In Chapter 1, Introduction to Sniffer Pro, we looked at basic network-troubleshooting methodology. What you learned from that chapter s discussion also holds true for this chapter and every network problem you diagnose. With time and experience, you will develop good troubleshooting methodologies. It is not something a person naturally knows how to do unless he or she truly gifted. Some of the best network experts in the world still overlook simple things that can solve problems simply because of the sheer volume of ever-changing information they need to digest. Learning how to monitor network performance is even trickier.

Let s look at Figure 5.1 for a moment. If someone on your network complained of slow database retrievals from a host with the IP address of 172.16.3.7, how in the world would you be able to diagnose the cause of the problem? Figure 5.1 shows a high-level topology map that clearly depicts the path that the client would travel to get to this database application. As a network analyst, what would you do? Where would you start to look for problems? If performance is the issue, what are the many things we can look at in the map to troubleshoot where the problems are occurring and how to diagnose them correctly? Questions you need to ask immediately upon starting performance analysis are:

• Is poor network performance affecting one user, several users, or the entire network?

• Is the poor performance centered at a particular location or the entire...