Troubleshooting guide

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Cisco PGW 2200 Softswitch Release 9.8 Operations, Maintenance, and Troubleshooting Guide
OL-0800-14
Chapter 4 Maintenance and Troubleshooting Overview
Troubleshooting Strategy Overview
Figure 4-1 General Problem-Solving Model
Step 2
Gather the necessary facts to help isolate the symptoms and their 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 causes that are based on the facts you have gathered. You can use these facts to
eliminate potential causes from your list.
For example, depending on the data, you might be able to eliminate hardware as a cause, which would
allow you to focus on software. Try to reduce the number of potential causes so that you can create an
efficient plan of action.
Step 4 Create an action plan that is based on the remaining potential causes. Begin with the most likely cause
and devise a plan by which only one variable at a time is manipulated.
This approach allows you to reproduce the solution to a specific problem. If you alter more than one
variable simultaneously, identifying the change that eliminates the symptom becomes more difficult.
Step 5 Perform each step of the action plan carefully, and test to see if the symptom disappears.
Step 6 Whenever you change a variable, gather the results. You should use the same method of gathering facts
that you used in Step 2.
Analyze the results to determine if the problem is resolved. If it is, then the process is complete.
Step 7 If the problem is not resolved, you must create an action plan that is based on the next most likely
problem in your list. Return to Step 2 and continue the process until the problem is solved.
Before trying out a new cure, be sure to undo any changes that you made when implementing your
previous action plan. Remember to change only one variable at a time.
Define the problem.
Gather the facts.
Consider possibilities based on the facts.
Create an action plan.
Implement the action plan.
Observe the results.
Repeat the process.
(If symptoms persist…)
(If symptoms stop…)
Problem resolved; terminate the process.
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