Re: WPD-6, WAA-8, and WAA-9 of draft-ietf-v6ops-ipv6-cpe-router-04

[Ole Troan <ot@cisco.com>]

>>> So, what is wrong with that scenario?
>> 
>> Section 12.1 of RFC 3633 forbids it:
>> 
>> "the requesting router MUST NOT assign any delegated prefixes or subnets
>> from the delegated prefix(es) to the link through which it received the
>> DHCP message from the delegating router."
> 
> I know, but why?
> 
> I always see a MUST NOT as something that would cause major harm or
> interoperability problems. But the DHCP PD RFC just says 'MUST NOT' without
> giving any reason what so ever.
> 
> So maybe it is time to revisit that requirement instead of using that to 
> force the weak host model onto CPEs.

the reason for that "MUST NOT" is to prohibit path of the delegated prefix from being used on the DR - RR link. if the DR chose to use part of the delegated prefix, that would be hard for the RR to detect and could potentially conflict with the RR's own use of the delegated prefix. "delegation" implies that the DR transfers control of the prefix to the RR.

this doesn't necessarily prohibit the RR from doing what you suggest. but, I haven't understood what problem you are trying to solve. could you expand on that?

cheers,
Ole