On 2014-05-26 01:37, Jean-Yves Bernier wrote: At 1:00 AM +0200 26/5/14, Johnny Billquist wrote: Well, that is not the full story... :-) 10.1>NCP SHO NOD 10.2 COU Node counters as of 30-MAR-82 00:21:30 Remote node = 10.2 (SNAKE) 1266 Seconds since last zeroed 272319 Bytes received 1723 Bytes sent 821 Messages received 373 Messages sent 1 Connects received 4 Connects sent 0 Response timeouts 0 Received connect resource errors 2 Node maximum logical links active 10.2>NCP SHO NOD 10.1 COU Node counters as of 30-MAR-82 01:10:34 Remote node = 10.1 (SHARK) 4212 Seconds since last zeroed 13475 Bytes received 1382813 Bytes sent 2626 Messages received 5177 Messages sent 26 Connects received 2 Connects sent 73 Response timeouts 0 Received connect resource errors 3 Node maximum logical links active Aha. So it is 10.2 that gets timeouts when sending packets to 10.1. So 10.1 are dropping packets. Good. Now, in which direction was the transfer attempted? Summary of my last experiments: Node A & node B inside VirtualBox (Linux) : that's the configuration i am running since the beginning of this discussion. Node A & node B on a same MacMini (BSD). VirtualBox out of the loop. => same problem. Node A on a MacPro, node B on the MacMini. VirtualBox out of the loop again. => same problem. Node A inside VirtualBox Linux (MacPro), node B on the MacMini (BSD). => same problem. We can rule out VirtualBox. We can rule out a Linux/BSD/pcap problem. We can rule out running multiple nodes on the same host (MAC addresses, etc). Two versions of simh were used, 3.6 and 3.9, in Mac and Linux build. Right. And I never expected any of the things listed above to be the problem to start with. This is a problem inside of DECnet on the simulated host. It gets packets faster than it can process them, so some packets are dropped. Unfortunately DECnet deals very bad with systematic packet loss like this. You get retransmissions, and after a while the retransmission timeout backs off until you have more than a minute between retransmission attempts. It is a known problem. [ Note: since simh 3.7, set console pchar=37777777777 if you want to use EDT/RMD/NTD at the console, took me an hour to figure. ] :-) Anyway, if you can get simh to throttle the ethernet interface, that might help you. (I don't remember offhand if it do support such functionality.) Johnny -- Johnny Billquist || "I'm on a bus || on a psychedelic trip email: bqt at softjar.se || Reading murder books pdp is alive! || tryin' to stay hip" - B. Idol