Although Cisco Systems Inc. (Nasdaq: CSCO - message board)'s flagship uBR10012 will be the vendor's first cable modem termination system (CMTS) to support Docsis 3.0, the cable tech supplier has also carved out a 3.0 migration path for its widely deployed mid-range product and a just-announced "compact" CMTS offering.

    On the latter, Cisco has introduced the uBR7225VXR, a two rack-unit CMTS targeted to cable systems or hubs that serve up to 5,000 subscribers or Docsis devices. When filled to capacity with two linecards, each CMTS unit can handle up to 16 upstream channels and four downstream. (See Cisco Unveils New CMTS.)

    Although the new CMTS will comply with Docsis 2.0 out of the blocks, it will be upgradeable to Docsis 3.0 with a new linecard and a fresh load of software, according to John Mattson, Cisco's senior director of CMTS products.

    In addition to IPv6 and IP multicasting, the Docsis 3.0 specs will use channel bonding techniques to produce shared speeds in excess of 100 Mbit/s. CableLabs is scheduled to launch its first round of official Docsis 3.0 certification and qualification tests in October when Certification Wave 56 gets underway. Cisco has already said it plans to submit the uBR10012 for "Bronze" qualification testing. While that product initially will support only downstream channel bonding, Cisco has recently demonstrated upstream channel bonding at CableLabs with a modem reference design powered by Texas Instruments Inc. (NYSE: TXN - message board) silicon. (See CableLabs Accelerates Docsis 3.0 Testing and Cisco, TI Paddle Upstream .)

    Mattson isn't saying when the new 3.0 linecards will become available, but, when they do, they also will support Cisco's mid-range CMTS product, the uBR7246VXR.

    That timing on the new 3.0 linecards "will be in line when we think [Docsis 3.0] modems will be available in volume," Mattson says. By that estimation, one can expect them to emerge sometime in 2008 or perhaps as late as 2009.

    Cisco claims it is the only supplier with a Docsis 3.0 upgrade strategy for CMTSs of the smaller "pizza box" variety. So far, that statement appears to be holding up.

    Arris International Inc. (Nasdaq: ARRS - message board), which is centering its 3.0 efforts on its flagship CMTS, the C4, doesn't have any definitive Docsis 3.0 plans for the C3, a one rack-unit CMTS designed to support as many as 3,000 modems.

    Mike Caldwell, Arris's senior director of product management, says his company has been exploring some 3.0 migration options for smaller form-factor CMTS products but isn't at the point of discussing an introduction date.

    "It's not that we won't do it; just not today," he says. Instead, Arris is focusing on an integrated CMTS model that would marry the capabilities of the C4 with those of its downstream-heavy D5 Universal Edge QAM, producing a device that can bond upstream and downstream channels within the same chassis. That will complement strategies for the modular CMTS, a newer architecture that will allow operators to scale capacity by using the "core" CMTS for the upstream and edge QAMs for the downstream. (See M-CMTS Is All in the Timing.)

    As for Cisco's new compact CMTS offering, Cisco said it has trials underway with two Danish cable operators: Dansk Kabel TV A/S and A+, which operates a mix of medium- and small-sized networks that would serve as candidates for the uBR7225VXR.

    Cisco has not announced any trials or deployments for the uBR7225VXR in the U.S., but "the natural sweet spot" for the product is with MSOs outside the top ten, Mattson says.