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

Mukul:

I think we disagree because of the definition of goal itself. The goal is an abstraction. Same goes for the term Objective in OF. RFC 6550 only gives examples of what G could be used for but that is not limiting. Certainly the abstraction may for instance mean that external nodes are reachable via the root. But it could be something else entirely. For instance it could designate a root that can aggregate data.

In practice, G is used to favor a root that reaches the goal vs. one that does not. But that's senseless for local instances that have by definition a single root.

So whatever you set it to does not make a difference for RFC 6550 operations. I figure it could be used for signaling a "transient goal" information to an OF that could use it for a purpose I can't fathom.

In any case, as I suggested earlier and as Richard also suggest now, G SHOULD probably be 1 by default but MAY be set otherwise.

Pascal

-----Original Message-----
From: Mukul Goyal [mailto:mukul@uwm.edu] 
Sent: mercredi 4 avril 2012 16:16
To: Pascal Thubert (pthubert)
Cc: roll@ietf.org; Richard Kelsey
Subject: Re: [Roll] [roll] #86: G flag: do we need that text?

Pascal

>If the goal is to reach the root, then G is 1...

I have told you multiple times that joining a P2P-RPL DAG does not give any sort of connectivity to the node.

Thanks
Mukul

----- Original Message -----
From: "Pascal Thubert (pthubert)" <pthubert@cisco.com>
To: "Mukul Goyal" <mukul@uwm.edu>, "Richard Kelsey" <richard.kelsey@ember.com>
Cc: roll@ietf.org
Sent: Wednesday, April 4, 2012 9:05:28 AM
Subject: RE: [Roll] [roll] #86: G flag: do we need that text?

Hello Mukul

Floating vs. Grounded depends on the goal of the DODAG. I asked you and will ask again what is your goal?
If the goal is to reach the root, then G is 1... If you want to signal something to the OF using the G bit, leave it  open.

Cheers,
Pascal

-----Original Message-----
From: roll-bounces@ietf.org [mailto:roll-bounces@ietf.org] On Behalf Of Mukul Goyal
Sent: mercredi 4 avril 2012 15:55
To: Richard Kelsey
Cc: roll@ietf.org
Subject: Re: [Roll] [roll] #86: G flag: do we need that text?

>The G flag is 0 if and only if the DODAG is floating.

I think that the G flag is 1 if and only if the DODAG is grounded. The temporary DAGs used in P2P-RPL are not grounded, they are temporary. I think that all transient/temporary DAGs are floating by their very nature.

Thanks
Mukul

----- Original Message -----
From: "Richard Kelsey" <richard.kelsey@ember.com>
To: roll@ietf.org
Cc: mukul@UWM.EDU, jpv@cisco.com, roll@ietf.org
Sent: Wednesday, April 4, 2012 8:36:50 AM
Subject: Re: [Roll] [roll] #86: G flag: do we need that text?

> From: roll issue tracker <trac+roll@trac.tools.ietf.org>
> Date: Wed, 4 Apr 2012 13:08:50 +0000
> 
> #86: G flag: do we need that text?
> 
>  Problem (resolition is proposed)
>  ------------------------------
>  Disagreement on the meaning of 'G' bit and imposed setting to 0;
> 
>  Proposed resolution
>  ---------------------------
>  The origin sets the G flag based on its perception of whether joining

> how the flag's value would affect the rank calculation under the OF 
> being used. By default, the G flag is set to zero given the temporary

> nature of the DAG being created.

I disagree with the proposed resolution.  It adds needless confusion.
The G flag is 0 if and only if the DODAG is floating.
There is no point to allowing floating DODAGs with a P2P-RDO option.  I suggest that the G bit be set to 1 and that routers be explicitly prohibited from creating floating DODAGs with a P2P-RDO option.
                                   -Richard Kelsey _______________________________________________
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