In general (by default), every 10seconds (Inactivity timer), the Communications Server for Windows sends test frame over Enterprice Extender DLC to the partner node to check whether the partner node is still active or not. If there is no response from the partner then the orginating node sends TEST frame three time before bringing down the link as inactive.
If your network is reliable then you can increase the TEST frame frequency by changing the inactivity timer to it max (255 Sec) interval. This change can be done either on the link or device. If the value is been set for the device then the changes applies to all the link, which uses the device property. Otherwise, it applies to the specific link, provided the "User Device Values" is unchecked in the link definition.