3Com Switch 8800 Advanced Software V5 Configuration Guide

1058 CHAPTER 84: RMON CONFIGURATION
information but four groups of information, alarm, event, history, and statistics,
in most cases.
Switch 8800 adopts the second way. By using RMON agents on network monitors,
an NMS can obtain information about traffic size, error statistics, and performance
statistics for network management.
RMON Groups RMON categorizes objects into ten groups. This section describes only the major
implemented five groups.
Event group
The event group defines event indexes and controls the generation and
notifications of the events triggered by the alarms defined in the alarm group and
the private alarm group. The events can be handled in one of the following ways:
■ Logging events in the event log table
■ Sending traps to NMSs
■ Both logging and sending traps
■ No action
Alarm group
The RMON alarm group monitors specified alarm variables, such as statistics on a
port. If the sampled value of the monitored variable is bigger than or equal to the
rising threshold, a rising alarm event is triggered; if the sampled value of the
monitored variable is lower than or equal to the falling threshold, a falling alarm
event is triggered. The event is then handled as defined in the event group.
The following is how the system handles entries in the RMON alarm table:
1 Samples the alarm variables at the specified interval.
2 Compares the sampled values with the predefined threshold and triggers events if
all triggering conditions are met.
n
If a monitored variable overpasses the same threshold multiple times, only the first
one can cause an alarm event. That is, the rising alarm and falling alarm are
alternate.
Private alarm group
The private alarm group calculates the sampled values of alarm variables and
compares the result with the defined threshold, thereby realizing a more
comprehensive alarming function.
System handles the prialarm alarm table entry (as defined by the user) in the
following ways:
■ Periodically samples the prialarm alarm variables defined in the prialarm
formula.
■ Calculates the sampled values based on the prialarm formula.
■ Compares the result with the defined threshold and generates an appropriate
event.