Re: [lwip-users] Duplicate ACK problem with LWIP 1.3.2

[Hafiz Bashir]

Hi,

I seem to have a problem sending the complete Wireshark capture file (is 
there a limit of the attachment size ?), so I have just sent the first 
200 packets which does show the problem

Best Regards

Hafiz

address@hidden wrote:
> Please attach wireshark captures in wireshark's own file format, not 
> as text export or any other format to make sure they are readable.
>
> Simon
>
>
> Hafiz Bashir wrote:
> > Hi,
> >
> > We seem to have a problem when using LWIP 1.3.2 to request a large file 
> > from a remote server. Our target is an ST7101 running OS21.
> >
> > Our application uses the netconn API to request a large file from a 
> > remote server using HTTP GET
> >
> >  From what I can see from Wireshark, the transfer begins OK with correct 
> > ACK's being sent.
> >
> > However at what appear to be random points during the transfer, I start 
> > to see duplicate ACK's. It seems LWIP is sending the same ACK for the 
> > next few segmemts it receives.
> >
> > I have experimented with adjusting the TCP_WND size in lwipopts.h with 
> > mixed results. It would appear that if TCP_WND > 8*TCP_MSS, then we 
> > start seeing the duplicate ACK problem. TCP_MSS is set to 1460. However 
> > having a lower TCP_WND size results in a lower transfer performance.
> >
> > I have attached a text file containing the Wireshark export.
> >
> > Any help would be greatly appricated.
> >
> > Thanks
> >
> > Hafiz
> >   
> >
> >
> > _______________________________________________
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> > address@hidden
> > http://lists.nongnu.org/mailman/listinfo/lwip-users
>
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dup_ack_1_lwip_1_3_2.pcap
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