System information

General Problem-Solving Model
Book Title
1-4
Figure 1-1 General Problem-Solving Model
The following steps detail the problem-solving process outlined in Figure 1-1:
Step 1 When analyzing a network problem, make a clear problem statement. You should define
the problem in terms of a set of symptoms and potential causes.
To properly analyze the problem, identify the general symptoms and then ascertain what
kinds of problems (causes) could result in these symptoms. For example, hosts might not
be responding to service requests from clients (a symptom). Possible causes might
include a misconfigured host, bad interface cards, or missing router configuration
commands.
Step 2 Gather the facts you need to help isolate possible causes.
Ask questions of affected users, network administrators, managers, and other key people.
Collect information from sources such as network management systems, protocol
analyzer traces, output from router diagnostic commands, or software release notes.
Step 3 Consider possible problems based on the facts you gathered. Using the facts you
gathered, you can eliminate some of the potential problems from your list.
Depending on the data, you might, for example, be able to eliminate hardware as a
problem, so that you can focus on software problems. At every opportunity, try to narrow
the number of potential problems so that you can create an efficient plan of action.
Step 4 Create an action plan based on the remaining potential problems. Begin with the most
likely problem and devise a plan in which only one variable is manipulated.
Changing only one variable at a time allows you to reproduce a given solution to a specific
problem. If you alter more than one variable simultaneously, you might solve the
problem, but identifying the specific change that eliminated the symptom becomes far
more difficult and will not help you solve the same problem if it occurs in the future.
Step 5 Implement the action plan, performing each step carefully while testing to see whether
the symptom disappears.
(If symptoms persist…)
(If symptoms stop…)
Define problem
Problem resolved; terminate process
Gather facts
Consider possibilities based on facts
Create action plan
Implement action plan
Observe results
Repeat process