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

>Floating vs. Grounded depends on the goal of the DODAG. I asked you and
will ask again what is your goal?

I am not sure there is a natural way to define this goal. Why is it that a route discovery should specify an application-level goal and that too in just one bit. My opinion is that the grounded bit is quite unnecessary even for core RPL. Connectivity to specific hosts via the root is specified using other means (the Route Information Option) and the relation to OF is not well defined and in my opinion artificial.

>If you want to signal
something to the OF using the G bit, leave it  open.

I have no problem leaving it open. But I think the reason has to be right. Richard, on the other hand, wants it to be closed in other direction (always set it to 1) (I dont agree with his reasoning though).

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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