Workshop

Black Box Troubleshooting
“Black box” troubleshooting refers to treating a complex system as a series of simpler sys-tems. Each
piece is a “mysterious little black box,” a box with hidden stuff in it that makes it do what it does. TThe
hidden stuff doesn’t matter while you do your “high level” troubleshooting. That is, you don’t care why
one of the pieces of the system is doing what it is doing; the important thing is that it is doing it. Much
like object-oriented programming, black-box troubleshooting allows you do more work in less time,
since you’re not worried about the picky little details!
For example, though you may know nothing about the internals of a fuel pump (and don’t really care to
know), you still might suspect it as a potential cause of your car’s random stalling. Since you treat it as
a black box, you rule it out or rule it in as a cause by replacing it with a “known good” fuel pump, and
see if the system (your car) starts behaving properly. After a day or so of a trouble-free car, you know
that the fuel pump was in fact the cause—all without having to know how a fuel pump works on the
inside. Black box troubleshooting is a way for a busy person to troubleshoot just about any problem you
can imagine.
Even if you rely on a vendor (and you will; even pros do!), knowing what you are doing can only help
speed up the resolution of your problems. Think of it as going into a limited partnership with your
professional network installers and troubleshooters—your “vendor.” You solve the simple stuff and look
like a hero, and you can hand off the really annoying stuff to them.
The ratio of users to network professionals is rather low, and lots of times a person (you, probably) gets
roped into being an unofficial, unsung, and (of course!) unpaid network troubleshooter. As long as you
are in this capacity, you might as well not be miserable doing it, so it makes sense to get comfortable with
the technology and techniques.
Of course, even if you’re lucky enough not to have been roped into being an unofficial network
troubleshooter, it’s likely that your job depends heavily on your network-ability. Whether your job is
obviously related to the network, like programming or help desk management, or whether your job simply
depends on your access to data, like engineering or medicine, the fact is that you need to be able to share
data to get your work done. If you can get past most network bugaboos by yourself, you’ll not only be able
to pat yourself on the back and allow yourself a congratulatory smile, but you’ll also work faster than the
guy in the next office who has to wait for the network geek to show up.
Do you have to become a geek yourself to be any good at this? Definitely not. There are topics and levels
of detail not covered by this book that are absolutely essential to being a professional network engineer,
designer, or manager. But the nit-picky details themselves are not essential to somebody employing blackbox
troubleshooting, where it is axiomatic that the non-essential details remain hidden. However, you’ll
learn enough in this book to have a competent conversation with a high-level network support person