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

Fernando Gont <fgont@si6networks.com> Sat, 13 February 2021 21:12 UTC

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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)
To: Ted Lemon <mellon@fugue.com>
Cc: Brian E Carpenter <brian.e.carpenter@gmail.com>, Fred Baker <fredbaker.ietf@gmail.com>, IPv6 Operations <v6ops@ietf.org>, "6man@ietf.org" <6man@ietf.org>
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From: Fernando Gont <fgont@si6networks.com>
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Date: Sat, 13 Feb 2021 18:03:03 -0300
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On 13/2/21 17:47, Ted Lemon wrote:
> On Feb 13, 2021, at 3:18 PM, Fernando Gont <fgont@si6networks.com 
> <mailto:fgont@si6networks.com>> wrote:
>> BUt that's again ULAs being special. And they usually have properties 
>> of "private" addresses -- e.g., can generally be expected to be valid 
>> if your link to your ISP goes down, are more unlikely of being 
>> renumbered, etc.
> 
> If your link is numbered with ULAs, then you’ll choose a ULA whenever 
> you’re communicating with another ULA, because of the longest match rule.

Scope rule is # 2.Longest match rule is #8.

So you don't necessarily get the same outcome.



> Source address selection is below the level of naming, so you’ve already 
> picked your destination address by the time you start doing it.

For Dst Addr selection, the scope comparison is, again, rule #2 & rule 
#8, while longest-matching prefix is rule #9.

The proper scopes would probably also benefit the other address "types" 
that David pointed out....

Thanks,
-- 
Fernando Gont
SI6 Networks
e-mail: fgont@si6networks.com
PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492