IETF Logo Mail Archive

Re: [v6ops] Q about IPv4-mapped IPv6 address & MPLS

Brian E Carpenter <brian.e.carpenter@gmail.com> Thu, 01 May 2014 23:18 UTC

Return-Path: <brian.e.carpenter@gmail.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 C5E021A882B; Thu, 1 May 2014 16:18:58 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2
X-Spam-Level:
X-Spam-Status: No, score=-2 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, FREEMAIL_FROM=0.001, 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 tI4kly5hdEFs; Thu, 1 May 2014 16:18:56 -0700 (PDT)
Received: from mail-pa0-x235.google.com (mail-pa0-x235.google.com [IPv6:2607:f8b0:400e:c03::235]) by ietfa.amsl.com (Postfix) with ESMTP id DE5411A8829; Thu, 1 May 2014 16:18:55 -0700 (PDT)
Received: by mail-pa0-f53.google.com with SMTP id ld10so4384151pab.40 for <multiple recipients>; Thu, 01 May 2014 16:18:53 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=message-id:date:from:organization:user-agent:mime-version:to:cc :subject:references:in-reply-to:content-type :content-transfer-encoding; bh=E8J5t2zwBb7fIQheP/TNx4iWEF6ghG08CIDi8SUWrRA=; b=Kql3njOjXa1/zkBTtQIWvyEDFtUK+kOnzAFYRc5I1NgQeWmTEow3IvwP3r0oYT5KX5 bsGHIlAfW11yAhqY7VOy939+24A5l3wFWyazNPtzfrYhsehivNvw4S50tiaKBhFCbzkV dE7sP95EKquEU/cnpM4flvmwKZY+LOHO9QOSZS1lTIg5x1y1D1VEvyrYmYsTEZuMmMQK gGC8b+Ju0d87WpMGgs5Uu/t4vzpI2qGMfGBbwP7xPg1EO2K1uEF6xtGVyTKLQd8+ZJji GQLnhcvOQHTftmXvyoOZSoB+5Fh0h7SFUg0xuKnSk9f7NfxUavLYIgNsnkMJlqUpG88z no9Q==
X-Received: by 10.66.153.80 with SMTP id ve16mr26839745pab.143.1398986333809; Thu, 01 May 2014 16:18:53 -0700 (PDT)
Received: from [192.168.178.20] (234.193.69.111.dynamic.snap.net.nz. [111.69.193.234]) by mx.google.com with ESMTPSA id vx10sm167396420pac.17.2014.05.01.16.18.51 for <multiple recipients> (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 01 May 2014 16:18:53 -0700 (PDT)
Message-ID: <5362D663.7090501@gmail.com>
Date: Fri, 02 May 2014 11:18:59 +1200
From: Brian E Carpenter <brian.e.carpenter@gmail.com>
Organization: University of Auckland
User-Agent: Thunderbird 2.0.0.6 (Windows/20070728)
MIME-Version: 1.0
To: "Rajiv Asati (rajiva)" <rajiva@cisco.com>
References: <CF875D2F.1951A9%rajiva@cisco.com> <20140501085939.GG43641@Space.Net>, <5362B2BD.7060602@gmail.com> <C1C2AD52-81C1-4BDB-87B6-550530F01389@cisco.com>
In-Reply-To: <C1C2AD52-81C1-4BDB-87B6-550530F01389@cisco.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
Archived-At: http://mailarchive.ietf.org/arch/msg/v6ops/xl4HBUydwBm4csAsLrOp156eCgY
Cc: "mpls@ietf.org" <mpls@ietf.org>, "v6ops@ietf.org" <v6ops@ietf.org>, "6man@ietf.org" <6man@ietf.org>
Subject: Re: [v6ops] Q about IPv4-mapped IPv6 address & MPLS
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: Thu, 01 May 2014 23:18:59 -0000

On 02/05/2014 10:21, Rajiv Asati (rajiva) wrote:
> Thanks, Brian. Which RFC 4038 section in particular should be referenced to?

I think section 4.2. "IPv6 Applications in a Dual-Stack Node".
It has a diagram that very clearly shows that packets that
are "decorated" inside the host with an IPv4-mapped address are
sent or received as native IPv4 packets.

It's an Informational RFC but even so it seem to be the
authoritative text in this case.

   Brian

> Cheers,
> Rajiv
> 
>> On May 1, 2014, at 4:47 PM, "Brian E Carpenter" <brian.e.carpenter@gmail.com> wrote:
>>
>>> On 01/05/2014 20:59, Gert Doering wrote:
>>> Hi,
>>>
>>>> On Thu, May 01, 2014 at 06:08:51AM +0000, Rajiv Asati (rajiva) wrote:
>>>> We need your guidance on handling v4-mapped v6 addresses (section 2.5.5.2
>>>> of [RFC4291]). 
>>>>
>>>> 1. Should/Would they appear in IPv6 routing table?
>>> "Yes and no".  It depends on the context - if the packet comes in and has
>>> an IPv6 header, address lookup happens via the IPv6 routing table.  If 
>>> a packet comes in with an IPv4 header, address lookup happens via the
>>> IPv4 routing table.  
>>>
>>> So, IPv4 should never "bleed over" to the IPv6 routing table, but if 
>>> you happen to receive an IPv6 packet with a destination IPv6 address
>>> in it's header of ::ffff:1.2.3.4, you'd either drop it right away,
>>> or use the IPv6 routing table to find the destination.
>>>
>>> The router itself should never ever source packets with a v4-mapped
>>> destination address in the packet (see below).
>>>
>>>> 2. Should an IPv6 packet with ::FFFF:127.0.0.0  be forwarded or dropped or
>>>> treated as a loopback packet, if ever received?
>>> Dropped.  v4-mapped is an internal representation of an IPv4 address
>>> recevied on an ipv6 socket, and should never ever appear in packets on
>>> the wire.
>> Nobody seems to have mentioned RFC 4038, which makes this very clear.
>> These addresses are an artefact and have no place in the routing
>> system as such, and still less on the wire.
>>
>>    Brian
>>
> .
>

v2.23.0 | Report a Bug | By Email