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any different tools exist for network troubleshooting.

Although a majority of them are not Cisco-specific or proprietary, many of
these tools can help to troubleshoot problems with Cisco equipment as well
as with networks in general.

Troubleshooting tools can be used to analyze several aspects of a net-

work, such as the physical connectivity and the protocols, as well as the
applications running on the network. Each area requires a different set of
tools and procedures. Often, troubleshooting tools and test equipment are
used only when there is a network failure or problem. It is important to rec-
ognize that many tools can be used in a proactive method, such as monitor-
ing. Certainly, some tools are not able or not designed to provide monitoring
functions. Many are capable of this task, however.

We begin this chapter by discussing the tools designed for physical media

troubleshooting, and then move on to protocol analyzers. After a thorough
discussion of these two types of instruments, we will discuss using some of
these tools in monitoring applications. Cisco has several software packages
that provide excellent network monitoring using SNMP (Simple Network
Management Protocol) and TCP/IP protocol debugging tools.

Some tools are part of the TCP/IP protocol stack, others are systems that

capture frames and decode them using software, and yet others are used to
test physical media. The use of all these types of tools provides coverage for
many of the seven layers of the OSI model.

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