IETF Logo Mail Archive

[DNSOP] Enough latency obsession Re: Review of draft-ietf-dnsop-cookies-00

Nicholas Weaver <nweaver@icsi.berkeley.edu> Tue, 16 December 2014 19:48 UTC

Return-Path: <nweaver@icsi.berkeley.edu>
X-Original-To: dnsop@ietfa.amsl.com
Delivered-To: dnsop@ietfa.amsl.com
Received: from localhost (ietfa.amsl.com [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 380E81A8739 for <dnsop@ietfa.amsl.com>; Tue, 16 Dec 2014 11:48:44 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: 0.789
X-Spam-Level:
X-Spam-Status: No, score=0.789 tagged_above=-999 required=5 tests=[BAYES_50=0.8, SPF_PASS=-0.001, T_RP_MATCHES_RCVD=-0.01] autolearn=ham
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 1C9raWqzioBH for <dnsop@ietfa.amsl.com>; Tue, 16 Dec 2014 11:48:43 -0800 (PST)
Received: from rock.ICSI.Berkeley.EDU (rock.ICSI.Berkeley.EDU [192.150.186.19]) by ietfa.amsl.com (Postfix) with ESMTP id 19E451A8737 for <dnsop@ietf.org>; Tue, 16 Dec 2014 11:48:43 -0800 (PST)
Received: from localhost (localhost.localdomain [127.0.0.1]) by rock.ICSI.Berkeley.EDU (Postfix) with ESMTP id 13B6A2C4058; Tue, 16 Dec 2014 11:48:43 -0800 (PST)
X-Virus-Scanned: amavisd-new at ICSI.Berkeley.EDU
Received: from rock.ICSI.Berkeley.EDU ([127.0.0.1]) by localhost (maihub.ICSI.Berkeley.EDU [127.0.0.1]) (amavisd-new, port 10024) with LMTP id a+osZDLIyJMq; Tue, 16 Dec 2014 11:48:42 -0800 (PST)
Received: from [172.20.10.3] (192.sub-70-208-146.myvzw.com [70.208.146.192]) (Authenticated sender: nweaver) by rock.ICSI.Berkeley.EDU (Postfix) with ESMTP id E192D2C4049; Tue, 16 Dec 2014 11:48:41 -0800 (PST)
Content-Type: text/plain; charset="us-ascii"
Mime-Version: 1.0 (Mac OS X Mail 8.1 \(1993\))
From: Nicholas Weaver <nweaver@icsi.berkeley.edu>
In-Reply-To: <549069CC.20309@redbarn.org>
Date: Tue, 16 Dec 2014 14:44:40 -0500
Content-Transfer-Encoding: quoted-printable
Message-Id: <EE59F273-8E3F-4F0E-A3AA-B8256DE5B3BD@icsi.berkeley.edu>
References: <20141216152511.GA22255@totoro.home.mukund.org> <20141216171318.GA23468@totoro.home.mukund.org> <549069CC.20309@redbarn.org>
To: Paul Vixie <paul@redbarn.org>
X-Mailer: Apple Mail (2.1993)
Archived-At: http://mailarchive.ietf.org/arch/msg/dnsop/VDpLta7uq90xOG-GibhRUmpGVKM
Cc: dnsop@ietf.org, Mukund Sivaraman <muks@isc.org>, Nicholas Weaver <nweaver@icsi.berkeley.edu>
Subject: [DNSOP] Enough latency obsession Re: Review of draft-ietf-dnsop-cookies-00
X-BeenThere: dnsop@ietf.org
X-Mailman-Version: 2.1.15
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: <http://www.ietf.org/mail-archive/web/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: Tue, 16 Dec 2014 19:48:44 -0000

Its time to stop obsessing over latency in DNS!

DNS doesn't exist in a vacuum, but then goes to at minimum, a TCP handshake, and who knows what else beyond it.  Amdahl's law matters.

How many headaches would go away if all DNS is over TCP?  And how much would it really make a difference in Latency?


> On Dec 16, 2014, at 12:20 PM, Paul Vixie <paul@redbarn.org> wrote:
> 
> 3 round trips, 7 packets, for an isolated tcp/53 query.
> 
> s   ->
>   <- s+a
> a   ->
> q   ->
>   <- r+a
> f+a ->
>   <- f+a
> 
> obviously, the dickenson tcp change proposal bears on this, but today, it's 3 rtt, 7 pkt, and that's assuming that the response fits in one window. axfr is obviously much longer.

And this is wrong:  The f+a RTT doesn't matter, thats AFTER the result has been received.  TCP is 2 RTT to actually get the result.

--
Nicholas Weaver                  it is a tale, told by an idiot,
nweaver@icsi.berkeley.edu                full of sound and fury,
510-666-2903                                 .signifying nothing
PGP: http://www1.icsi.berkeley.edu/~nweaver/data/nweaver_pub.asc

v2.23.0 | Report a Bug | By Email