Re: about violation of standards

[Kerry Lynn <[e-mail]>]

On Thu, Apr 18, 2019 at 3:30 PM Kerry Lynn <[e-mail]> wrote:

> On Thu, Apr 18, 2019 at 2:59 PM Alexandre Petrescu <
> [e-mail]> wrote:
>
>> In private conversation this debate happened:
>>
>> is an implementation that uses fe80:1::2 address on an interface a
>> violation of standards? (RFC 4291 does not allow for '1' to be there).
>>
>> My point of view is that as long as that mplementation is widely used,
>> that is not a violation of standards.  Rather, the situation makes it
>> that that standard is not in agreement with implementations.
>>
>> Alex
>>
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>
> Which came first, the standard or the egg?
>
> Kerry
>

Let me expand on my answer, which was (perhaps) pithy but not very helpful.
I don't believe, in general, that standards are created in a vacuum or for
no
purpose.  Particularly when one is working in very constrained environments,
it is often the case that violating one constraint may have knock-on
effects.

In the case of 6LoWPAN HC1 compression, it is assumed the 54 bits following
fe80::/10 are zero, which, in turn, allows the lower 64 bits of the IPv6
address to
be elided for all 6lo data links that I'm familiar with.

I suppose one could argue that for link-local traffic, all the nodes could
agree
that fe80:1::/64 is the local convention, but 1) don't then claim
conformance with
HC1 header compression and 2) prepare to write your own sniffer.

Kerry