Re: [v6ops] SLAAC renum: Problem Statement & Operational workarounds

Owen DeLong <owen@delong.com> Fri, 01 November 2019 15:40 UTC

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From: Owen DeLong <owen@delong.com>
In-Reply-To: <8f46bb68-1713-8c68-96b1-c46cf2003325@si6networks.com>
Date: Fri, 1 Nov 2019 08:39:45 -0700
Cc: Ted Lemon <mellon@fugue.com>, Philip Homburg <pch-v6ops-9@u-1.phicoh.com>, v6ops@ietf.org
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To: Fernando Gont <fgont@si6networks.com>
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Subject: Re: [v6ops] SLAAC renum: Problem Statement & Operational workarounds
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> On Oct 31, 2019, at 8:06 PM, Fernando Gont <fgont@si6networks.com> wrote:
> 
> On 31/10/19 16:39, Owen DeLong wrote:
>> 
>> 
>>> On Oct 31, 2019, at 12:25 PM, Fernando Gont <fgont@si6networks.com> wrote:
>>> 
>>> On 27/10/19 10:54, Ted Lemon wrote:
>>>> On Oct 27, 2019, at 9:41 AM, Philip Homburg <pch-v6ops-9@u-1.phicoh.com
>>>> <mailto:pch-v6ops-9@u-1.phicoh.com>> wrote:
>>>>> The little bit missing is that the CPE should write prefixes
>>>>> advertised using
>>>>> SLAAC to persistent storage which allows the CPE to invalidate stale
>>>>> prefixes
>>>>> after a reboot.
>>>> 
>>>> Actually I do not believe this is correct behavior.   Let us assume
>>>> prefix delegation.   If we have prefix delegation, then when the CPE
>>>> comes back from a power cycle, it should reconfirm the prefix it had
>>>> previously; the assumption is that that prefix is still valid.  This can
>>>> be handled in infrastructure—the ISP edge router should know whether the
>>>> prefix is still valid, because if it is it should be advertising a route
>>>> for it.   If it is not still valid, then the CPE router should attempt
>>>> to renew it, which would go to the DHCP server (possibly both messages
>>>> would).
>>> 
>>> That assues the CPE has stored the previously-leased prefix on stable
>>> storage -- which does not need to be the case. Hence the related text in
>>> our I-D.
>> 
>> IMHO, the CPE requirements should be increased and the CPE should be required
>> to store the prefix and it’s expected valid and preferred expiration times in persistent
>> storage. I would like to see the text in the I-D updated accordingly.
> 
> It's already there (draft-gont-v6ops-slaac-renum-00):
> 
> 3.2.1.  Signaling Stale Configuration Information
> 
>   In order to phase-out stale configuration information:
> 
>   o  A CPE router sending RAs that advertise dynamically-learned
>      prefixes (e.g. via DHCPv6-PD) on an interface MUST record, on
>      stable storage, the list of prefixes being advertised on each
>      network segment.

Where is the mention of storing the expiration times?

Did I miss it, or did you miss that part of my comment?

Owen

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