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

Richard Patterson <> Wed, 06 January 2021 15:30 UTC

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From: Richard Patterson <>
Date: Wed, 6 Jan 2021 15:29:47 +0000
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Subject: Re: Scope of Unique Local IPv6 Unicast Addresses (Fwd: New Version Notification for draft-gont-6man-ipv6-ula-scope-00.txt)
To: Philip Homburg <>
Cc: 6man WG <>, Fernando Gont <>, IPv6 Operations <>
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On Wed, 6 Jan 2021 at 15:14, Philip Homburg <>

> Applications should not do widely different things if they encouter a ULA.
But they do.
Some OSes will see the presence of a ULA address on an interface, and start
sending AAAA queries, some will not.
Some applications will see a ULA destination address and simply ignore it,
preferring the IPv4 destination address returned.

We need to ask the question why this is happening, and if the answer is
"They're doing it wrong", great, let's point them at the existing RFCs and
educate them, but if not...... we need to do something, and I think this
I-D is a good starting point for WG discussion at least.

We have policy tables for source and destination address selection. Those
> should be used to decide what to do.

As above, it's not just about simple routing table lookups, or source
address selection. But I do also think there's room for improvement here as
well, with a new scope for ULA.