The Ultimate in Weird?

Jay Ashworth

Well-Known Member
Just cleared a network problem, and I thought everyone might enjoy a nice saga...

We've been having a problem, the last month or so, where our Production LAN fell off the Internet -- I have ScreenConnect set up to get me to the two Mac Mini's, one in each booth, in case I have to support something, and each of them would disappear somewhere in the 9am hour weekdays, and come back on somewhere between 2 and 5pm.

If you think that sounds human-driven, you have much to go on, but *I* didn't get it until today, while the campus IT guy was pedaling over here with all his gear...

It turned out that the root cause was that some time During The Emergency, someone had unplugged the control Ethernet cable from the relevant jack on the back of the A&H Qu-16 desk...

... and plugged it back into the *D-Snake* jack. An Ethercon style jack, not a standard box jack. Me and my supervisor are the only 2 people who could reasonably be expected to unplug that wire, and we're both pretty sure we didn't, so it was clearly Bil Keane's kid, Ida Know.

That rack was only powered on for those 4 weeks ... weekdays, approximately the times that we saw the network go down. (We had a dance company renting it for intensives over the summer.)

No way to tell how long it was patched wrong. It only caused a problem while it was powered up.

What I'd love to know, though, is why patching a D-snake jack into the production LAN took down the whole LAN, including the upstream router (an ASUS RT-AC86U). Took it down so bad that SACN commands from our Ion to our movers executed... but only seconds (or minutes) later. Anybody sufficiently familiar with the D-Snake to speculate on why that connection might have caused such a foofaraw?
dSNAKE doesn't play nicely with non-dSNAKE devices. You can run it through a network switch under certain circumstances, but it must be on its own VLAN without any other devices connected to that VLAN. I'm not super familiar with the intricacies of that protocol, but it could be that you are running on a Layer 2 unmanaged switch and multicast traffic is becoming broadcast and creating a broadcast storm of audio traffic out to every other port on the network. Also, dS is high bandwidth. It'll throw bidirectional 100Mbps down your network links.

Best guess, either a broadcast storm or simply saturating the bandwidth on your network or switch.
Got it. I thought it might be something like that, but I wasn't sure how much stuff it was trying to route down that connection. Since it was a tributary or two away from my FS728 core switch, VLANs wouldn't have helped. Thanks.
If the guest wifi password isn't posted, people go looking for ethernet cables. Finding one and plugging in their laptop is easy. Remembering where the cable came from is harder.
True, though our campus provides its own Guest wifi, and most people use that -- we only give out the password to ours to people we trust.

And if I caught someone plugging in without asking, I would... well, become quite exasperated; I'm the IT director, but I'm still overhire.

Stop! Or I'll yell 'Stop', again!
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