Re: Objection to draft-ietf-6man-rfc4291bis-07.txt

Alexandre Petrescu <alexandre.petrescu@gmail.com> Thu, 30 March 2017 01:39 UTC

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Subject: Re: Objection to draft-ietf-6man-rfc4291bis-07.txt
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From: Alexandre Petrescu <alexandre.petrescu@gmail.com>
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Date: Wed, 29 Mar 2017 20:39:27 -0500
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Le 28/03/2017 à 08:19, Simon Hobson a écrit :
> Alexandre Petrescu <alexandre.petrescu@gmail.com>; wrote:
[...]
>>> But to be frank, I still can't see what the proposal is about -
>>> just what use case does it solve ?
>>
>> Well, the discussion is issued from the following observations: -
>> rfc4291bis calls it fe80::/10 with a 64bit IID, whereas rfc2464bis
>>  calls it fe80::/64 - which is right?
>
> Right, so this is really nothing about using masks, prefix notation,
> etc - it's purely that somewhere along the line there's been an
> inconsistency in definition. One definition says one thing, another
> says something else. By one definition, fe81::<some 64 bit ID> is a
> link local address, while by another definition it isn't.

I tend to agree, but I think others think otherwise.

I think some people think that fe80::/64 is right whereas others think 
that fe80::/10 is right.

> I would suggest that the way to deal with that is to discuss which is
> correct and have one or both RFCs updated so they say the same thing.

I agree.

> Unless there's something in the context that makes them both right.

What is that?

> Given that there are implementations "in the wild" relying on
> fe80::<something>/64, it might be hard to settle on the wider
> ranging definition and accept that the rest of fe80::/10 is
> effectively lost to other uses - having been lost in the gap between
> the definitions.

The BSD code that was shown earlier checks the src of a received ND 
packet against fe80::/10 (not against fe80::/64).

And other code in same OS BSD adds fe80::/64 (not fe80::/10) in the rt 
table.

Because of this there can be problems.

Alex

>
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