Chapter 4
The first section is simpler, as it's pretty much a human-based process. The second part appears
similar to the process in Figure 4.1, but configuration templates aren't available. The peer review
is an important step, but a significant risk is that there is nothing really enforcing it; in the
previous process, the tool could prevent unreviewed changes from being deployed. In this
instance, adherence to the process is more on the honor system. Change deployment is less
sophisticated, too; although it is easy to back up the configuration of most servers and
applications, there is no central, version-controlled repository in which to do so. Standard
backups are the best alternative.
If a change is deployed that causes problems, the only option is to restore from a previous
backup--a process often much less automated than a configuration rollback offered by network
configuration management tools.
In addition, this process doesn't incorporate any notification for changes, whether authorized or
not. There is no tool to detect unauthorized changes, and typically no means for delaying or
scheduling the release of a change; changes occur immediately when they're made.
This process isn't bad; it just suffers from a lack of automation and enforcement. However,
when dealing with devices that can't be readily incorporated into a central configuration
management system, this type of process is often the best you can do. Complex devices such as
Windows or Linux servers simply don't offer the features and technologies necessary for real
configuration management.
Third-party software solutions exist that can help automate some or all of these steps. However,
these solutions are almost by necessity platform-specific, working not only with a particular OS but
generally with a specific
version
of that OS. Thus, completely automating configuration management
in a heterogeneous environment could mean deploying half-dozen different configuration
management solutions. This is one reason why the term "network management" is often held to
include only network devices: They're simply easier to manage because they're more standardized
and less complex.
Managing Without Help
It is not a foregone conclusion that you'll use a network management solution. For example,
smaller networks might rely on manually performing network configuration management tasks
without a specific software solution. In such cases, IT staff will use basically the same process
that Figure 4.2 shows except that they won't have any tools to help accomplish each step. Figure
4.3 expands on this process, noting the manual steps that must be taken to implement
configuration management and points out potential risks that a network change management
solution would catch automatically.
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Summary :
If a change is deployed that causes problems, the only option is to restore from a previous backup--a process often much less automated than a configuration rollback offered by network configuration management tools. Thus, completely automating configuration management in a heterogeneous environment could mean deploying half-dozen different configuration management solutions. Figure 4.3 expands on this process, noting the manual steps that must be taken to implement configuration management and points out potential risks that a network change management solution would catch automatically.
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