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Cable Show 2011: The 1-Gig Cable Modem -- Perfect for Piracy?

When I saw Comcast’s demo of a souped-up cable modem rig blasting more than 1 Gigabit per second downstream in the Windy City, part of me thought: Well, big deal (see Comcast’s Roberts Pulls Out ‘Xcalibur’ TV, Gigabit DOCSIS).

I was more impressed with the great-looking Xcalibur guide and the personalization features Comcast CEO Brian Roberts showed off. That is potentially a bigger near-term deal, as Comcast needs to at least match the on-screen interfaces provided by other video services, which will inevitably be a point of comparison (e.g., Netflix, Apple TV, Verizon FiOS).

The 1-Gig demo was less of a “wow” for me because, for one thing, the Brits and the Germans have already gotten there (see Virgin to Test DOCSIS at 1.5 Gig — 240 Times U.K.’s Average Broadband Speed and Mach Schnell! Germany’s Kabel Deutschland Tops 1 Gbps in Field Trial).

Then there’s the question of usefulness, at least today. What the heck are you gonna do with throughput like that, except start streaming your Netflix movie a few seconds faster?

Roberts, in response to a question on this point from CNN’s Erin Burnett, gave the familiar answer that bandwidth consumption has always just pointed up. “Where will we be in 2015?” he asked. “I think it’s a certainty that we will want more bits into our homes…. We’re confident that if we build it, they will come.”

Some take a cynical view of what high-bandwidth services will be used for.

One very senior cable-tech exec, discussing the Comcast 1-Gbps demo, said bluntly, “I just don’t see any other application for that other than piracy.” (I’m not identifying him because the conversation was not a formal interview, and he wasn’t expecting to be quoted.)

But there’s another important point about the massive capacity possible with DOCSIS 3.0, which is that it has a lot of runway (5 Gbps total in an 860 MHz system) to meet the aggregate last-mile needs of subscribers in a given service group.

Arris showed its C4 CMTS delivering real file-transfer throughput of 4.5 Gigabits per second of DOCSIS 3.0 downstream traffic as well as 575 Mbps upstream to a single fiber node (see Arris To Stage Monster DOCSIS Demo). The demo used 16 DOCSIS 3.0 modems with 8×4 capability — that is, eight downstream and four upstream — bonding an aggregate of 128 channels down and 24 up (see pic of the modem bank, left).

To Arris senior director of solution architecture and strategy Mike Emmendorfer, the point was not that you would want to deliver that kind of bandwidth to an individual sub — after all, no single residential customer is going to need a ridiculously huge 4.5 Gbps downloads anytime soon.

Emmendorfer pointed out that DOCSIS 3.0 lets MSOs load balance the total capacity per node, to continue to serve the increasing average bandwidth consumed per subscriber. According to Cisco’s recently updated VNI Forecast, average broadband speeds worldwide will jump from 7 Mbps in 2010 to 28 Mbps in 2015.

“Peak speeds are cool,” Emmendorfer said. “But what we’re seeing is the need to maintain capacity to keep up with overall growth.”