One of the skills a network administrator must have is the ability to effectively troubleshoot network problems. To emphasize the importance of network troubleshooting, Cisco has dedicated an entire exam to the topic as part of the Cisco Certified Network Professional (CCNP) certification. Additionally, the Cisco Internetwork Troubleshooting (CIT) course is recommended curriculum for anyone pursuing the much-coveted CCIE certification.
Although the CIT material presents Cisco’s troubleshooting model, the same steps can be applied to just about any type of network or system failure you will encounter.
The eight steps
The most important part of troubleshooting any problem is to divide the tasks of problem resolution into a systematic process of elimination. Cisco has broken this process into eight steps:
- Define the problem.
- Gather detailed information.
- Consider probable cause for the failure.
- Devise a plan to solve the problem.
- Implement the plan.
- Observe the results of the implementation.
- Repeat the process if the plan does not resolve the problem.
- Document the changes made to solve the problem.
Define the problem and gather facts
How many times have you heard this: “My computer does not work”? Which leads us to the network administrator’s response: “Could you please be more vague?”
Often the user reporting the problem is frustrated and only knows that the computer is preventing the completion of a task. It is the responsibility of the network administrator to find out what aspect ofthe user’s machine is not working.
Handling such situations goes more smoothly when you have a good rapport with your support personnel and users. A good network administrator can explain that more information is required to diagnose the problem and more information must be obtained in order to quickly resolve the problem.
Often, administrators will not receive all the information needed to thoroughly define the problem. They must then rely on tools such as ping, trace, or a network monitor to identify the trouble.
Consider the possibilities
After a problem has been identified, the next step is to consider all of the possible causes. Connectivity issues can be very difficult to trace to a single point of failure. In most situations, there are several possible causes for a network error, and the administrator should identify each probable cause.
Create and implement an action plan
Once the network problem and possible causes have been identified, it’s time to produce a solution. When developing a solution, it’s critical to thoroughly analyze the proposed solution and brainstorm with your peers the potential impacts your solution may have.
Here are a few of the most important guidelines to follow when implementing a solution:
- Make one change at a time.
- Make transparent changes first. This means if there are multiple possible causes for a problem, solve those problems that have the least impact on your users first.
- Do not create security holes when implementing your changes.
- Finally, and most importantly, always be sure you can back out of any changes you make.
Observe results and, if necessary, try another solution
Some changes may take time to trigger. Observe the results of your solution. Go back to the fact-gathering phase and determine if your solution solved the problem. If the trouble still exists, reference your list of possible causes and attempt to resolve the next most likely cause of the problem.
Eureka! I’ve got it!
After a problem has been corrected, the work of the network administrator is not over. Too many times, network administrators end up solving the same problem repeatedly. The best way to prevent this is to maintain a problem log and to update this log every time a network failure occurs.
Solve problems before they happen
Using these eight steps to quickly and efficiently solve problems is great, but the best solution for your network woes is to solve the problem before it affects your users. The only way to do that is to devote time to creating baselines for your network and to continually monitor your network for changes. In network administration, an ounce of prevention can prevent a 24-hour shift to solve an unnecessary network failure.
Warren Heaton CCDA, CCNA, MCSE+I is the Cisco Program Manager for A Technological Advantage in Louisville, KY.If you'd like to share your opinion, please post a comment below or send the editor an e-mail.