Network World ADSL article.
nwfusion.com
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 |
