Constrained Application Protocol (CoAP) Hop Limit Option
draft-ietf-core-hop-limit-00

Document Type Active Internet-Draft (core WG)
Last updated 2018-09-17
Replaces draft-boucadair-core-hop-limit
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CORE                                                        M. Boucadair
Internet-Draft                                                    Orange
Intended status: Standards Track                                T. Reddy
Expires: March 21, 2019                                           McAfee
                                                              J. Shallow
                                                               NCC Group
                                                      September 17, 2018

        Constrained Application Protocol (CoAP) Hop Limit Option
                      draft-ietf-core-hop-limit-00

Abstract

   The presence of Constrained Application Protocol (CoAP) proxies may
   lead to infinite forwarding loops, which is undesirable.  To prevent
   and detect such loops, this document specifies the Hop-Limit CoAP
   option.

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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   Drafts is at https://datatracker.ietf.org/drafts/current/.

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   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 March 21, 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
   Provisions Relating to IETF Documents
   (https://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

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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Hop-Limit Option  . . . . . . . . . . . . . . . . . . . . . .   3
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
     4.1.  CoAP Response Code  . . . . . . . . . . . . . . . . . . .   4
     4.2.  CoAP Option Number  . . . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   More and more applications are using Constrained Application Protocol
   (CoAP) [RFC7252] as a communication protocol between involved
   application agents.  For example, [I-D.ietf-dots-signal-channel]
   specifies how CoAP is used as a distributed denial-of-service (DDoS)
   attack signaling protocol seeking for help from DDoS mitigation
   providers.  In such contexts, a CoAP client can communicate directly
   with a server or indirectly via proxies.

   When multiple proxies are involved, infinite forwarding loops may be
   experienced.  To prevent such loops, this document defines a new CoAP
   option, called Hop-Limit, which is inserted in particular by on-path
   proxies.  Also, the document defines a new CoAP Response Code to
   report loops together with relevant diagnostic information to ease
   troubleshooting.

2.  Terminology

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

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

   Within this document, CoAP agent refers to both CoAP client and CoAP
   proxy.

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3.  Hop-Limit Option

   Hop-Limit option (see Section 4.2) is an elective option used to
   detect and prevent infinite loops when proxies are involved.  Only
   one single instance of the option is allowed in a message.
   Therefore, any message carrying multiple Hop-Limit option instances
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