Re: some OOB packet loss stats

Quoting Zlatin Balevsky <[email protected]> from ml.gnutella.dev-forum:
:We look forward to your comments.

Loss of UDP message is to-be-expected.  It's not a big surprise that
it happens.  What's more surprising is the actual drop rate.

However, from your data, it is not clear whether the cause is overall
network congestion, or is due to the fact that the recipient's socket
queue is full, hence messages are dropped.

Gtk-gnutella increases the UDP socket's RX buffer size to 128K to ensure
there is enough room to "buffer" the received UDP datagrams in the kernel
until they can be processed.  If you leave that to 8K as it is usually
configured by default, and if you don't use the UDP compression scheme
(I don't think you implemented that), that could be a cause for the
high drop rate.

My suggestion is to first increase the RX buffer size to see whether it
makes a difference, and to also implement UDP compression.  It's a trivial
feature and it can make a difference because a host receiving many
OOB replies could quickly fill the RX buffer, so it pays to have compressed
messages.

UDP compression is completely backward compatible and is negotiated between
the hosts.  If you don't have the specs, I can forward you a copy.

Raphael