Re: I-D Action: draft-smith-6man-in-flight-eh-insertion-harmful-00.txt

[Fernando Gont <[e-mail]>]

On 13/10/19 19:19, Brian E Carpenter wrote:
> One comment at the end:
> 
> On 14-Oct-19 11:48, Mark Smith wrote:
>> On Sun, 13 Oct 2019 at 21:25, Nick Hilliard <[e-mail]> wrote:
>>>
>>> Brian E Carpenter wrote on 13/10/2019 01:36:
>>>> The packet is too dumb to know anything ;-). My question is how each
>>>> node it traverses knows. Indeed, Mark's draft describes a scenario
>>>> where the controlled domain argument breaks, because the exit node
>>>> might not know that the packet had suffered EH insertion. The
>>>> draft-voyer- scenario is not like that, because the affected IPv6
>>>> headers are created locally and identifiable as such.
>>>
>>> the world isn't nearly this pigeonholed though.  The edge around this
>>> "controlled domain" that you're implicitly suggesting is sharply-defined
>>> is in reality more of a blurry smear.  Think tunnels, leaks, back-doors,
>>> "SD-WAN" (whatever that means), policy routing, routed VPNs, etc.
>>>
>>> If the ietf wants to define a new ipv6-like protocol which is not
>>> guaranteed to be interoperable with 8200, there's still space in
>>> www.iana.org/assignments/version-numbers to accommodate this :-)
>>>
>>
>> This is one of the fundamental observations.
>>
>>  The trouble is calling this sort of closed/limited domain variant
>> that doesn't obey RFC 8200 "IPv6".
>>
>> Protocols are more than just packet structures and reserved values,
>> they also specify field value rules, interpretations and permitted and
>> non-permitted behaviours. All of these latter properties are relied on
>> and expected by other implementations.
>>
>> I think there are parallels with how human languages work.
>>
>> For example, If I define the word "dog" (noun) to mean "wash" (verb)
>> within the domain of my house, can I still claim English is being
>> spoken in my house? The spelling and pronunciation of "dog" is the
>> same, but the meaning of "dog" and where it can be used in sentences
>> is different.
>>
>> So it isn't English being spoken in my house anymore, even though it
>> resembles it, and there is quite a lot of commonality. English
>> dictionaries can't be reliably used for any word definitions in my
>> house once just one word is redefined. The more words I redefine the
>> less applicable the conventional English dictionary is in my house,
>> even though the word spellings and soundings continue to be the same.
>>
>> This could be solved by calling it "Mark's English" or "Mark's Version
>> Of English", which clearly states it is different to conventional
>> English dictionary English. There needs to be a "Mark's English"
>> dictionary.
>>
>> So as Nick said, if the IETF want to have non-interoperable versions
>> or variants of "IPv6", then they need different version numbers
>> somewhere or somehow - either minor e.g. 6.1, 6.2, or major e.g.
>> IPv10.
> 
> Be careful what you wish for. It would be easy enough to define a
> (probably hop-by-hop) option for this:
>       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>       |   110xxxxx    |   00000001    | IPv6 version  |
>       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

It's easier than that. There's an in IP version field in the IPv{4,6}
header.

Thanks,
-- 
Fernando Gont
SI6 Networks
e-mail: [e-mail]
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