When you connect to the Internet, you might
connect through a regular modem (dial-up), through a local-area
network (LAN) connection in your office, through a cable modem (Cable
Internet) or through a Digital Subscriber Line (DSL) connection.
For me DSL connection is the most
cost-effective solution that home based and small business office can
leverage to grow a business. It is not only widely available but its
reliability and high-speed capability is what it makes one of the most
preferred access service.
DSL is a broadband high-speed connection that
uses the same wires (2-wire) as a regular telephone line. Simultaneous
use of voice and data (internet) one can log on to the internet while
also using the line to make voice calls. The speed connection is much
higher than a regular modem which can hit to a max of 56Kbps only. DSL
can use existing phone line or delivered as stand-alone DSL
connection. The company that offers DSL will usually provide the modem
as part of the installation.
A drawback with DSL is that a DSL connection
works better when you are closer to the provider's central office. The
connection is faster for receiving data than it is for sending data
over the Internet. The service is not available everywhere again owing
to distance limitation.
All types of DSL service fall into one of two
basic categories: symmetric and asymmetric. Symmetric types of DSL
support the same bandwidth between the subscriber and the service
provider in both directions.
Asymmetric types of DSL or ADSL support
relatively more bandwidth in the downstream direction (from the
service provider to the subscriber) and less bandwidth in the upstream
(from the subscriber to the service provider). ADSL is popular among
Internet Service Providers (ISP).
ADSL uses two pieces of equipment, one on the
customer end and one at the Internet service provider which is usually
telephone company or other provider of DSL services. At the customer's
location there is a DSL transceiver also called Customer-Premise
Equipment or CPE, which may also provide other services. The DSL
service provider has a DSL Access Multiplexer (DSLAM) to receive
customer connections.
A DSL Modem or CPE is like transceiver
equipment, it transmit and receive data packets (information) over
ordinary telephone cable. This data packets are actually digital
signals but since digital signal cannot travel far, the DSLAM from the
ISP’s head end transform the signal from digital to analog signal for
transmission over an analog channel (two-wire telephone cable) usually
at a distance of up to 5Km from central office and the DSL Modem or
CPE converts the signal back to digital. The DSL Modem is the
equipment where data from the user's computer or network is connected
to the DSL line. DSL Modem can connect to a customer's equipment in
several ways, though most residential installation uses USB or 10
base-T Ethernet connections (RJ-45).
The DSLAM at the service provider is the
equipment that really allows DSL to happen. A DSLAM is the
point-of-contact where a dedicated, high-speed link to the internet
called backhaul connection is terminated. An E1 (2048Kbps) or T1
(1536Kbps) Dedicated Internet is an example of a backhaul internet
link that can be use to service between 80-100 DSL subscribers. DSL
technology is the reason why internet connection is becoming cheaper
by the days. It is able to share or distributed for greater use a
dedicated connection (backhaul) to several subscribers while
maintaining quality of service. Cost-of-service is significantly
lowered.
The DSLAM takes connections from many DSL
subscribers and aggregates them onto a single, high-capacity
connection to the Internet. DSLAMs are flexible and able to support
multiple types of DSL in a single central office, and different
varieties of protocol and modulation. In addition, the DSLAM may
provide additional functions including routing or dynamic IP address
assignment for the customers.
ADSL is a distance-sensitive technology: as
cable connection's length increases, the signal quality decreases and
the connection speed goes down. Connection is much more stable the
nearer the user is to the central office. With a maximum 18,000 Feet
(5,640 meters) effective service length, some ADSL providers generally
limit distance it serves to a max of 3.5Km. Beyond this some
subscribers enjoy speeds below the promised maximums.
Bursting and Committed Information Rate (CIR)
are two factors to consider in choosing a DSL service. Remember, DSL
is a shared internet connection service depending on the port
configuration or package variation of the service providers. Bursting
is the term use to describe a service which does not guarantee a
certain speed. Connection bandwidth may vary from maximum of the
port-speed subscribed (as provided by the ISP) to a minimum of as much
as 32Kbps. DSL that offers Committed Information Rate (CIR) or minimum
guaranteed speed is much more desirable for it assures a sure
connection to the international internet gateway.
In choosing an ADSL package fit for your
home-based or small business requirements, try to ask the ISP of the
recommended count of users and type of application that the DSL
package can support. Usually, residential package can support only up
to 1 or 2 PC. However, with competition and greater availability of
other broadband internet access, ADSL packages currently being offered
by ISPs can support all type voice, data and video applications and at
greater speed.