Re: [VRRP] Fwd: RFC5798 - clarification on checksum calculation

"Nair, Anoop Govindan" <anoop.g@hp.com> Thu, 17 May 2012 04:16 UTC

Return-Path: <anoop.g@hp.com>
X-Original-To: vrrp@ietfa.amsl.com
Delivered-To: vrrp@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 67D9311E808E for <vrrp@ietfa.amsl.com>; Wed, 16 May 2012 21:16:14 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -110.599
X-Spam-Level:
X-Spam-Status: No, score=-110.599 tagged_above=-999 required=5 tests=[BAYES_00=-2.599, RCVD_IN_DNSWL_HI=-8, USER_IN_WHITELIST=-100]
Received: from mail.ietf.org ([12.22.58.30]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id dzsUtTRRf5CT for <vrrp@ietfa.amsl.com>; Wed, 16 May 2012 21:16:13 -0700 (PDT)
Received: from g4t0016.houston.hp.com (g4t0016.houston.hp.com [15.201.24.19]) by ietfa.amsl.com (Postfix) with ESMTP id DA4E911E8089 for <vrrp@ietf.org>; Wed, 16 May 2012 21:16:12 -0700 (PDT)
Received: from G6W1798G.americas.hpqcorp.net (g6w1798g.atlanta.hp.com [16.230.17.175]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by g4t0016.houston.hp.com (Postfix) with ESMTPS id 13E6414715; Thu, 17 May 2012 04:16:10 +0000 (UTC)
Received: from G6W0644.americas.hpqcorp.net (16.230.34.80) by G6W1798G.americas.hpqcorp.net (16.230.17.175) with Microsoft SMTP Server (TLS) id 14.2.283.4; Thu, 17 May 2012 04:13:25 +0000
Received: from GVW1105EXC.americas.hpqcorp.net ([16.230.34.94]) by G6W0644.americas.hpqcorp.net ([16.230.34.80]) with mapi; Thu, 17 May 2012 05:13:25 +0100
From: "Nair, Anoop Govindan" <anoop.g@hp.com>
To: Hermin Anggawijaya <hermin.anggawijaya@gmail.com>, "vrrp@ietf.org" <vrrp@ietf.org>
Date: Thu, 17 May 2012 05:13:21 +0100
Thread-Topic: [VRRP] Fwd: RFC5798 - clarification on checksum calculation
Thread-Index: Ac0y4ChGqFPlRYRfQ/WGVb4k5amguQBAu0qQ
Message-ID: <D1917596EC5A6045810BC9BDA0B0E16244C9D3D4EE@GVW1105EXC.americas.hpqcorp.net>
References: <20120515024148.38FF8108E26@melchior.iij.ad.jp> <CAJgsEzXL5iRqwGuea0OEpa9cUYOQtA=rv957bGh+NzYb4c8bgg@mail.gmail.com> <CAJgsEzWTSsc2=O3=93mAuhn+ETcHn8LgHfikbrZOLSAq3S7WGA@mail.gmail.com>
In-Reply-To: <CAJgsEzWTSsc2=O3=93mAuhn+ETcHn8LgHfikbrZOLSAq3S7WGA@mail.gmail.com>
Accept-Language: en-US
Content-Language: en-US
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
acceptlanguage: en-US
Content-Type: text/plain; charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
Subject: Re: [VRRP] Fwd: RFC5798 - clarification on checksum calculation
X-BeenThere: vrrp@ietf.org
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: Virtual Router Redundancy Protocol <vrrp.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/vrrp>, <mailto:vrrp-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/vrrp>
List-Post: <mailto:vrrp@ietf.org>
List-Help: <mailto:vrrp-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/vrrp>, <mailto:vrrp-request@ietf.org?subject=subscribe>
X-List-Received-Date: Thu, 17 May 2012 04:16:14 -0000

My interpretation of the specification is that for IPv4 checksum is calculated without pseudo-header.

It would be nice if RFC authors can clarify.

Regards,

-----Original Message-----
From: vrrp-bounces@ietf.org [mailto:vrrp-bounces@ietf.org] On Behalf Of Hermin Anggawijaya
Sent: Wednesday, May 16, 2012 2:47 AM
To: vrrp@ietf.org
Subject: [VRRP] Fwd: RFC5798 - clarification on checksum calculation

Hello

I am thinking of submitting an errata for RFC 5798 Sec. 5.2.8 to make
it more precise in describing the checksum calculation for each address family.

But reading a few responses here, I gathered that there is no general
agreement as to the original intention of the text,
I believe that for IPv4, the checksum is calculated without
pseudo-header so that it is backward compatible with RFC 3768.

Any other opinions - particularly from original authors ?


Kind Regards

Hermin Anggawijaya



On Tue, May 15, 2012 at 2:41 PM,  <kura@iij.ad.jp>; wrote:
> Hello list,
>
> Has there been any progress with regard to this topic?
> I know that in an implementation of VRRPv3 for IPv4 the checksum
> is calculated without pseudo-header currently, but I believe that
> pseudo-header should be involved in the calculation as same as
> IPv6 case.
>
> Regards,
> --
> Tomohiko Kurahashi <kura@iij.ad.jp>;
>
>
> From: sahara@surt.net
> Date: Mon Apr 02 2012 20:41:51 JST
>>
>> Forwarded.
>> Any other VRRPv3/IPv4 implementation?
>>
>>
>> Thanks,
>> Tomoyuki
>>
>>
>> Date: Mon, 2 Apr 2012 03:26:15 +0200
>> Subject: Re: [VRRP] RFC5798 - clarification on checksum calculation
>> From: Hermin Anggawijaya <hermin.anggawijaya@gmail.com>;
>> To: Tomoyuki Sahara <sahara@surt.net>;
>>
>> Sahara-san
>>
>> Thanks for your input.
>>
>> Anyone else with either/other interpretation of the clause ?
>>
>>
>> Thanks
>>
>> On Mon, Apr 2, 2012 at 1:48 AM, Tomoyuki Sahara <sahara@surt.net>; wrote:
>> > Hi,
>> >
>> > On Thu, Mar 29, 2012 at 4:29 PM, Hermin Anggawijaya
>> > <hermin.anggawijaya@gmail.com>; wrote:
>> >> Would someone be able to help clarifying RFC5798 Sec. 5.2.8 on
>> >> checksum for me please...
>> >>
>> >> It says that
>> >>
>> >>  "The checksum is the 16-bit one's complement of the one's complement
>> >>   sum of the entire VRRP message starting with the version field and a
>> >>   "pseudo-header" as defined in Section 8.1 of [RFC2460].  The next
>> >>   header field in the "pseudo-header" should be set to 112 (decimal)
>> >>   for VRRP.  For computing the checksum, the checksum field is set to
>> >>   zero.  See RFC1071 for more detail [RFC1071]."
>> >>
>> >> My interpretation of the above clause is, for IPv4 VRRP the checksum would be
>> >> defined as:
>> >>
>> >> "The checksum is the 16-bit one's complement of the one's complement
>> >>  sum of the entire VRRP message starting with the version field"
>> >>
>> >> as per RFC 3768, instead of involving "pseudo header" (as defined in
>> >> Section 8.1 of [RFC2460]).
>> >
>> > My understanding is only reference text ("as defined in Section 8.1 of
>> > [RFC2460]") is irrelevant for IPv4.  Our implementation calculates checksum
>> > including pseudo header as for TCP/UDP/DCCP.
>> >
>> >> If my interpretation is correct, would it be useful to change the text to
>> >> reflect specific checksum detail for IPv4 ?
>> >
>> > My interpretation is different from yours but clarification should be
>> > very useful.
>> > It's vital for interoperable implementations of VRRPv3/IPv4.
>> >
>> >
>> > Thanks,
>> > Tomoyuki
> _______________________________________________
> vrrp mailing list
> vrrp@ietf.org
> https://www.ietf.org/mailman/listinfo/vrrp
_______________________________________________
vrrp mailing list
vrrp@ietf.org
https://www.ietf.org/mailman/listinfo/vrrp