In an attempt to clear remaining hurdles blocking progress toward certification of vendors under the PacketCable standard, Cable Television Laboratories is about to begin a round of interoperability testing that marks a significant departure from the pre-certification tests it’s been conducting so far.
In essence, the shift marks recognition that certification of vendor products supporting cable’s version of IP telephony, which is key to operators’ commercial rollouts of VoIP services, remains an elusive target, notwithstanding intensifying pressure from CableLabs members for a deployable solution. “People really want to move forward at this point, even those who are using circuit switches to support established voice operations,” said an executive at one of the vendors participating in the testing process, who spoke on background. “It’s frustrating to everyone concerned that they’re not ready to begin certifying product.”
In one sign of the growing demand for what is being called the hybrid IP/circuit-switched solution Toshiba America Information Systems, now the leading supplier of cable modems, has added a GR-303 interface to its line of voice-capable DOCSIS (Data Over Cable Service Interface Specification) 1.1 modems. Under this model, voice travels in IP mode across the cable distribution network, conserving bandwidth and lowering operating and premises equipment costs while relying on the GR-303 connection to circuit switches to set up the feature provisioning.
“It wasn’t that hard for us to do, given the resources in engineering we have, but it took significant demand to get us to do this,” says Christopher Boring, manager for new business development at Toshiba’s Network Products Division. In fact, he adds, one customer, Cox Communications, is already making use of the new modem for a test of the hybrid model in Oklahoma City, where it presently offers circuit-switched voice. Comcast Corp. and AT&T Broadband have also signaled they want to pursue this model.
This need among companies following a circuit-switched model for PacketCable- certified equipment has put more immediate, commercially driven pressure on the PacketCable compliance process than was there before. But these and other cable companies involved in PacketCable, many of whom had not yet been informed of the change in strategy at CableLabs, will probably have to wait longer than they had been expecting.
There appeared to be considerable confusion in industry circles over just what was happening with the PacketCable process. Sources close to developments said that a widely held perception among vendor representatives that the first wave of certification had been postponed was in error. “There’s been no delay in any certification wave, because none has yet been scheduled,” a spokesman said, speaking on background. He declined to go into further detail about developments.
Another highly knowledgeable source says CableLabs has been conducting what amounts to pre-certification trial runs and that another trial run had been scheduled to begin for the third quarter when the decision was made to go another route. “Based on our need to better understand the differences among vendor interpretations of the standard and how that affects the way their products interact, we’ve decided to have a big open interoperability event as the next step in preparations for future certification waves,” the source said.
The aim is to determine to what extent various products interoperate with each other so as to help decide which interpretations of the various profiles under the PacketCable umbrella should be locked in as the ones for everyone to follow, he added.
Varying vendor interpretations of specifications is commonplace in the standards-setting process across all categories of telecom and cable platforms, but PacketCable is especially difficult because there are so many components in the chain, each of which must be shown to work with various versions of each of the other components that the tested component is meant to work with. For example, a media terminal adapter must interface with subscribers’ modems, the call management server, the cable modem termination system, the system OSS and various servers that deliver certain applications such as security. All of these interfaces must be tested against a variety of signaling and other applications, and all the connected components in the test of an MTA product’s compliance must themselves be compliant.
These complexities promise to continue to challenge CableLabs’ engineers ability to structure a final certification process. “We’re doing our best to get to an official certification wave this year, but we’re not making any predictions,” the source said.
