Using an *external* DHCPv6 server for prefix-delegation in conjunction with PPPoE

[Mikael Abrahamsson]

On Fri, 14 Jan 2011, Per Carlson wrote:

> Hi Bjørn.
>
>>> It's even better: You can directly assign a PD address on the WAN
> interface:
>>
>> Really? rfc3633 says
>>
>>   Upon the receipt of a valid Reply message, for each IA_PD the
>>   requesting router assigns a subnet from each of the delegated
>>   prefixes to each of the links to which the associated interfaces are
>>   attached, with the following exception: 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 don't know the reasoning behind the MUST NOT, but it is configurable and
> seams to work fine. Clearly Cisco do violate the RFC here, but without any
> apparent harm.

I'd say Cisco has made it possible to violate the RFC, which I think is 
the correct decision on their part.

The text from RFC3633 should be followed for default configuration, but 
it's common that RFC-violating behaviour is allowed through specific 
configuration. I'm very happy this is the case.

-- 
Mikael Abrahamsson    email: swmike at swm.pp.se