Cisco Systems Inc. (Nasdaq: CSCO - message board) and Texas Instruments Inc. (NYSE: TXN - message board) are the first, but apparently not the only, vendor pair to successfully demonstrate interoperable Docsis 3.0 upstream channel bonding at CableLabs ' Louisville, Colo.-based R&D house.

    The lab demo, conducted in July, teamed Cisco's flagship cable modem termination system (CMTS), the uBR10012, with TI's Puma 5 Docsis 3.0 modem chipset and reference design, which was introduced in May at the 2007 Cable Show. (See TI Chips In.)

    For Cisco's part, the upstream channel bonding was handled in the core CMTS chassis via the company's uBR10-MC5X20S/U/H Cable Interface Line Card, which contains 20 upstream ports, according to Paul Yesnosky, Cisco's senior product line manager for CMTS products.

    The CMTS, he explains, can then address a key challenge of upstream channel bonding: taking in fragments from multiple upstream channels and reassembling everything back to its original order.

    Upstream channel bonding is just one feature of Docsis 3.0. The platform, designed to offer shared speeds in excess of 100 Mbit/s, also bonds downstream channels and supports IPv6 and IP multicast applications. Deployments and trials involving pre-Docsis 3.0 equipment have been largely limited to downstream channel bonding.

    "The upstream test was one of the final pieces that had to be put into place to show some major progress on Docsis 3.0," Yesnosky says.

    A Cable Labs spokesman confirmed that TI and Cisco were the first to demonstrate upstream interoperability, but he added that other CMTS vendors have also achieved it. The spokesman would not say who else has joined the CableLabs 3.0 upstream interop club, but the most likely candidate is Casa Systems Inc. , a next-gen CMTS startup based in Andover, Md.