Re: [v6ops] Scope of Unique Local IPv6 Unicast Addresses (Fwd: New Version Notification for draft-gont-6man-ipv6-ula-scope-00.txt)

Michael Richardson <mcr+ietf@sandelman.ca> Wed, 06 January 2021 17:48 UTC

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From: Michael Richardson <mcr+ietf@sandelman.ca>
To: Ted Lemon <mellon@fugue.com>
cc: Fernando Gont <fgont@si6networks.com>, IPv6 Operations <v6ops@ietf.org>, ipv6@ietf.org, Gert Doering <gert@space.net>
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Date: Wed, 06 Jan 2021 12:48:51 -0500
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Subject: Re: [v6ops] Scope of Unique Local IPv6 Unicast Addresses (Fwd: New Version Notification for draft-gont-6man-ipv6-ula-scope-00.txt)
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Ted Lemon <mellon@fugue.com> wrote:
    > It is of course not even obvious how to solve this, because sometimes
    > you do want ULA in DNS, and sometimes you don’t. And it depends on what
    > DNS.
    > If you are doing split DNS, then you can scope the DNS that
    > advertises ULAs only to serve those networks where those ULAs are
    > in-scope.

Ideally.... but that's a lot of policy stuff to put into DNS.
I think that geolocated answers in DNS is already a bad thing.
We should be using a better anycast.

    > The DNS that is advertised globally would of course contain
    > no ULAs.

I'm not sure that I agree!  I think that ULAs often do belong.

There are potentially many GUA (2000::/3) addresses that could be in DNS,
which would not work for some originators due to ACLs, and yet a different
entry might work just fine.  Why would ULA be any different?

I think that happy eyeballs and source address selection ought to cut out
many possibilities.
It's just too bad that libcurl doesn't implement Happy Eyeballs...
     {ideally in a system-wide, privacy-preserving, maybe even LAN-wide
     [RFC2186-like] way}

(I also lament shim6, but feel that MPTCP and QUIC might give us something
equivalent.  Again... anycast)

    > How this is arranged is either a matter of local configuration
    > or an interesting topic of future work, depending on how you look at
    > it.

Also, is this an operational or architectural issue?

--
Michael Richardson <mcr+IETF@sandelman.ca>   . o O ( IPv6 IøT consulting )
           Sandelman Software Works Inc, Ottawa and Worldwide