I had a large area LAN. There were many switch and AP on it, then somehow I couldn't ping my servers, and it's said that the IP was duplicated. I use arpwatch and found out that one of the switch flip-flop-ing the IP. I isolated that troublesome switch using his mac-address.
But, since this a large area LAN... I doubt this will be the last cases. If there any software or hardware that I can use to prevent this kind of error?
Sorry for my bad English.