Our office experienced an outage the other day and another network tech said it was caused by someone in the office connecting a hub into one of our access switch ports. He said this caused a loop and both of our distribution switches, which are Cisco 6509s, went unreachable due to high cpu (%100). He said the issue did not clear up until the hub was taken off the network. The office is setup with multiple access switches, then two Cisco 6509s as distribution switches, and then 2 Cisco routers. Is it possible that someone could plug in a hub and take down the entire network and office, putting both distribution switches at %100 cpu?