draft-ietf-core-too-many-reqs-01.txt   draft-ietf-core-too-many-reqs-02.txt 
Network Working Group A. Keranen Network Working Group A. Keranen
Internet-Draft Ericsson Internet-Draft Ericsson
Intended status: Standards Track June 29, 2018 Intended status: Standards Track July 2, 2018
Expires: December 31, 2018 Expires: January 3, 2019
Too Many Requests Response Code for the Constrained Application Protocol Too Many Requests Response Code for the Constrained Application Protocol
draft-ietf-core-too-many-reqs-01 draft-ietf-core-too-many-reqs-02
Abstract Abstract
A Constrained Application Protocol (CoAP) server can experience A Constrained Application Protocol (CoAP) server can experience
temporary overload because one or more clients are sending requests 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 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 to handle. This document defines a new CoAP Response Code for a
server to indicate that a client should reduce the rate of requests. server to indicate that a client should reduce the rate of requests.
Status of This Memo Status of This Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 31, 2018. This Internet-Draft will expire on January 3, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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publication of this document. Please review these documents publication of this document. Please review these documents
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include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. CoAP Server Behavior . . . . . . . . . . . . . . . . . . . . 2 3. CoAP Server Behavior . . . . . . . . . . . . . . . . . . . . 3
4. CoAP Client Behavior . . . . . . . . . . . . . . . . . . . . 3 4. CoAP Client Behavior . . . . . . . . . . . . . . . . . . . . 3
5. Security Considerations . . . . . . . . . . . . . . . . . . . 3 5. Security Considerations . . . . . . . . . . . . . . . . . . . 3
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 3 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
8.1. Normative References . . . . . . . . . . . . . . . . . . 4 8.1. Normative References . . . . . . . . . . . . . . . . . . 4
8.2. Informative References . . . . . . . . . . . . . . . . . 4 8.2. Informative References . . . . . . . . . . . . . . . . . 4
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 4 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction 1. Introduction
The Constrained Application Protocol (CoAP) [RFC7252] Response Codes The Constrained Application Protocol (CoAP) [RFC7252] Response Codes
are used by a CoAP server to indicate the result of the attempt to are used by a CoAP server to indicate the result of the attempt to
understand and satisfy a request sent by a client. understand and satisfy a request sent by a client.
CoAP Response Codes are similar to the HTTP [RFC7230] Status Codes CoAP Response Codes are similar to the HTTP [RFC7230] Status Codes
and many codes are shared with similar semantics by both CoAP and and many codes are shared with similar semantics by both CoAP and
HTTP. HTTP has the code "429" registered for "Too Many Requests" HTTP. HTTP has the code "429" registered for "Too Many Requests"
[RFC6585]. This document registers a CoAP Response Code "4.29" for [RFC6585]. This document registers a CoAP Response Code "4.29" for
similar purpose and also defines use of the Max-Age option to similar purpose and also defines use of the Max-Age option to
indicate when a client can try the request again. 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] 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 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 signal an overload situation. However the 4.29 code indicates that
the too frequent requests from the requesting client are the reason the too frequent requests from the requesting client are the reason
for the overload. for the overload.
2. Terminology 2. Terminology
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL NOT', The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL NOT',
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indicate the number of seconds after which the server assumes it is indicate the number of seconds after which the server assumes it is
OK for the client to retry the request. OK for the client to retry the request.
An action result payload (see Section 5.5.1 in [RFC7252]) can be sent An action result payload (see Section 5.5.1 in [RFC7252]) can be sent
by the server to give more guidance to the client, e.g., about the by the server to give more guidance to the client, e.g., about the
details of the overload situation. details of the overload situation.
4. CoAP Client Behavior 4. CoAP Client Behavior
If a client receives the 4.29 Response Code from a CoAP server to a 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 request, it SHOULD NOT send a similar request to the server before
time indicated in the Max-Age option has passed. 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 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 Response Code in an overload situation because an overloaded server
may not be able to reply to all requests at all. may not be able to reply to all requests at all.
5. Security Considerations 5. Security Considerations
Replying to CoAP requests with a Response Code consumes resources Replying to CoAP requests with a Response Code consumes resources
from a server. For a server under attack it may be more appropriate from a server. For a server under attack it may be more appropriate
to simply drop requests without responding. to simply drop requests without responding.
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o Response Code: 4.29 o Response Code: 4.29
o Description: Too Many Requests o Description: Too Many Requests
o Reference: [[This document]] o Reference: [[This document]]
7. Acknowledgements 7. Acknowledgements
This Response Code definition was originally part of the "Publish- This Response Code definition was originally part of the "Publish-
Subscribe Broker for CoAP" document [I-D.ietf-core-coap-pubsub]. Subscribe Broker for CoAP" document [I-D.ietf-core-coap-pubsub].
Author would like to thank Carsten Bormann, Gyorgy Rethy, Klaus Author would like to thank Abhijan Bhattacharyya, Carsten Bormann,
Hartke, and Sandor Katona for their contributions and reviews. Gyorgy Rethy, Klaus Hartke, and Sandor Katona for their contributions
and reviews.
8. References 8. References
8.1. Normative References 8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/ Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
RFC2119, March 1997, <https://www.rfc-editor.org/info/ RFC2119, March 1997, <https://www.rfc-editor.org/info/
rfc2119>. rfc2119>.
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