Hi Thomas, No, that's exactly what I ment.
I was just thinking about how the network would behave when for example 20 o 30 nodes are switched on simultaneously in Minimal. If the initial value of BE is low (1 or 2), collisions are expected to be very frequent in the shared cell. And since the first messages for joining the network (EBs and DIOs) are broadcasted without expecting an ACK, the BE could remain unmodified and the joining process could last forever. Could this scenario happen? Or am I missing something important? But indeed maybe this is out of the scope of Minimal since is just matter of sizing the number of shared cells in the schedule and the topic is rather related with the 802.15.4 standard than with 6tisch. Kind regards, Esteban On Thu, 2017-02-09 at 23:46 +0000, Thomas Watteyne wrote: > Esteban, > > > I believe this is fully specified in the 802.15.4 standard. In a > nutshell, the back-off mechanism is triggered only when the cell is > marked as "shared". When a mote sends a packet and doesn't get an ACK, > the BE is changed. If you send a frame to link-layer destination > 0xffff, you're not expecting an ACK, so BE will not change. > > > I may be missing your point? > > > Thomas > > On Thu, Feb 9, 2017 at 10:59 AM, Esteban Municio > <[email protected]> wrote: > Hi all, > > I was wondering if there is any recommendation about how set > up the > Backoff mechanism in shared cells when no ACKs are expected. > > According to the standard, macMaxBE and macMinBE are defined > and the BE > is increased at every attempt. However, if the node is not > expecting any > ACK (i.e sending DIOs or EBs), I guess the BE will be always > the same. > Is there any recommendation in Minimal about how to choose > this value? > > Maybe a value related with the number of nodes or DIO/EB > period? > > Kind regards, > Esteban > > -- > Esteban Municio > IDLab - Dept. Mathematics and Computer Science > University of Antwerp - imec > Middelheimlaan 1 , 2020 Antwerp, Belgium > Office M.G.325 > > _______________________________________________ > 6tisch mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/6tisch > > > > > -- Esteban Municio IDLab - Dept. Mathematics and Computer Science University of Antwerp - imec Middelheimlaan 1 , 2020 Antwerp, Belgium Office M.G.325
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