Troubleshooting guide

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ATM and Layer 3 Switch Router Troubleshooting Guide
OL-1969-01
Chapter 1 Troubleshooting Overview
Preparing for Network Failures
Make sure that you undo anything you changed while implementing your action plan. Remember that
you want to change only one variable at a time.
Note If you exhaust all the common causes and actions (either those outlined in this publication or others
that you have identified in your environment), contact customer service. See Appendix F, “Technical
Support,” for additional information.
Preparing for Network Failures
It is always easier to recover from a network failure if you are prepared ahead of time. To determine if
you are prepared for a network failure, answer the following questions:
1. Do you have an accurate physical and logical map of your internetwork that outlines the physical
location of all of the devices on the network and how they are connected, as well as a logical map
of network addresses, network numbers, and subnetworks?
2. Do you have a list of all network protocols implemented in your network for each of the protocols
implemented and a list of the network numbers, subnetworks, zones, and areas that are associated
with them?
3. Do you know which protocols are being routed and the correct, up-to-date configuration information
for each protocol?
4. Do you know which protocols are being bridged? Are there any filters configured in any of these
bridges, and do you have a copy of these configurations?
5. Do you know all the points of contact to external networks, including any connections to the
Internet? For each external network connection, do you know what routing protocol is being used?
6. Has your organization documented normal network behavior and performance so that you can
compare current problems with a baseline?
If you can answer yes to these questions, then you should be able to recover from a failure quickly and
easily.
Troubleshooting General Problems
This section describes where to find troubleshooting, installation, and configuration information for
non-ATM related switch router problems, and includes:
• Troubleshooting Hardware and Booting Problems
• Troubleshooting Ethernet Media Problems
• Troubleshooting Console, Auxiliary Line, and Modem Problems
Refer to the following publications for ATM-specific software configuration and command reference
information:
• ATM Switch Router Software Configuration Guide
• ATM Switch Router Command Reference