Re: [Roll] New Version Notification for draft-gnawali-roll-rpl-recommendations-03.txt

Hi John,

> 
> Koojana,
> 
> In terms of why the DIS is sent at different intervals is rather simple
> to explain. A Trickle Timer is typically used when the network is
> stable and nothing needs to happen. At least this is the philosophy I
> tried to follow when implementing TinyRPL. However, when a node is NOT
> connected, this indicates that the network is not stable AT ALL.
> Therefore, it should try to aggressively find a next hop node rather
> than to save power. The goal of the node should be, at this point, to
> connect to a DODAG.
>

[koo] Yes

> Furthermore, it is not really necessary to install the root last in a
> RPL deployment. I don't see why this HAS TO be the case. 

[koo] Unfortunately, this is not the case for our scenario in reality. E.g.,
Fruits will be placed in boxes together with sensor nodes (at the field) and
will be loaded to a container (at the harbor) later. The DODAG root (the BR)
will be attached to the container. Until the sensor nodes see any reachable
DODAG root, it may takes 1 - 2 days. 
Therefore, the sending of DIS messages periodically is not a good option.

As Pascal pointed out, the use of exponential back-off would be an
alternative to reduce numbers of DIS generated. I am not very familiar with
RPL draft. I think, there is no possibility to let a sensor node know to
trigger sending of DIS messages after a certain time. This may helpful for
some scenarios like ours to save the power during the setup time. 

Thanks

Koojana

If you install
> the root first, then nodes will quickly connect to the network and the
> Trickle Timer for DIO packets will start operating.
> 
> Thanks!
> 
> -John
> 
> ------
> JeongGil Ko
> Ph.D. Candidate
> Department of Computer Science
> Johns Hopkins University
> http://www.cs.jhu.edu/~jgko
> 
> On Mar 14, 2012, at 1:14 AM, Koojana Kuladinithi wrote:
> 
> > Hi,
> >
> > I read your draft. We have done some tests with TinyRPL (RPL
> implementation
> > in TinyOS) in container filled with fruits.
> > In one test, we had a situation that the border router (RPL root
> node) was
> > disconnected for several hours. The sensor nodes start sending DIS
> > (DIS-INTERVAL was set to 3 sec for this test). We found that this
> degrades
> > the use of  battery voltage. One alternative is to use a higher value
> for
> > DIS-INTERVAL.
> >
> > In real deployment, the RPL root node should setup at the last, after
> > loading all the sensors.
> >
> > I would like to know ->
> >
> > Why is DIS sending at a constant interval (I am not sure this is set
> > constant only in the implementation)? Should it be adaptive if it
> does not
> > receive a DIO?
> > Is this an issue ("setting of DIS INTERVAL for different cases") that
> your
> > draft should address?
> >
> > Kind regards
> >
> > Koojana
> >
> >
> >
> >> -----Original Message-----
> >> From: roll-bounces@ietf.org [mailto:roll-bounces@ietf.org] On Behalf
> Of
> >> Omprakash Gnawali
> >> Sent: Sunday, March 11, 2012 2:36 AM
> >> To: ROLL WG
> >> Subject: [Roll] Fwd: New Version Notification for draft-gnawali-
> roll-
> >> rpl-recommendations-03.txt
> >>
> >> Dear ROLL WG,
> >>
> >> I just refreshed this draft with comments from JP, Cedric, Joakim,
> and
> >> Ulrich. Please keep your comments coming, especially those who have
> >> implemented and deployed RPL.
> >>
> >> Thanks.
> >>
> >> - om_p
> >>
> >> ---------- Forwarded message ----------
> >> From:  <internet-drafts@ietf.org>
> >> Date: Sun, Mar 11, 2012 at 1:34 AM
> >> Subject: New Version Notification for
> >> draft-gnawali-roll-rpl-recommendations-03.txt
> >> To: gnawali@cs.uh.edu
> >> Cc: pal@cs.stanford.edu
> >>
> >>
> >> A new version of I-D, draft-gnawali-roll-rpl-recommendations-03.txt
> >> has been successfully submitted by Omprakash Gnawali and posted to
> the
> >> IETF repository.
> >>
> >> Filename:        draft-gnawali-roll-rpl-recommendations
> >> Revision:        03
> >> Title:           Recommendations for Efficient Implementation of RPL
> >> Creation date:   2012-03-10
> >> WG ID:           Individual Submission
> >> Number of pages: 6
> >>
> >> Abstract:
> >>   RPL is a flexible routing protocol applicable to a wide range of
> Low
> >>   Power and Lossy Networks.  To enable this wide applicability, RPL
> >>   provides many configuration options and gives implementers choices
> on
> >>   how to implement various components of RPL.  Drawing on our
> >>   experiences, we distill the design choices and configuration
> >>   parameters that lead to efficient RPL implementations and
> operations.
> >>
> >>
> >>
> >>
> >> The IETF Secretariat
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> >
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