Re: how to detect udp packets drops ?

From: Måns Rullgård
Date: Wed Mar 10 2004 - 16:24:22 EST

KyoungSoo Park <kyoungso@xxxxxxxxxxxxxxxx> writes:

> Thank you for your kind response. But, if I follow your test
> senario, I cannot know which entity drops the packets. Routers on
> the path also can get congested and may drop the packets.

That is true.

> What I really want is to know is if the "kernel"(whch is supposed to
> receive packets) drops packets.

Do you mean you want to know if the kernel's receive buffer overflows?
That could be possible in theory, but I don't know whether it's
possible with the current Linux kernels.

> Also I don't want to contribute to the congestion by sending test UDP
> packets, because that may worsen the situation.
> Isn't there any way to monitor the packet drops at the end host by
> just looking at the "packet drop counter"?

If the packet reaches the end host the only reason for dropping it
would be a filled receive buffer. The size of the buffer can be set
using setsockopt().

Måns Rullgård
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