Re: [v6ops] ULA precedence [Thoughts about wider operational input]

[Fred Baker <[e-mail]>]

> On May 5, 2022, at 4:56 PM, Ed Horley <[e-mail]> wrote:
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> On Thu, May 5, 2022 at 4:45 PM Fred Baker <[e-mail]> wrote:
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> > On May 4, 2022, at 11:02 AM, Ed Horley <[e-mail]> wrote:
> > 
> > Just for clarification - when you say "same prefix" for ULA - are you assuming in the same /48? Or do you mean within all of ULA (fc00::/7 or the useable fd00::/8)?
> 
> You might look at section 3 of RFC 4193, and specifically at the global ID mentioned in section 3.2. I'm looking at the first 48 bits of the address and calling it a routing prefix. Let me put the question back to you: starting from RFC 4193, what other prefix would be under consideration, and why would it be under consideration?
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> Yes, I am familiar with section 3.2 - my question is because several on this mailing list in the past have said to ignore the stated pseudo-random requirement in that section and not to follow this section which states "Specifically, these prefixes are not designed to aggregate." Obviously, if you don't follow that then the question comes back to are we still assuming a /48? Or do we mean something different when we say "same prefix"? Is that defaulting to just the overall ULA prefix itself because people are designing networks starting at fd01::/32, fd02::/32, fd03::/32... fdff::/32, etc. which I completely understand is not how 4193 says to do it, but it is happening, so we need to be thinking about it perhaps? Just curious if anyone else is seeing this behavior with their customers at all?

Absent other knowledge, I should think that one would think in terms of following the specification.