The first thing we've got to do in order to document our network is to create a network baseline. After all, if we don't know our goals, we can't accomplish them. A baseline is really a “network snapshot", a picture of our network devices and their performance - which also helps us spot issues before they happen.
Every network has its “breaking point", the point at which it can no longer transfer data effectively. By creating a baseline, you can see what the current network load is now - and by maintaining that baseline, you can spot network issues well before they become critical. For example, say you baseline all your network routers, and part of that is noting the CPU capability and usage. By maintaining the network baseline, you can note smaller, gradual increases in CPU usage and do something about it before the situation becomes critical.
Establishing a baseline also gives less-experienced network personnel a starting point for troubleshooting, and it gives new network support personnel a starting point as well.
To begin that task, we've got to define where this baseline will begin and end - in other words, we must define the scope of the baseline. Some questions to ask:
What is the scope of this baseline?
What goals do we have for our network?
What network devices will be part of this baseline?
What is the objective here? Why are we creating this baseline?
Baseline construction methods differ from one vendor to another, but I recommend the first thing you do when creating a baseline is taking inventory. Why? First, it's hard to create a full network picture if you don't know everything that's in your network; second, many networks are poorly inventoried.
When you're creating network documentation, consistency is vital. This goes for abbreviations, symbols, and icons. There are sets of Cisco icons for use in Microsoft Visio - find and use these icons when documenting and diagramming your network. Keep your usage of these icons consistent as well.
Decide upon your scope and your goals, and stick with that decision. Don't start documenting one part of the network and then jump to another part.
Also, don't hide the documentation! If I have to substitute for you at a client site, I should be able to find the documentation without asking anyone.
Most importantly, maintain the documentation. Nothing is worse than seeing a date at the top of a network baseline doc that's from last year. (Or the last century. ) Don't fall into the trap of “I'll catch the documentation up next week", because I can practically guarantee that no matter how great your work ethic is, something's going to happen that will distract you from getting the documentation done. Do it now.
In short, when creating network documentation, follow these rules:
Define the scope of the documentation and stick to it.
Define your objective and the values to be documented.
Consistency is key. Keep abbreviations and terminology consistent from document to document.
Make sure the appropriate personnel have access to the documentation.
Keep the documentation current.
Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage, home of over 200 free certification exam tutorials, including CCNA certification training articles. His exclusive CCNA study guide is also available!
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