User's Manual

RuggedSwitch™ User Guide
RMON Alarms And Events Concepts And Issues
The Alarm Process
The RMON Alarms Table allows the user to create records that configure the
switch to examine the state of a specific statistic variable.
The record contains an upper and a lower threshold for legal values of the statistic
in a given interval. This provides the ability to detect events occurring more
quickly than a specified maximum rate or less quickly than a specified minimum
rate.
When a statistic value’s rate of change exceeds its limits an internal alarm of INFO
level is always generated. Internal alarms can be viewed using the Diagnostics
menu, View Alarms command.
Additionally, the record’s owner can decide whether a statistic threshold crossing
should result in further activity. The RMON Alarm record points to a particular
RMON Event Record, which can generate an SNMP trap, an entry in the switch’s
event log or both. The RMON Event Record can “steer” alarms towards different
communities of trap receivers.
The alarm record can point to a different event record for each of the thresholds,
so combinations such as “trap on rising threshold” or “trap on rising threshold,
log and trap on falling threshold” are possible.
System
Statistics
Internal Alarm
RMON Alarm Record RMON Event Record
Rising Alarm
Falling Alarm
Rising Trap
Rising Log
Falling Trap
Falling Log
Threshold
Crossing
Logic
First
Alarm
Logic
Event
Generation
Logic
Figure 57: The Alarm Process
The owner of the alarm has the choice what happens if the very first statistic
measurement (after switch reset or after the record is created) immediately exceeds
the configured thresholds. The owner can decide whether or not to generate an
alarm.
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