net.inet.udp.blackhole issue

[Yony Yossef]

Hi All,

I'm facing lots of UDP "Connection refused" errors while running
multistream iperf test.
Analyzing it with wireshark showed several "ICMP Port Unreachable" problems.

I've overriden it with "sysctl net.inet.udp.blackhole=1", but I'm not
sure this is the correct thing to do, I feel like I've sweeped the
problem under the carpet.

PS - I see similar failures with TCP bidirectional iperf test, it can
also be overriden by "sysctl net.inet.tcp.blackhole=1".

My question is -
can it be a NIC problem?
If so, how can a driver problem cause an iperf UDP socket to be in a
"non listening state"?

Thanks,
Yony