Can't get enough DSL
Early implementers tout the easy installation and
attractive pricing of digital subscriber line service -
when they can get it.
By Susan Breidenbach
Network World, 11/16/98
Early digital subscriber line (DSL) adopters, for the
most part, give the service top marks, but they have one
complaint: DSL needs to be more widely available.
According to telecom consulting firm TeleChoice, only
about 825 of the 32,500 central and remote telephone
company offices in the U.S. offer DSL; that's about
2.5%. The 825 central offices represent 20 million
subscriber lines, but not all of them have been - or in
some cases even can be - conditioned for DSL.
Claudia Bacco, a senior DSL analyst with TeleChoice
in Dallas, estimates that 50% to 60% of all the copper
loops in the country can ultimately support DSL.
Where DSL can be supported, it's a safe bet users will
want it. Driven by pent-up demand for high-speed
access to corporate networks and the Internet, small
offices and telecommuters are snapping up DSL
bandwidth as fast as carriers and service providers can
provision it.
Cheaper than T-1 and faster and often less expensive
than ISDN, the highly reliable technology puts a
continuous connection within reach of many who
couldn't afford one before. DSL is easy to install and
even easier to upgrade. Instead of requiring hardware
or software changes at the customer site, carriers can
provision higher speeds with a flip of the switch.
Given the user demand, the relative ease of provisioning
and the myriad potential providers, it appears there's no
need to worry that DSL might parallel the slow and
troubled deployment history of ISDN.
Speedy video
Vazda Studios of Birmingham, Ala., recently began
using DSL to expand its business beyond the local area.
The post-production facility assembles various elements
into digital video television commercials and has
traditionally kept local courier services busy exchanging
computer disks and VHS cassettes with the firm's
clients. One small graphic component might be 10M
bytes to 15M bytes, making transmission via modem too
slow to contemplate, says Bob Askew, chief engineer
at Vazda.
Askew experimented with asymmetric DSL (ADSL) at
his home when BellSouth began testing the service
early this year. He then implemented ADSL in the
office when the technology became commercially
available this fall. Now customers can send Vazda
graphics via the Internet, with DSL speeding up
downloads.
Vazda gets ADSL from WWISP, a local ISP that
resells BellSouth ADSL service. WWISP charges
about $250 per month for a line with a maximum speed
of 1.04M bit/sec downstream and 256K bit/sec
upstream, Internet access, a static IP address and DSL
router rental.
Askew's only real complaint is that BellSouth's DSL
deployment to date is limited to DSL.Lite, a slower
version of ADSL based on the new G.Lite standard.
"Right now, when we finish a commercial we have to
make a VHS tape and use a courier to deliver it to the
client for approval," Askew says. "If we had 8M bit/sec
bandwidth combined with MPEG compression, we
could let clients retrieve the video from our server for
review." This would save time and let the company
expand its client base geographically.
Like Vazda, many other early implementers are
enjoying the benefits of DSL. "It's been incredibly easy
to implement - almost plug and play," says Gary Welsh,
president of Welsh Consulting, a network integrator in
Boston. Welsh has helped the ISP Shore.Net deploy the
service to some of his clients.
Carl Hu, the group program manager for Microsoft's
public network projects team, is already spoiled by
ADSL. Microsoft began testing GTE's DSL services
more than two years ago, and now has about 1,000
employees using ADSL lines to telecommute to
corporate headquarters in Redmond, Wash. Speeds
range from 1M bit/sec to 6M bit/sec downstream and
from 64K bit/sec to 2M bit/sec upstream.
But Hu recently moved from a house across the street
from the GTE central office that serves the Microsoft
campus to a new home on a different GTE loop. He's
back in dial-up mode and chafing under the bandwidth
constraints.
Implementation advice
Many DSL problems were ironed out during extensive
pilot tests over the past few years, Hu says. Applying
lessons he learned from Microsoft's DSL rollout, Hu
advises telecommuters to ensure the IP stack in their
PCs is configured to use the Dynamic Host Control
Protocol and their service providers are set up to
support DHCP.
Simply determining whether you can get DSL at a
particular location may be your biggest implementation
problem. Some phone companies have databases with
availability information on their Web sites, but the
databases are often wrong, says Robert Palmer,
president of Problem Solvers Interactive, a computer
consultancy in Birmingham.
If you're fortunate enough to live in an area where DSL
is available, examine all the service options before you
choose one. Be sure to avoid unnecessary equipment
rentals, read the fine print about performance and shop
around if you need a static IP address.
Page Law Firm in Birmingham jumped onto the DSL
bandwagon this year to speed online legal research.
The company replaced dial-up ISDN access and
dynamic IP addressing with an ADSL bundle from
WWISP that includes a static IP address.
"We were initially set up with a router that cost an
additional $130 a month," says Rick Honsberger, Page's
network administrator and president of its Controllex
subsidiary, which develops case management software.
"I suspected that since we had a proxy server, we didn't
really need a router, and that turned out to be true."
For $140 per month, Page gets a maximum bandwidth
of 1.5M bit/sec downstream and 256K bit/sec
upstream, a DSL modem and one static IP address.
"We're experiencing close to maximum speeds during
off-peak hours, but only about a quarter to half of that
when the network is busy," Honsberger says. Even so,
"the speed is wonderful."
Some carriers don't offer static IP addresses with DSL
services, which might be part of their attempts to
protect T-1 revenue. If you need a static IP address for
your site, check with alternative service providers and
compare rates.
However, static IP addresses raise security concerns
because DSL is a persistent connection. The door is
always open, and you're sharing a router port at your
service provider's facility with other customers. Unlike
plain old telephone service and ISDN lines, DSL doesn't
provide a secure point-to-point connection. And a
permanent address makes it easier for cybercrooks to
find you.
In single-user telecommuter installations, it's best to
stick with dynamic addressing. Also, keep in mind that
today's desktop operating systems have a lot of built-in
network capabilities. Hackers can use these facilities to
gain access to Internet-attached PCs, so be careful
how telecommuters' hard drives are set up for sharing,
and limit the availability of IP ports.
It's not possible to disable sharing mechanisms in LAN
environments, so heavy-duty firewall protection is
essential. "Don't put your firewall/proxy server in the
same box as your main file server because you don't
want that server on the Internet," Palmer cautions. "A
lot of people are doing that and don't realize what can
happen." To plug this hole, Problem Solvers Interactive
developed a Linux-based firewall that can double as a
router and connect up to 253 devices to a DSL line.
A grain of salt
Despite the glowing reviews of DSL services, there is
still a lot of uncharted territory. Performance is great
now because there aren't many subscribers, but it
remains to be seen whether users will be able to get
near the maximum bandwidth rates as new users pile
onto DSL nets.
DSL coverage is still scanty, especially as you move
away from big metropolitan areas. The new G.Lite
standard for ADSL may help the technology proliferate
because it's easier to install. However, there are still
several issues to resolve.
"G.Lite could allow for more rapid ADSL deployment
because the phone companies wouldn't have to send a
technician out to install splitters at every residential or
business account they want to open," says Lisa Pelgrim,
a senior analyst with Dataquest, a market research firm
in San Jose, Calif. "But it's still in a test mode or early
adoption phase."
DSL is also by definition a copper-only technology that
can't be deployed in subloops that are connected to the
central office via fiber. Service providers are coming up
with hybrid ISDN/DSL services, called IDSL, to
address this problem, but IDSL falls far short of full
DSL capabilities. For example, the maximum speed of
an IDSL connection is 144K bit/sec.
Availability problems, coupled with standards issues and
the lack of a single national DSL provider, make it
difficult for a large organization to implement DSL
networks. "If you're a network manager in a big
company, you don't want to deal with a lot of different
providers and manage a lot of different types of
services," Pelgrim says.
Moreover, while DSL users so far report smooth
sailing, these trial populations are generally skewed
toward the more tech-savvy users. And early adopters
tend to get lots of attention and handholding from
vendors and service providers.
"If the service provider comes in and does all the
customer-premise installation and configuration - opens
the PC, installs the Ethernet card and configures the
software - that's one thing," TeleChoice's Bacco says.
"But if they just install the line and leave all the rest of
this to the customer, a lot of people are going to have
problems."
That said, the entry level for DSL is low enough that
you might as well exploit it where it's available, as long
as security concerns are addressed.
Review: Hotwire MVL
Our lab tests show it
performs as
promised. Network
World, 11/16/98.
DSL in the real world
We take Hotwire MVL
out for a spin outside
the lab. Network
World, 11/16/98.
DSL Net Resources
DSL background.
Breidenbach is a
consultant and
freelance writer in
San Mateo, Calif. She
can be reached at
sbreidenbach
@usa.net.
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