Subject: Re: [lp-wan] some topics to discuss related to schc-lorawan draft

From: Olivier Gimenez <[email-masked]>
Date: Wed, 22 Jan 2020 08:41:26 +0000

From: Arunprabhu Kandasamy <[email-masked]>
Sent: 18 December 2019 09:26

In order to avoid overlapping the state machine of the receiver, the sender could wait some time, if he has knowledge of the inactivity timer configured at receiver, (inactivity timer + delta) before sending the fragments from next session. But I think, this is not the behavior that is specified in the draft.
So, it would be good to have some section or sentence that gives the implementors some suggestions on how to interleave fragments when there is no dtag.

Topic 2(new):
 Since we don't have a dtag in the headers, it might create some ambiguity in the receiver to manage statemachines for the devices when it receives a new fragmented packet while the inactivity timer is still active. Note that the sender doesn't have the knowledge of the inactivity timer.
It would be nice to have a section in the draft to discuss this behavior and probably a solution to overcome it.

Hi Arun,

I try to understand this but I have hard time figuring out how to enter in the state where sender starts the fragmentation session N+1, when the receiver did not end the session N ?
Although, if we enter in such case, the receiver will be able to see wrong windows & FCN counters then transmit a Receiver-Abort message, so both sender/receiver can be reset.

Olivier

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