Re: [lp-wan] IANA registry for command and control rules

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

Hello Olivier

For 1b I guess it might be out of scope but I thought that the content of the command could be compressed using a compression rule;
e.g., this can be a way to transform human readable formats.

The way I see it, we could have a train of rules, some expressing commands, some expressing compressed parameters for the previous command.

But this is very abstract till we have a draft that uses the commands

Pascal


From: Olivier Gimenez <[e-mail]>
Sent: vendredi 20 mars 2020 10:47
To: Pascal Thubert (pthubert) <[e-mail]>; [e-mail]
Subject: RE: IANA registry for command and control rules

Thank you Pascal for the email.

To answer your questions

  1.  Yes, obviously :)
  2.

     *   I also think that values should be express as TLV so we can send several commands at a time
     *   I do not understand the "expressed in SCHC-compressed form": in order to avoid mixing layers this message should not be fragmented nor compressed
     *   This has to be acknowledged by the receiver; two ways I can see: receiver is re-emitting the same payload or receiver is sending a hash of the received payload

  1.  The need I foresee for now in SCHC over LoRaWAN draft:
2.1) IID nonce sharing
2.2) Eventually multicast setup, not be defined later

IID nonce sharing: I initially presented the need for this mechanism to send a rejoin request to a device, but sharing a nonce between the SCHC gateway and the device is better:

  1.   After each join the "IID nonce" is reinitialised to 0 on device and SCHC gateway
  2.  Both sides are using IID = F(devEui, AppSKey, IID nonce)
  3.  If there is a conflict gateway generates a new nonce then share it with the device
This way there is no more the cross layer issue we discussed when an IID conflicts triggers a rejoin, the gateway is also able to trigger an IID change is required (like the change over time requirement of RFC8065)


Best regards
Olivier


Questions:
0) Do we agree it's a good idea?
1) what do I miss in the above that should be in the draft?
2) what's your initial set of command/control/response?

All the best

Pascal


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