Re: [Roll] Retrying DCO/DAO, retry parameters

["Pascal Thubert (pthubert)" <[e-mail]>]

Looks good to me, Rahul

All the best,

Pascal

> -----Original Message-----
> From: Rahul Arvind Jadhav <[e-mail]>
> Sent: vendredi 5 juillet 2019 14:30
> To: Pascal Thubert (pthubert) <[e-mail]>
> Cc: Routing Over Low power and Lossy networks <[e-mail]>; Mirja
> Kühlewind <[e-mail]>; Alvaro Retana <[e-mail]>
> Subject: RE: [Roll] Retrying DCO/DAO, retry parameters
> 
> Can we add something like;
> 
> The DCO retry time should be dependent on the maximum depth of the
> network and average per hop latency. Thus this could range from 2 sec to 120
> seconds depending on the deployment. The number of retries could be set
> between 2 to 6 depending upon how critical the route invalidation could be
> for the deployment and the link layer retry configuration. For networks
> supporting only MP2P and P2MP flows, such as in AMI and telemetry
> applications, the 6LRs may not be very keen to invalidate routes, unless they
> are highly memory-constrained. For home and building automation networks,
> with P2P traffic, the 6LRs might be keen to invalidate efficiently because it
> may additionally impact the forwarding efficiency.
> Note that the DCO might in turn be retried at link layer if link layer supports
> Ack for unicast packets. In such cases where link layer employs retry-
> mechanism for unicast packets, retrying more than 3 times may not be
> necessary, depending on link layer retry configuration.
> 
> Any thoughts?
> 
> Regards,
> Rahul
> 
> 
> -----Original Message-----
> From: Roll [mailto:[e-mail]] On Behalf Of Mirja Kuehlewind
> Sent: 04 July 2019 19:28
> To: Pascal Thubert (pthubert) <[e-mail]>
> Cc: Routing Over Low power and Lossy networks <[e-mail]>
> Subject: Re: [Roll] Retrying DCO/DAO, retry parameters
> 
> I think that is also a good additional to have. I would recommend to discus
> the boundaries in both directions: what the maximum rate I should ever to
> for in order to not permanently overload the network and what are the usual
> considerations to set these parameters correctly for my use case.
> 
> Mirja
> 
> 
> > On 4. Jul 2019, at 13:22, Pascal Thubert (pthubert) <[e-mail]>
> wrote:
> >
> > You have a point there, Mirja.
> >
> > UDP over LLNs may have to live with durations that are 1 to 2 orders of
> magnitude longer than usual in more classical links these days. It can take a
> minute and more to get a message through.
> >
> > So yes, a bit of text that says that the typical latencies and turn-around-trip
> delays observed on the Internet and the default settings that derive from that
> may not apply in LLNs and need to be revisited depending on the link type
> and the number of hops in case of a mesh network.
> >
> > Is that what you are indicating to us?
> >
> > Pascal
> >
> >> -----Original Message-----
> >> From: Mirja Kuehlewind <[e-mail]>
> >> Sent: jeudi 4 juillet 2019 13:05
> >> To: Alvaro Retana <[e-mail]>; Pascal Thubert (pthubert)
> >> <[e-mail]>
> >> Cc: Routing Over Low power and Lossy networks <[e-mail]>
> >> Subject: Re: [Roll] Retrying DCO/DAO, retry parameters
> >>
> >> Hi,
> >>
> >> My request wasn’t to specify this in detail for every scenario, it
> >> was to set boundaries about what's safe to do. The 3 seconds I
> >> mentions are the recommendation given in RFC8085, however, if you
> >> have a good reason to use different values that possible but it would
> >> be good to provide more reasoning then about when it is still safe to
> >> use the values and when it should be avoided.
> >>
> >> Mirja
> >>
> >>
> >>> On 4. Jul 2019, at 12:44, Alvaro Retana <[e-mail]> wrote:
> >>>
> >>> On June 27, 2019 at 1:54:11 AM, Pascal Thubert (pthubert)
> >> ([e-mail]) wrote:
> >>>
> >>> Hi!
> >>>
> >>>> RPL is designed to operate in very different environment, and some
> >>>> LLNs
> >> can be very slow, very lossy or even both. This is why RFC 6550
> >> refrains from being too specific.
> >>>> Maybe it is good enough to add text indicating that the values used
> >>>> for DCO
> >> are expected to be similar/consistent with those used in DAO?
> >>> I agree with Pascal.  In fact, the diversity of environments not
> >>> only makes it
> >> very hard to be too specific, but it is one of the reasons the WG has
> >> produced Applicability Statements for them: not all deployments are the
> same.
> >>>
> >>> Thanks!
> >>>
> >>> Alvaro.
> >>>
> >>>
> >
> 
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