Cisco ASR 9000 Serie Configuration Manuals page 356

PM Threshold Monitoring Overview
If the threshold condition is composed of...
...an attribute, an operation, and a value expressed
as a percentage,
...an attribute, an operation, a specific value, and
the rearm toggle keywords...
Cisco ASR 9000 Series Aggregation Services Router System Monitoring Configuration Guide, Release 4.2.x
340
Implementing Performance Management
Then...
The threshold condition is relative because the
threshold value that is used for comparison is taken
as a percentage of the previous sample.
• For example, suppose that a threshold
condition for an entity is configured to check
whether an attribute for an instance increases
by more than 50 percent of the threshold
value in the previous sample. Now, suppose
that after the sample interval elapses, the
value of an instance of the attribute is 250.
Because the threshold condition is configured
to generate a system logging message when
any instance of the attribute is greater than
50 percent of the previous threshold value,
the PM system would check to see whether
that particular instance of the attribute is
greater than 375 (250 + 125 [50 percent of
250]) in the following sample interval.
The PM system matches the threshold
Note
condition against all instances of the
attribute; therefore, the threshold value
for this type of threshold condition is
relative to the value of each instance of
the attribute.
• The PM system generates a system logging
message for each instance of the attribute that
matches the threshold condition after the
sample interval elapses.
• If no instances of the attribute match the
threshold condition, system logging messages
are not generated for that sample interval.
The threshold condition is modified such that if an
instance of an attribute matches the threshold
condition, a system logging message is generated
for that instance of the attribute, after the sample
interval elapses. However, if the same instance of
the attribute matches the threshold condition in
successive sample intervals following the initial
match, system logging messages for that instance
of the attribute are suppressed until the instance
does not match the threshold condition for a sample
interval.