Subject: [core] Time Scale Option

From: Laurent Toutain <[email-masked]>
Date: Tue, 29 May 2018 11:01:54 +0200

Hi,

We have published few month ago a draft defining a new CoAP option.

https://datatracker.ietf.org/doc/draft-toutain-core-time-scale/

The main idea is to inform a server when devices will not have the same
reaction time. Current CoAP RFC defines a default 5 minutes window during
which any message will be consider as a retransmission.  This delay is too
small for LPWAN network, where small bandwidth, duty cycles are introducing
larger delays. One solution is to change the default window value, but this
period will be too long for “regular” devices and force the server to
memorize more message ID.

That’s why we propose the Time Scale option, the client informs the server
of the window period where messages will be considered as retransmitted.
The server will be informed for this device and will adapt its timers.

We would like to know, as we discussed during London IETF, what is the
position of the core wg on this option.

Ana and Laurent

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From: Klaus Hartke <[email-masked]>
Date: Tue, 29 May 2018 11:36:59 +0200

Wouldn't ACK_TIMEOUT, MAX_LATENCY, etc. need to be adjusted, since
EXCHANGE_LIFETIME is just a calculated value?

Klaus

On 29 May 2018 at 11:01, Laurent Toutain
<[email-masked]> wrote:
> of the window period where messages will be considered as retransmitted. The
> server will be informed for this device and will adapt its timers.
>
>
>
> _______________________________________________
> core mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/core
>

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From: Laurent Toutain <[email-masked]>
Date: Tue, 29 May 2018 12:08:29 +0200

Hi Klaus,

Yes, ACK_TIMEOUT and MAX_LATENCY are known from the LPWAN device and the
value carried in the option result of this computation.

Laurent

On Tue, May 29, 2018 at 11:37 AM Klaus Hartke <[email-masked]> wrote:

> The