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| 3.6 |  | Implementing Physical Layer Solutions |
| 3.6.1 |  | Solving common problems – methodology |

A doctor would not be considered successful unless he could follow up his diagnosis of a patient’s problem with a successful solution. The same idea applies to network troubleshooters. Isolating a problem is a big step in troubleshooting, but the process is not considered complete until the problem is solved and the network returned to its baseline state.

To correct an isolated problem at the physical layer:

- Make initial configuration changes.
- If the correction requires more than one change, make only one change at a time.
- Evaluate and document the results of each change made.
- If the problem-solving steps are performed and the results are unsuccessful, immediately undo the changes. If the problem is intermittent, it may be necessary to wait to see if the problem occurs again before evaluating the effect of any changes.
- Stop making changes when the original problem appears to be solved.
- Verify that the changes made actually fixed the problem without introducing any new problems.
- The network should be returned to the baseline operation and no new or old symptoms should be present. If the problem is not solved, undo all the changes made. If new or additional problems are discovered during trouble-shooting and problem correction, step back and modify the correction plan.
- If necessary, get input from outside resources.
- If none of the attempts to correct the problem are successful, take the problem to another person. This may be a coworker, consultant, or Cisco Technical Assistance Center (TAC). On rare occasions it may be necessary to perform a core dump, which creates output that a specialist at Cisco Systems can analyze.
- Once the problem is resolved, document the solution.