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

From: Philip Levis <[email-masked]>
Date: Mon, 2 Nov 2009 08:05:19 -0800

On Oct 30, 2009, at 11:39 AM, [email-masked] wrote:

>
> HiPhil,
>
> Leaving Neighbor Cache building and maintenance to the discretion of  
> the implementer seems to open the door toward non-interoperable  
> implementations on multi-vendor systems.  How one builds and  
> maintains its neighbor cache seems to me to be a very important  
> primitive operation of a mesh system.
>
> If all implementations must all support the full suite of messages  
> and the implementation is just deciding which message it will use to  
> build its cache, that's ok.  However, if implementer A picks message  
> X to build its neighbor cache while implementer B picks message Y  
> and elects not to support message X; that would not be a good thing.
>
> The point of all this babble is to please keep in mind  
> nonhomogeneous networks composed of many vendors' implementations.

I think we agree? There needs to be a specified set of operations  
which a node can use to discover other nodes, in that a RPL  
implementation MUST implement them. As it's a MUST, I'm of the opinion  
that such a set should be as simple and minimal as possible.  
Implementations can use other mechanisms as desired, but have to be  
able to use the standardized ones, such that they place a MUST on what  
other nodes do.

Phil