Re: [tcpm] 793bis: IP ID

Fernando Gont <fgont@si6networks.com> Wed, 22 January 2020 19:05 UTC

Return-Path: <fgont@si6networks.com>
X-Original-To: tcpm@ietfa.amsl.com
Delivered-To: tcpm@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id BDAE9120804 for <tcpm@ietfa.amsl.com>; Wed, 22 Jan 2020 11:05:59 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.9
X-Spam-Level:
X-Spam-Status: No, score=-1.9 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-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 Yx47wFc1uBTg for <tcpm@ietfa.amsl.com>; Wed, 22 Jan 2020 11:05:58 -0800 (PST)
Received: from fgont.go6lab.si (fgont.go6lab.si [91.239.96.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 29C64120802 for <tcpm@ietf.org>; Wed, 22 Jan 2020 11:05:58 -0800 (PST)
Received: from [192.168.100.103] (unknown [186.183.3.105]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by fgont.go6lab.si (Postfix) with ESMTPSA id 040A3860E3; Wed, 22 Jan 2020 20:05:53 +0100 (CET)
To: tcpm@ietf.org
References: <5D669BDA.3000506@erg.abdn.ac.uk> <5D66A044.3060904@erg.abdn.ac.uk> <f4d75224-d7d0-002b-2bca-f93505d6c9d3@mti-systems.com> <4D99C7DD-F57E-4708-8F02-824EB4BF8E24@weston.borman.com> <333A2AF9-7DDD-4FAA-B0BD-E6871564850F@strayalpha.com> <F9E41A50-83FA-477C-8E19-5CE6A58931D3@weston.borman.com>
From: Fernando Gont <fgont@si6networks.com>
Message-ID: <a7080caa-18ce-94ec-3bbf-ae5c8d1bc17c@si6networks.com>
Date: Wed, 22 Jan 2020 16:05:31 -0300
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.1
MIME-Version: 1.0
In-Reply-To: <F9E41A50-83FA-477C-8E19-5CE6A58931D3@weston.borman.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Archived-At: <https://mailarchive.ietf.org/arch/msg/tcpm/vLDY79J5p4K90p5wNYGAbal2mvE>
Subject: Re: [tcpm] 793bis: IP ID
X-BeenThere: tcpm@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: TCP Maintenance and Minor Extensions Working Group <tcpm.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/tcpm>, <mailto:tcpm-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/tcpm/>
List-Post: <mailto:tcpm@ietf.org>
List-Help: <mailto:tcpm-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/tcpm>, <mailto:tcpm-request@ietf.org?subject=subscribe>
X-List-Received-Date: Wed, 22 Jan 2020 19:06:00 -0000

Hi, Dave,

On 20/12/19 17:37, David Borman wrote:
> Yes, the IPID is only used for doing IP fragment reassembly, so the IPID really doesn’t matter on retransmission when IP fragmentation is not possible.

Some boxes are know to clear DF and fragment packets. That's why some 
implementations have resorted to ensure IP ID uniqueness (or try to), 
even when they send packets with DF=1.

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