LPWAN Static Context Header Compression (SCHC) for CoAP
draft-ietf-lpwan-coap-static-context-hc-07
lpwan Working Group A. Minaburo
Internet-Draft Acklio
Intended status: Standards Track L. Toutain
Expires: November 25, 2019 Institut MINES TELECOM; IMT Atlantique
R. Andreasen
Universidad de Buenos Aires
May 24, 2019
LPWAN Static Context Header Compression (SCHC) for CoAP
draft-ietf-lpwan-coap-static-context-hc-07
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 header packet 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 Notice
Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved.
Minaburo, et al. Expires November 25, 2019 [Page 1]
Internet-Draft LPWAN CoAP compression May 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 field, CoAP option Uri-Host and Uri-
Port fields . . . . . . . . . . . . . . . . . . . . . . . 8
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 . . . . . . . . . . . . . . . . . . . . . . . . . 10
6.1. Block . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6.2. Observe . . . . . . . . . . . . . . . . . . . . . . . . . 10
6.3. No-Response . . . . . . . . . . . . . . . . . . . . . . . 10
6.4. Time Scale . . . . . . . . . . . . . . . . . . . . . . . 10
6.5. OSCORE . . . . . . . . . . . . . . . . . . . . . . . . . 11
7. Examples of CoAP header compression . . . . . . . . . . . . . 12
7.1. Mandatory header with CON message . . . . . . . . . . . . 12
7.2. OSCORE Compression . . . . . . . . . . . . . . . . . . . 13
7.3. Example OSCORE Compression . . . . . . . . . . . . . . . 17
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