Cisco Catalyst 4000 series Hardware Troubleshoot page 3

Hidden Commands
Some commands presented in this document are known as hidden, which means that they cannot be parsed
with a "?", and you cannot Tab in order to complete. When a hidden command is suggested in this document,
simply gather the output and send it to the TAC engineer, if you open a case. It is possible that this output is
useful in solving your case. These commands are undocumented, and therefore the TAC engineer is not
required to explain the output to the customer.
If you want to troubleshoot any problem, this requires a method or set of procedures which, if followed
correctly, produces a solution. Begin by understanding general problem solving for LAN networks.
General Problem Solving Model
If you want to troubleshoot any problem, this requires a method or set of procedures which, if followed
correctly, produces a solution. Begin by understanding general problem solving for LAN networks. Hardware
failures in LAN networks are characterized by certain symptoms. These symptoms can be general such as the
inability to Telnet between switches, more specific such as link flapping, or perhaps the switch is resetting
itself. Each symptom can be traced to one or more causes if you use specific troubleshooting techniques. A
systematic approach works best. Define the specific symptoms, identify all potential problems that could be
causing the symptoms, and then eliminate each potential problem, from most likely to least likely, until the
symptoms disappear.
General Problem Solving Flow Chart
This diagram outlines the steps that detail the problem−solving process:
Complete these steps:
1. Define the problem.
It is important to first identify the problem being experienced. This allows you to identify what kinds
of causes can result in these symptoms. In order to help determine the problem, ask yourself these
questions:
♦
What is the primary symptom?
♦
Is the problem specific to this switch or does it affect other switches on the network as well?
♦
Is this a problem with one or more ports on a specific module? What type of ports: 10/100,
Multimode Fiber (MMF), Singlemode Fiber (SMF), GigabitEthernet, and so forth?