10. Interoperability And Coexistence

Although I knew that HomePlug and DS2-based devices would not communicate (interoperate) with one another, I at least hoped that they would somehow cooperate so that they could coexist when plugged into the same electrical grid. So I threw together the testbed shown in Figure 18 to find out.

Figure 18: DS2 and HomePlug Turbo coexistence testbed

The three computers in Figure 16 were all set to different static IP addresses in the 10.168.3.X subnet and all adapters were plugged directly into outlets in my office lab. The two Netgear XE104 HomePlug Turbo adapters had their Network ID set to the default "HomePlug" and the two AV200 powerline adapters had their blank default Network IDs.

I modified the IxChariot script used for the throughput testing so that in one case I gave the AV200 test pair a 10 second head start in one case and the HomePlug Turbo the head start in the other. I also had both scripts send data from the IxChariot console to the remote endpoints instead of one receive and one transmit used in the performance tests.

Figure 19: HomePlug and DS2 competing for bandwidth
(click image to enlarge)

Figure 19 shows that the two powerline networking technologies battle each other so that only one can operate at a time. The results I got over repeated runs were highly variable and would also depend on the distance between the various adapters. The bottom line is that the two technologies neither interoperate nor coexist without severly interfering with each other. This behavior was confirmed as expected by both Intellon and DS2.