step one: disable spanning tree, because the LAN is so big it takes half an hour for a port to come up after plugging something in step two: plug a very cheap

step one: disable spanning tree, because the LAN is so big it takes half an hour for a port to come up after plugging something in step two: plug a very cheap switch into the network step three: have someone move their desk around, and plug a spare cable into the switch at both ends step four: spend a day doing a binary search by unplugging banks of switches to figure out where the heck all these packets are coming from.