Proxy Operations for CoAP Group Communication
draft-tiloca-core-groupcomm-proxy-00

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CoRE Working Group                                             M. Tiloca
Internet-Draft                                                   RISE AB
Intended status: Standards Track                                 E. Dijk
Expires: September 10, 2020                            IoTconsultancy.nl
                                                          March 09, 2020

             Proxy Operations for CoAP Group Communication
                  draft-tiloca-core-groupcomm-proxy-00

Abstract

   This document specifies the operations performed by a forward-proxy,
   when using the Constrained Application Protocol (CoAP) in group
   communication scenarios.  Proxy operations involve the processing of
   individual responses from servers, as reply to a single request sent
   by the client over unicast to the proxy, and then distributed by the
   proxy over IP multicast to the servers.  When receiving the different
   responses via the proxy, the client is able to distinguish them and
   their originator servers, by acquiring their addressing information.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  The Multicast-Signaling Option  . . . . . . . . . . . . . . .   3
   3.  The Response-Forwarding Option  . . . . . . . . . . . . . . .   4
   4.  Requirements and Objectives . . . . . . . . . . . . . . . . .   5
   5.  Protocol Description  . . . . . . . . . . . . . . . . . . . .   6
     5.1.  Request Sending . . . . . . . . . . . . . . . . . . . . .   6
     5.2.  Request Processing at the Proxy . . . . . . . . . . . . .   7
     5.3.  Request and Response Processing at the Server . . . . . .   8
     5.4.  Response Processing at the Proxy  . . . . . . . . . . . .   8
     5.5.  Response Processing at the Client . . . . . . . . . . . .   9
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
     7.1.  CoAP Option Numbers Registry  . . . . . . . . . . . . . .  10
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  12
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   The Constrained Application Protocol (CoAP) [RFC7252] allows the
   presence of forward-proxies, as intermediary entities supporting
   clients to perform requests on their behalf.

   CoAP supports also group communication over IP multicast
   [I-D.dijk-core-groupcomm-bis], where a group request can be addressed
   to multiple recipient servers, each of which may reply with an
   individual unicast response.  As discussed in Section 2.3.3 of
   [I-D.dijk-core-groupcomm-bis], this group communication scenario
   poses a number of issues and limitations to proxy operations.

   In particular, the client sends a single unicast request to the
   proxy, which the proxy forwards to a group of servers over IP
   multicast.  Later on, the proxy delivers back to the client multiple
   responses to the original unicast request.  As defined by [RFC7252]
   the multiple responses are delivered to the client inside separate
   CoAP messages, all matching (by Token) to the client's original
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