Re: [Cse461] packet loss in emulator and simulator

From: Eileen Hash (esp_at_cs.washington.edu)
Date: Mon Feb 23 2004 - 11:05:00 PST

  • Next message: Janet Davis: "[Cse461] Homework 2 summary"

    Anybody have a fix for how to do loss rate in the emulator?

    On Mon, 23 Feb 2004, Janet Davis wrote:

    > Sorry to everyone who's suffered from this. We won't deduct points for
    > subtle bugs in your retransmission algorithm if the overall design is
    > correct.
    >
    > To enable packet loss in the simulator, make the following change at line
    > 89 of commands.rb:
    >
    > # lossRate = $1.to_f if opts =~ /lossRate:\s*([0-9\.]+(:?[eE]\d*)?)/
    > lossRate = 0.05
    >
    > Cheers,
    > Janet
    >
    > On Sun, 22 Feb 2004, Janet Davis wrote:
    >
    > > On Sun, 22 Feb 2004, Matthew Burkhart wrote:
    > >
    > > > We were trying run our test cases for the turnin and we cannot get the
    > > > simulator or emulator to produce any packet loss!
    > > > We looked in the code and found that that schedulePkt(src, size, now)
    > > > method in topology.rb (which causes packet loss) is not used at all in
    > > > the emulator/trawler. Ok so the emulator can't do packet loss...?
    > > >
    > > > So we then tried the simulator it didnt work immediately, so we checked
    > > > out the code and found two issues:
    > > > lossRate = $1.to_f if opts =~ /lossRate:\s*([0-9\.]+(:?[eE]\d*)?)/
    > > > so our topo file should use "lossRate: 0.05" instead of "loss: 0.05"?
    > > > Furthermore, the $POSTMATCH use in parseEdgeOptions($POSTMATCH) is nil
    > > > ONLY when we run simulator, but parses correctly in the trawler.
    > > > What is going on here?? What are we missing? Have you all been able to
    > > > get packet loss to work?
    > >
    > > Looks like we screwed up. Thanks for debugging; this should help Evan
    > > straighten it out.
    > >
    > > > Should we just hard code the default loss rate in simulator to 0.05?
    > >
    > > That sounds like a fine idea.
    > >
    > > Cheers,
    > > Janet
    > >
    > > --
    > > Janet Davis
    > > jlnd_at_cs.washington.edu
    > > http://www.cs.washington.edu/homes/jlnd/
    > >
    > > _______________________________________________
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    > > Cse461_at_cs.washington.edu
    > > http://mailman.cs.washington.edu/mailman/listinfo/cse461
    > >
    >
    > --
    > Janet Davis
    > jlnd_at_cs.washington.edu
    > http://www.cs.washington.edu/homes/jlnd/
    >
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