Re: [Roll] [roll] #7: RPL bootstrap question: neighbor cache and DIOs dependency

[Jonathan Hui <jhui at archrock.com>]

On Nov 5, 2009, at 9:56 AM, Philip Levis wrote:

> On Oct 29, 2009, at 5:02 AM, roll issue tracker wrote:
>
> > #7: RPL bootstrap question: neighbor cache and DIOs dependency
> > -------------------------------- 
> > +-------------------------------------------
> > Reporter:  jpv at …               |       Owner:  wintert at …
> >    Type:  defect              |      Status:  new
> > Priority:  major               |   Milestone:
> > Component:  rpl                 |     Version:
> > Severity:  Active WG Document  |    Keywords:
> > -------------------------------- 
> > +-------------------------------------------
> > Email From Julien
> >
> > Hi all,
> >
> > as explained in section 5.4.2 of RPL, a DIO must not be processed  
> > if the
> > source is not in the neighbor cache. The question is how do we  
> > expect the
> > neighbor cache to be filled?
>
> The current proposal is to change the direction of specification.
>
> Rather than state a node MUST NOT process a DIO if the SRC is not a  
> candidate neighbor, the document will state that a node MUST process  
> a DIO if the SRC is a candidate neighbor. This rewording also  
> removes the problem of a node ignoring DIOs.
>
> Does anyone think this is not a good fix? What are people's opinions?


I agree that Rule 2 of 5.4.2 is problematic.  Though, after your  
proposed fix, I'm not sure Rule 2 provides any value.  I would propose  
to simply strike Rule 2 from 5.4.2.

I think the real issue is with the "candidate neighbor" abstraction.   
Currently, as specified, candidate neighbor and DAG parent selection  
are independent processes.  These processes should be more coupled.   
For example, it is useful to also consider routing information  
contained within the DIO to determine if a neighbor should be a  
candidate neighbor.

--
Jonathan Hui