Extreme Networks ExtremeWare XOS Guide Manual page 379

counters. When you use a counter statement in an ACL, you are defining the counter used by CLEAR-
Flow to monitor your system.
The following sections discuss the CLEAR-Flow rule expressions in detail:
Count Expression on page 379
●
Delta Expression on page 380
●
Ratio Expression on page 381
●
Delta-Ratio Expression on page 382
●
Rule-True-Count Expression on page 383
●
Count Expression
A CLEAR-Flow count expression compares a counter with the threshold value. The following is the
syntax for a CLEAR-Flow count expression:
count <counterName> REL_OPER <countThreshold> ;
The statement specifies how to compare a counter with its threshold. The
count
name of an ACL counter referred to by an ACL rule entry and the
compared with the counter. The
great than or equal to, less than, or less than or equal to (>, >=, <, <=).
Here is an example of a count expression used in a CLEAR-Flow rule:
entry cflow_count_rule_example
if { count counter1 > 1000000 ;
period 10 ;
}
then {
<actions>;
}
}
The actions will be discussed in the section,
In Table 51 is an example of evaluating the CLEAR-Flow count expression above multiple times. Notice
that the rule is not triggered until evaluation 3, when the value of the counter is greater than 1,000,000.
Table 51: Count Expression Evaluation Example
Evaluation
1
2
3
4
See the section, "Count Expression Example" on page
Flow rule using a count expression.
ExtremeWare XOS 11.3 Concepts Guide
is selected from the relational operators for greater than,
REL_OPER
{
"CLEAR-Flow Rule Actions" on page
counter1 value
384625
769250
1153875
1538500
Adding CLEAR-Flow Rules to ACLs
<countThreshold>
Rule triggered?
No
No
Yes
Yes
389, for a full example of an ACL and a CLEAR-
is the
<counterName>
is the value
384.
379