-- Doug > On 27 June 2021, at 12:41, Michael Chang <[email protected]> wrote: > > 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 > <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) > <https://wiki.archlinux.org/title/IPv6#Prefix_delegation_(DHCPv6-PD)> might > be what you're looking for? (See the note about `sla-len`.)
The addresses could be done that way. However, the issue still remains, how does router B distribute the prefix? Is using a dual dhcp6c - dhcp6s the way to go and how does dhcp6s get the prefix from dhcp6c? > > > On Sun, Jun 27, 2021 at 12:05 PM Kristian McColm > <[email protected] <mailto:[email protected]>> > wrote: > RFC 5375 advises against prefixes longer than /64. > > https://datatracker.ietf.org/doc/html/rfc5375#appendix-B.2 > <https://datatracker.ietf.org/doc/html/rfc5375#appendix-B.2> > > A /48 gives you 65535 /64’s, why not use some of them? > > From: [email protected] > <mailto:[email protected]> > <[email protected] > <mailto:[email protected]>> on behalf of Doug Hardie > <[email protected] <mailto:[email protected]>> > Sent: Sunday, June 27, 2021 2:54:01 PM > To: [email protected] <mailto:[email protected]> > <[email protected] <mailto:[email protected]>> > 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 > > > > > > This communication is confidential. We only send and receive email on the > basis of the terms set out at www.rogers.com/web/content/emailnotice > <http://www.rogers.com/web/content/emailnotice> > > > > Ce message est confidentiel. Notre transmission et réception de courriels se > fait strictement suivant les modalités énoncées dans l’avis publié à > www.rogers.com/aviscourriel <http://www.rogers.com/aviscourriel> > > > -- > Michael Chang
