Extreme Networks ExtremeWare XOS Guide Manual page 257

The
period <interval>
statement specifies how often the rule is evaluated by the CLEARFlow agent. If not specified, the
default value is 5 seconds.
The
hysteresis <hysteresis>
After the statement is true, the value of the threshold is adjusted so that a change smaller than
delta
the hysteresis value will not cause the statement to become false. For statements using the REL_OPER >
or >=, the hysteresis value is subtracted from the threshold; for < or <=, the hysteresis value is added to
the threshold.
For example, if the match condition had the clauses
then the condition would only be true after the delta of the counter reached at least 100. At the time it
became true, the hysteresis value would be subtracted from the threshold. With the threshold now at 90,
the condition would stay true until the delta of the counter became less than 90.
If the statement becomes false, the threshold is reset to its original value. You would use the hysteresis
value to prevent the rule from vacillating between the true and false states if the difference between the
counter values is near the threshold. If the hysteresis value is greater than the threshold value, the
hysteresis value will be set to zero.
The action lists will be discussed in the section,
See the section, "Delta Rule Type Example" on page
Ratio Rule Type
A CLEARFlow ratio rule compares the ratio of two counter values with the threshold value. The
following is the syntax for a CLEARFlow ratio rule:
entry <CLFrulename>
if { ratio <counterNameA> <counterNameB> REL_OPER <countThreshold> ;
period <interval> ;
min-value <min-value> ;
hysterisis <hysterisis> ;
}
then {
<actions>;
} else {
<actions>;
}
}
The statement specifies how to compare the ratio of two counters with its threshold. The value of
ratio
is divided by the value of
<counterNameA>
compared with the
<countThreshold>
greater than, great than or equal to, less than, or less than or equal to (>, >=, <, <=).
The
period <interval>
statement specifies how often the rule is evaluated by the CLEARFlow agent. If not specified, the
default value is 5 seconds.
The min-value statement is optional, and sets a minimum value for the counters. If either counter is less
than the minimum value, the expression evaluates to false. If not specified, the minimum value is 1.
The
hysteresis <hysteresis>
After the statement is true, the value of the threshold is adjusted so that a change smaller than
ratio
ExtremeWare XOS 11.1 Concepts Guide
statement is optional and sets the sampling interval, in seconds. This
statement is optional, and sets a hysteresis value for the threshold.
"CLEARFlow Rule Actions" on page
{
<counterNameB>
. The
REL_OPER
statement is optional, and sets the sampling interval, in seconds. This
statement is optional, and sets a hysteresis value for the threshold.
Adding CLEARFlow Rules to ACLs
delta counter1 >= 100
262, for an example.
, to compute the ratio. That ratio is
is selected from the relational operators for
and ,
hysteresis 10
259.
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