Cisco Cisco MGX-FRSM-HS2 B Serial Frame Service Module Libro blanco
Deployment Guide
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Figure 27. Enabling NetFlow Data Collection Using the Cisco NAM GUI
Backup
DiffServ: This screen breaks down monitored traffic by the value of the DSCP field in the header. The table provided
allows you to determine what proportion of the traffic uses DSCP0, what proportion uses DSCP1, and so on. When
applications with differing QoS needs share the network, it is imperative to provide superior resources to business-
critical applications that have special bandwidth and latency requirements. These screens help drive your analysis.
Note that this screen has alternate views. For example, you can configure DSCP4 to be voice traffic; all future traffic
on DSCP4 will be profiled as voice traffic, enabling you to trend voice traffic in your network.
URL Monitoring: NAM’s URL monitoring feature helps calculate the number of hits received by a particular URL (a
specific file). If multiple URLs are located behind one IP address, it is useful to know if one URL was hit much more
than the other. A good example is that of a movie theater that wishes to determine which of its movies was receiving
the most interest from its weekend audience (based on number of hits).
TCP/UDP port table: In addition to the ability to break down traffic usage by protocol, NAM also provides traffic
usage per protocol per Layer 4 port. This view is very useful to analyze popular protocols such as FTP, HTTP, and
so on. Also, if you are concerned about excessive usage of recreational traffic, such as bittorrent, it is easy to
determine current usage levels of this protocol. Note that NAM provides the ability to add home-grown protocols (or
any protocol that is not already listed) in the protocol directory.
Switching data sources using the drop-down menu: Notice that all real-time screens have a drop-down menu
that allows you to switch from a SPAN data source to a NetFlow data source. With NAM 4.0, the software supports
WAAS data sources as well. It is often useful to compare the output of one data source with that of another.
Familiarize yourself with the different sources of data and the information that you can glean from each. Notice that
data sources that provide full packet streams (for example, SPAN) are the ones that provide capture capabilities,
response time measurements, and voice quality analysis. In contrast, a NetFlow data source cannot provide these
metrics, and only provides more basic information about host statistics, conversation statistics, and so on.
Viewing options, including current rates, cumulative rates, and Top N charts: Many screens on the NAM GUI
provide these options. The “Current rates” option, which is set by default, provides live information. The “Cumulative
rates” option provides information that has accumulated since the NAM booted up. The top N chart provides a
pictorial view of the data, whereas the tabular format provides more quantitative details. Note that you can directly
start a historical report from any of the live monitoring screens. Simply click a host or application or conversation of
interest, and then click the Report button at the bottom of the screen.