[v6ops] Re: DHCPv6 PD in a multi-prefix environment

[Ted Lemon <[e-mail]>]

No, I mean can you describe a real-world scenario where this would happen.
I get that you could configure a DHCP server to do this. The question is,
when would someone configure the DHCP server that way?

On Tue, Jul 23, 2024 at 7:49 PM David Farmer <[e-mail]> wrote:

> I already did scenario A.3 in draft-ietf-snac-simple. It is appropriate
> for the SNAC router to obtain a ULA prefix instead of a GUA prefix to
> reduce the attack surface of the IOT devices.
>
> On Tue, Jul 23, 2024 at 9:33 PM Ted Lemon <[e-mail]> wrote:
>
>> Can you give us an example of a situation where such a decision would
>> need to be made?
>>
>> On Tue, Jul 23, 2024 at 6:48 PM David Farmer <farmer=
>> [e-mail]> wrote:
>>
>>> The classic ISP use case for DHCPv6 PD, as envisioned initially by
>>> RFC3633 and integrated into RFC8415, typically expected a single prefix to
>>> be delegated to a requesting router from the ISP. Meanwhile, many of the
>>> draft-ietf-v6ops-cpe-lan-pd use cases probably expect a subdelegation from
>>> this ISP provided prefix. Nevertheless, an RFC7084 CE Router may also have
>>> a ULA prefix to subdelegate from, and a ULA prefix may be more appropriate
>>> for some of the use cases. Not to mention, there may be prefixes from more
>>> than one ISP or additional prefixes while renumbering.
>>>
>>> Should the delegating router in draft-ietf-v6ops-cpe-lan-pd advertise
>>> subdelegations from all prefixes it may have and let the requesting router
>>> choose one or more? How does the requesting router know which prefixes it
>>> is appropriate to select in what circumstances? If the delegating router
>>> doesn't advertise subdelegations from all prefixes, how does it know which
>>> prefixes to advertise to which requesting routers?
>>>
>>> You can also ask the question from the opposite direction: How does the
>>> requesting router solicit for a ULA prefix instead of a GUA prefix if that
>>> is more appropriate for its use case?
>>>
>>> These questions came to mind while reading draft-ietf-snac-simple, as it
>>> would seem reasonable to want the SCAC router to obtain a ULA prefix from
>>> the delegating router and not a GUA prefix, especially in the scenario
>>> described in A.3. However, similar questions exist for downstream RFC7084
>>> or PD-per-device in a multi-prefix environment.
>>>
>>> Thanks.
>>> --
>>> ===============================================
>>> David Farmer               Email:[e-mail]
>>> Networking & Telecommunication Services
>>> Office of Information Technology
>>> University of Minnesota
>>> 2218 University Ave SE        Phone: [phone]
>>> Minneapolis, MN 55414-3029   Cell: 612-812-9952
>>> ===============================================
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>>>
>>
>
> --
> ===============================================
> David Farmer               Email:[e-mail]
> Networking & Telecommunication Services
> Office of Information Technology
> University of Minnesota
> 2218 University Ave SE        Phone: [phone]
> Minneapolis, MN 55414-3029   Cell: 612-812-9952
> ===============================================
>