IETF Logo Mail Archive

Re: [v6ops] PMTUD issue discussion

"Templin, Fred L" <Fred.L.Templin@boeing.com> Tue, 26 August 2014 16:34 UTC

Return-Path: <Fred.L.Templin@boeing.com>
X-Original-To: v6ops@ietfa.amsl.com
Delivered-To: v6ops@ietfa.amsl.com
Received: from localhost (ietfa.amsl.com [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id BA6361A0066 for <v6ops@ietfa.amsl.com>; Tue, 26 Aug 2014 09:34:03 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -4.569
X-Spam-Level:
X-Spam-Status: No, score=-4.569 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, MIME_8BIT_HEADER=0.3, RCVD_IN_DNSWL_MED=-2.3, RP_MATCHES_RCVD=-0.668, SPF_PASS=-0.001] 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 YDpOeeGIEsZp for <v6ops@ietfa.amsl.com>; Tue, 26 Aug 2014 09:34:02 -0700 (PDT)
Received: from stl-mbsout-02.boeing.com (stl-mbsout-02.boeing.com [130.76.96.170]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id EB1C91A0024 for <v6ops@ietf.org>; Tue, 26 Aug 2014 09:34:01 -0700 (PDT)
Received: from localhost (localhost [127.0.0.1]) by stl-mbsout-02.boeing.com (8.14.4/8.14.4/DOWNSTREAM_MBSOUT) with SMTP id s7QGY1FC012719; Tue, 26 Aug 2014 11:34:01 -0500
Received: from XCH-PHX-309.sw.nos.boeing.com (xch-phx-309.sw.nos.boeing.com [130.247.25.163]) by stl-mbsout-02.boeing.com (8.14.4/8.14.4/UPSTREAM_MBSOUT) with ESMTP id s7QGXsYW012635 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=OK); Tue, 26 Aug 2014 11:33:55 -0500
Received: from XCH-BLV-404.nw.nos.boeing.com (2002:82f7:199d::82f7:199d) by XCH-PHX-309.sw.nos.boeing.com (2002:82f7:19a3::82f7:19a3) with Microsoft SMTP Server (TLS) id 14.3.181.6; Tue, 26 Aug 2014 09:33:54 -0700
Received: from XCH-BLV-504.nw.nos.boeing.com ([169.254.4.6]) by XCH-BLV-404.nw.nos.boeing.com ([169.254.4.121]) with mapi id 14.03.0181.006; Tue, 26 Aug 2014 09:33:54 -0700
From: "Templin, Fred L" <Fred.L.Templin@boeing.com>
To: Fernando Gont <fgont@si6networks.com>, "Fred Baker (fred)" <fred@cisco.com>, Andrew 👽 Yourtchenko <ayourtch@gmail.com>
Thread-Topic: [v6ops] PMTUD issue discussion
Thread-Index: AQHPwUNN3jcR+fTlj0+il5BtQavN3ZvjBboAgACAAAD//432MA==
Date: Tue, 26 Aug 2014 16:33:53 +0000
Message-ID: <2134F8430051B64F815C691A62D9831832CFCACA@XCH-BLV-504.nw.nos.boeing.com>
References: <0D370E74-688B-4EB3-A691-309A03AF20BA@cisco.com> <53FBA174.2040302@isi.edu> <53FBA6E1.90905@bogus.com> <CAPi140PMeM9omtm11+NHa2ywUfof_tE7HknKExtoEb32mm7L_w@mail.gmail.com> <71D0D5E8-80E9-430B-8ED4-16C1F99082CC@cisco.com> <53FCA926.9080206@si6networks.com> <2134F8430051B64F815C691A62D9831832CFC96E@XCH-BLV-504.nw.nos.boeing.com> <53FCB378.6060209@si6networks.com>
In-Reply-To: <53FCB378.6060209@si6networks.com>
Accept-Language: en-US
Content-Language: en-US
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
x-originating-ip: [130.247.104.6]
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: base64
MIME-Version: 1.0
X-TM-AS-MML: disable
Archived-At: http://mailarchive.ietf.org/arch/msg/v6ops/F8oVxj7rPOEW1RhR8buQlNvuQbI
Cc: IPv6 Ops WG <v6ops@ietf.org>
Subject: Re: [v6ops] PMTUD issue discussion
X-BeenThere: v6ops@ietf.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: v6ops discussion list <v6ops.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/v6ops>, <mailto:v6ops-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/v6ops/>
List-Post: <mailto:v6ops@ietf.org>
List-Help: <mailto:v6ops-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/v6ops>, <mailto:v6ops-request@ietf.org?subject=subscribe>
X-List-Received-Date: Tue, 26 Aug 2014 16:34:04 -0000

Hi Fernando,

> -----Original Message-----
> From: Fernando Gont [mailto:fgont@si6networks.com]
> Sent: Tuesday, August 26, 2014 9:19 AM
> To: Templin, Fred L; Fred Baker (fred); Andrew 👽 Yourtchenko
> Cc: IPv6 Ops WG
> Subject: Re: [v6ops] PMTUD issue discussion
> 
> On 08/26/2014 12:42 PM, Templin, Fred L wrote:
> >> On 08/26/2014 12:13 PM, Fred Baker (fred) wrote:
> >>>> I think it would be useful to see the discussion of this measure
> >>>> and its applicability/tradeoffs in the draft.
> >>>
> >>> It seems like it might have value to also test the interaction
> >>> with various initial window settings, and look at its inclusion in
> >>> other relevant OS’s including FreeBSD, Windows, and MacOSX.
> >>
> >> FWIW, while RFC4821 can work without relying on PLPMTUD at all, some
> >> OSes (such as Windows) only fall back to ICMP-less PMTUD as part of
> >> "ICMP blackhole detecion" -- and they have been doing this for years
> >> now...
> >
> > I think the point is that PLPMTUD is not well supported in modern
> > OSes in the spirit in which it was specified in RFC4821. That
> > needs to change.
> 
> FWIW, I'm all in favor of RFC4821, since it improves robustness of PMTUD.
> 
> That said, as far as I can recall, using RFC4821 for blackhole detection
> (when traditional PMTUD fails) is well within the spirit of RFC4821
> (RFC4821 doesn't push ICMP-less as the only implementation strategy).
> 
> What I recall from discussing this with Linux developers circa 2005 is
> that a complete ICMP-less PMTUD is rather undesirable, since it tends to
> have longer convergence time when compared with "traditional PMTUD" ||
> "Traditional PMTUD + RFC4821 for blachole detection".

Accepting and processing PTBs as part of the PLPMTUD procedure is
desirable and speeds convergence. But, the mechanism still needs to
work when there are no PTBs.

So, the network should still do its best to return PTBs, and hosts
should still do their best to observe them.

Thanks - Fred
fred.l.templin@boeing.com

> Thanks,
> --
> Fernando Gont
> SI6 Networks
> e-mail: fgont@si6networks.com
> PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492
> 
> 
>

v2.23.0 | Report a Bug | By Email