VLAN config took down the whole office network in 20 mins

I was messing with a new VLAN on our Meraki switch last Tuesday and forgot to set the native VLAN correctly. Suddenly no one in accounting could reach the server, then the printer queue froze, and the guest wifi stopped handing out IPs. I had to drive back to the office at 8pm and factory reset the switch to undo my mistake. Anyone else accidentally nuke their production network with a simple VLAN change?

2 comments

2 Comments

matthewperry11d ago

Subnet mask typo is my personal favorite way to ruin a Tuesday. I set a /22 instead of a /24 once and suddenly the whole building thought it was in the same broadcast domain. Ended up with duplicate IPs and a switch that looked like a christmas tree of errors. Took me two hours to realize my fingers just slipped one number.

felix_jones11d ago

Heard a buddy did the same thing with VoIP VLANs a while back. Had the voice VLAN set to tag everything including the management interface, then suddenly no phones could register and the receptionist’s PC couldn’t even get an IP. By the time he figured out he had to hardcode the native VLAN back to 1, the whole front desk had already lost three sales calls and his boss was standing behind him watching him panic at the console. He still gets nervous when he sees a VLAN dropdown menu.