user manual

Chapter 1 Voice Health Monitor Overview
Overview of VHM
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User Guide for Voice Health Monitor
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VHM and DFM Interdependencies
Note For all DFM references in this guide, refer to the User Guide for Device Fault
Manager for more detailed information.
Device Fault Manager (DFM) and VHM both analyze Cisco device failures. The
two products often identify problems before users of network services realize that
a problem exists. Both VHM and DFM:
• Use a top-down approach that starts with users identifying problems and their
symptoms:
– Identify the problems affecting managed systems that are critical to
correlate.
– Describe the symptoms, developing a “problem signature” that specifies
which conditions are present in a faulty element when the problem
occurs.
• Create a causality mapping between the problems and the symptoms.
Problems and symptoms are coded in correlation models that VHM and DFM
use to:
– Analyze network conditions.
– Generate faults and exceptions.
The event information necessary to diagnose problems is present in the
correlation model. Therefore, VHM and DFM monitor only the events necessary
to diagnose problems.
Table 1-1 lists the interdependencies between VHM and DFM.