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machine to self UDP problem

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Leon Hurst

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Jul 28, 1997, 3:00:00 AM7/28/97
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I wrote UDP producer and consumer programs. They use the
DatagramSocket class in java.net. The consumer always
receive()s all possible packets on port 7001 of whatever
machine it is run on. The producer sends 2000
DatagramPackets to port 7001 of a machine specified at the
command line.

Running them on different machines is fine. However, if I
run them on the same machine I observe a packet failure
rate in access of 50%. The larger the packets the greater
the failure rate. I know UDP is unreliable, but not at 50%
on to the same machine.

Can anyone indicate what is wrong?

I have tested it on NT and Unix boxes.

Many thanks,
Leon.

David Hopwood

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Jul 29, 1997, 3:00:00 AM7/29/97
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In message <33DC6459...@cs.tcd.ie>
Leon Hurst <leon....@cs.tcd.ie> writes:

> I wrote UDP producer and consumer programs. They use the
> DatagramSocket class in java.net. The consumer always
> receive()s all possible packets on port 7001 of whatever
> machine it is run on. The producer sends 2000
> DatagramPackets to port 7001 of a machine specified at the
> command line.

> Running them on different machines is fine. However, if I
> run them on the same machine I observe a packet failure
> rate in access of 50%.

You're probably sending the packets faster than they can be
processed (which is easy to do when sending to localhost), so
the excess are being dropped.

David Hopwood
david....@lmh.ox.ac.uk, hop...@zetnet.co.uk

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