . . . . . . . . . . . . . . . . . . .  12
     7.3.  Example OSCORE Compression  . . . . . . . . . . . . . . .  16
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  26
   9.  Security considerations . . . . . . . . . . . . . . . . . . .  26
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