DHCPv6 PD & Routing Questions

Sat Nov 21 00:20:20 UTC 2015

On 2015-11-20 15:36, Owen DeLong wrote:
>> On Nov 20, 2015, at 13:35 , Jim Burwell <jimb at jsbc.cc> wrote:
>>
>> Hi,
>>
>> Have a simple couple of questions here. 
>>
>> In my admittedly cursory glances over the DHCPv6 RFCs, I don't see any
>> reference to the protocol having any role in managing the routing of
>> prefixes it delegates.  Perhaps I missed it, but I somewhat expected the
>> omission of this responsibility would be the case.
>>
>> My questions are:
>>
>> 1) Does the DHCPv6 protocol include any standards/mechanisms/methods for
>> managing routes to prefixes it delegates, or does it consider this
>> outside of its function?  (I suspect the latter)
> Yes and no…
>
> DHCPv6 doesn’t include anything specifically per se, but it does require that
> the local router sees the DHCPv6 PD answer in the process of passing it
> along to the target, and there’s a pretty obvious expectation that said router
> will have to arrange to do the needful in that respect.
>
>> 2) What are the most common ways of managing the routing of delegated
>> prefixes in the ISPs routing domain?  Has a standard method/best
>> practice emerged yet?  Routing protocols?  IPv6 RAs?
> RAs really only apply to subnet local advertisement of routers and
> the on-net prefixes in most implementations.
>
> I don’t think any of the various methods of using routing protocols,
> static pre-routed blocks from which PDs are delegated, etc.  could
> necessarily be called “standardized”, but there are probably a few
> that are more popular than most of the others.
>
> Unfortunately, PD is really still in its infancy in terms of development
> and real running code for complete implementations throughout any
> sort of site hierarchy.
>
> Owen
>
>

On 2015-11-20 15:36, Owen DeLong wrote:
>> On Nov 20, 2015, at 13:35 , Jim Burwell <jimb at jsbc.cc> wrote:
>>
>> Hi,
>>
>> Have a simple couple of questions here. 
>>
>> In my admittedly cursory glances over the DHCPv6 RFCs, I don't see any
>> reference to the protocol having any role in managing the routing of
>> prefixes it delegates.  Perhaps I missed it, but I somewhat expected the
>> omission of this responsibility would be the case.
>>
>> My questions are:
>>
>> 1) Does the DHCPv6 protocol include any standards/mechanisms/methods for
>> managing routes to prefixes it delegates, or does it consider this
>> outside of its function?  (I suspect the latter)
> Yes and no…
>
> DHCPv6 doesn’t include anything specifically per se, but it does require that
> the local router sees the DHCPv6 PD answer in the process of passing it
> along to the target, and there’s a pretty obvious expectation that said router
> will have to arrange to do the needful in that respect.
>
>> 2) What are the most common ways of managing the routing of delegated
>> prefixes in the ISPs routing domain?  Has a standard method/best
>> practice emerged yet?  Routing protocols?  IPv6 RAs?
> RAs really only apply to subnet local advertisement of routers and
> the on-net prefixes in most implementations.
>
> I don’t think any of the various methods of using routing protocols,
> static pre-routed blocks from which PDs are delegated, etc.  could
> necessarily be called “standardized”, but there are probably a few
> that are more popular than most of the others.
>
> Unfortunately, PD is really still in its infancy in terms of development
> and real running code for complete implementations throughout any
> sort of site hierarchy.
>
> Owen
>
>
Thanks for the answer Owen!

So it sounds like things are still in flux.  But it least it answers my
main question of "have I missed something here"?

Could you elaborate on the "local router seeing the PD answer" a bit?  I
presume by "local router" you mean router acting as DHCPv6 relay?  Or do
you mean the router which made the original request?

Would it be fair to say that the RFCs only really talk about delegating
the prefixes, and leave what to do with the prefixes themselves up to
the implementer?

I'm asking these questions because I'm doing a little class for some
folks on IPv6 and this is one area where I couldn't find answers. 

- Jim