Re: [v6ops] Updating RFC 7084

I agree it's useful to recommend that CE routers hand out prefixes via
DHCPv6 PD. Even my own network has this problem - the only fiber ISP that
serves my apartment has a CE router that I can't replace, and it doesn't
enable PD, which is limiting.

That said - IIRC we discussed this in homenet and we decided that it was a
bit tricky. Supporting one level of delegation is trivial, but hierarchical
delegation is more difficult. What size should be supported? Do you rely on
the downstream router hinting correctly? But how will the downstream router
know how many routers are downstream of itself? That's why we ended up with
the homenet protocol.

This proposal solves that by making all routers turn on relay agents such
that the topmost router hands out individual /64s. From an address
management perspective this will work, I guess, but I see a couple of
problems:

   1. When a CE router gets a relayed PD request from a downstream
   interface, will it know what to do? In particular, will it know that it
   needs to route that prefix to the relay address and not to the client?
   There are CE routers that support DHCPv6 PD today, and I don't know how
   they will react. OTOH I don't know much about PD, so maybe this will just
   work?
   2. If the topmost CE router gets handed a /64 by the ISP, and implements
   LPD-6, then the ISP will get relayed DHCPv6 requests. Do we think ISP
   relays and servers will deal with this correctly? I'd guess the correct
   response would be to respond with NoPrefixesAvail, but will they?

On Fri, Nov 18, 2022 at 11:47 PM Timothy Winters <tim@qacafe.com> wrote:

> Hello,
>
> I've started a draft to update RFC 7084 to support prefix delegation on
> the LAN interfaces.  The current state of IPv6 in home networks is ISP are
> assigning prefixes of appropriate sizes but they currently are under
> utilized due to the lack of prefix delegation on LAN interfaces.
>
> This draft is an attempt to add that support to the draft.
>
> https://datatracker.ietf.org/doc/draft-winters-v6ops-cpe-lan-pd/
>
> This is only an update to 7084 at the moment, there has been some
> discussion on the snac working group about leveraging this work as well.
>
> One item being discussed is this currently doesn't solve multi-homed
> networks.
>
> I welcome any feedback about the proposal.
>
> ~Tim
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