Product Documentation

Managing Threshold

May 21, 2015

The adaptive threshold functionality in NetScaler Insight Center dynamically sets the threshold value for the maximum number of hits on each URL. If the maximum number of hits on a URL is greater than the threshold value set for the URL, a syslog message is sent to an external syslog server. The threshold value interval can be either days or weeks

Threshold-value calculation uses the following formula: Threshold value = Max hit * Threshold multiplier, where
  • Max hit is the maximum number of hits on a URL.
  • Threshold multiplier is a user-defined integer value (default: 2).
Note: The adaptive threshold functionality is supported only on NetScaler 10.1.e and NetScaler release 10.5 onwards.

Example

In the following example, duration of the threshold has been set to Day, and the threshold multiplier is 2.

On day 1, a syslog message is not sent, because a threshold value is not calculated by NetScaler Insight Center for the previous day. The largest number of hits on any URL is 15 on day 1.

On day 2, the maximum number of hits on any URL is 60, and the threshold value set by NetScaler Insight Center is 30 (Max Hit on day 1 * Threshold multiplier). The threshold value on day 2 is less than the maximum number of hits on day 2. Therefore, a syslog message is sent to an external syslog server.

On day 3, the maximum number of hits on any URL is 10, and the threshold value is 120 (maximum hit on day 2 * Threshold multiplier). The threshold value on day 3 is greater than the maximum number of hits on day 3. Therefore, a syslog message is not sent to an external syslog server.

The following table shows an example of how a threshold value is calculated:

Day URL Max Hit Threshold Multiplier Threshold value = Max Hit * Threshold multiplier Syslog sent
Day 1 URL1 15 2 No threshold value is configured for Day1 No
Day 2 URL1 60 2 15*2 = 30 Yes Day 2 Max Hit (60) > Day 2 threshold value (30)
Day 3 URL1 10 2 60*2 = 120 No Day3 Max hit (10) < Day 3 threshold value (120)
Note: To configure a syslog server, see Monitoring Syslog Events.

To enable adaptive threshold

  1. On the Configuration tab, in the navigation pane, click System and in the right pane click Change Adaptive Threshold Settings.
  2. On the Change Adaptive Threshold Settings page, select the check box and click OK.

To set the threshold value in NetScaler Insight Center

  1. On the Configuration tab, navigate to NetScaler Insight Center>Thresholds.
  2. Click Add.
  3. In the Create Thresholds dialog box, set the following parameters:
    • Name—Threshold name
    • Resource Type—URL
    • Duration—Duration of the threshold (Day or Week)
    • Threshold Multiplier—User-defined integer value
  4. Click Create.