Re: [Roll] How to react if Trickle Interval > Default Lifetime

Hello,

In Contiki I do think we are typically using infinite lifetime on the installed route between the child to parent.
If the child needs a downward route it would register that via DAO and keep that re-sent at less than default lifetime as specified
by the DIO (default lifetime and lifetime unit).

Best regards,
— Joakim

> On 02 May 2016, at 21:55, Simon Duquennoy <simonduq@sics.se> wrote:
> 
> Dear Cenk,
> 
> In Contiki we send periodic multicast DIS until the node has joined any DAG.
> After that, one thing you can do if enable "probing", which will periodically send a unicast DIS to your preferred parent (and also cover other candidates neighbors, to keep link estimates up-to-date).
> 
> In general wouldn't it be the expected practice to advertise trickle parameters that never surpass the default lifetime?
> 
> Simon
> 
> 
> On Mon, May 2, 2016 at 9:25 PM, Cenk Gündogan <cnkgndgn@gmail.com <mailto:cnkgndgn@gmail.com>> wrote:
> Dear RPL Veterans,
> 
> I recently came across the question of how a RPL router may react,
> if a parent's default lifetime (and unit -- specified in the DODAG Conf. Opt.)
> is surpassed by the parent's continuously rising trickle interval?
> 
> Without any action from the children, I would assume that the upward link to
> the parent would time out before the next DIO arrives to refresh the lifetime,
> hence breaking the child -> parent relation.
> 
> Implementations seem to handle this case very differently..
> 
> * The RPL implementation of RIOT uses unicast DIS messages to request a one-shot DIO
> from a parent that has a link which is about to expire.
> * From what I could gather in [1], Contiki also seems to send unicast DIS
> messages randomly in an interval of 30~55 seconds (Please correct me if I am wrong).
> * In an off-list discussion with Michael, I learned that unstrung is e.g. handling
> this case by not letting the Trickle interval exceed the default lifetime
> (Again, please correct me if I am wrong).
> 
> I couldn't find any hints regarding this situation in RFC6550.
> Is there actually an obvious way to handle this, but I am just not seeing it?
> 
> Best,
> Cenk Gündoğan
> 
> [1] https://github.com/contiki-os/contiki/blob/master/core/net/rpl/rpl-timers.c <https://github.com/contiki-os/contiki/blob/master/core/net/rpl/rpl-timers.c>
> 
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