Re: [Roll] [roll] #86: G flag: do we need that text?

[Philip Levis <[e-mail]>]

On Apr 4, 2012, at 9:28 AM, Michael Richardson wrote:

> I think we need to determine what a grounded DODAG is.
> Does it mean that a node announcing such a thing is attached to the Internet? (In which case P2P usage should G=0)
> Or does it mean that a node is attached to the resource named in the DIO? (In which case origin P2P should G=1)
> 

The text in 6550 is pretty clear: 

   Goal: The Goal is an application-specific goal that is defined
         outside the scope of RPL.  Any node that roots a DODAG will
         need to know about this Goal to decide whether or not the Goal
         can be satisfied.  A typical Goal is to construct the DODAG
         according to a specific Objective Function and to keep
         connectivity to a set of hosts (e.g., to use an Objective
         Function that minimizes a metric and is connected to a specific
         database host to store the collected data).

   Grounded: A DODAG is grounded when the DODAG root can satisfy the
         Goal.

   Floating: A DODAG is floating if it is not grounded.  A floating
         DODAG is not expected to have the properties required to
         satisfy the goal.  It may, however, provide connectivity to
         other nodes within the DODAG.

The common case of the Goal is "has connectivity to the Internet" but that's not the only case. I think given the Goal for P2P traffic, I agree with Pascal and Richard that it should be 1.

Phil