We have a strange problem since yesterday. Suddenly, in the morning, we lost all network functionality. I could not ping any machine and nothing worked anymore (printer, as400, net, mail, ...). Since it was everything at once I thought it was the switch.
We tested a bit and then changed one switch. It worked fine for 2 hours. Then again, we lost all connections. We replaced another switch and the problem went away. 2 months ago we had to change another switch, so now all the switches on the network are relatively new. It worked fine for the remainder of the day.
this morning, after five minutes I was in, same thing happened. No more network. Two minutes later the network came back. 20 minutes later it went down again. We searched for an hour, shut down the server and router, but we didn't find why it went down. Finally, 20 minutes ago the problem went away. We could ping any machine again and everything seemed to work.
When the network is down, the switch still shows all the computers connected to it and we have blinking lights meaning there is traffic.
So we still have no idea where is the problem coming from and have no solution if it comes back. Does anyone know where it could be coming from?
I'm going to verify what you said because it might not be so hard to find for me since we don't have so much connections. And I have been asked to draw a plan of what is connected where on those switches. That's gonna be fun.