Rmon Hysteresis Mechanism - 3Com LANPLEX 2500 EXTENDEDPLEX®2500 EXTENDED User Manual

13-8 C 13: R M (RMON) T
HAPTER EMOTE ONITORING ECHNOLOGY
RMON Hysteresis The RMON hysteresis mechanism provides a way to prevent small
Mechanism fluctuations in counter values from causing alarms. This mechanism
generates an alarm only under the following conditions:
The counter value exceeds the high threshold after previously exceeding
the low threshold. (An alarm does not occur if the value has not fallen
below the low threshold before rising above the high threshold.)
The counter value exceeds the low threshold after previously exceeding the
high threshold. (An alarm does not occur if the value has not risen above
the high threshold before falling below the low threshold.
In Figure 13-3, for example, an alarm occurs the first time the counter
exceeds the high threshold , but not at the second time. At the first
instance, the counter is rising from the low threshold, while in the second
instance, it is not.