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Like surgeons about to embark upon a heart transplant, network professionals with years of training and experience gear up to tackle a complex network problem. They might tote complex and costly tools and speak network protocols as a second language. Pretty scary!
Yet, most network problems do not require a degree in rocket science to solve. In fact, just like you are the person who clears the paper jam or changes your toner cartridge on your own photocopier without having to call Mr. Xerox, you can also be the person who unclogs your offices email when it snarls up. Why not? You have a brain, and with a basic understanding of how this stuff works, you can come to logical conclusions just like the next person. You may annoy your dependency-oriented consultant by calling him or her less frequently, but such is the price of success.
Do network professionals really need expensive toys to solve most of your network problems? Not really. The reality is that network folks who rely on network toys rather than their brains, gumption, and common sense do not tend to be very good troubleshooters at all. They tend to concentrate on the accumulation of cool toys rather than solutions that address your business needs.
Most really good networking professionals are able to make these expensive network toys work for them only because of their keen observation abilities and plain old common sense. And much of the time, they dont even need the expensive toy to troubleshoot the problem. Why? Because they understand the fundamentals of black box troubleshooting, principles that you can learn in the second section of this book, Black Box Troubleshooting Strategies. Of course, they also understand the underlying principles of computer networking, but those principles are actually pretty simple. This is great news, because it means that you do not have to spend $10,000 on a network analyzer to get similar results most of the time.
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 doesnt matter while you do your high level troubleshooting. That is, you dont 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 youre not worried about the picky little details! For example, though you may know nothing about the internals of a fuel pump (and dont really care to know), you still might suspect it as a potential cause of your cars 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 causeall 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 troubleshootersyour 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 youre lucky enough not to have been roped into being an unofficial network troubleshooter, its 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, youll not only be able to pat yourself on the back and allow yourself a congratulatory smile, but youll 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 black-box troubleshooting, where it is axiomatic that the non-essential details remain hidden. However, youll learn enough in this book to have a competent conversation with a high-level network support person about your more complex network issues.
Youre also about to learn a lot of the simple-but-powerful concepts that professionals rely on. In addition to network fundamentals, even the best troubleshooting professional needs:
To help you get up to speed on network terms and the framework in which networks live, youll learn about The Telephone Analogy in Hour 1. After you get through that, youll feel pretty comfortable with this stuff; more importantly, youll understand a lot of the main terms and principles of networking. This will allow you to understand the way a network conversation flows from start to finish, and youll start to understand why your network might be broken. You can skip this if you feel comfortable with networking terms and principles and want to dive right into the troubleshooting methods.
Troubleshooting a network, particularly a large network, is very much like figuring out a puzzle. If youve got a basic idea about how the network should work, and if you know which piece depends on which (much like how you always place the edge pieces on a jigsaw puzzle before delving into the middle ones) and the way information should flow, pointing the finger at the general problem area is usually not a problem. Once you figure out the general area of the problem, you can then use basic troubleshooting techniques to figure out which specific piece of the puzzle is causing your grief. After all, you dont need to be a Rembrandt expert to do a jigsaw puzzle of a Rembrandt painting, do you?
Lets take a real-life puzzle that youd probably be pretty good at troubleshooting. Say that youre a teacher; your problem is that you have three boys who tend to cause trouble in your classroom. You will probably engage in two of the most powerful black-box troubleshooting techniques, divide and conquer, and the delta method. Youll realize that one of the boys is new in town, and the only thing that has changed recently in your classroom, which up until now has been serene. You separate him from the group, reasoning that he is almost certainly the cause. By dividing him from the other two boys, and watching the problem move to another section of the classroom, you rule him in as a cause, and rule out the other two boys. Easy, right? So, right away, before even reading the rest of this book, youve got some ammunition to use against network problems.
Lets consider a similar problem to your classroom problem. Since skilled labor is hard to come by, your retailer has hired some gorillas to come in and install a new PC in your office. They come in, install it, and everything seems fine. The next day, nobody can send email! One of the gorillas decides that its time to rebuild your email server, but you cleverly realize that the only thing that has changed since yesterday is the new PC. You insist that the gorillas disconnect it from the network, and voila! The problem miraculously goes away. Upon inspection, the new PCs network cable has visible damage to it, which has caused a network problem affecting the email server. One of the gorillas replaces the network cable and walks away muttering something about still need to rebuild that server. Youre a hero, have avoided the risks of having a gorilla rebuild a perfectly fine mail server, and you havent broken a sweat.
Of course, its not always that easy. A lot of times, its tough to know what has changed, or even whos changed it. Or, something may legitimately break without a new element even entering the picture. Unfortunately, since networks are what tie everything together, pretty much anything in the mix, soup-to-nuts, can be a source of trouble. And since everything is tied into the network, its easy to blame the network. Actually, a lot of times, you simply have to figure out that the trouble is NOT the network!
The bottom line is, you really have to know a little bit about everything in order to start troubleshooting a problem, and then adapt and learn as necessary in order to solve a given problem. And you will!
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