Re: [DNSOP] draft-tale-dnsop-serve-stale

Jared Mauch <jared@puck.nether.net> Mon, 27 March 2017 22:56 UTC

Return-Path: <jared@puck.nether.net>
X-Original-To: dnsop@ietfa.amsl.com
Delivered-To: dnsop@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id C9B13126BFD for <dnsop@ietfa.amsl.com>; Mon, 27 Mar 2017 15:56:04 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -4.202
X-Spam-Level:
X-Spam-Status: No, score=-4.202 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, RP_MATCHES_RCVD=-0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001, URIBL_BLOCKED=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 UyM7tGnXirSL for <dnsop@ietfa.amsl.com>; Mon, 27 Mar 2017 15:56:03 -0700 (PDT)
Received: from puck.nether.net (puck.nether.net [IPv6:2001:418:3f4::5]) by ietfa.amsl.com (Postfix) with ESMTP id 44035127B52 for <dnsop@ietf.org>; Mon, 27 Mar 2017 15:56:03 -0700 (PDT)
Received: from t2001067c03700128ac2e96399422f6c8.v6.meeting.ietf.org (t2001067c03700128ac2e96399422f6c8.v6.meeting.ietf.org [IPv6:2001:67c:370:128:ac2e:9639:9422:f6c8]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by puck.nether.net (Postfix) with ESMTPSA id E054D5409AD; Mon, 27 Mar 2017 18:55:48 -0400 (EDT)
Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\))
Content-Type: text/plain; charset=us-ascii
From: Jared Mauch <jared@puck.nether.net>
In-Reply-To: <20170327224654.uaijxchvqhdgxb4m@mycre.ws>
Date: Mon, 27 Mar 2017 18:55:36 -0400
Cc: paul vixie <paul@redbarn.org>, dnsop@ietf.org, Dave Lawrence <tale@dd.org>
Content-Transfer-Encoding: quoted-printable
Message-Id: <919241A2-8618-478A-A34A-5F7F1E5A729D@puck.nether.net>
References: <22745.35498.811412.936974@gro.dd.org> <69EA837B-77BE-4202-8BFF-0243CF6AAC07@redbarn.org> <B18C12F9-D3EF-46D7-90D4-E58CEA575966@puck.nether.net> <20170327224654.uaijxchvqhdgxb4m@mycre.ws>
To: Robert Edmonds <edmonds@mycre.ws>
X-Mailer: Apple Mail (2.3124)
Archived-At: <https://mailarchive.ietf.org/arch/msg/dnsop/DEvd4Jti0Nlt3VZZOlShSYL0Ciw>
Subject: Re: [DNSOP] draft-tale-dnsop-serve-stale
X-BeenThere: dnsop@ietf.org
X-Mailman-Version: 2.1.22
Precedence: list
List-Id: IETF DNSOP WG mailing list <dnsop.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/dnsop>, <mailto:dnsop-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/dnsop/>
List-Post: <mailto:dnsop@ietf.org>
List-Help: <mailto:dnsop-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/dnsop>, <mailto:dnsop-request@ietf.org?subject=subscribe>
X-List-Received-Date: Mon, 27 Mar 2017 22:56:05 -0000

> On Mar 27, 2017, at 6:46 PM, Robert Edmonds <edmonds@mycre.ws> wrote:
> 
> Jared Mauch wrote:
>> IOn Mar 27, 2017, at 5:59 PM, P Vix <paul@redbarn.org> wrote:
>>> 
>>> I agree to review and comment. Note that I am provisionally negative to the idea itself, and my review may reflect that. Vixie
>> 
>> 
>> I will note there are other implementations out there as well, such as in unbound.  serve-expired configuration directive is available there as well.
> 
> Though, the algorithm described in this document is a much different
> algorithm than the one in Unbound.

At least the initial implementation is documented (via code) here:

https://github.com/jedisct1/unbound/commit/e03d89343e4031be15b2ee78bd432f83cdc79889


> If I understand Unbound's serve-expired algorithm correctly, it always
> serves from cache if available (regardless of expiration status), and if
> what it served to the client happened to be expired, it triggers a
> post-response fetch to update the cache asynchronously. That can end up
> serving a lot more stale bread than is strictly necessary if your
> Unbound server only serves a few clients.

I see the perceived damage here as very low due to the "few clients" you already
commented on.

- Jared