About ADSL Broadband
DSL is the next generation
of internet access technology.
A house or business with
DSL has a data socket,
that looks like a phone
socket. DSL is a direct
connection to the internet,
always on.
To connect, a "DSL
modem" is needed;
DSL modems are starting
to be available on the
open market, but they
are normally supplied
by the DSL provider you
choose, since DSL standards
are varied, and the modem
must be compatible with
the equipment favored
by the provider. (When
talking to your provider,
you may ask if they allow
you to source your own
equipment, for example,
second-hand).
DSL modems are of three
basic types: external,
internal or USB. For external
modems, on the back is
a socket, usually marked
LAN. A cable (ethernet
cable) connects this to
your computer, which needs
an ethernet card, (known
as a Network Interface
Card, or NIC), such cards
are available from dozens
of vendors at prices as
low as $20, and for this
purpose, they all work
the same way and are all
compatible.
Many current computers,
such as the iMac, come
with a NIC, and socket,
built-in, simplifying
things still further.
Unlike advanced graphics
boards or other specialized
hardware, even the oldest
computer can accept a
NIC card, as long as it
has a spare slot. For
internal DSL modems, or
USB modems, the equipment
is plugged in, and some
driver software must be
loaded into your computer
before it can be used.
Basic features of
a Broadband ADSL Router
The Broadband ADSL Router
provides data access for
multiple users who wish
to combine broadband access
with a telephone service.
The user must have direct
copper line connection
from his premise to the
local exchange where the
DSL is available. The
premise must be within
5 km from the exchange.
- WAN interface:
High Speed Asymmetrical
(ADSL) Data Transmission
on Single Twisted Pair
Copper Wire
- LAN interface:
One 10Base-T Ethernet
port for Computer or
LAN connections
- Bandwidth:
Auto-negotiation rate
adaptation up to 8Mbps
downstream and 1Mbps
upstream (varies with
different ISPs)
Minimum PC requirements:
- Pentium 100 or equivalent
processor
- Windows 95 (Windows
98 is preferred) or
Windows XP, Windows
NT and above (depends
on the type of modem)
- 32 MB RAM
- 2.1GB hard disk capacity
(20MB of free hard disk
space)
- LAN connection card
(NIC)
- CD ROM Drive (for
loading Home/SOHO Modem
Software)
Basic components:
- Telephone line - direct
line
- PC with network card
- ADSL Modems (usually
provided by ISP)
- Splitters (usually
provided by ISP)
- Microfilters (usually
provided by ISP)
- Hubs, Routers, Server
(for Networking purpose)
Definitions:
ATM Asynchronous
Transfer Mode
A high speed network protocol
composed of 53 byte cells
having 48 byte payloads.
Especially good for real
time voice and video.
DSL lines normally use
ATM as the underlying
data-transport protocol
beneath tcp/ip.
DSLAM Digital
Subscriber Line Access
Multiplexer
The device placed in the
CO that accepts all the
DSL lines.
PSTN Public
Switched Telephone Network
CO Central
Office
A circuit switch that
terminates all the access
lines in a particular
area; a physical building
where the local switching
equipment is found. xDSL
lines running from a subscriber's
home connect at their
local central office.
Connecting the wires:
- Telephone Socket to
POTS Splitter - RJ11
- POTS Splitter to Telephone
set - RJ11
- POTS Splitter to ADSL
Router- RJ11
- ADSL Router to Hub/Customer
PC - RJ45
This next diagram is
of a basic ADSL (a common
form of residential DSL)
in a home. The splitter
depicted here is a small
box that strips off the
phone signal from the
line from the Telco, and
leaves the data (indicated
by the red shaded lines),
to be routed to the data
equipment, on RJ11 (phone)
inside wires.
A DSL setup, with a filter
instead of a splitter,
allows the data and telco
voice signal to flow through
the house phone wires,
but filters it from the
telephone or fax machines.
Connecting remote
offices with broadband:
Norman, 2003
|
