[v6ops] DHCPv6 PD in a multi-prefix environment

[David Farmer <[e-mail]>]

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.
-- 
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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
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