Ten years ago, the network was relatively simple. There were hubs, bridges and routers. Each was a discrete box, readily identifiable from the others. Troubleshooting was also simple. At the point where the collision domain attached to a bridge, all errors stopped. Troubleshooting using a protocol analyzer was the best available option, and it was very effective once the user knew the basics of the network and the protocols in use. Then, switches appeared on the scene.

Problems found in a switched environment are similar to those discovered in a shared media environment. What happened, who did it, and how overloaded is it? The answers in each case relate to a specific port. The difficulty stems from an inability to "see" inside the switch. Our whitepaper, "Troubleshooting Switched Environments," describes five fundamental approaches to gaining visibility into a switch.