Re: [v6ops] Updating RFC 7084

[Alexandre Petrescu <[e-mail]>]

Ted,

Le 18/11/2022 à 16:13, Ted Lemon a écrit :
> Pretty much any CE router should ask for a /48,

My question is not about a CE (customer edge) router, presumably
connected on the DSL or optical line.

I am asking aboout a trivial off-the-shelf access point router, or some
other such router like a tv router, or a printer router, or any box
router?  This router would not be the CE, would not be managed by the ISP.

I am trying to understand whether any such off-the-shelf box made for
home networks runs DHCPv6-PD clients at all.

> although I think a lot of them don't. I don't think that the behavior
> currently specified in RFC7084 is quite right. I think what we want
> is for the CE router to always ask for a /48.

I think it makes sense for the CE router managed by the ISP to ask for a
/48 from the ISP network, either with its own DHCPv6-PD client or with
some other protocol means.

> If it gets anything narrower than a /64, it sets up a DHCPv6 PD 
> server to sub-delegate. If it gets a /64, it sets up a relay agent 
> and relays any downstream PD requests to the DHCP server from which 
> it got its /64. If a prefix is delegated through the relay, it puts
> a route to that prefix in its routing table, using the IP address of 
> the DHCP client or relay from which it received the PD request as
> its next-hop.
> 
> The DHCP server on the CE router only ever allocates /64s.

I think the DHCP server on the CE router should allocate any prefix
length on the LAN interface, not necessarily /64.

The CE router could get a /48 on its DSL line, then form a /56 and
allocate it to an in-home router on the LAN, which would further form a
/57 and so on.  All with DHCPv6-PD.

  In this
> way, if the end user plugs a bunch of networks together, the edge 
> router winds up being responsible for all sub-delegations.

Fair enough.

> 
> Of course, there's probably a way for this to all go very very wrong
>  if the end user creates a loop. I'm not sure how they'd do that, but
>  it's probably possible.

True.  There are countless opportunities for this loop.  But these
opportunities are there anyways, regardless of the DHCPv6-PD presence.
With a NAT everywhere concept too it is possible to create difficult
loops, briges-vs-router impossible behaviours and so on, especially when
there are too numerous brands of devices in that home network.

Alex

> 
> On Fri, Nov 18, 2022 at 10:01 AM Alexandre Petrescu 
> <[e-mail] <mailto:[e-mail]>>
>  wrote:
> 
> 
> 
> Le 18/11/2022 à 15:47, Timothy Winters a écrit :
>> 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/
> <https://datatracker.ietf.org/doc/draft-winters-v6ops-cpe-lan-pd/>
>> <https://datatracker.ietf.org/doc/draft-winters-v6ops-cpe-lan-pd/
> <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.
> 
> A general comment: my freebox would indeed take advantage of this 
> proposal.  Currently the freebox relies on a grandma personnage to 
> manually configure, and 'delegate' /64s to routers on LAN, out of a 
> /56 obtained on its DSL line.  She needs to add lines like this:
> 
> IPaddress-of-in-home-router  prefix interface
> 
> Were the freebox to implement a DHCPv6-PD server software, that work 
> would be much easier, it would be automated.
> 
> But, is there a wifi in-home access point, or some other such kind
> of in-home router, that would run a DHCPv6-PD Client to request the 
> prefixes from a freebox?
> 
> Alex
> 
>> 
>> ~Tim
>> 
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