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

Owen DeLong <owen@delong.com> Sun, 27 October 2019 19:31 UTC

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From: Owen DeLong <owen@delong.com>
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Date: Sun, 27 Oct 2019 12:31:14 -0700
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To: Philip Homburg <pch-v6ops-9@u-1.phicoh.com>
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Subject: Re: [v6ops] SLAAC renum: Problem Statement & Operational workarounds
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> On Oct 27, 2019, at 07:07 , Philip Homburg <pch-v6ops-9@u-1.phicoh.com> wrote:
> 
>>   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 is not required behavior for a DHCP client. Traditionally, a client
> does not have to write a lease it received in persistent storage. In 
> fact, in the case of DHCPv6-PD in some cases that actually triggers bugs
> on the ISP side and delays obtaining a new lease.
> 
> Now I'm not opposed to trying to renew the previous lease. It makes the
> whole thing more complex and probably more fragile, but it is the right
> thing to do.
> 
> However, the thing that actuualy makes it work (and no need for SEND there)
> is to have the CPE to advertise a stale prefix with lifetimes zero to
> inform hosts that this prefix no long works.

How does the CPE identify a stale prefix if it hasn’t written its previous prefixes
to persistent storage?

Owen