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Re: [lwip-users] Re transmission behaviour?


From: Simon Goldschmidt
Subject: Re: [lwip-users] Re transmission behaviour?
Date: Mon, 02 Jul 2012 17:39:23 +0200

Fred39 <address@hidden> wrote:
> LWIP is the slave which response!

Just to rule out any uncertainties, this would be 192.168.0.222 in your 
captures (that would be the info requested, simply put)?

In that case, how can you change the tcp timer interval of the master? Or isn't 
that what you did?

> http://old.nabble.com/file/p34102440/master2sec.pcap master2sec.pcap   
> http://old.nabble.com/file/p34102440/master30msec.pcap master30msec.pcap 
> 
> here are 2 packets one with 30msec master cycle one with 2 seconds hope
> this
> helps by diagnose my problem

The RTO (retransmission timeout, based on the connection's RTT) is initialized 
to 3 seconds in lwIP. Given the fact that your lwIP retransmits after 60ms 
right at the start of the connection (where there was no time yet to lower the 
RTT or RTO - we need ACKed data for that), it actually seems that your TCP 
timer is running way too fast. Please ensure it is configured to run every 
250ms and that this timing actually works (e.g. by toggeling an IO pin of your 
target from tcp_tmr()).

Simon



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