From owner-svn-src-head@FreeBSD.ORG  Thu Apr  2 18:46:33 2015
Return-Path: <owner-svn-src-head@FreeBSD.ORG>
Delivered-To: svn-src-head@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115])
 (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits))
 (No client certificate requested)
 by hub.freebsd.org (Postfix) with ESMTPS id 9D84758C;
 Thu,  2 Apr 2015 18:46:33 +0000 (UTC)
Received: from cyrus.watson.org (cyrus.watson.org [198.74.231.69])
 by mx1.freebsd.org (Postfix) with ESMTP id 6A524C0;
 Thu,  2 Apr 2015 18:46:33 +0000 (UTC)
Received: from fledge.watson.org (fledge.watson.org [198.74.231.63])
 by cyrus.watson.org (Postfix) with ESMTPS id 1276D46B66;
 Thu,  2 Apr 2015 14:46:33 -0400 (EDT)
Date: Thu, 2 Apr 2015 19:46:32 +0100 (BST)
From: Robert Watson <rwatson@FreeBSD.org>
X-X-Sender: robert@fledge.watson.org
To: Hans Petter Selasky <hps@selasky.org>
Subject: Re: svn commit: r280971 - in head: contrib/ipfilter/tools
 share/man/man4
 sys/contrib/ipfilter/netinet sys/netinet sys/netipsec sys/netpfil/pf
In-Reply-To: <551D8C6C.9060504@selasky.org>
Message-ID: <alpine.BSF.2.11.1504021939390.64391@fledge.watson.org>
References: <201504012226.t31MQedN044443@svn.freebsd.org>
 <1427929676.82583.103.camel@freebsd.org> <20150402123522.GC64665@FreeBSD.org>
 <20150402133751.GA549@dft-labs.eu> <20150402134217.GG64665@FreeBSD.org>
 <20150402135157.GB549@dft-labs.eu>
 <1427983109.82583.115.camel@freebsd.org> <20150402142318.GC549@dft-labs.eu>
 <20150402143420.GI64665@FreeBSD.org> <20150402153805.GD549@dft-labs.eu>
 <alpine.BSF.2.11.1504021657440.27263@fledge.watson.org>
 <551D8143.4060509@selasky.org> <551D8945.8050906@selasky.org>
 <8900318B-8155-4131-A0C3-3DE169782EFC@FreeBSD.org>
 <551D8C6C.9060504@selasky.org>
User-Agent: Alpine 2.11 (BSF 23 2013-08-11)
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed
Cc: Mateusz Guzik <mjguzik@gmail.com>, Ian Lepore <ian@freebsd.org>,
 svn-src-all@freebsd.org, src-committers@freebsd.org,
 Gleb Smirnoff <glebius@FreeBSD.org>, svn-src-head@freebsd.org
X-BeenThere: svn-src-head@freebsd.org
X-Mailman-Version: 2.1.18-1
Precedence: list
List-Id: SVN commit messages for the src tree for head/-current
 <svn-src-head.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/svn-src-head>,
 <mailto:svn-src-head-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/svn-src-head/>
List-Post: <mailto:svn-src-head@freebsd.org>
List-Help: <mailto:svn-src-head-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-head>,
 <mailto:svn-src-head-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 02 Apr 2015 18:46:33 -0000

On Thu, 2 Apr 2015, Hans Petter Selasky wrote:

>>> Does somebody here know what happens in these two cases:
>>> 
>>> If we are transmitting using TSO, will the network adapter increment the 
>>> IP ID field somehow? What happens if an outgoing IP packet resulting from 
>>> a TSO packet get fragmented by a router?
>> 
>> Quite possibly -- this is presumably specified by the NIC vendor, but it 
>> would be good to do a bit of a survey and see what happens in practice.
>> 
>>> In ip_fragment() when we create fragments we should increment the ip_id 
>>> value for each fragment?
>
> I'm asking because the code in FreeBSD, since the beginning probably, just 
> copies the IP header, and use the same IP ID for all the fragments ! This 
> just hit my mind after some recent work in this area.

I honestly cannot believe you are proposing that.

Please go read about how IP fragmentation works.  Having an identical IP ID in 
ip_fragment() is the point of the function!

Robert