BBH Report Home Page
April 23, 2002 Provided by System Dynamics Inc.

CableLabs - Expanding Its Borders

When Dave first visited CableLabs in Boulder, Colorado nine years ago, it was a small technical organization, largely unknown except to its North American cable operator members. Founded in 1988, its mission was to "seize the technological initiative" for the cable industry. Its early research was largely addressed to improving the underlying cable infrastructure.

CableLabs has come a long way from its early days. Now based in Louisville just down the road from Boulder, most of its effort is addressed to digital applications running over cable: cable modems, IP telephony and advanced multimedia telecommuncations, digital television, interactive TV, and home networking. It has assumed the leading role in specifying and certifing the technologies for delivering advanced services over cable, and now plays an increasing role beyond the Americas and far beyond TV and entertainment services.

The ITU recently issued a press release on IPCablecom, describing it as a framework for a "new global communication system". Its goal is global end-to-end IP multimedia communications - integrating voice, video and data. IPCablecom is based on two longstanding CableLabs projects - PacketCable and DOCSIS. The specifications for CableHome - which extends PacketCable into the home network - have just been released.

We thought it was time to bring our readers up to date, so we visited CableLabs earlier this month and met with several people to discuss the status of key projects. We followed up with a telephone interview with Dick Green, CableLabs CEO.


Cable Television Laboratories Inc. is a non-profit research and development consortium "dedicated to pursuing new cable telecommunications technologies and to helping its cable operator members integrate those technical advancements into their business objectives." CableLabs originally served only the North American (United States and Canada) cable industry, but now accepts members from around the world. CableLabs is funded by member and certification fees.

CableLabs organizes and manages projects requested by its member companies. Each project starts with research into emerging broadband technologies. If appropriate, CableLabs leads a multi-vendor effort to develop common specifications for interoperable products, and then performs certification testing of proposed products. Certified products receive a CableLabs Certified logo sticker.

Three of the CableLabs projects are closely related:

  • DOCSIS - cable modems
  • PacketCable - IP-based telephony and advanced multimedia services
  • CableHome - extending cable services to network devices within the home

DOCSIS and PacketCable have become global standards through the ITU, and it's reasonable to assume that CableHome will move in the same direction.

(We'll cover the OpenCable project, which is developing specifications for interoperable digital set-top boxes, in a later article.)

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IPCablecom - Working Towards End-to-End IP

IPCablecom is a project in Study Group 9 of ITU-T - the Telecommunications Standardization Sector of the ITU. Study Group 9 is the lead study group on "integrated broadband cable and television networks". It's responsible for recommendations on the use of integrated broadband networks to carry voice, other time critical services, VOD and interactive services. IPCablecom is a special project on "time-critical interactive services over cable television network using IP-protocol, in particular Voice and Video over IP".

Dr. Richard R. Green, CableLabs President and CEO, is the Chairman of Study Group 9. We've known Dick for many years, and we called him to discuss the significance and status of IPCablecom.

"We'd like to see cable networks migrate to all-digital all-packet based networks" he told us. "The real importance is that this is the first end-to-end packet-based telecommunications standard. All elements are expressed in IPCablecom. While a lot of IETF work is embedded in it, we've tried to fill in all the gaps. The first stage is telephony - then video, and later full multimedia communications."

We observed that IPCablecom was heavily based on PacketCable and asked how it would work outside North America. "While the US was the incubator, it translates very well internationally." The standard provides annexes which allow it to match specific environments. "There are many regional differences around the world - IPCablecom already handles the major ones in North America, Europe, Asia and can be extended to accomodate local issues."

Since IPCablecom is designed specifically for cable systems, we asked Dick about interoperability with other forms of broadband Internet access, like DSL and fiber. He told us that IPCablecom was designed to interface to other networks through the PSTN, but that approach "is not elegant in the long term. There's no reason why the standard can't be extended when the market begins to sort out the standard for DSL and for telephony on DSL."

We posed another question to clarify the potential for end-to-end IP. Most cable operators in North America seem to be focused on connecting PacketCable systems directly to legacy circuit switches using the GR303 interface, so we asked whether the "end-to-end IP" strategy was drifting off or whether the current impetus on GR303 (V5.2 in Europe) was just a near-term tactic.

Dick's answer was encouraging. "The long term will center around a complete IP implementation. But IPCablecom is flexible. Since some cable operators own circuit switches, there are provisions in the standard to allow that kind of interconnection - this addresses the specific economic interests of manufacturers and cable operators."

We're sure Dick is right that economic interests, not protocol theology, will be the key determinant.

[Note: We have written about end-to-end IP in prior isues of BBHR. See the two-part article "End-to-end IP: How Will The ILECs Survive?" in the 9/26/2000 and 10/26/2000 issues. For back issues see ]

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If you didn't track how CableLabs' focus on product specification and certification began, it's worth understanding the history. In 1996 cable modems were proprietary systems tying a vendor's cable modems in the home with the same vendor's cable modem termination system (CMTS) at the cable headend. Since cable operators wanted to buy interoperable CMTS and cable modems from many vendors, and to move toward retail sales, they chartered CableLabs to undertake a collaborative multi-vendor effort. This resulted in the Data Over Cable Service Interface Specification version 1.0 (DOCSIS 1.0), a complete set of specifications for interoperable cable modems and CMTS.

Once the DOCSIS 1.0 specifications were completed, CableLabs set up a formal "certification" process for cable modems and a "qualification" process for CMTS. The process has been very successful: the first DOCSIS 1.0 modems were certified in early 1999; at last count, 203 modems have been certified and 26 CMTS qualified, from more than 60 vendors. We view this extraordinary effort as one of the key reasons for cable modems market share advantage over DSL in North America.

Next came DOCSIS 1.1. To support PacketCable (which handles time-sensitive communications) it enables multimedia communications over cable - primarily managing and enforcing "quality of service" (QoS). The specs were issued in early 1999, first equipment was certified late in 2001; 21 modems and 4 CMTS have passed. [More info on DOCSIS 1.1 is contained in our article on the Western Cable Show in BBHR 12/19/2001.]

DOCSIS 2.0, the third phase, extends the specs to provide increased upstream bandwidth and more reliable operation during plant impairments. With 2.0 specs completed in early 2002, CableLabs is hoping to start certification testing later this year. Meanwhile, several companies have released products based on the technologies used in DOCSIS 2.0.

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PacketCable is developing interoperable specs for advanced, real-time multimedia services such as IP telephony, multimedia conferencing and interactive gaming. It is built on and closely coordinated with DOCSIS 1.1.

Like DOCSIS, PacketCable is a multi-phased project. Three sets of specifications have been issued: 1.0 and 1.1 together make it possible to provide IP-based "carrier-grade" primary telephone service within a single "zone" (typically, a single cable system). 1.2 adds the inter-zone mechanisms to permit end-to-end IP between cable systems.

Now that some vendors have received DOCSIS 1.1 certification, they are focusing resources on PacketCable. Although no products have yet achieved PacketCable certification, people in the industry are hopeful that some will be approved this year. The main focus is currently on 1.0 and 1.1.

Cable operators are not waiting for certified products to gain experience with IP telephony. Many are conducting field trials of IP telephony, using pre-certification technology. Some of these trials have been under way for some time. Several vendors recently announced that their DOCSIS 1.1 equipment is being used in a trial Comcast has been running in Detroit since last year.

[For related information, see "Residential Broadband Telephony - How and When?" from our VON Asia 2000 talk at ]

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With broadband service being the single largest driver for home networking, it's natural that cable operators want to extend their services into this arena. They want to standardize specifications to simplify installation, lower equipment costs, and enable remote troubleshooting of problems in the home. These capabilities would simplify life for the consumer and provide a revenue stream for the MSO.

While the combination of DOCSIS 1.1 and PacketCable bring "carier-grade" IP telephony to the customer's home, CableHome provides the mechanisms to maintain the quality to a telephone (or other device) within the home. More broadly, the goal of the CableHome architecture is to "establish a home network infrastructure to manage the delivery of high-quality, cable-based multimedia services." With CableHome, a cable operator can manage, support and upgrade the network on the customer premises.

The phase 1.0 specification of CableHome, released earlier this month, includes hands-off provisioning of the residential gateway device, tools to help the cable operator assist in diagnosing and resolving home networking issues, configuration and management of gateways and firewall management.

CableLabs is establishing a certification process for CableHome, as it has for its other projects. Since many vendors are planning to integrate DOCSIS modems with CableHome and/or PacketCable functionality, CableLabs is organizing to enable parallel certification testing of integrated devices.

ITU-T Study Group 9 has already added the definition of a new set of "IPCable2Home" specifications to its work program. As cable operators start taking end-to-end responsibility for IP-based telephony and multimedia communications, it's very likely that the CableHome effort will provide the basis for global standards for home networking management.

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