Re: Mcast packet loss kernel

From: David Stevens
Date: Thu Nov 15 2007 - 04:02:22 EST

Well, that output doesn't show any new (intentional) drops, but the kernel
age means there could be an already-fixed bug, too.

A couple things I'd suggest:

1) if you can run your program with a unicast address
and see if you have similar drops
2) even if you can't update your entire kernel, if you can
run the test program on a current kernel (even on a
different system), you may get a hint whether it's a problem
that has been fixed (figuring out which patch(es) you need is
another matter!)
3) if the test program (sender and receiver) is reasonably small,
you can post that here and I can try it on a current kernel
to see if I can reproduce the results on different hardware, as
well as look for any problems in the application.

I don't think promiscuous mode directly relates, but tcpdump
has an option to run with or without promiscuous mode. So you should
be able to look at the packets both ways. But the IP receive count
won't go up if there's a problem with device receives (like the
multicast filter not matching), and you said when you had drops the
packet count was correct, I believe.


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