IP Democracy: AT&T: Sample Cable Modem Speeds Average 400 kbps

AT&T Group President John Stankey said today that a 150-home test of cable modem service in one market found that cable modem download throughput rates averaged 300 kbps to 400 kbps, far below the 6 to 8 mbps advertised by the cable companies. Speaking at Merrill Lynch's Communications Forum (webcast here), Stankey presented the results of the test, which took place in one unnamed market.

In that market, AT&T recruited over 150 different residential homes, which then purchased cable modem services. AT&T put probes on the network to track for several months the cable operator's (or maybe multiple operators') high-speed Internet performance.

Even though peak speeds averaged around 3 Mbps during periods of low congestion, still far below the 6 to 8 Mbps speeds, average speeds hovered around 300 kbps to 400 kbps.

Stankey's point in raising these test results is to argue that "it's not just good enough to talk about access speeds" at the local level. "The local access speed is not indicative of what the end-to-end performance is."

Rather, "the way you manage performance is by having a complete set of skills that you manage across the network," Stankey said. As it so happens, AT&T has a national fiber-based backbone that feeds its own DSL connections. "The IP backbone gives us tremendous capability to manage the service."

Stankey's test raises more questions than it answers. How is it possible that the advertised throughputs are so much dramatically higher than the average speeds delivered? Would AT&T's own DSL service produce the same kind of results? How does this square with conflicting information obtained from users themselves?

Posted by Cynthia Brumfield on February 27, 2008 2:22 PM to IP Democracy