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

Ted Lemon <mellon@fugue.com> Sun, 14 February 2021 20:40 UTC

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From: Ted Lemon <mellon@fugue.com>
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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)
Date: Sun, 14 Feb 2021 15:40:45 -0500
In-Reply-To: <9DD46169-462F-454B-A5B2-26FCB1B0C6EF@fugue.com>
Cc: Brian E Carpenter <brian.e.carpenter@gmail.com>, David Farmer <farmer@umn.edu>, Fred Baker <fredbaker.ietf@gmail.com>, IPv6 Operations <v6ops@ietf.org>, "6man@ietf.org" <6man@ietf.org>
To: Fernando Gont <fgont@si6networks.com>
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On Feb 14, 2021, at 3:39 PM, Ted Lemon <mellon@fugue.com> wrote:
> In theory, a GUA is globally unique. But there’s no mechanism for ensuring that this is in fact the case. I could configure a GUA prefix on my local network that’s also in use somewhere else. The “architecture” does not guarantee that I have not done so. The mechanism for ensuring that GUAs are unique is delegation; this is a fairly solid mechanism, but what actually makes GUAs unique is the practicality that if you screw up the allocation and wind up with two GUAs identifying two different interfaces on two different links, you may experience communication difficulties.

This would have made a lot more sense if I’d said, as I intended:

>  if you screw up the allocation and wind up with a single GUA identifying two different interfaces on two different links on two different hosts, you may experience communication difficulties.