Comcast Corp. (Nasdaq: CMCSA, CMCSK) is conducting a small, technical trial of a network DVR that closely mimics what Cablevision Systems Corp. (NYSE: CVC) has already deployed to its customers, Light Reading Cable has learned.

And when we say small trial, we're talking tiny small. The Boston test, says an industry source, has fewer than a dozen people on it during the early phases.

The test, though limited, is an indication that Comcast is giving the network DVR idea a serious look. While there's no guarantee the MSO will launch such a product in the near term, it's not a huge surprise that it's gotten this far. Comcast executives have expressed interest in testing a network DVR since last June's Cable Show in Chicago. (See Comcast Explores Network DVRs and Comcast to Run Small Net-DVR Trial .)

One source described 2012 as the "proof of concept" year for Comcast's project, and the MSO will vet all the technical angles before it tries to do anything more.

"They are going slow," says a person who's familiar with the Boston test. "It's more about affirming the technical and operational feasibility of deploying a network DVR."

Comcast is said to be emulating Cablevision's remote storage-DVR (RS-DVR) architecture, and one source notes that Cablevision is cooperating with Comcast on the Boston trial. Comcast declined to comment about the project.

Cablevision's RS-DVR architecture requires customers to set up their own recording requests. The system then writes and stores individual copies that can only be accessed by the subscribers that made them. So if 25,000 subscribers set up a recording for Game of Thrones, the RS-DVR has to make 25,000 individual copies.

It's not super-efficient from a storage perspective, but it's currently the only way to sidestep existing copyright laws. It's also considered to be more power- and cost-efficient than deploying set-tops outfitted with local hard drives. The all-IP "X3" HD client box said to be on Comcast's roadmap is the kind of device that could take advantage of a network DVR. (See Supremes Stand Clear of RS-DVR Case and Comcast Sizes Up All-IP Set-Top .)

And Comcast isn't alone. Other service providers and suppliers, including Aereo Inc. and EchoStar Corp. LLC (Nasdaq: SATS), are following Cablevision's technical lead as they deploy or plan their own network DVR products. (See EchoStar Sets Sights on a Network DVR , Can Aereo Survive a Broadcaster Assault? and EchoStar Readies Over-the-Top Video Play.)

New Charter Communications Inc. CEO Tom Rutledge championed the network DVR cause when he was the COO of Cablevision, but that sort of product does not appear to be on Charter's list of short-term priorities. (See Charter Keeps RS-DVR on Sidelines.)

— Jeff Baumgartner, Site Editor, Light Reading Cable