Re: Updating to RFC6434 to deal with 8200-style header insertion by IPIP

Fernando Gont <fgont@si6networks.com> Mon, 06 November 2017 19:50 UTC

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Subject: Re: Updating to RFC6434 to deal with 8200-style header insertion by IPIP
To: Brian E Carpenter <brian.e.carpenter@gmail.com>, Fernando Gont <fernando@gont.com.ar>, "C. M. Heard" <heard@pobox.com>, 6man WG <ipv6@ietf.org>
Cc: Michael Richardson <mcr+ietf@sandelman.ca>
References: <CACL_3VETxNVQ+YD5j6ZiWjycQ=ojAuWwB23offNdVKm+S9c_7A@mail.gmail.com> <23308.1509623865@obiwan.sandelman.ca> <CACL_3VFrcombGczXU6Zz=Pk1u2GE=wGG-r+yEefdHai1REqXmQ@mail.gmail.com> <c8911f45-2afc-9d26-c0a8-1017d034a251@gmail.com> <1e62fab6-c434-a474-e53b-e4c7f2d83de0@gont.com.ar> <5cb2b9fd-8546-31fd-d984-d161aef16349@gmail.com>
From: Fernando Gont <fgont@si6networks.com>
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Date: Mon, 6 Nov 2017 16:46:38 -0300
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On 11/06/2017 04:35 PM, Brian E Carpenter wrote:
> Hi Fernando,
> 
> On 07/11/2017 07:02, Fernando Gont wrote:
>> On 11/02/2017 04:33 PM, Brian E Carpenter wrote:
>>> On 03/11/2017 04:26, C. M. Heard wrote:
>>>> On Thu, Nov 2, 2017, Michael Richardson <mcr+ietf@sandelman.ca>; wrote:
[....]
>>>>> Both AH and IPIP are well known and recognized extension headers.
>>>
>>> AH is an extension header. "IPIP" isn't. It's Protocol 41, and Protocol 41
>>> is otherwise known as IPv6. (That's why it's also called IPPROTO_IPV6).
>>> In RFC8200 terms that makes it an "upper-layer header". Strictly speaking,
>>> RFC8200 doesn't specify what to do with an unrecognized upper-layer header.
>>
>> Based on the std, anything that is unknown is an EH. In the context of
>> RFC8200/FC2460, there's only:
>>
>> * Known EHs
>> * Known ULP
>> * Unknown EHs
> 
> Yes, that's what the text says but I wish we'd fixed it in 8200 to
> acknowledge that there is a 4th case (Unknown ULP) and that it
> cannot be distinguished from the 3rd case. Acknowledging that is
> much better than ignoring it.

In that sense we probably did a bit worse: the merge of RFC6564 seems to
imply a "unified format" helps... but it doesn't.. because if the type
is unknown, you cannot infer the syntax of what's comming next.


> I'm happy with Ole's suggestion that
> this (and the resulting ICMP 1 behaviour) should be mentioned in
> 6434bis - as a clarification, not a new invention.

mmm.. would this RFC8200 (jut curious...)



> I also agree that there are enough potential issues in unexpected
> IPv6-in-IPv6 that is deserves its own draft.

Agreed. Just curious: why is this "behaviour" nw found to be of
interest? -- I missed this bit (if it was actually mentioned).

Thanks!

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