Prefix delegation to sub nets

[Michael Chang]

If you actually want that topology, I think in practice the downstream
router (B) must be at least a /64; if you got a /48 then I think you can
set up A with /56s, which it can use to sub-allocate a /64 to B.

https://tools.ietf.org/id/draft-ietf-homenet-arch-01.html

The config in section 7.2 of
https://wiki.archlinux.org/title/IPv6#Prefix_delegation_(DHCPv6-PD) might
be what you're looking for? (See the note about `sla-len`.)


On Sun, Jun 27, 2021 at 12:05 PM Kristian McColm <
Kristian.McColm at rci.rogers.com> wrote:

> RFC 5375 advises against prefixes longer than /64.
>
> https://datatracker.ietf.org/doc/html/rfc5375#appendix-B.2
>
> A /48 gives you 65535 /64’s, why not use some of them?
>
> ------------------------------
> *From:* ipv6-ops-bounces+kristian.mccolm=rci.rogers.com at lists.cluenet.de
> <ipv6-ops-bounces+kristian.mccolm=rci.rogers.com at lists.cluenet.de> on
> behalf of Doug Hardie <bc979 at lafn.org>
> *Sent:* Sunday, June 27, 2021 2:54:01 PM
> *To:* ipv6-ops at lists.cluenet.de <ipv6-ops at lists.cluenet.de>
> *Subject:* Prefix delegation to sub nets
>
> I am trying to setup an IPv6 environment.  There is a primary router (A)
> that receives a /48 prefix via DHCP6 from the ISP. That router configures
> itself properly via dhcp6c.  It also creates 2 LAN /64 prefixes and creates
> EUI-64 addresses on the two LAN interfaces.  One of those interfaces is
> connected to a second router (B), among other devices.  The B router
> receives the prefix via SLAAC and creates its own EUI-64 address.  However,
> that router needs to create a smaller subnet, /72, and distribute it to the
> devices on that LAN.  I have not been able to figure out how to make that
> happen.
>
> Clearly, manual configuration would work, but the prefix received from the
> ISP can change which would raise havoc with the network.  I suspect that
> dhcp6s needto be run alongside dhcp6c on router B and then the other
> devices run dhcp6c.  However, I don't see how to get the prefix that dhcp6c
> receives on router B to the dhcp6s process on router B.  I believe I am
> missing something, but haven't been able to find it.  Thanks,
>
> -- Doug
>
>
>
>
>
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>


-- 
Michael Chang
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