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Software Test Equipment
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Although monitoring line conditions is an option with these types of
tools, they are not capable of analyzing protocol information on a line. Their
primary use is to verify that digital communication is sent and received
by the two devices that are connected to the ends of the cable. A few exam-
ples: testing between a PC and a printer, a router and CSU/DSU, or even a
modem and a PC.
Software Test Equipment
T
here are many programs available that help to troubleshoot network
problems. We begin by talking about generic programs that can provide
troubleshooting capabilities, and then we will move on to Cisco-specific
solutions. There are basically two types of software used for aiding network
troubleshooting: network monitoring and network analyzing.
Network Monitors
As the word
monitor
describes, this software-based tool simply monitors the
network. It can do this in several ways, including the Simple Network Man-
agement Protocol (SNMP) and the Internet Control Message Protocol
(ICMP).
The
Simple Network Management Protocol (SNMP)
is the most widely
used method of gathering network statistics. Once a machine has sufficient
information about a network, it continually monitors the availability and
connectivity of each device that is specified in its configuration.
No packet analysis is performed by network monitors. It is simply used to
gather and keep statistical information about the network. The historical
data that monitoring provides can be used to create a network
baseline
.
A baseline is a very important tool. How can you effectively troubleshoot a new
problem on a network if you don't know what the network used to be like or
how it was configured? By keeping a baseline, you can compare previous perfor-
mance and traffic levels to what you are currently seeing. Perhaps your problem is
a new application that was introduced into your network.
SNMP is not the only method of monitoring a network, however. There
are tools that use protocol tools to isolate network problems. For instance,
the
Internet Control Message Protocol (ICMP)
can be used to ping a list of
hosts. If a host does not respond, the program adds the host to a list and
displays it to a monitor.
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