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Re: A common problem with SLAAC in "renumbering" scenarios

Mikael Abrahamsson <swmike@swm.pp.se> Mon, 11 February 2019 09:11 UTC

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Date: Mon, 11 Feb 2019 10:11:43 +0100
From: Mikael Abrahamsson <swmike@swm.pp.se>
To: Mark Smith <markzzzsmith@gmail.com>
cc: Michael Richardson <mcr+ietf@sandelman.ca>, 6man WG <ipv6@ietf.org>
Subject: Re: A common problem with SLAAC in "renumbering" scenarios
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On Mon, 11 Feb 2019, Mark Smith wrote:

> The decision on for the production residential IPv6 broadband deployment 
> I worked on back in 2010 was to do dynamic GUA /64s on the PPPoE 
> session/link, and a static/stable PD prefix provided via RADIUS. So 
> outside the BNG, there was only 1 PD route per customer.

For IPoE this is not great as you don't want the ND table growing 
potentially large. Most people I see do this with an optional IA_NA on WAN 
and then PD. The two examples I have available at home neither announces 
any PIO on WAN but instead have M=1 and one of them only offers single 
IA_NA plus /56 PD (DOCSIS ISP with modem in bridge mode), the other one 
(my FTTH AE IPoE provider) just offers IA_PD with unnumbered WAN.

I think both models are fine.

With PPPoE of course the ND scalability problem doesn't exist so just 
routing the /56 down it and using PD exclude for a /64 for WAN that is 
then announced in RA+PIO seems like a perfectly sensible thing to do.

-- 
Mikael Abrahamsson    email: swmike@swm.pp.se

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