Some history of Cable v. DSL. Skip if you don't want to know.
DSL delivers high speed communications over a plain old twisted pair of
wires. Since the telcos have this stuff installed in nearly every home
they like selling you DSL service. The main problem is distance
limitations. That wire pair has to go all the way from your house to the
central office (CO) for your town/community. For voice it was no big
deal if that distance was large, they could just crank up the
power/frequency a bit but for DSL more power/frequency meant more
interference and cross-talk between the different pairs in the same
bundle of wire. This is why you can generally get faster DSL if you're
close to the central office and slower or no service if you are far
away. DSL has a number of variants and they have differing
distance/throughput limitations. Verizon's ADSL (Asymetric DSL, faster
one direction than the other) used to only make it 12000 feet (3.7km)
from the CO but as they technology improved they've bumped it up to
18000 (5.4km). Meanwhile IDSL uses the old ISDN lines (a whole other
topic) to reach out to 27000 feet (8.2km) but at fairly slow data rates
(128kbps). Still better than dialup. Even then some rural areas are too
far away since the distances are by the length of wire. If your
connection zigs and zags following streets you could still be too far
away for service or have to accept a slower or more expensive service.
All the DSL lines come back to the CO into something called a Digital
Subscriber Line Access Multiplexer or DSLAM which is shared amongst a
bunch of users. So in the end, you don't really get all the bandwidth
dedicated to you, you share it with the other DSLAM users.
Cable uses coaxial cables that were built for broadband television
signals to deliver broadband data signals. Because these cables were
designed for this purpose they are shielded and can handle high
frequencies and power with causing issues. I'm not as familiar with the
backend of cable but generally they don't have the distance degradation
issues that DSL has. Either you can get service or you can't. All the
cable users connect to a concentrator in the community and that
concentrator is connected to the cable head end via a number of possible
technologies. Some use fibre optics and some use hardline (sort of a
waveguide) to take the fat signal back and forth. The main advantage
cable has is a design intended for high bandwidth. DSL is kind of a hack
but coax was meant to handle broadband. This is probably why the telcos
are rolling out fibre to the home like Verizon's FIOS. DSL was a stopgap
to buy time to roll out a real broadband solution. It was still better
than dialup but can't compete with what coax can deliver. The new DOCSIS
3 cable modem standard is to bond 4 6Mhz channels together to deliver up
to 160MBps downstream so the telcos need to get their fibre delivery
platform lit up soon.
CB
Scott Howell wrote:
Well cable and ADSL are two Different things here in the U.S. Cable is
provided by a cable company such as Comcast and ADSL or DSL is
provided by a company like Verizon. The issue may actually be tied to
the use of PPPOE which is PPP over Eathernet. I don't remember all the
technical details, but I believe it has something to do with the way
you connect to the provider's system. I think and someone correct me
if I'm way wrong, but PPPOE is sort of like connecting using dial-up,
but at of course DSL speeds. Maybe a more accurate way to explain it
is the way the connection is negociated.
You shouldn't be having that many issues per day and if you can safely
clear any issues locally, I'd contact the provider and have them check
things out.
On Aug 19, 2008, at 5:42 AM, will lomas wrote:
maybe a couple of times per day
I have cable or ADSl as the americans call it I think, smile. It is
strange how we get 4 of 4 bars (I do in my case anyway) but no
connection
I am pleased it is not my mac.
Incidentally as I have the new card in my macbook supporting N, can I
find out what my wireless network uses like a, b g or n and its speed
at all?
Thanks Will
On 19 Aug 2008, at 10:07, Scott Howell wrote:
I suspect that is your issue. I've seen that happen here. I don't
know if you have ADSL, but that's what I have here and I setup my
AirPort to stay connected all the time and that could possibly have
something to do with it, but not overly sure at this point. How
often does this happen?
On Aug 19, 2008, at 2:38 AM, will lomas wrote:
Hi to all
I don't know if this is an airport issue on my mac but sometimes I
get 4 of 4 bars, but no connection to the internet?
could it be my ISP having problems?
will
Scott Howell
[EMAIL PROTECTED]
Scott Howell
[EMAIL PROTECTED]
