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5-24 C
HAPTER
5: A
DVANCED
M
ANAGEMENT
important occurrences, you can depend on the
Event group for notification. Through the SNMP
traps, events can trigger other actions providing a
mechanism for an automated response to certain
occurrences.
Benefits of RMON
Using the RMON features of your Switch has three
main advantages:
■
RMON improves your efficiency
Using RMON probes allows you to remain at one
workstation and collect information from widely
dispersed LAN segments or VLANs. This means
that the time taken to reach a problem site, set
up equipment, and begin collecting information
is largely eliminated.
■
RMON allows proactive management
If they are configured correctly, RMON probes
deliver information before problems occur. This
means that you can take action before they
impact on users. In addition, probes record the
behavior of your network, so that you can ana-
lyze the causes of problems.
■
RMON reduces the traffic load
Traditional network management involves a man-
agement workstation polling network devices at
regular intervals to gather statistics and identify
problems or trends. As network sizes and traffic
levels grow, this approach places a strain on the
management workstation and also generates
large amounts of traffic.
An RMON probe, however, autonomously looks
at the network on behalf of the management
workstation without affecting the characteristics
and performance of the network. The probe
reports by exception, which means that it only
informs the management workstation when the
network has entered an abnormal state.
RMON and the Switch
RMON requires one probe per LAN segment, and
stand-alone RMON probes have traditionally been
expensive. Therefore, 3Com’s approach has been to
build an inexpensive RMON probe into the Smart-
Agent of each Switch. This allows RMON to be
widely deployed around the network without cost-
ing more than traditional network management.
One other problem with stand-alone RMON probes
is that they are passive; able to monitor and report,
but nothing more. Placing probe functionality inside
the network device allows integration of RMON
with normal device management to allow proactive
management.
As an example, statistics can be related to individ-
ual ports and the Switch can take autonomous
actions such as disabling a port (temporarily or per-
manently) if errors on that port exceed a pre-defined
threshold. Also, since a probe needs to be able to
see all traffic, a stand-alone probe has to be
attached to a non-secure port. Implementing
RMON in the Switch means all ports can have secu-
rity features enabled.