Figure 7 shows the results plotted so that it's easy to see the differences in the connections vs. throughput characteristics of the routers. The plot also contains a baseline trace showing test results with a straight 10/100 Ethernet connection. This was run both to ensure that my test setup could handle the test connection load and also to establish a baseline for connection vs. throughput. The graph shows that the Ethernet connection throughput does drop off with the number of connections; most likely due to IxChariot overhead.
Figure 7: Router Throughput vs. Simultaneous Connections
While none of the products tested locked up due to the heavy connection load, most were unable to successfully complete all five runs. I judged a run to be a failure when IxChariot either threw an error telling me that a test pair (a connection) failed to be initialized, ended abruptly, or failed to return a result after 2-3 minutes.
The Netgear RangeMax 240 tops the chart with 2, 64 and 128 connection performance virtually equal to the reference Ethernet connection. The RangeMax 240 isn't perfect, however, since its throughput starts to degrade more than the other products above 128 connections. But on the plus side, the 240 survived all five tests, which is more than can be said for every other router except for the D-Link DGL-4300.
Speaking of the D-Links, Figure 7 shows that the DI-634M and DGL-4300 have nearly identical throughput for the runs that they both completed. But I'm not sure why the DGL-4300 was able to complete all five tests while the DI-634M was reliable only up to the 128 connection run, since both use the Ubicom processor and have 16 MB of RAM.
The poor showing of the Zyxel X-550 is also a puzzle, since its hardware design is virtually identical to that of the DI-634M. The Zyxel only completed the 2 and 64 connection runs and also had lower throughput than the D-Links.
The next throughput tier was occupied by the Belkin Pre-N and Linksys WRT54GX twins. Throughput was virtually identical, but the Belkin managed to complete the 160 connection test, while the Linksys was unable to go beyond 128.
The Netgear WPN824 RangeMax had the poorest showing, managing to complete only the two connection test. While the single-chip Atheros processor design may be good for product margins, it apparently can't hold up to the rigors of P2P.