Re: [Roll] Semantics of DAO ACK

[Joakim Eriksson <[e-mail]>]

> On 29 Sep 2015, at 23:08, Cenk Gündogan <[e-mail]> wrote:
> 
> This is an interesting question and I also couldn't find any answers in RFC 6550.
> However, my thoughts on this are as follows:
> Since a sub-set of the announced RPL targets could have been accepted before filling up
> the routing table (e.g.), I would choose a status code between 1 and 127.
> I would expect a node to choose another parent if a more aggressive status code is received ([128-255]).
> But a full routing table can have free space again until the next or any subsequent DAO arrives ..
> therefore I prefer a "mild rejection" with a status code of [1-127].

Yes, but I am in bad need to know exactly what was accepted or not since I would like to
provide full scalability and reliability of the “promised” routes. But it is very hard to know
the best thing to do for aggregated DAOs. At the moment I am keeping the single DAO target
model that we have been using for registration - but I am considering to do aggregation
on no-path DAOs since they can not fail in the same way.

> 
> To give some feedback to the originator of the DAO, it might be sensible to copy the
> rejected RPL Target options from the affected DAO to the DAO-ACK, so that the originator is fully
> aware of which Target prefixes got rejected (and which ones got accepted, implicitly).
> I would choose this method, because it doesn't require the originator of the DAO to save any extra state
> about the DAO and its contents.

Yes, that would work - but I guess we would need to specify clearly in a RFC-add-on how
to handle this. 

> Nonetheless, everything I wrote is nonconform and I am also interested in the RPL experts' opinions
> and solutions.

Yes, I think this topic is something we need to figure out to get out the full potential of RPL. 


Best regards,
— Joakim

> Best,
> Cenk