When to use the Device.InterDevice.Ping
The Device.InterDevice.Ping activity is a useful network management tool because it allows you to perform and report on multi-directional testing across your whole network. In many router networks, pinging the routers is not a sufficient test to provide a high level of confidence in the proper working of the network, because the router is closer to you than the devices that use the network.
It is reasonably common, for example, for pings to remote routers to use a WAN interface IP address. So as long as the WAN and router are functional the ping request may succeed, but this type of test does not tell you that the LAN on the far side of the router is operating as intended. It only tests your ability to ping the router from a particular point in your network. Pinging a router does not test from other points, nor does it test the ability of devices on the far side to successfully use your network.
If you have a Linux device on each remote LAN segment, or at least "behind" each remote router, you can access those devices from CatTools and use an activity to ping other significant parts of your network. This provides better evidence that the network is operating properly than pinging the routers WAN interface from a single central point.
Checking availability of a central device
The Device.InterDevice.Ping activity test allows you to test, for example, branch office connectivity back to the central office server. Select all the branch office routers (or a Linux machine sitting in the branch office) and have them ping the server back in central office. This verifies that your customers can access the central server.