Re: [Int-area] Resubmit - requesting WG Adoption draft-moskowitz-intarea-schc-ip-protocol-number

[Joel Halpern <[e-mail]>]

There are multiple "protocols" that are essentially tunnel headers that 
use UDP.   Many of them have extension points in those headers.  And 
almost all of them can carry IP packets which can themselves ccntain IP 
extension headers.

My view is that the registry for extension headers is not about whether 
the function of what is carried extends IP (many things not listed there 
effectively extend the IP header information) but whether the field 
beign defined is structurally an IP extension header.  Thus, I have no 
problem with SCHC supporting the various use cases Pascal describes 
without claiming that SCHC is an extension header.  Structurally, it 
isn't an extension header.

Yours,

Joel

On 9/8/2022 3:38 AM, Antoine FRESSANCOURT wrote:
> Hello,
>
> Out of curiosity, as I am far less experienced than most people in this discussion, what do you have in mind when you mention " UDP-carrying headers-with-next-header as extension headers" ?
>
> Thanks a lot for your clarifications,
>
> Antoine Fressancourt
>
> -----Original Message-----
> From: Int-area <[e-mail]> On Behalf Of Joel Halpern
> Sent: mercredi 7 septembre 2022 23:54
> To: Robert Moskowitz <[e-mail]>
> Cc: Internet Area <[e-mail]>
> Subject: Re: [Int-area] Resubmit - requesting WG Adoption draft-moskowitz-intarea-schc-ip-protocol-number
>
> 8200 implies that the first bye of the extension header is the next header field.  explicitly and visibly.  So that one can walk the next header chain.
>
> I would like us to articulate a clear meaning of when something is an extension header.   I have tried to lay one such out. (Recognizing that there are a few historical exceptions).  If we want instead to redefine IP-in-IP and UDP-carrying headers-with-next-header as extension headers I wouldn't like it, but I could live with it.  Or we can say it si completely random I suppose.  Although I have trouble seeing how that is a good answer.
>
> Yours,
>
> Joel
>
> PS: In case anyone is unclear, I am not criticizing Robert M. (or Bob H.).  He is trying to do the right thing.  And yes, we should give him a code point for this use.
>
> On 9/7/2022 5:49 PM, Robert Moskowitz wrote:
>> ESP, RFC 4303 most DEFINITELY DOES have a Next Header Field.
>>
>> It is just at the end of the datagram, before the ICV.
>>
>>
>> On 9/7/22 17:35, Joel Halpern wrote:
>>> My reading of 8200 is that an extension header MUST start with a one
>>> byte "Next Header" field.  SCHC does not.  Therefore, it is a carried
>>> / upper layer protocol, not an extension header.  Much like IPv6 (in
>>> IPv6).  Or UDP (with carrying an application protocol or carrying
>>> some routing header like GRE, LISP, ...) or ...
>>>
>>> Yours,
>>>
>>> Joel
>>>
>>> PS: I grant we are not fully consistent in this regard.  ESP does not
>>> have a next-header field.  (AH does).   But if we are going to
>>> pretend that some headers are extensions headers and some are not, we
>>> should try to be consistent with the description in 8200 (and 2460).
>>>
>>> On 9/7/2022 4:57 PM, Robert Moskowitz wrote:
>>>>
>>>> On 9/7/22 16:35, Carsten Bormann wrote:
>>>>> On 7. Sep 2022, at 22:04, Bob Hinden <[e-mail]> wrote:
>>>>>> To clarify my question, it only relates to if SCHC should be added
>>>>>> to the IPv6 Extension Header Types registry.   I continue to think
>>>>>> that adding it to the IP Protocol Number registry is fine.
>>>>> I believe the answer should be the same as for 142 (RFC 5858),
>>>>> which is not in the list.
>>>>>
>>>>> I couldn’t find out quickly what an IPv6 Extension Header Type
>>>>> is(*), so maybe that is an oversight for 142.
>>>>  From my limited understanding and which Protocols are listed as
>>>> Extension Header Types and which not (other than 142), it is a
>>>> Protocol that transports other Protocols.
>>>>
>>>> Though with that definition, I wonder how HIP got in the list.
>>>>
>>>> It is fun to open a can of worms!
>>>>
>>>>> Grüße, Carsten
>>>>>
>>>>> (*) An IP protocol number, apparently.
>>>>> But what specifically does it make an IPv6 Extension Header Type as
>>>>> well?
>>>>> The references given in the registry don’t seem to say.
>>>>>
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