In a surprise reversal, Cable Television Laboratories Inc.
late last week certified two more cable modems after determining that a software glitch
had spoiled their latest interoperability tests.
Modems manufactured by General Instrument Corp. and by
Arris Interactive LLC under the LANcity name won the coveted approval under the Data Over
Cable Service Interface Specification, joining 3Com Corp. as the only gear passing the
certification round that ended two weeks ago.
GI and Arris did not initially win certification, which is
considered a key milestone in creating a retail channel for cable modems.
But a review of test results isolated a common problem that
was later traced to an anomaly in headend equipment used in interoperability testing.
Ironically, the software-related problem was with the Cisco
Systems Inc. cable-modem-termination system -- the only CMTS CableLabs has qualified as a
DOCSIS-compliant headend so far.
"I think it's a fair assumption that this glitch
probably affected the other modems that didn't get certified," CableLabs
president Richard Green said. "But this was the only factor for those two modems. The
others that were not passed obviously had additional problems."
Green said the problem became apparent during testing, and
staffers worked to isolate it over the weekend after the last testing wave, the results of
which were released April 29.
Because it took time to determine whether the problem was
with the headend, the tested modems or the testing gear, CableLabs decided to certify
3Com, while continuing to evaluate how the others may have been affected by the snafu.
Steve Nevalsky, senior manager of engineering for
Cisco's cable group, said the problem manifested itself as an error signal from the
But after CableLabs staff determined that test results
showed that the problem was common to a number of modems, further investigation determined
that the condition was actually a warning, rather than an error condition, and Cisco
quickly installed a software patch to address it.
Nevalsky said the problem has cropped up only in the
complicated CableLabs tests so far, and not in reports from the field, where the Cisco
CMTS is widely deployed.
"The DOCSIS spec itself has got a lot of options in it
if you look at all of the ways it can be configured," Nevalsky said. "These will
pop up from time to time. We view it as a minor problem."
Once the problem was determined and CableLabs tested the
software fix to ensure that it did not cause further problems, data from the tests were
presented to the DOCSIS-certification board last Thursday. The board then agreed to pass
GI and Arris.
Green agreed that while news of the testing problem might
not sit well with vendors that are anxious to get certified, the incident showed that the
certification process worked. The process, after all, is supposed to ensure that modems
sold at retail will work with a variety of headend equipment, and that the CMTS works with
all certified modems.
"I look at this as a process for determining the
interoperability of equipment," Green said. "When we're able to isolate
potential glitches, then it's a win-win for everybody. The process is designed to
find things like this."
Although Cisco and CableLabs found and fixed the CMTS
problem relatively quickly, the incident generated griping among vendors frustrated by the
pace of cable-modem certifications. Before last week, only 3Com, Thomson Consumer
Electronics and Toshiba America Consumer Products passed muster.
"It really calls into question the processes at
CableLabs," said an executive at one vendor, who asked not to be identified. "I
think their purity just went out the window."
But others said the outcome showed that the testing setup
works, and that isolated snafus would not prevent worthy gear from getting certified.
At the same time, some stressed that they would rather err
on the side of slower deployment than possibly put balky equipment into the hands of
"There's been a tremendous amount of effort
expended to maintain the integrity of the process," Time Warner Cable chief technical
officer Jim Chiddix said.
"Naturally, everybody who's not yet certified is
a little unhappy, but I'm absolutely confident it's a fair process," he
added. "It would be easy to cut corners and get product to market quickly, but there
would be a terrible price to pay."