Funny story: so, my junior tech, who at some point had taken some Cisco course or another, had been tasked with finishing up some gigabit connections between two buildings.
In the main building, the network cabinet has two unmanaged Netgear Prosafe switches; one 10/100, and one gigabit.
Without thinking about it, he plugged some of the cables for the other building into one switch, and some into the other.
Both sets of cables ran to the other building, and then into another Netgear unmanaged switch. (There were multiple cables primarily for redundancy.)
So naturally the next day the network just starts going wild. He's tied a gigabit-size loop into the network, and the unmanaged switches are helpfully forwarding traffic back and forth to eachother, even though they're really not supposed to do that.
He's totally stumped. I get called in, sit down for a few minutes with tcpdump, and watch the traffic for a few devices on the network. Didn't take very long before I had a rough idea of what had happened, opened up the network cabinet, and found the misplaced connections.
Funny story: so, my junior tech, who at some point had taken some Cisco course or another, had been tasked with finishing up some gigabit connections between two buildings.
In the main building, the network cabinet has two unmanaged Netgear Prosafe switches; one 10/100, and one gigabit.
Without thinking about it, he plugged some of the cables for the other building into one switch, and some into the other.
Both sets of cables ran to the other building, and then into another Netgear unmanaged switch. (There were multiple cables primarily for redundancy.)
So naturally the next day the network just starts going wild. He's tied a gigabit-size loop into the network, and the unmanaged switches are helpfully forwarding traffic back and forth to eachother, even though they're really not supposed to do that.
He's totally stumped. I get called in, sit down for a few minutes with tcpdump, and watch the traffic for a few devices on the network. Didn't take very long before I had a rough idea of what had happened, opened up the network cabinet, and found the misplaced connections.
So much for Cisco courses!