3Com 3C16371 - LinkBuilder FMS - Hub, User Manual

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Counters and RMON Alarms E - 9
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Figure E-2 Counter Values After Setting Thresholds
Alarms can be set up with two actions; one is associated with the high
threshold and the other with the low threshold. Whether an action is
taken depends on the circumstances surrounding each crossing of a
threshold. The numbered paragraphs below describe the conditions
applying at the points correspondingly numbered in the diagram.
1 The running value has exceeded the high threshold. If an action has
been assigned to the high threshold, that action will be performed.
2 No action will be taken because the value has not fallen below the low
threshold before rising above the high threshold. This gap between
high and low thresholds is called Alarm Hysteresis.
3 The running value has fallen below the low threshold. If an action has
been assigned to the low threshold, that action will be performed.
4 The running value had fallen below the low threshold before rising
above the high threshold. If an action has been assigned to the high
threshold, that action will be performed.