Re: [v6ops] Erik Kline's Discuss on draft-ietf-v6ops-cpe-slaac-renum-05: (with DISCUSS and COMMENT)

Fernando Gont <fgont@si6networks.com> Thu, 28 January 2021 01:20 UTC

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To: Erik Kline <ek.ietf@gmail.com>, Ted Lemon <mellon@fugue.com>
Cc: The IESG <iesg@ietf.org>, V6Ops Chairs <v6ops-chairs@ietf.org>, v6ops list <v6ops@ietf.org>, draft-ietf-v6ops-cpe-slaac-renum@ietf.org
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From: Fernando Gont <fgont@si6networks.com>
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Date: Wed, 27 Jan 2021 22:17:57 -0300
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Subject: Re: [v6ops] Erik Kline's Discuss on draft-ietf-v6ops-cpe-slaac-renum-05: (with DISCUSS and COMMENT)
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Hi, Erik,

This one remained unresponded. Apologies for that.

On 22/10/20 11:28, Erik Kline wrote:
> I agree.  I just think then the text about "the lesser of two lifetime
> values" doesn't quite read correctly nor give the impression that this
> applies to things like ULA prefixes.  I think it's probably pretty
> easy to fix with minimal text.

What you say does indeed make sense.

How about this:

After this para in Section 3.1:
    CE Routers providing stateful address configuration via DHCPv6 SHOULD
    set the DHCPv6 IA Address Option preferred-lifetime to the lesser of
    the remaining preferred lifetime and ND_PREFERRED_LIMIT, and the
    valid-lifetime of the same option to the lesser of the remaining
    valid lifetime and ND_VALID_LIMIT.

Add (as a parenthetical note?) the following text:

    If the prefix employed for DHCPv6 stateful address configuration
    has been locally-generated (e.g., a locally-generated ULA prefix)
    or manually-configured on the CE router,
    the preferred-lifetime and the valid-lifetime of the
    corresponding DHCPv6 IA Address Option SHOULD be set to
    ND_PREFERRED_LIMIT, and ND_VALID_LIMIT, respectively.


Then, right after this para:
    CE Routers providing DHCPv6-PD on the LAN-side SHOULD set the DHCPv6
    IA Prefix Option preferred-lifetime to the lesser of the remaining
    preferred lifetime and ND_PREFERRED_LIMIT, and the valid-lifetime of
    the same option to the lesser of the remaining valid lifetime and
    ND_VALID_LIMIT.


Add this text (parenthetical note or main text?):
    If the prefix employed for DHCPv6-PD
    has been locally-generated  (e.g., a locally-generated ULA prefix)
    or manually-configured on the CE router,
    the preferred-lifetime and the valid-lifetime of the
    corresponding DHCPv6 IA Address Option SHOULD be set to
    ND_PREFERRED_LIMIT, and ND_VALID_LIMIT, respectively.

?


Since this resulting value is then used throughout Section 3.2, I wonder if:

* We can assume that it is clear what we mean by e.g. "lesser of
    the remaining preferred lifetime", or,

* Whether we should coin some term for the values resulting from Section 
3.1 (e.g. "effective preferred-lifetime" and "effective valid-lifetime", 
or something like ND_PREFERRED, and ND_VALID), and then use that 
throught Section 3.2.

Thoughts?

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