Re: [6tisch] 6P and Sf0 issue: Token to identify transactions in 6P

Tero Kivinen <kivinen@iki.fi> Mon, 07 March 2016 13:24 UTC

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Date: Mon, 7 Mar 2016 15:24:13 +0200
From: Tero Kivinen <kivinen@iki.fi>
To: "Pascal Thubert \(pthubert\)" <pthubert@cisco.com>
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Cc: "6tisch@ietf.org" <6tisch@ietf.org>, "Prof. Diego Dujovne" <diego.dujovne@mail.udp.cl>, Tengfei Chang <tengfei.chang@gmail.com>
Subject: Re: [6tisch] 6P and Sf0 issue: Token to identify transactions in 6P
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Pascal Thubert (pthubert) writes:
> But if the ack is sent and not received then the parent does not
> allocate the cells and the child uses them...

And ACK only tells you that the frame was received, it does NOT mean
that the frame was processed. I.e. the recipient end might send an
ACK, and then send the frame to the upper layer, but if there is not
enough buffer space available there, it might drop it before it
actually reaches the upper layer.

So do not use ACK for anything else than indication that there is no
need to retransmit this frame anymore as other end already received it
(altough it might have dropped it after that, but retransmissions does
not help with that).
-- 
kivinen@iki.fi