>>> Kieran Mansley <[EMAIL PROTECTED]> schrieb am 20.06.2007 um 12:14: > On Wed, 2007-06-20 at 11:52 +0200, Matthias Weisser wrote: >> Hi >> >> Today I found some time to do some deeper testing of my lwIP port. I >> used wireshark and tested around a bit. >> >> The first thing I saw that there are TCP retransmissions from time to >> time. These retransmissions happens about 5-10ms after the original >> packet was transmitted but not for every packet. That seems a little >> to early to me. > > Were there any ACKs from the other side between the sending of the > packet and its retransmission? If so, it could be fast retransmission
No. There where no ACKs from the PC side. BTW: Its a simple echo server. > and not a problem. If not, it does seem a bit early. Perhaps you could > send a wireshark/ethereal capture file to illustrate the problem? Attached to this mail you find a pcap file. 210 is the PC (echo client) and 34 is the lwIP device running the echo server on port 6666. >> Another question is about the TCP window size. Which value makes sense >> together with all the other options in the lwipopts.h? Maybe its worth >> to write a little bit more about these options and how they depend on >> each other. > > You're right that this the links between many options are not obvious, > and it's been a frequently asked question/problem on the mailing list. > I agree that more documentation would be good. Any volunteers? There > was a useful post on the mailing list a few months ago documenting some > "good" settings for everything, but I don't have a link to hand at the > moment. > > As for the window size, apart from making sure it's at least twice the > MSS, and that you have sufficient buffer space to accept a window worth > of data in one go, there's not a lot more to it. Of course, bigger is > better in terms of performance, but will require more memory for > buffers. I ask because when I send big data packets (10k+) at once to my echo server I have lost data from time to time and I think that has something to do with bad settings in my lwipopt.h file. Matthias
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