Too Many Requests Response Code for the Constrained Application Protocol
draft-ietf-core-too-many-reqs-02

Document Type Active Internet-Draft (core WG)
Last updated 2018-07-02
Replaces draft-keranen-core-too-many-reqs
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Network Working Group                                         A. Keranen
Internet-Draft                                                  Ericsson
Intended status: Standards Track                            July 2, 2018
Expires: January 3, 2019

Too Many Requests Response Code for the Constrained Application Protocol
                    draft-ietf-core-too-many-reqs-02

Abstract

   A Constrained Application Protocol (CoAP) server can experience
   temporary overload because one or more clients are sending requests
   to the server at a higher rate than the server is capable or willing
   to handle.  This document defines a new CoAP Response Code for a
   server to indicate that a client should reduce the rate of requests.

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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   This Internet-Draft will expire on January 3, 2019.

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
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   (http://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.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  CoAP Server Behavior  . . . . . . . . . . . . . . . . . . . .   3
   4.  CoAP Client Behavior  . . . . . . . . . . . . . . . . . . . .   3
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   4
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   The Constrained Application Protocol (CoAP) [RFC7252] Response Codes
   are used by a CoAP server to indicate the result of the attempt to
   understand and satisfy a request sent by a client.

   CoAP Response Codes are similar to the HTTP [RFC7230] Status Codes
   and many codes are shared with similar semantics by both CoAP and
   HTTP.  HTTP has the code "429" registered for "Too Many Requests"
   [RFC6585].  This document registers a CoAP Response Code "4.29" for
   similar purpose and also defines use of the Max-Age option to
   indicate a back-off period after which a client can try the request
   again.

   While a server may not be able to response to a one kind of request,
   it may be able to respond to a different request, even from the same
   client.  Therefore the back-off period applies only to similar
   requests.  For the purpose of this response code, a request is
   similar if it has the same method, Request-URI, and payload.  Also if
   a client is sending a sequence of requests that are part of the same
   series (e.g., a set of measurements to be processed by the server)
   they can be considered similar even if request payloads or URIs may
   be different.  Because request similarity is context-dependent, it is
   up to the application logic to decide how similar requests should be
   suppressed.

   The 4.29 code is similar to the 5.03 "Service Unavailable" [RFC7252]
   code in a way that the 5.03 code can also be used by a server to
   signal an overload situation.  However the 4.29 code indicates that
   the too frequent requests from the requesting client are the reason
   for the overload.

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2.  Terminology

   The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL NOT',
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