o solve. If you're seeing packets that have bits transposed, it's probably not due to aliens altering your data in an effort to destroy the world. I'd check the cabling first. NORAD won't take my calls anymore, anyway. Do a Physical Audit If you've been going round and round in circles, and nothing is making sense, do a physical audit. Chances are that assumptions are being made, and an audit will dis- prove those assumptions. Sometimes, the documentation is outdated, or simply wrong. When in doubt, redraw the networking diagrams from scratch. Using a whiteboard or a legal pad is fine for this exercise. You're not looking for beautiful documents, but rather, factual data. In the mainframe example I described earlier, a physical audit would have solved the problem because we had standing orders to remove unterminated serial cables. I once got involved in a network problem after another team had worked on it for more than a week. The network was deceptively simple: the nodes involved included two T1s, four routers, and two servers. A team of people could not find the prob- lem, no matter what they tried. When I got involved, I looked over their notes, and instructed them to do a complete audit of the network, down to every device, inter- face, and IP address. I also instructed the team to test connectivity from every node to every other node in the network. Within an hour, I was informed that they had discovered the problem. A T1 WIC had gone bad and was deforming packets. The problem did not become obvious until they'd run through the process of auditing the network in detail. By testing connectivity between all points in the simple network, they soon discovered the root cause. Troubleshooting Escalate If you can't figure out what's wrong, escalate to someone else. Usually, your boss will want you to escalate to Cisco if the network is the problem (and Cisco is your vendor). If you have an internal department you can call first, by all means, do that. If you feel the problem is beyond you, don't waste any time-cal