The easiest way to solve network problems is to be able to compare current configurations
against previous configurations. This sounds easy enough, but it requires a lot of effort to get
a system established for keeping a historical
baseline
of your network. A historical
baseline is
simply a collection of network settings and configurations that are maintained over time. This
baseline makes it easy to locate changes and identify the differences between a current configuration
and a previous one.
A network baseline is sometimes referred to as a baseline network model.
Baseline information is actually a composite of various network and end-system documentation.
This collection includes
Network configuration table
Network topology diagram
End-system network configuration table
End-system network topology diagram
The first two items—the network configuration table and the network topology diagram—
are covered in this chapter. The latter two items—the end-system network configuration table
and the end-system network topology diagram—are discussed in Chapter 35, “End-System
Documentation and Troubleshooting.”
When creating any documentation of this sort, there are several things to keep in mind:
First, before you start, determine the scope of what the documentation should cover. Without
clearly understanding what is inside and outside of the scope of the documentation
effort, you could end up taking on more than you bargained for.
The second rule is to be consistent. If you do not collect the same information for all the
devices in the network, the documentation may have holes that will come back to haunt
you later.
Third, know your objective. When you are collecting your information, be certain you
understand what the documentation will be used for, and include all relevant pieces.
Be sure to use the documentation and ensure that it is accessible in the event of an emergency.
This information was not put together just as an exercise; it is meant to be useful.
Finally, after putting together your baseline information, you must maintain it. If the baseline
is out-of-date, troubleshooting will be much more difficult.
After you your start using the documentation, if you are finding that you are consistently
going back to the network devices to find a particular bit of information, it may be a good idea
to include that information on your baseline. Likewise, if you notice that you are never using
certain information, it may be best to remove that data from the baseline documentation to prevent
clutter.