Experimental Physics and
Industrial Control System

Benjamin Franksen <[email protected]> · Mon, 31 Oct 2016 16:33:36 +0100

On 31.10.2016 15:30, Michael Davidsaver wrote:
> On 10/31/2016 07:09 AM, Benjamin Franksen wrote:
>> we finally found out what caused this strange behaviour. There was
>> indeed a misconfiguration in the network: a new device was mistakenly
>> copnfigured to use the same IP address as the IOC. For reasons that
>> remain mysterious to me this condition was/is not detected by our
>> network administrators. Instead we found out by trial and error and a
>> bit of luck: someone had the idea to unplug the IOC and then issue a
>> ping (which was answered by the 'imposter'). If the new device had been
>> configured to not answer pings we would still be wondering...
> 
> FYI, looking at the MAC in the arp cache of the client machine is a sure
> way to detect this.

If you know what kind of problem to look for, yes. BTW I don't even know
how to do that ("look at the arp cache"). For Linux I might find the
answer to that with some googling but the problem manifested only on a
Windows client.

Anyway, this sort of problem (duplicate IP adresses) should be detected
automatically by the network infrastructure IMO, and not left to be
debugged by control system engineers after they lead to obscure CA
connection failures.

Cheers
Ben
-- 
"Make it so they have to reboot after every typo." ― Scott Adams

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System