Re: [v6ops] new draft: draft-taylor-v6ops-fragdrop

Ole Trøan <otroan@employees.org> Thu, 08 November 2012 19:06 UTC

Return-Path: <otroan@employees.org>
X-Original-To: v6ops@ietfa.amsl.com
Delivered-To: v6ops@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 7E01A21F8531 for <v6ops@ietfa.amsl.com>; Thu, 8 Nov 2012 11:06:24 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -10.299
X-Spam-Level:
X-Spam-Status: No, score=-10.299 tagged_above=-999 required=5 tests=[BAYES_00=-2.599, MIME_8BIT_HEADER=0.3, RCVD_IN_DNSWL_HI=-8]
Received: from mail.ietf.org ([64.170.98.30]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id oNaSFRFqSeby for <v6ops@ietfa.amsl.com>; Thu, 8 Nov 2012 11:06:24 -0800 (PST)
Received: from ams-iport-2.cisco.com (ams-iport-2.cisco.com [144.254.224.141]) by ietfa.amsl.com (Postfix) with ESMTP id C78BA21F8507 for <v6ops@ietf.org>; Thu, 8 Nov 2012 11:06:23 -0800 (PST)
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: Av0EAD4CnFCQ/khN/2dsb2JhbABEDsNOgQiCHgEBAQMBEgEnPwULC0ZXBjWHYgabfqA2kXhhA4ham3mBa4IyWw
X-IronPort-AV: E=Sophos;i="4.80,739,1344211200"; d="scan'208";a="78095221"
Received: from ams-core-4.cisco.com ([144.254.72.77]) by ams-iport-2.cisco.com with ESMTP; 08 Nov 2012 19:06:01 +0000
Received: from dhcp-10-61-102-126.cisco.com (dhcp-10-61-102-126.cisco.com [10.61.102.126]) by ams-core-4.cisco.com (8.14.5/8.14.5) with ESMTP id qA8J5xEM023041 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NO); Thu, 8 Nov 2012 19:06:00 GMT
Content-Type: text/plain; charset="us-ascii"
Mime-Version: 1.0 (Mac OS X Mail 6.1 \(1498\))
From: Ole Trøan <otroan@employees.org>
In-Reply-To: <509A8993.4000803@isi.edu>
Date: Thu, 08 Nov 2012 14:05:59 -0500
Content-Transfer-Encoding: quoted-printable
Message-Id: <55E816CE-22B4-4C81-BC8C-61D932782192@employees.org>
References: <CAKD1Yr13cNspdWvTaXxHt4R_8UB-CKeA4nq8_XWrkbFGCgW7Gg@mail.gmail.com> <5090DECF.3050100@gmail.com> <CAKD1Yr1dUy-f78A2+kfA7NjpzD0WQRT8iwqGYAm5A=Erodpn-A@mail.gmail.com> <20121031.122110.41655699.sthaug@nethelp.no> <50910E41.2030100@gmail.com> <CAKD1Yr0mTTcVeq+Qf0fLv3UCBP_90QmStkK3Ha4tDdm3FxJjVA@mail.gmail.com> <50915F86.7050304@gmail.com> <509165B8.404@si6networks.com> <509169C2.9040208@isi.edu> <50916F21.6030303@si6networks.com> <509174F1.8080809@isi.edu> <50924264.7040300@gmail.com> <5092C0BA.4090000@isi.edu> <5092C846.5090009@gmail.com> <5092D5B1.2000201@isi.edu> <509381B3.9040602@gmail.com> <5093CF61.9090301@isi.edu> <509A7922.9080000@gmail.com> <509A8993.4000803@isi.edu>
To: Joe Touch <touch@isi.edu>
X-Mailer: Apple Mail (2.1498)
Cc: Fernando Gont <fgont@si6networks.com>, v6ops@ietf.org
Subject: Re: [v6ops] new draft: draft-taylor-v6ops-fragdrop
X-BeenThere: v6ops@ietf.org
X-Mailman-Version: 2.1.12
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: Thu, 08 Nov 2012 19:06:24 -0000

Joe,

> There's remains other problematic language in 2460, however:
> 
>   Each extension header should occur at most once, except for the
>   Destination Options header which should occur at most twice (once
>   before a Routing header and once before the upper-layer header).
> 
> So it still seems open to have more than one HBH header, which certainly complicates things even though they'd be clearly marked.

I don't see how you can read that to imply you can have more than one Hop-by-Hop extension header.
my reading (and what I think the _intention_ of the text was) is that there can only be one Hop-By-Hop extension header, and
that the HBH header must be the first extension header in the chain. this way routers only need to check the Next Header field
for the value of 0.

cheers,
Ole