Re: [v6ops] draft-buraglio-v6ops-ula discussion

On 06-Aug-22 09:19, Eric Vyncke (evyncke) wrote:
> Brian,
> 
> Happy that we disagree as the IETF is based on consensus ;-) and no problem to be in the rough.
> 
> A concern of mine is about distinct/disconnected networks using 10/8 or fd00:0:0:1::/64 and *discovering* those addresses and believing that they are connected.

That's exactly why RFC1918 is bad and a proper (statistically unique) ULA is OK. Using
fd00::/48 is a really bad blunder.

Mind you, I once encountered a hotel that used 1.1.1.0/24 and the world did not end.

    Brian

> 
> ULA can be useful and are always a sensitive topic.
> 
> Regards
> 
> -éric (still no hat)
> 
> 
> On 05/08/2022, 23:04, "Brian E Carpenter" <brian.e.carpenter@gmail.com> wrote:
> 
>      Eric,
> 
>      On 06-Aug-22 08:13, Eric Vyncke (evyncke) wrote:
>      > David,
>      >
>      > You are correct. I think that the priority order should be (from most suitable to least suitable):
>      >
>      >   * Global IPv6
>      >   * Global IPv4
>      >   * ULA
>      >   * RFC 1918
> 
>      That may be your opinion, but many people disagree and that is why the consensus is otherwise.
> 
>      My own order of default preference for *destination* address selection would be:
> 
>      ULA
>      Global IPv6
>      RFC 1918
>      Global IPv4
> 
>      The rationale is: Prefer IPv6 always. Prefer local addressing when available.
> 
>      Obviously this requires similar rules in discovery (whether by DNS or some other method). If you can't discover a ULA, you will never use a ULA.
> 
>      Source address selection is simple: longest match with the destination.
> 
>           Brian
> 
> 
>      >
>      > I.e., there should be a distinction between global IPv4 and RFC 1918 addresses. Now, we can wonder whether it still makes sense to update RFC 6724 in 2022.
>      >
>      > Of course, LLA are also in the picture but what it important, for me, is global connectivity.
>      >
>      > Regards
>      >
>      > -éric
>      >
>      > *From: *David Farmer <farmer=40umn.edu@dmarc.ietf.org>
>      > *Date: *Friday, 5 August 2022 at 18:08
>      > *To: *Eric Vyncke <evyncke@cisco.com>
>      > *Cc: *Fred Baker <fredbaker.ietf@gmail.com>, v6ops list <v6ops@ietf.org>
>      > *Subject: *Re: [v6ops] draft-buraglio-v6ops-ula discussion
>      >
>      > On Fri, Aug 5, 2022 at 4:45 AM Eric Vyncke (evyncke) <evyncke=40cisco.com@dmarc.ietf.org <mailto:40cisco.com@dmarc.ietf.org>> wrote
>      >
>      >     This may be an unexpected behavior, but I still prefer using global IPv4 addresses (not RFC 1918) rather than ULA. The I-D should cover this.
>      >
>      > Currently, the RFC6724 default table doesn't distinguish between global IPv4 addresses and local RFC1918 IPv4 addresses. They are treated the same. They are both part of the same entry (::ffff:0:0/96         35     4). However, the default table does distinguish between global IPv6 addresses and ULA IPv6 addresses. So are you suggesting the default table needs to distinguish global IPv4 addresses and local RFC1918 IPv4 addresses?
>      >
>      >     -éric
>      >
>      >
>      > Thanks
>      >
>      > --
>      >
>      > ===============================================
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