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Re: [PLUG] Re: Verizon DSL
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> Date: Fri, 7 Jun 2002 12:04:48 -0400
> From: gabriel rosenkoetter <gr@eclipsed.net>
>
> On Fri, Jun 07, 2002 at 10:19:40AM -0400, Jon Galt wrote:
> > This is what I don't get. What does this "access" consist of? Clearly
> > there has to be more than simply a physical wire. I understand that, but
> > *what* do I get from the ISP? Surely one could say "everything else
> > besides the physical wire", but that wouldn't tell me what I want to know.
>
> Wayne, you really need to step back and understand how TCP/IP
> networks work. There are many good books on this, many probably at
> your local library. (Anything that gets used as a text for a
> computer networking class will do).
>
That's only part of it. The real issue is the "business model" here.
You have to understand the way in which the "Internet" works, not simply
TCP/IP networks. The reality is much, much more complicated than most
people realize -- especially anyone who simiply calls it the "world wide
web"... argh!!!
The Internet, as such, simply does not exist.
The Key thing to remember about the Internet is its definition.... It is a
network of networks.
The organizational structure of the Internet is no different than that of
what everyone calls POTS (Plain Old Telephone Service). In fact the two are
virtually identical, especially at the physical level.
You also have to realize that there are two Verizons -- Verizon the
Regulated RBOC (Regional Bell Operating Company) and Verizon the
Unregulated competitive ISP. That they both use the same name simply adds
to the confusion.
The thing which is throwing everybody a curve ball is AOL. You have to
understand how AOL has worked all these years to understand the business
model many ISPs use.
AOL provides the model which the Cable Industry is following. NEITHER
offers "direct" connection to the Internet. They offer you a connection to
"their network" (which is really nothing more than a classic old-time,
multi-user, time-sharing system). All of your packets go through their
equipment exclusively -- their cacheing servers, their mail servers,
etc. Only if you force your way through (like with a telnet/ssh connection)
do you finally get through their "gateway" into the Internet at large.
AOL and @comcast ISPs just like DCAnet or Speakeasy. The difference is
that with DCAnet, and any other vendor where you can get static IP
addresses, you become a PEER on the Internet. Your system trully does
become part of the Internet. It's accessable from anywhere in the world for
any reason by anyone. There are no filters or virus traps or any kind of
anti-hacking controls on your conection -- it's up to you to provide such
things yourself. With AOL or Comcast or VERIZON the ISP, you are NOT a peer
on the Internet, all of your traffic is filtered in some way by the ISP.
[I'm oversimplifying here, but without going into seriously ugly
discussions about routing and the like, this is close enough to get the
idea across... there ARE differences in ISPs.]
> Your phone line connects you only to a punch-down block (well, a
> more modern equivalent, since it's all digital these days) at your
> phone company's nearest CO.
Actually, no. The line from your home to the CO is NOT Digital. It really
is still analog, and will continue to be analog into the forseeable future.
If it really were a digital line, you would not be able to use an analog
modem (ie dial-up) on that line. That's why in may hotels you can't use
your modem -- they DO have a digital PBX.
The line from your home to the CO is normally a "dry-copper" pair. If you
live in an apartment building or development, you may have a "green box."
in which case, the line is analog from your wall jack to that "green box,"
where it is multiplexed together with "everybody else" onto a "T-circuit"
and shipped back to the CO.
But analog is why you can have DSL service. DSL was developed as a
technique for providing digital service over an analog line. Similarly,
until they put the DSLAM in the "green box" at the curb, instead of at the
CO, people in many appartment buildings and developments can't get DSL
because they do have T-service into that "green box."
And you though you asked a simple question....!!!
In short, the ISP is exactly what the name implies, your "Internet Service
Provider." DSL or ISDN or ATM has nothing to do with anything but the
physical layer - "the wire." It's up to the ISP to do something with the
bits which appear "on the wire," to assemble them into meaningful packets,
and "route" them someplace.
--
T.T.F.N.
William H. Magill Senior Systems Administrator
Information Services and Computing (ISC) Networking & Telecommunications
University of Pennsylvania
magill@isc.upenn.edu magill@acm.org
http://www.isc-net.upenn.edu/~magill/ magill@mcgillsoceity.org
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