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Re: Sending streams stall due to bad flow control by KPPP

Brendon Lloyd Higgins wrote:
If anyone is interested, August last year I started a thread called "(Sid) Net broken - Sending streams stall" about how sending files over my modem seemed to stall after only a few 10s of kB were sent.

Well, after giving up for a while and using gpppon instead of KPPP as I would prefer, I came back and had a look at how KPPP was calling pppd. It turns out that even though "Hardware [CRTSCTS]" flow control was set in the KPPP config it would call pppd with a "xonxoff" argument. This is due to a bad test in connect.cpp near line 1273. It ought to read something like:

  QString flowCtrl = gpppdata.flowcontrol();
  if(flowCtrl != "None" && flowCtrl != i18n("None")) {
    if(flowCtrl == "CRTSCTS" || flowCtrl == i18n("Hardware [CRTSCTS]"))
      command += " crtscts";
      command += " xonxoff";

Of course, my poor modem being swamped with outgoing data faster than it could send it due to non-existent flow control was the reason I was getting these symptoms. Recompiling kdenetwork source with the above change seems to have fixed the problem.

Just FYI,
Brendon Higgins

Thanks for this info. This could be my problem. I tried searching your subject on the mailing list archive, but came up with no results. Anyway, how does one determine which options are in effect for the connection?


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