Internet DRAFT - draft-keranen-core-too-many-reqs
draft-keranen-core-too-many-reqs
Network Working Group A. Keranen
Internet-Draft Ericsson
Intended status: Standards Track March 19, 2018
Expires: September 20, 2018
Too Many Requests Response Code for the Constrained Application Protocol
draft-keranen-core-too-many-reqs-01
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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 20, 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
Provisions Relating to IETF Documents
(http://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
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Keranen Expires September 20, 2018 [Page 1]
Internet-Draft Too Many Requests Response Code for CoAP March 2018
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
Keranen Expires September 20, 2018 [Page 2]
Internet-Draft Too Many Requests Response Code for CoAP March 2018
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
request, it SHOULD NOT send the same request to the server before the
time indicated in the Max-Age option has passed.
A client MUST NOT rely on a server being able to send the 4.29
Response Code in an overload situation because an overloaded server
may not be able to reply to all requests at all.
5. Security Considerations
Replying to CoAP requests with a Response Code consumes resources
from a server. For a server under attack it may be more appropriate
to simply drop requests without responding.
If a CoAP reply with the Too Many Requests Response Code is not
authenticated and integrity protected, an attacker can attempt to
spoof a reply and make the client wait for an extended period of time
before trying again.
6. IANA Considerations
IANA is requested to register the following Response Code in the
"CoRE Parameters Registry", "CoAP Response Codes" sub-registry:
o Response Code: 4.29
o Description: Too Many Requests
o Reference: [[This document]]
7. Acknowledgements
This Response Code definition was originally part of the "Publish-
Subscribe Broker for CoAP" document [I-D.ietf-core-coap-pubsub].
Author would like to thank Gyorgy Rethy, Klaus Hartke, and Sandor
Katona for their contributions and reviews.
8. References
Keranen Expires September 20, 2018 [Page 3]
Internet-Draft Too Many Requests Response Code for CoAP March 2018
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
RFC2119, March 1997, <https://www.rfc-editor.org/info/
rfc2119>.
[RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
Application Protocol (CoAP)", RFC 7252, DOI 10.17487/
RFC7252, June 2014, <https://www.rfc-editor.org/info/
rfc7252>.
8.2. Informative References
[I-D.ietf-core-coap-pubsub]
Koster, M., Keranen, A., and J. Jimenez, "Publish-
Subscribe Broker for the Constrained Application Protocol
(CoAP)", draft-ietf-core-coap-pubsub-04 (work in
progress), March 2018.
[RFC6585] Nottingham, M. and R. Fielding, "Additional HTTP Status
Codes", RFC 6585, DOI 10.17487/RFC6585, April 2012,
<https://www.rfc-editor.org/info/rfc6585>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing", RFC
7230, DOI 10.17487/RFC7230, June 2014, <https://www.rfc-
editor.org/info/rfc7230>.
Author's Address
Ari Keranen
Ericsson
Email: ari.keranen@ericsson.com
Keranen Expires September 20, 2018 [Page 4]
