Re: [core] RFC7252 - PROBING_RATE

Carsten Bormann <cabo@tzi.org> Sun, 04 July 2021 11:31 UTC

Return-Path: <cabo@tzi.org>
X-Original-To: core@ietfa.amsl.com
Delivered-To: core@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id AC5E43A0C47 for <core@ietfa.amsl.com>; Sun, 4 Jul 2021 04:31:27 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.9
X-Spam-Level:
X-Spam-Status: No, score=-1.9 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id W9Y8maJd4GLc for <core@ietfa.amsl.com>; Sun, 4 Jul 2021 04:31:24 -0700 (PDT)
Received: from gabriel-2.zfn.uni-bremen.de (gabriel-2.zfn.uni-bremen.de [134.102.50.19]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 2A61A3A0C44 for <core@ietf.org>; Sun, 4 Jul 2021 04:31:24 -0700 (PDT)
Received: from smtpclient.apple (p548dcc89.dip0.t-ipconnect.de [84.141.204.137]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by gabriel-2.zfn.uni-bremen.de (Postfix) with ESMTPSA id 4GHmqF1MMRz2xGt; Sun, 4 Jul 2021 13:31:21 +0200 (CEST)
Content-Type: text/plain; charset=utf-8
Mime-Version: 1.0 (Mac OS X Mail 14.0 \(3654.100.0.2.22\))
From: Carsten Bormann <cabo@tzi.org>
In-Reply-To: <6e7a8ec1-121c-03ae-8e4a-f615e5b4d83a@gmx.net>
Date: Sun, 4 Jul 2021 13:31:20 +0200
Cc: "core@ietf.org" <core@ietf.org>
Content-Transfer-Encoding: quoted-printable
Message-Id: <DABF494F-E9EE-40CC-8995-E4248B420E30@tzi.org>
References: <6e7a8ec1-121c-03ae-8e4a-f615e5b4d83a@gmx.net>
To: Achim Kraus <achimkraus@gmx.net>
X-Mailer: Apple Mail (2.3654.100.0.2.22)
Archived-At: <https://mailarchive.ietf.org/arch/msg/core/vaKZ5iX6cEG9H8wcJ5hdVmbfWOc>
Subject: Re: [core] RFC7252 - PROBING_RATE
X-BeenThere: core@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: "Constrained RESTful Environments \(CoRE\) Working Group list" <core.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/core>, <mailto:core-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/core/>
List-Post: <mailto:core@ietf.org>
List-Help: <mailto:core-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/core>, <mailto:core-request@ietf.org?subject=subscribe>
X-List-Received-Date: Sun, 04 Jul 2021 11:31:28 -0000

On 4. Jul 2021, at 12:08, Achim Kraus <achimkraus@gmx.net> wrote:
> 
> With both, sending a CON request, e.g. about 20 bytes, and receiving no
> message back for the ACK_TIMEOUT, sending again 20 byte short after
> these 2s seems to violate the PROBING_RATE.

Outside millibit networks, any packet instantaneously exceeds the default value of PROBING_RATE.
So this is indeed meant as an average value over time — an application should not send a sustained rate of more than about 1 B/s to a peer endpoint that might not be reachable (“into thin air”).

> Or may consider, a special
> definition of "average data rate". Assuming, that a "normal CON
> transfer" will then take 62 and sends the 20 bytes 5 times results in
> 1,6 bytes/second.

Indeed, the value chosen for the default PROBING_RATE was oriented after the average rate in which CON retries are sent.

Grüße, Carsten