and Cable broadband are doing well in Asia. A closer
look at both technologies. by Dr Seamus Phan
terrestrial broadband seems to be doing exceptionally
well in Asia-Pacific, surpassing the US and Europe.
According to US-based RHK, Asia-Pacific had over 7.5
million DSL (Digital Subscriber Line) subscribers at
the end of 2001, which is 44 percent of the world's
Innovation continues in Asia, with the likes of Global
Telecom in the Philippines about to launch the first
publicly-deployed wireless LAN service coupled with
DSL Internet access. Globe Telecom plans to launch the
"Blink" service with hot spots in populated
areas, including airports, coffee shops, hotels, and
schools, using the 802.11b WLAN technology connected
to standard copper DSL lines.
Already, the Oakwood Premier Ayala Center is equipped
with this trial service, making the building the first
service hotel in the Philippines to offer broadband
Internet service in all of its rooms.
DSL is usually served by service providers in the ADSL
(asymmetric DSL) variety, which means that your download
speed is far more than your upload speed. This is a
marketing and practical strategy since most consumers
and small business users do not require consistently
high-volume uploads, but usually require bursty high-volume
downloads. By mechanically limiting the uplink speed,
the upstream service provider can better plan their
existing infrastructure resources without running into
There is another form of DSL known as SDSL (symmetric
digital subscriber line), which means that your download
and upload speeds are identical. For example, Pacific
Internet in Singapore offers the Unlimited SDSL service
providing 512 Kbps upload and download speeds for a
fixed fee. This service is targeted at growing businesses
with a need for always-on, unlimited bandwidth that
runs almost like a fractional T1 line.
In practice, other than infrequent scheduled downtime,
the SDSL performs just like a dedicated leased circuit,
with less hassle or
administrative headaches associated with more traditional
technologies such as ISDN, and costs
far less than a dedicated leased circuit.
DSL services frequently require just a simple DSL CPE
(customer premise equipment), which looks like a small
box with three ports (one for power, usually DC, one
for the DSL line, and another for RJ45). The RJ45 port
is connected to your network through a switch, hub or
router, and the service provider usually provides a
single IP for your organization. Should you require
the running of mail, DNS or Web servers behind the DSL
connection, you can request additional fixed IPs from
your service provider for additional costs, or run port
mapping through your routers.
Cable modem is different from DSL, but offers a reasonably
high access speed as well. Cable modem technology uses
two radio frequency (RF) carrier signals from the CATV
spectrum to provide a low latency broadband service,
typically to residential customers. It is a shared access
service, which means that if there are only 10 users
in a small neighborhood, the aggregate bandwidth will
be shared by the 10 users, and users can typically experience
a decent speed in accessing the Internet.
However, if there are more than 100 users, the same
aggregate bandwidth will be shared by the 100 users,
and the experience can be best described as slow.
leads in DSL adoption
to RHK in a report by Newsbytes early this year,
South Korea is the leading DSL success in Asia-Pacific,
with a conservative estimate of 4 million subscribers
at the end of 2001. Japan trails behind South Korea,
and countries such as mainland China and Taiwan
are expected to grow exponentially once the networks
roll out. Separately,
according to a commissioned study by the Japanese
government, there were net additions of 263,000
DSL subscribers in January 2002 and 288,704 subscribers
in February 2002, with a total of 2.08 million subscribers
In contrast, the traditional technological giant
US, has fallen from fifth to 10th place in terms
of DSL connections per 100 people, according to
the DSL Worldwide Retail Directory published by
UK-based Point Topic in April 2002. The US DSL
subscriber base stands at around 4.4 million for
the entire country holding a ratio of just 1.6
DSL lines per 100 people, while just South Korea
alone has 11 DSL lines per 100 people, with a
total of 5.2 million subscribers by the end of
2001. According to Point Topic, Hong Kong SAR
has 4.8 lines per 100 people and Taiwan has 5.5
lines per 100 people.
and other caveats
Cable modem technology is promiscuous, since it is a
shared medium Ethernet service where all stations sharing
the same medium can read and write frames transmitted
over the same medium. This raises security concerns,
including the possibility of passive monitoring, forgery,
and denial of service (DoS) attacks.
For personal and corporate customers running DSL or
cable services, it is advisable that a decent firewall
protection is erected before the network resources.
Some proponents of broadband technology have claimed
that users may experience more than 10 hacks per day
when using cable modems, and it is wise to leave yourself
out of the intruders' hacking list with adequate protection.
Immediately, users of cable and DSL connections should
disable port 80 access from the Internet, since this
port (http) is the most often used by intruders to create
DDoS (distributed DOS) attack platforms. There is no
reason for you to enable incoming port 80 access, and
in fact, for residential customers using cable and DSL
connections, it is also against most usage policies
set by service providers to enable incoming port 80
to run http services, or any server service for that
Some service providers may shut down residential connections
if they are found to be running Internet servers of
Service providers commissioning DSL connections typically
have to ensure that the line quality is up to par with
the technical demands of DSL. Before DSL is installed,
service providers will test the line to ensure that
it can be used, and when installed, is properly provisioned
to ensure a minimum standard that customers expect.
It does not end here. DSL connections are notorious
for occasional line drops and reduced quality. Service
providers often have to check and provision the lines
again, sometimes requiring a hard reset of the line.
This makes DSL very different from leased circuits which
can be typically described as "plug, use and forget",
at least until the month-end bill arrives.
Should you experience a drastic drop in performance
in your DSL connection, especially if it is a corporate
connection, call your service provider's network operations
centre (NOC) and ask if there is something wrong with
your line. The NOC typically will perform a short test
and will inform you if your line is working fine, or
if some kind of reset or house call is necessary. This
level of diligence is necessary for DSL connections.
As for cable, any degradation of performance is usually
attributed to the fact that it is a shared medium, and
you typically have no resolution with your service provider.
If you really depend on your broadband connection, and
should cable not work well for you in your neighborhood,
you may speak with DSL service providers instead.
Seamus Phan is research director at KnowledgeLabs
News Center (www.knowledgelabs.net), an independent
technology news bureau and writes for Network Computing-The
Asian Edition. He can be reached at firstname.lastname@example.org