Re: [core] RFC 7252 - 8.2 - Multicast - Request / Response Layer, page 67, top

Thomas Fossati <tho.ietf@gmail.com> Thu, 02 April 2020 10:19 UTC

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From: Thomas Fossati <tho.ietf@gmail.com>
Date: Thu, 2 Apr 2020 11:19:37 +0100
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To: Esko Dijk <esko.dijk@iotconsultancy.nl>
Cc: Jim Schaad <ietf@augustcellars.com>, Klaus Hartke <hartke@projectcool.de>, "core@ietf.org" <core@ietf.org>
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Subject: Re: [core] RFC 7252 - 8.2 - Multicast - Request / Response Layer, page 67, top
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On Wed, Apr 1, 2020 at 9:19 AM Esko Dijk <esko.dijk@iotconsultancy.nl> wrote:
> Because (to me) this is not fully compatible with the definitions of
> "endpoint" and messaging model in RFC 7252 that I quoted, it would be
> good to clarify this aspect more in draft-ietf-core-groupcomm-bis i.e.
> refine the RFC 7252 endpoint definitions for the multicast case and
> clarify the multicast messaging model.

+1

Ideally, this new "multicast CoAP endpoint" definition should also
include an explanation why source address and port of the unicast
response are irrelevant to the successful processing at the client.

If we can express that clearly I don't think we need "SHOULD keep the
same UDP port": an implementation is left with its own local choice.

As a bonus we could also have implementation (in which scenario port
translation is a useful technique) as well as operational considerations
(Achim's wireshark filtering argument).

My two cents,
cheers!