Flowmon ADS - DOS method event trigger calculation
This article is aimed to thoroughly describe the trigger calculation of the DOS method in ADS above what's provided in the ADS user guide
Product: Flowmon ADS
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This condition needs to be fulfilled for the event to trigger:
current packet ratio - avarage packet ratio >= Threshold * deviation
Both the current packet ratio and the average packet ratio are usually available in the event detail.
Threshold is set by the user in the method parameters configuration and it basically defines the sensitivity of the method (how easily it triggers). Here is the full definition of the parameter from the user guide:
Threshold is defined by the user and it defines how much of minimal increase of the ratio between received and sent packets they want to allow (as said in the user guide).
Then there is the deviation. That one isn't displayed in the event detail and varies over time. The ratio of outgoing and incoming packets is calculated every 5 minutes. Subsequently, the average for the last WindowLength (by default 1 hour), the average of incoming and outgoing packets are determined from this value. The standard deviation then determines how these values differ from the average every 5 minutes.