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Chapter 9
Ethernet Operation
Figure 9-26 Creating RMON thresholds
Step 4
From the Slot menu, choose the appropriate Ethernet card.
Step 5
From the Port menu, choose the Port on the Ethernet card.
From the Variable menu, choose the variable.
Step 6
Variables available in this field.
Step 7
From Alarm Type, indicate whether the event will be triggered by the rising threshold, falling threshold,
or both the rising and falling thresholds.
Step 8
From the Sample Type pull-down menu, choose either Relative or Absolute. Relative restricts the
threshold to use the number of occurrences in the user-set sample period. Absolute sets the threshold to
use the total number of occurrences, regardless of any time period.
Step 9
Type in an appropriate number of seconds for the Sample Period.
Type in the appropriate number of occurrences for the Rising Threshold.
Step 10
Note
Type in the appropriate number of occurrences for the Falling Threshold. In most cases a falling
Step 11
threshold is set lower than the rising threshold.
A falling threshold is the counterpart to a rising threshold. When the number of occurrences is above the
rising threshold and then drops below a falling threshold, it resets the rising threshold. For example,
when the network problem that caused 1001 collisions in 15 minutes subsides and creates only 799
collisions in 15 minutes, occurrences fall below a falling threshold of 800 collisions. This resets the
rising threshold so that if network collisions again spike over a 1000 per 15 minute period, an event again
triggers when the rising threshold is crossed. An event is triggered only the first time a rising threshold
is exceeded (otherwise a single network problem might cause a rising threshold to be exceeded multiple
times and cause a flood of events).
Step 12
Click the OK button to complete the procedure.
November 2001
For a rising type of alarm to fire, the measured value must shoot from below the falling
threshold to above the rising threshold. For example, if a network is running below a falling
threshold of 400 collisions every 15 seconds and a problem causes 1001 collisions in 15
seconds, these occurrences fire an alarm.
Remote Monitoring Specification Alarm Thresholds
Table 9-10
lists and defines the Ethernet Threshold
Cisco ONS 15454 Installation and Operations Guide
9-33
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