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generation. Information provided by RMON can be used for identifying sources
of network problems, for fine-tuning network performance, and planning for
network expansion.
RMON uses SNMP for communication between the network management station
and RMON agents. Unlike SNMP devices, RMON keeps polling traffic overhead
to a minimum as the RMON probes are not continuously polled.
Note
RMON provides a lot of statistical data detailing the network operations at
the media level. This information, though very useful, should be used in the
context of the nature of the activities occurring in the network. They should
be used in assisting further investigations. For instance, when RMON reports
a high packet rate and high utilization, we need to investigate further what is
the nature of the traffic that caused those statistics to rise significantly. Are
those data packets or non-data packets? Non-data packets require further
investigation while data packets could simply result from someone
performing a large file transfer.
10.1.1 Network Probes
The implementation of RMON requires network probes to be installed on each
managed LAN segment throughout the enterprise network as depicted in
Figure 116 on page 193. These network probes are devices whose resources
are dedicated to managing the LAN segments they are attached to. Resources
required by these network probes are very much dependent on the number of
devices in the segment to be managed, traffic flow, type of data to be collected,
frequency of collection, multiple manager requests, etc. Usually, one probe per
segment is recommended for monitoring and data collection.
Network probes can be stand-alone specialized probes, integrated
hub/bridge/router agents, or RMON agent software running on workstations. A
subset of the RMON MIB must be present on these devices to function as an
RMON agent. RMON agents can be found in bridges, routers, and hubs.
Bridges and routers are not recommended as RMON agents as their primary
roles are to get the traffic moving without imposing additional overhead.
10.6, “Monitoring Functions Supported In 8260” on page 212 discusses the
RMON agents implemented in the 8260 DMM (along with T-MAC and E-MAC
daughter cards).
192 8260 Multiprotocol Intelligent Switching Hub