Delta Expression Example

In this example, every ten seconds the CLEAR-Flow agent will request the counter1 statistics from the hardware.

After it receives the counter value, it will then evaluate the rule. If the delta (change) of the counter1 value from the last sampled value ten seconds ago is greater than or equal to 1,000 packets, the CLEAR-Flow agent will send a trap message to the SNMP master and change the ACL acl_rule1 to move the traffic to QP3. In addition, reduce the peak rate to 5 Kbps on QP3. As long as the delta continues to be greater than or equal to 1000 packets, the CLEAR-Flow agent will repeatedly send a trap message every 120 seconds. When the delta falls below the threshold, the agent will execute the two actions in the else portion; it will send a single SNMP trap message, return the traffic to QP1, and reset QP3 to its original bandwidth.

entry acl_rule1 {
if {
destination-port 2049;
protocol tcp;
} then {
count counter1;
entry cflow_delta_rule_example  {
if  { delta counter1 >= 100000 ;
period 10 ;
} then {
snmptrap 123 "Traffic to exceed rate limit" 120;
qosprofile acl_rule1 QP3;
cli "configure qosprofile qp3 peak_rate 5 K ports all" ;
} else {
snmptrap 123 "Traffic to falls below rate limit";
qosprofile acl_rule1 QP1;
cli "configure qosprofile qp3 maxbw 100 ports all" ;