System information

CHAPTER
Troubleshooting Tools 2-7
2
Troubleshooting Tools
This chapter presents information about the wide variety of tools available to assist you in
troubleshooting your internetwork, including information on using router diagnostic commands,
using Cisco network management tools, and third-party troubleshooting tools.
Using Router Diagnostic Commands
Cisco routers provide numerous integrated commands to assist you in monitoring and
troubleshooting your internetwork. The following sections describe the basic use of these
commands:
• The show commands help monitor installation behavior and normal network behavior, as well as
isolate problem areas.
• The debug commands assist in the isolation of protocol and configuration problems.
• The ping commands help determine connectivity between devices on your network.
• The trace commands provide a method of determining the route by which packets reach their
destination from one device to another.
Using show Commands
The show commands are powerful monitoring and troubleshooting tools. You can use the show
commands to perform a variety of functions:
• Monitor router behavior during initial installation
• Monitor normal network operation
• Isolate problem interfaces, nodes, media, or applications
• Determine when a network is congested
• Determine the status of servers, clients, or other neighbors
Following are some of the most commonly used show commands:
• show interfaces—Use the show interfaces exec command to display statistics for all interfaces
configured on the router or access server. The resulting output varies, depending on the network
for which an interface has been configured.
Some of the more frequently used show interfaces commands include the following:
— show interfaces ethernet
— show interfaces tokenring