Smart Probe Detection

The Smart Probe Detection object is created under each Logical Interface object (Control, Data A, Data B). The Smart Probe Detection object configures the Smart Probe functionality for each logical interface. Information such as whether Smart Probing will be enabled on the logical interface, how many seconds between each Gratuitous ARP request, and the number of Gratuitous ARP requests can be sent before the switchover of the logical interface occurs. Once this functionality is configured, the individual external VoIP endpoints can then be configured under it. Refer to the information below.

Web GUI Page

Dialogic > IMG 2020 > IP Network > Logical Interfaces > Logical Interface > New Smart Probe Detection

Maximum Objects

One Smart Probe Detection object per Logical Interface. (Control, Data A, Data B)

Field Descriptions

Probe Detection

To enable the Smart Probing Feature on the chosen interface, select Enabled from drop down menu. To disable the Smart Probing Feature on the chosen interface, select Disabled from the drop down menu.

Probe Interval (Seconds)

If Smart-Probing feature is enabled, the IMG 2020 will send a Gratuitous ARP to a network endpoint. If a response is not heard within the interval configured in the Probe Interval field, a second ARP, third ARP and so on will be sent. The IMG 2020 will continue sending Gratuitous ARPS until it reaches the setting on the Probe Threshold field explained below. To change the number of seconds between ARPs, click in the Probe Interval field and enter a time in seconds from the drop down menu.

(Range = 1-60 seconds)

Probe Threshold (Count)

If Smart-Probing feature is enabled, the IMG 2020 will count the number of Gratuitous ARPs sent to the network Smart Probe Endpoint. Once the configured threshold is reached, the IMG 2020 will automatically switch-over to the configured standby interface. To change the number of counts, click in the Probe Threshold field, highlight the default value, and enter a different count value.

(Range = 1-10 Counts)

Additional Information

The IMG 2020 can get into a scenario where a switchover occurs on one of the interfaces (Control, Data, Signaling) because none of the Probe Endpoints on that particular interface are responding to the ARP requests. After a specific interval of time the switchover will be initiated (i.e. Data0 to Data1 interface). The interval of time before the first switchover is calculated as follows:

(Probe Interval * Probe Threshold) = (2*5)=10 seconds

Using the value calculated above, the first switchover would occur after not receiving an ARP response for 10 seconds. However the interface (Data 1) that the IMG 2020 switched to is also not getting a response from the Probe Endpoints. A second interval of time is calculated which is the time of the second switchover. See below:

(Probe Interval * Probe Threshold) + Probe Interval = (2*5)+2 = 12 seconds

Knowing that the first interval was 10 seconds, the second will be at 22 seconds and the third at 34 seconds. The switch-overs will continue at 12 second intervals until the network issue is resolved. The switching back and forth is referred to as the Ping Pong effect.

Dialogic Integrated Media Gateways