DSL
TUTORIAL
Digital
Subscriber
Line
(DSL)
is
a
broadband
transmission
line
developed
for
use
with
existing
physical
(copper)
phone
line
runs.
DSL
was
developed
since
the
early
90's
but
was
never
brought
to
market
because
of
the
many
constraints
it involved
then
for
both
users
and
providers.
However,
technology
today
is
winning
the
battle
against
these
limitations.
DSL
is
being
successfully
deployed
more
and
more
everywhere
in
North
America
and
the
world.
DSL
requires
excellent
structured
phone
wiring
in
the
residential
environment
if
part
of
it
is
to
be
used
for
your
premise
DSL
equipments.
It
surely
requires
the
physical
copper
lines
from
the
Central
Office
to
the
home
to
be
in
optimum
conditions.
DSL
requires
a
maximum
of
3.5
miles
of
copper
wire
runs
between
the
home
and
the
providing
Telephone
Central
Office
(CO).
It
might
not
work
well
for
you
even
if
you
are
at
about
2.5
miles
to
the
CO.
At
that
distance
the
bit
rate
drop
might
be
significant
and
performance
fairly
inconsistent.
Therefore,
in
a
word,
you
might
not
be
eligible
for
DSL
for
the
time
being.
At
this
time,
however,
various
CO
equipment
providers
are
delivering
to
Telcos
DSL
equipments
that
increase
the
loop
threshold
beyond
3.5
miles
or
otherwise
significantly
improve
data
rate
past
2.5
miles!
DSL
provides
simultaneous
voice
and
data
transmission
over
the
twisted
pair.
However
the
voice
network
provider
and
the
data
network
provider
are
not
necessarily
the
same.
If
you
order
DSL
from
an
ISP,
the
ISP
will
contact
and
contract
with
your
local
telephone
company
to
install
DSL
equipments
at
your
termination
at
the
Central
Office
and
inside
your
premises
as
well.
Your
local
telephone
company
will
send
out
a
field
technician
to
run
end-to-end
tests
on
your
physical
copper
phone
line
to
determine
its
suitability
for
DSL.
If
your
phone
line
complies
to
the
distance
limitation
and
is
yet
determined
not
to
be
suitable
for
DSL,
it
will
be
replaced
by
a
new
twisted
pair
at
no
extra
cost.
No
one
can
guarantee
at
which
exact
bit
rate
your
DSL
line
will
perform.
While
it
will
certainly
be
much
higher
than
the
56
Kb/s
of
a
dial-up
modem
by
multiple
folds,
it
might
not
reach
the
nominal
rate
of
your
DSL
line
type.
ADSL,
which
is
the
DSL
type
for
the
residential
environment,
runs
at
148
Kb/s
from
your
computer
to
the
public
network
and
768
Kb/s
from
the
network
to
your
computer.
Higher
bit
rates
and
symmetric
DSL
(SDSL:
same
high
rate
in
both
directions)
are
available
depending
on
your
needs.
It
might
take
weeks
to
complete
the
installation
of
your
new
DSL
line.
The
phone
technician
might
install
a
splitter
at
the
demarcation
point
of
your
phone
wiring,
dividing
your
inside
home
wiring
network
into
two
main
branches.
One
branch
for
all
your
voice
and
dial-up
equipments
and
one
other
for
your
DSL
connection.
This
creates
what
is
called
a
splittered
environment.
The
splitterless
environment,
by
which
DSL
is
delivered
in
full
at
every
single
home
phone
jack
with
the
dial
tone,
is
however
becoming
very
popular.
In
a
splittered
environment,
at
the
far
end
of
the
DSL
branch,
which
will
be
wired
by
the
phone
technician
to
the
location
you
indicate,
a
phone
jack
will
be
made
available
for
plugging
in
your
DSL
modem.
In
a
splitterless
environment,
DSL
will
be
available
at
all
the
home
phone
jacks
and
you
will
need
to
use
a
filter
at
the
jacks
to
prevent
mutual
interference
between
the
phones
and
the
DSL
carrier
frequency.
(The
late
multi-line
intercom
phones
denominated
KSU-less
phones
are
completely
incompatible
with
DSL
splitterless
environments
and
may
still
malfunction
in
a
splittered
environment.
For
DSL-compatible
phone
systems,
see
here.)
You
will
have
to
configure
the
network
connections
of
your
system
platform
in
order
to
enable
it
for
DSL.
If
you
have
more
than
one
desktop
computer
at
home,
you
will
certainly
need
10BaseT
or
100BaseT
networking
for
your
additional
computers
to
ride
the
Internet
over
your
DSL
connection.
Some
providers
have
introduced
a
Do-it-Yourself
kit
that
would
allow
the
users
to
do
the
required
inside
wiring
by
themselves,
and
so
cut
the
installation
time.
The
better
you
understand
structured
telephone
wiring,
the
better
you
may
help
yourself
with
this
kit.
User
feedback?
A
few
are
angry,
many
satisfied
and
many
more
happy.
DSL
technology
is
in
its
infancy,
compulsive
developments
being
underway
to
hastily
improve
it.
New
developments
that
defeat
inherent
constraints
are
now
hitting
the
market.
Some
cable
modem
users
are
not
happy
either
about
having
to
share
bandwidth
with
lots
of
neighbors
(meaning
lower
speed
for
each
user),
or
getting
frequently
disconnected
from
the
network,
and
at
times
for
over
30
minutes!
Also
difficult
to
get
in
many
older,
urban
buildings!
Further,
with
cable
modem,
you
can't
straightforwardly
share
your
internet
connection
with
multiple
home
computers!
more...>>
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