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Re: [lwip-users] Missing ACKs using LWIP 1.3.2

From: Sergio R. Caprile
Subject: Re: [lwip-users] Missing ACKs using LWIP 1.3.2
Date: Fri, 08 May 2015 09:37:18 -0300
User-agent: Mozilla/5.0 (Windows NT 5.1; rv:31.0) Gecko/20100101 Thunderbird/31.6.0

I bet you won't find specific lwIP patches on this because it doesn't
seem to be an lwIP bug. Polling the ethernet controller every 10ms is a
very bad idea, unless you are absolutely sure there won't be more frames
arriving in that time frame than what can fit in its buffer. You should
interrupt and buffer/signal  and/or poll the controller as frequently as
you can.
Another common mistake is polling the controller for last frame only,
two or more consecutive frames arriving between polls cause only the
first one to be retrieved. My bet is that you are constantly losing
frames you don't care about, and once a day you lose an important one.

You can try fixing the code to be more responsive, or you can try
another port. Anyway, I suggest you check it for proper behavior by
running netio or something similar.

Porting lwIP is not as cumbersome as it might seem, I did.
You can try this ARM Coortex-M3 vendor-agnostic port here:


you can probably keep your link-layer driver. Let us know.


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