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Re: [6tisch] Questions on RPL Settings in RFC 8180

Yasuyuki Tanaka <yasuyuki.tanaka@inria.fr> Mon, 27 August 2018 16:06 UTC

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From: Yasuyuki Tanaka <yasuyuki.tanaka@inria.fr>
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Date: Mon, 27 Aug 2018 18:06:16 +0200
Cc: Yasuyuki Tanaka <yasuyuki.tanaka@inria.fr>, "6tisch@ietf.org" <6tisch@ietf.org>
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To: "Pascal Thubert (pthubert)" <pthubert@cisco.com>
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Subject: Re: [6tisch] Questions on RPL Settings in RFC 8180
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Thank you, Pascal!

> [PT>] True, so we never reach 9 and stay compatible with OF0. I guess the max ETX of 3 is arbitrary, we could have gone up to 11/3...

OK! That is what I understood. It's very clear now.

> The initial value of I (see RFC 6206) is between Imin and Imax. With the default, that is between 8ms and 2.3 hours. Hopefully I is not always 8ms! The DIO will not fire before I/2.


Regarding the Trickle timer, yes, the initial value of "I" is chosen between Imin and Imax. And it's not always 8ms.

But, "I" is reset to Imin (8 ms) when Trickle hears something "inconsistent". After that, "I" will be just doubled at the end of interval: 16ms, 32ms, 64ms, ... This could pile up DIOs in the TX queue and consume bandwidth for nothing. :-/

Best,
Yatch

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