Workshop

and so on—is to measure. Everything else is guesswork. What do you measure first? It depends on your
theory. Remember, you’ll be applying good black box troubleshooting measures when someone tells you
that “the network is slow.” You’ll identify all of the pieces that constitute the whole connection and then
rule out one item at a time as the cause of the slowness. If you rule out the local segment for the moment
(other people are working fine on this segment) and the route (other people who use that route for
different applications are also working fine), you might suspect the server. If the server is working fine
for two other applications, but you don’t know what’s happening on the network segment where the user
is complaining, it’s time to take measurements on the segment in question.
How do you measure? It depends. For long-term monitoring, distributed network analyzers or
management probes are probably best; for short-term problem determination, you can rely on your trusty
standalone network analyzer. Intermittent problems are probably better suited to probes, and standalone
analyzers for ongoing problems.
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