Troubleshooting guide

1-2
ATM and Layer 3 Switch Router Troubleshooting Guide
OL-1969-01
Chapter1 Troubleshooting Overview
General Model of Problem Solving
Basic troubleshooting processes, such as troubleshooting Ethernet connections, not specific to the ATM
switch router, are not described in this document. This information is found online in other
troubleshooting guides such as the Internetwork Troubleshooting Guide.
General Model of Problem Solving
When troubleshooting a network environment, define the specific symptoms, identify all potential
problems that could be causing the symptoms, and then systematically eliminate each potential problem
(from most likely to least likely) until the symptoms disappear.
Figure 1-1 illustrates the general problem-solving model. This process is not a rigid outline for
troubleshooting an internetwork. It is a foundation on which you can build a problem-solving process
for your environment.
Figure 1-1 General Model of Problem Solving
The following steps detail the problem-solving process outlined in Figure 1-1:
Step 1 Analyze the network problem and create a clear problem statement. Define symptoms and potential
causes.
Step 2 Gather the facts you need to help isolate possible causes.
Step 3 Consider possible causes based on the facts you gathered.
Step 4 Create an action plan based on those causes. Begin with the most likely problem and devise a plan in
which you manipulate only one variable.
Step 5 Implement the action plan, performing each step carefully while testing to see whether the symptom
disappears.
Step 6 Analyze the results to determine whether the problem has been resolved. If it has, the process is
complete.
Step 7 If the problem has not been resolved, create an action plan based on the next most probable cause on
your list. Return to Step 4 and repeat the process until the problem has been solved.
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.
S1228a