>>Hi Joe - Do you know if the DSL modem that Bell Atlantic sells is a 3COM product?
"DSL Modem: $325.00 "
3COMS should do well with both their cable and DSL modems. Let's hope that both Bell Atlantic and AT&T (w/ TCI) use their products.<<
Great news, I didn't know that. But still, xDSL and Cable
Modems is not a money maker in '98 for 3COM. Please prove
me wrong, for I would love to be wrong on this fact, since I
know that when xDSL and Cable Modems get hot, 3COM will have
the best products in this area. Bandwidth problems would
be on their way to being solved, and this will do nothing
but HELP 3Com.
Here's an article, talks about some of xDSL's problems:
(btw...if you can get a copy of the print magazine, this
article has a nice table with all the variations of
xDSL, and descriptions, pro's/cons, too bad the online
version doesn't have it)
Do the problems below remind you of similar problems for
another 3Com product??? They are solvable, but, imo, multiply
the hype time by 3 before you see progress.
techweb.com
September 01, 1998, Issue: 916
Section: Workshops
DSL Rides The Rocky Road To Standards
Jason Levitt
The grumbling in the comp.dcom.xdsl newsgroup is getting louder. It
seems that for every new DSL (digital subscriber line) user who can't
believe he or she has obtained 1-Mbps Internet access from a home
office, there are two others who are dying to tell you their latest horror
stories involving some clueless administrative flunky representing a
major CLEC (competitive local exchange carrier) or local carrier who
can't, or won't, get them DSL hookups. Let's just say that the entire
DSL industry is a bit stressed right now. And it is with good reason.
DSL is widely perceived as the best bet in the United States for
consumer, mass-market, high-speed Internet access, and it is expected
to drive a new wave of applications in both the corporate and consumer
markets. In the corporate arena, DSL is the clear choice for
home-office workers and telecommuters who want their home
desktops connected at LAN speeds, as well as for companies seeking a
VPN (virtual private network) for extranet applications. To sweeten the
deal, software and hardware vendors agree that DSL is the wave of the
future. With Bill Gates publicly cooing over the prospect of the
forthcoming DSL G.lite standard, and numerous vendors shipping or
planning to ship DSL CPE (customer premises equipment), DSL's
future seems assured.
And yet, many areas of the United States are still waiting for
deployment of DSL and the technology lacks a standard that will drive
a new commodity market for DSL equipment. For business customers,
it's eerily similar to 1994, when ISDN rollouts didn't happen nearly as
fast as press releases would have led you to believe. DSL, like ISDN at
that time, lacks the standards and interoperability testing that will give
businesses and consumers a variety of inexpensive choices for both
client and server hardware.
The DSL newsgroup noise, which would also ring a bell with those
early ISDN customers, is symptomatic of the industry's relative
inexperience with DSL technology, but also is the result of corporate
posturing and overpromising designed to generate a feeling of
well-being among customers and stockholders.
"No one is making money on DSL right now," says Glenn Ward, vice
president of broadband development for Bell Canada, referring mainly
to the CLECs and ILECs (incumbent local exchange carriers) that are
scrambling to build a DSL infrastructure. "They're in this for market
share and experience." Ward echoes the general sentiment that DSL
won't become profitable and widely accepted until the G.lite standard
is in place. This standard is expected to shift the cost of the
CPE-meaning the DSL modem-to the consumer and eliminate the
"truck roll," or the need for skilled technicians to visit each DSL
customer site. Currently, a technician must split the connection into
separate voice and data wire segments using low-pass filters that
separate the voice frequencies, at 400 Hz to 4,000 Hz, from the
higher-rate data frequencies.
The Road to G.lite Just as the ISDN market was jump-started by the
NI-1 standard and interoperability testing that created a
standards-based market for ISDN equipment in the United States,
customers and vendors alike are anxiously awaiting a standard for DSL
equipment interoperability that will let the same sort of commodity
market emerge. That standard, dubbed G.lite but also called variously
Consumer ADSL (Asymmetrical DSL)-not to be confused with
Rockwell International Corp.'s defunct QAM-based Consumer DSL
chipset announced last fall-or Universal ADSL, is being developed by
the Universal ADSL Working Group (www.uawg.org), an advisory
group consisting of nearly all the major DSL equipment manufacturers.
The initial draft proposal, Working Document 1.0, was announced at
the Supercomm trade show in June. On October 23, the preliminary
G.lite standard will be put to a vote by the UAWG and then is expected
to be passed on as a recommendation to the ITU (International
Telecommunication Union). The ITU is expected to ratify an official
standard for G.lite by the end of this year.
Some details of the future G.lite standard are clear, and CPE based on it
may appear as early as December. The G.lite standard, which is ADSL,
will be based on the ANSI standard T1.413 Issue 2 DMT Line Code and
has targeted 1.5 Mbps upstream and 384 Kbps downstream as its
maximum speeds. "Rate-adaptive" fractional amounts less than those
maximums also are part of the standard, so an ISP could offer 256 Kbps
symmetric as a G.lite connection speed. However, to simplify
equipment and provisioning requirements, equipment will be
technically limited to those maximum speeds and will have
autoconfiguring firmware that should require no customer intervention.
The 1.5-Mbps/384-Kbps speed limitation may seem restrictive
compared with DSL's typically advertised maximum downstream
speed of 7 Mbps, but it is a rational limitation based on empirical
testing of typical customer wiring scenarios and on the current overall
bandwidth available through ISPs.
The Tools for DSL Deployment DSL lines require quality copper
loops-that means no load coils, no more than 2,500 feet between bridge
taps and generally a (driving) distance of 18,000 feet or less from the
CO (central office). At higher speeds, distance requirements become
more critical and lines are more easily disrupted by "disturbers," such
as ISDN and T1 lines in the same wire bundles as the DSL lines.
Although G.lite is being promoted as a "splitterless" standard, the
engineering realities of new standards and new silicon, coupled with
the wide variety of possible installation scenarios, mean that, initially,
there likely will still be some need for splitters, filters and, in some
cases, even new customer-premises wiring. As the G.lite standard
matures with a better understanding of the issues, as well as better
vendor chip implementations, it probably will become closer to being
truly splitterless.
Of course, even at G.lite speeds, the UARTs (Universal Asynchronous
Receiver/Transmitters) on conventional PC serial ports will be unable
to keep up. Thus, external, single-user PC modems that utilize serial
technology will use USB (Universal Serial Bus) ports on PCs or
possibly enhanced parallel ports.
Router and bridge units, the only DSL modems currently available, use
Ethernet. Newer chipsets coming to market, such as Rockwell's
recently announced V.90/ADSL combo chipset, combine the G.lite and
V.90 standards in one modem, offering customers a choice of
connection profiles.
Available bandwidth for Internet access is another consideration. When
Bellcore first published its DSL work in 1989, the intention was to use
DSL for video-on-demand services, not pure data traffic.
Few service providers could handle 1,000 users with 7-Mbps DSL
links to the Internet. G.lite's 1.5-Mbps/384-Kbps limit is a reasonable
maximum, and, in any case, it's likely that many customers will opt for
slower symmetric speeds to handle applications like high-quality,
point-to-point videoconferencing, which generally requires 384-Kbps
symmetric bandwidth.
What to Buy and When to Buy It For IT buyers, it's a confusing time.
Despite frequent press releases touting rollouts of DSL access,
corporate mergers and equipment deals, the fact is that DSL
availability is still sparse and there is almost no interoperability among
equipment.
Further, at least nine varieties of DSL are available (see "Key DSL
Variants" on page 104), many using incompatible modulation schemes,
such as QAM, CAP, DMT and 2B1Q. Many vendors are using
proprietary DSL chipsets, further complicating the issue. So, IT buyers
right now are faced with single-vendor solutions.
In addition, because the DSLAMs (DSL access multiplexers) that are
connecting corporate users are selected and owned by ISPs, CLECs and
ILECs, corporate IT buyers must accept the carrier's vendor choice.
Only a very large IT account might be able to influence a provider's
choice of DSL equipment.
Does this single-vendor state of affairs and grab bag of DSL
implementations matter? The answer is both yes and no. Ultimately,
any particular end-to-end solution is simply another card in a DSLAM
box and a corresponding CPE unit. When the G.lite standard arrives, it
too will be another card that slides into the DSLAM with a
corresponding CPE unit. Therefore, the penalty for customers buying
into DSL today may only be the eventual replacement of nonstandard
CPE and, if the company owns the DSLAM, upgrading some of its
rack-mount cards.
Because DSL technology is evolving quickly, with new hardware
revisions that are more noise-tolerant and can traverse longer distances,
these upgrades likely would be necessary even if the standard were not
available within a year's time. If your company can wait until the
second quarter of 1999, that may be the best time to consider deploying
a DSL technology. By then, G.lite equipment should be widely
available and more nationwide sites should have DSL lines available.
In any case, if your speed requirements exceed 384 Kbps symmetric or
1.5 Mbps asymmetric, you'll need to go with a non-G.lite solution
anyway. A future standard, probably based on the G.lite work, will
likely arrive by the end of 1999.
At today's price points-which set DSL access and equipment at easily a
factor of five less than comparable technologies, such as T1, and at least
that much faster than ISDN at a similar price point-some companies
are willing to buy DSL equipment now even if it means having to
migrate to standards-based DSL later.
Jim Southworth, director of advanced network services and
technologies for Concentric Network Corp., one of the larger ISPs
focusing considerable resources on DSL, sees the forthcoming G.lite
standard as the basis for a vast amount of future DSL deployment. He
cautions, though, that customers buying in today will likely have to
purchase new equipment within two years.
The TI Competition But despite DSL's radically less expensive
equipment and service, Southworth says he doesn't see any of the DSL
iterations supplanting T1 lines anytime soon. If anything, he says, he
sees DSL driving T1 sales. The reason is manageability. T1 connections
have been a staple of corporate America for years now and are
comparatively easy to manage, with 24x7 monitoring, a wide array of
routing options and guaranteed response time.
Also, unlike DSL lines, which have distance limitations of typically
18,000 feet from the CO, T1 line distances can be extended much
farther from the CO using repeaters-roughly up to 50 miles in the local
loop and much farther for long-haul T1 connections.
Although T1 services may not disappear in the short term, ultimately
they will be used only for access. If you are close enough to the CO,
DSL is the way to go, especially if you trust real-time services
(voice/video) over packet networks.
The CLEC Playing Field Today's single-vendor source market for
DSL hardware might make some customers wary of buying in, but it
isn't stopping CLECs from aggressively pursuing collocation at COs
around the country and deploying single-vendor solutions. Customers
will have to purchase, at a minimum, the same vendor-specific CPE
that the carrier is using. Later, when G.lite does come around and G.lite
cards for the DSLAM equipment are available, existing customers are
likely to stick with the same equipment vendors because of familiarity.
Because some DSLAM vendors already support multiple varieties of
DSL in the same box, the move to G.lite is expected to simply require
another variety of DSL card that slides into the rack. Thus, existing
CPE will remain and new installations can proceed with G.lite.
Additionally, some CLECs are already deploying multiple DSL
technologies for different purposes. Covad Communications Co., a
DSL CLEC that is collocating its DSLAMs in COs around the country
and selling its DSL service through various ISPs, uses RADSL (Rate
Adaptive DSL) equipment from Diamond Lane Communications for
its DSL service and IDSL (ISDN DSL) equipment from Cisco Systems
for customers who aren't close enough to the CO or who want to
change their existing ISDN equipment to DSL.
IDSL, which uses ISDN's 2B1Q line encoding and runs over existing
ISDN copper that has been rerouted at the CO from the switched voice
network, can be extended using repeaters as far as 30,000 feet from the
CO. The downside is that it is limited to 144-Kbps symmetric speed.
Also, IDSL customers lose their ISDN voice services. But in some
markets where ISDN lines are metered, including California, IDSL
lines are attractive to customers because they are not metered and are
deployed as "always-on" connections as opposed to dial-up links.
Covad deploys both IDSL and RADSL in order to reach as many
customers as possible in any given region, according to company
officials. However, that means deploying at least two DSLAMs, one
from Cisco and one from Diamond Lane, in every CO. With CO
collocation space at a premium and each DSLAM box requiring its own
expensive back-haul circuit, the fewer DSLAMs required, the better.
And while no one is making money with DSL technology yet, Covad
says it expects that to change. "The economics of this business are the
best of any business I've ever been in," says Rex Cardinale, vice
president of engineering for Covad. "When you look at the take rate
[the number of customers in a region that subscribe to the service] that
we have to get in order to be profitable, it's really small."
Alternative Choices The economics of eliminating the truck roll while
still holding down equipment prices have not been lost on major DSL
equipment vendors.
Several proprietary, splitterless technologies have been released over
the past six months with varying degrees of success. Paradyne Corp.'s
MVL (Multiple Virtual Lines), Cisco's EZ-DSL and Northern
Telecom's Etherloop technologies all trade off on standards in favor of
inexpensive equipment implementations and relaxed deployment
requirements. Etherloop features lower power requirements, more
resistance to disturbance in the same wire bundle and greater speeds.
It's not a DSL technology, but neither does it suffer from many of
DSL's drawbacks.
Paradyne's MVL, another non-DSL technology that runs over the same
copper loops, has been stretched as far as 24,000 feet from the CO, with
multiple 768-Kbps streams running on a single telephone wire. Cisco's
EZ-DSL, which uses the CiDSL chipset from GlobeSpan
Semiconductor, is the only DSL technology of the three. It's RADSL
and splitterless, but requires that filters be placed on any telephone sets
used while the data line is in use.
Both Nortel and Paradyne are aggressively pursuing standards bodies
with their technologies, but it's still too early to say whether they will
make any serious inroads against the forthcoming G.lite standard.
End Note DSL companies are consolidating rapidly, and it's likely that
only a handful of major players will be left by the middle of 1999,
when the consumer market is expected to really take hold. That market
should drive DSL equipment prices down and, if enough competition
exists between CLECs and ILECs, connection prices should also drop
precipitously. For Covad rival Northpoint, regulatory issues that could
impede competition are a major concern. The 1996
Telecommunications Act states that ILECs must provide collocation
space if they have space available. In COs where little space is
available, there may be few, if any, opportunities for CLECs to
compete.
Whether you perceive DSL as a pain, a potential gold mine or a "quick
and dirty hack," as Andrew Tanenbaum called it in his widely used
reference work Computer Networks, it's valuable to IT departments as
a big, inexpensive pipeline to the corporate LAN and the Internet, and it
will drive a new class of high-bandwidth applications for consumers.
Noise or no noise, it's the best thing going for general-purpose,
high-bandwidth connectivity.
Send your comments on this article to Jason Levitt at jlevitt@cmp.com.
Copyright r 1998 CMP Media Inc.
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