Too Many Requests Response Code for the Constrained Application Protocol
draft-ietf-core-too-many-reqs-00

Document Type Active Internet-Draft (core WG)
Last updated 2018-04-06
Replaces draft-keranen-core-too-many-reqs
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Network Working Group                                         A. Keranen
Internet-Draft                                                  Ericsson
Intended status: Standards Track                           April 3, 2018
Expires: October 5, 2018

Too Many Requests Response Code for the Constrained Application Protocol
                    draft-ietf-core-too-many-reqs-00

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
   Task Force (IETF).  Note that other groups may also distribute
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on October 5, 2018.

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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   described in the Simplified BSD License.

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Table of Contents

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

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 when a client can try the request again.

   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.

2.  Terminology

   The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL NOT',
   'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'MAY', and 'OPTIONAL' in this
   specification are to be interpreted as described in [RFC2119].

   Readers should also be familiar with the terms and concepts discussed
   in [RFC7252].

3.  CoAP Server Behavior

   If a CoAP server is unable to serve a client that is sending CoAP
   request messages more often than the server is capable or willing to
   handle, the server SHOULD respond to the request(s) with the Response
   Code 4.29, "Too Many Requests".  The Max-Age option is used to

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   indicate the number of seconds after which the server assumes it is
   OK for the client to retry the request.

4.  CoAP Client Behavior

   If a client receives the 4.29 Response Code from a CoAP server to a
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