[lacnog] Articulo: Understanding why IPv6 renumbering problems occur

Fernando Frediani fhfrediani en gmail.com
Dom Sep 15 12:48:14 -03 2019

Hello Fernando

Thanks for sharing your article.
In fact this issue is quiet common and annoying in many situations and 
must be addressed.

The first point to look at is for what reason ISPs would change/renew 
the DHCPv6-PD in use in a active connection, even after a long time. I 
understand it happens upon disconnection/re-connection but not in a 
active connection which is something that perhaps can be eliminated too.
The point about ISPs deliver static prefixes I personally quiet like 
that and prefer to employ that as much as possible, but in the other 
hand I recognize there are a few challenges as how to properly aggregate 
these prefixes in a multi-BRAS environment as also the lack of a 
workable Delegated-IPv6-Prefix RADIUS Attribute on some BRAS or this 
functionality in some ERP/CRM Systems.
I also don't really take that stable prefixes is a big issue in the 
point of view, but cannot ignore the concerns of some that see the 
implications in privacy.

The point about the router recording DHCPv6-PD in stable storage not 
sure if will always solve the problem because it is likely then when the 
router is rebooted and re-connects to ISP it may receive a new prefix. I 
think the think here is somehow the DHCPv6 Daemon properly talk to SLAAC 
(RADVd) to start advertising the new prefix and mainly that device 
properly understand, remove and start to use the new prefix. One issue 
here is if they will properly honor the lifetime and if they do that 
there will still be a interim and problematic period.

I seems to me it would be more productive if somehow SLAAC could, one it 
is aware there was a prefix change to send a broadcast message with some 
kind of flag which devices should understand and fully refresh their 
IPv6 addresses immediately.

Best regards
Fernando Frediani

On 14/09/2019 23:43, Fernando Gont wrote:
> Estimados,
> FYI:
> https://searchnetworking.techtarget.com/tip/Understanding-why-IPv6-renumbering-problems-occur
> Relacionado con este tema, escribimos este draft:
> https://tools.ietf.org/html/draft-gont-v6ops-slaac-renum
> Los comentarios son bienvenidos, especialmente por la lista del v6ops wg
> de IETF.
> Saludos, y gracias!

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