Re: [babel] info model: configurability of intervals

Juliusz Chroboczek <jch@irif.fr> Fri, 26 February 2021 19:31 UTC

Return-Path: <jch@irif.fr>
X-Original-To: babel@ietfa.amsl.com
Delivered-To: babel@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 19FA83A15B7 for <babel@ietfa.amsl.com>; Fri, 26 Feb 2021 11:31:11 -0800 (PST)
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 9z1QyIRJ68ro for <babel@ietfa.amsl.com>; Fri, 26 Feb 2021 11:31:09 -0800 (PST)
Received: from korolev.univ-paris7.fr (korolev.univ-paris7.fr [IPv6:2001:660:3301:8000::1:2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 5BD3E3A15B6 for <babel@ietf.org>; Fri, 26 Feb 2021 11:31:08 -0800 (PST)
Received: from potemkin.univ-paris7.fr (potemkin.univ-paris7.fr [IPv6:2001:660:3301:8000::1:1]) by korolev.univ-paris7.fr (8.14.4/8.14.4/relay1/82085) with ESMTP id 11QJV5C7024500 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Fri, 26 Feb 2021 20:31:05 +0100
Received: from mailhub.math.univ-paris-diderot.fr (mailhub.math.univ-paris-diderot.fr [81.194.30.253]) by potemkin.univ-paris7.fr (8.14.4/8.14.4/relay2/82085) with ESMTP id 11QJV5bf017514; Fri, 26 Feb 2021 20:31:05 +0100
Received: from mailhub.math.univ-paris-diderot.fr (localhost [127.0.0.1]) by mailhub.math.univ-paris-diderot.fr (Postfix) with ESMTP id 99FFC108471; Fri, 26 Feb 2021 20:31:05 +0100 (CET)
X-Virus-Scanned: amavisd-new at math.univ-paris-diderot.fr
Received: from mailhub.math.univ-paris-diderot.fr ([127.0.0.1]) by mailhub.math.univ-paris-diderot.fr (mailhub.math.univ-paris-diderot.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id 6GYjeSWczqqs; Fri, 26 Feb 2021 20:31:03 +0100 (CET)
Received: from pirx.irif.fr (unknown [78.194.40.74]) (Authenticated sender: jch) by mailhub.math.univ-paris-diderot.fr (Postfix) with ESMTPSA id 9152B10846F; Fri, 26 Feb 2021 20:31:03 +0100 (CET)
Date: Fri, 26 Feb 2021 20:31:03 +0100
Message-ID: <87czwmiq2w.wl-jch@irif.fr>
From: Juliusz Chroboczek <jch@irif.fr>
To: "STARK, BARBARA H" <bs7652@att.com>
Cc: "'babel@ietf.org'" <babel@ietf.org>
In-Reply-To: <DM6PR02MB6924C2CF2ACCCFD1FDBE0C23C39F9@DM6PR02MB6924.namprd02.prod.outlook.com>
References: <DM6PR02MB6924C2CF2ACCCFD1FDBE0C23C39F9@DM6PR02MB6924.namprd02.prod.outlook.com>
User-Agent: Wanderlust/2.15.9 (Almost Unreal) Emacs/27.1 Mule/6.0
MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue")
Content-Type: text/plain; charset=US-ASCII
X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (korolev.univ-paris7.fr [IPv6:2001:660:3301:8000::1:2]); Fri, 26 Feb 2021 20:31:05 +0100 (CET)
X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (potemkin.univ-paris7.fr [194.254.61.141]); Fri, 26 Feb 2021 20:31:05 +0100 (CET)
X-Miltered: at korolev with ID 60394C79.000 by Joe's j-chkmail (http : // j-chkmail dot ensmp dot fr)!
X-Miltered: at potemkin with ID 60394C79.001 by Joe's j-chkmail (http : // j-chkmail dot ensmp dot fr)!
X-j-chkmail-Enveloppe: 60394C79.000 from potemkin.univ-paris7.fr/potemkin.univ-paris7.fr/null/potemkin.univ-paris7.fr/<jch@irif.fr>
X-j-chkmail-Enveloppe: 60394C79.001 from mailhub.math.univ-paris-diderot.fr/mailhub.math.univ-paris-diderot.fr/null/mailhub.math.univ-paris-diderot.fr/<jch@irif.fr>
X-j-chkmail-Score: MSGID : 60394C79.000 on korolev.univ-paris7.fr : j-chkmail score : . : R=. U=. O=. B=0.000 -> S=0.000
X-j-chkmail-Score: MSGID : 60394C79.001 on potemkin.univ-paris7.fr : j-chkmail score : . : R=. U=. O=. B=0.000 -> S=0.000
X-j-chkmail-Status: Ham
X-j-chkmail-Status: Ham
Archived-At: <https://mailarchive.ietf.org/arch/msg/babel/PodsojJoe-dgZmwcGg5dZZqIQYI>
Subject: Re: [babel] info model: configurability of intervals
X-BeenThere: babel@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: "A list for discussion of the Babel Routing Protocol." <babel.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/babel>, <mailto:babel-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/babel/>
List-Post: <mailto:babel@ietf.org>
List-Help: <mailto:babel-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/babel>, <mailto:babel-request@ietf.org?subject=subscribe>
X-List-Received-Date: Fri, 26 Feb 2021 19:31:11 -0000

> Juliusz indicates in this that IHU intervals are dynamically computed.

In babeld, the IHU interval is equal to the update interval on lossy
links, and equal to three times the update interval on lossless links.
(On lossless links, the IHU is essentially repeating "this link is still
lossless", so it may be suppressed with no ill effect; on lossy links, it
is used to update the link cost in a timely manner.)

> I can't find it in any of the emails, but I think somehow there was
> a determination that configuration of all intervals was done by the
> implementation based on costs/metrics, and that no *external*
> configuration of intervals was supported (or desirable). Is that
> accurate, or should intervals be configurable via the info/data models?

I am concerned that making these values writable will constrain
implementations to use static intervals.  The protocol is very carefully
engineered to make dynamic intervals usable.  (If the intervals are
static, then the Hello seqno, for example, serves no useful purpose.)

-- Juliusz