chapt 2
Some followup to the discussion so far:
> Thank you, Sandy, for your timely answer. But, I just start to learn something
> in ADSL and I don't quite get some of your answers.
>
> 1)
> >Sometimes I think it is pointless to debate the merits of the competing
> >technologies, because I think what really counts is - how is the technology
> >being used? When you try to answer this question, you leave the technical
> >arena and venture into the business and marketing arena.
>
> Sometimes I think whether a technology has a bright future does not depend
> on the technology itself, instead, it depends on what the customers need
> and if the technology fits the market. From my beginner's understanding,
> both ADSL and cable modems are trying to provide all the services, including
> internet service, television service, video conference service, and so on.
> It seems to me that whoever wins the technology will win the market. Put it
> in another way, whoever loses the market will die out. For example, if ADSL
> can finally beat cable modem, why would the customers waste their money in
> getting the cable modem since ADSL can provide all the services cable modem
> can provide? As long as the price is concerned, I think if the technology
> is attractive enough, many people will start to work on it and will speed up
> the development of the technology and as a result, will cut the price.
The price of the product/service, and the way in which it is marketed/sold, have a
very large impact, especially in consumer markets, compared to the quality of the
technology. For example, consider the Beta vs VHS videotape wars. Beta produced
better pictures, but VHS won out in a pure marketing and pricing battle.
Which product family (technology, if you will) ultimately wins will be far more
driven by how effectively the products are sold, and how aggressive (read, how
much money the early sellers are willing to invest!) the early sellers are. Cable
modems are way ahead in the residential market right now, both in numbers
installed, and in lower cost to the consumer. Some people's crystal balls show
cable modems continuing to do very well in the residential market, as long as the
cable companies continue to invest in making their cable plants two-way.
In the business market, cable modems seem almost non-existent. Why? I've
forgotten who said it first on this list, but cable doesn't go to any business but
bars and bowling alleys (and stock brokers desks). Yeah, sure, the cable
company's fiber goes down the street nearby, but it takes an awfully big truck
(with backhoe) roll to get the bandwidth into the office building. Once fiber is
into the building, there will be a number of choices for getting bits to customers
- cable modems will likely play little role here.
But for businesses not served by fiber, DSL will likely do very well - every
business has phone wires, so DSL will be the solution of choice for everyone who
doesn't want/can't afford T-1 (or wireless or satellite or ballon-in-the-sky or
what ever else Jim S has in his lab :-).
So, we have some forces that would show both cable modems and DSL competing for
years to come with no clear outcome. Nor is there any reason that a customer
would need to make a long-term choice. I bought a new modem every year or two for
the last ten. I currently have cable modem, but I don't see that having much
impact on what my network access is next year - let the best service win!
>
>
> 2)
> >The cable modem network architecture is very similar to ethernet. So, if you
> >and a neighbor are all downstream of the same headend, your neighbor may have
> >access to your computer, if you have allowed any shared resources.
>
> Thank you for your answer. I don't know the detailed technology in cable
> modem, but I guess it's kind of broadcasting the information? If cable
> modem is providing internet service and many people are doing on-line
> shopping and on-line investing right now, how can people use cable modem
> without worrying about credit card or other personal information being
> stolen? Why are there so many people using cable modems if it is insecure?
The insecurity of cable comes from some cable operators not setting up their
internet routers correctly. With cable, it doesn't really operate quite like a
LAN (where all stations see every packet), since all traffic from subscribers goes
only "uplink" on the uplink frequency to the head end. A non-clever (OK,
clueless) implementation at the headend would send every "up" packet, or perhaps
the broadcast packets, back down to the other subscribers. This is the opening
your neighbor needs to use, for example, Win95 file sharing to "see" your PC. If
you turn off file sharing and other servers, or install a firewall, you disk is
safe. By the way, PC's an DSL networks are subject to pretty much the same
security attacks, except for the broadcast bit.
Yes, a sufficiently clever hacker could re-design or modify a cable modem and see
addiitonal traffic, but this seems to me the same risk as that hacker illegally
tapping your DSL line - protect yourself as best you can, but don't go off the
paranoid deep end.
>
>
> 3)
> >Load coils reduce loop qualification. So do DLCs, bridge taps, bad copper,
> >and excessive loop lengths. In order to correct line problems, phone
> >companies have to send out a truck and technicians. Therefore, the problem
> >is that correcting the problems leads to a much higher installation cost per
> >customer. Phone companies want to reduce the cost of installation, not
> >increase it.
>
> Maybe they can find a way to bypass the load coils? I guess I need to turn
> to my books to learn about knowledge on other stuff.
>
> Thank you very much for your time and your explanation, Sandy.
You're welcome.
George Marshall OnPrem Networks |
