ROADMAP FILE: NET INTRO


     "Civilization advances by extending the number of important
      operations which we can perform without thinking about them."
      -- Alfred North Whitehead, An Introduction to Mathematics


Ask a computer scientist what the Internet is and you are likely to
hear something about "transmission control protocols," "Internet
protocols," "T1" lines, and some organization called ARPA (which
changed its name to DARPA but then got nostalgic and changed its
name back to ARPA).

That's all fine and dandy -- and, in fact, all quite accurate --
but that's probably not going to be helpful for someone new to the
Internet.

The Internet is set up a lot like the United States' Interstate
highway system. In fact, both the Internet and the Interstate were
designed for the same basic purpose: to enable and to secure the
flow of "stuff" ... military stuff.

The military needs two things to survive: supplies and intellegence.
In the 1950's, the United States undertook a massive building campaign
to link all of the major cites in the United States with high speed,
limited-access highways. The main purpose for these highways was to
give the military the ability to quickly reinforce any military front
in case the United States was ever invaded.

The Interstate highway system, in it's concept, is brilliant. Because
all of the major cites are linked together, if one highway -- or, for
that matter, if one entire city -- is destroyed, it has no effect on
the overall flow of supplies. The supplies are just diverted around
the destroyed highway (or city).

Also, as long as we are talking about the military, what is the first
thing that the military attacks in a war? The opponent's headquarters!
Where is the headquarters of the United States' Interstate highway
system? It doesn't have one!

So, the Interstate highway system is a way to ensure safe transport of
supplies and troops, with unlimited alternate routes in case of an attack,
and with no centralized control or headquarters.

That takes care of the supplies. Now its time to secure the intellegence.

In the late 1960s, the Military was looking for a way to link all
of the mainframe computers in the United States. The military wanted
a system that could ensure safe transport of the data shipped between
the different mainframes, that had unlimited alternate routes in case
of an attack (especially a nuclear attack), and that had no centralized
control or headquarters. Gee ... where have we seen THAT before?

In 1969, the Department of Defense Advanced Research Projects Agency
(ARPA) connected four mainframes -- at Stanford Research Institute, the
University of California at Los Angeles, the University of California
at Santa Barbara, and the University of Utah -- at a cost of one
million dollars (US, 1969). ARPA called the network connecting these
four sites the "ARPANet," and the network grew by leaps and bounds.
The ARPANet eventually linked to MilNet, and these two networks
grew into today's Internet. (Actually, it would be more accurate
to say that ARPANet was partitioned into the smaller, research-only
oriented ARPANet, and the larger production MilNet (1)).

Computer scientists often say that the Internet is a "network of
networks." They're right, and here is what they mean:

Your house (or apartment) is connected to a local network of roads
that allow you to drive around and do things inside your city.
If you live in the United States, your local network of roads
is connected to a system of state roads that allow you to drive to
another city inside your state and do things inside that other city.
Your state's network of roads is connected to other states' networks
of roads, allowing you to drive to another city in another state and
do things in that city. So, you have a local network of roads which
is connected to a state network of roads, and the state network
of roads is connected into a national network of roads (gee, this
is starting to sound like a civics lesson).

The Internet is set up the same way! Your local system of "roads" --
the wires that connect you and everyone else to your server --
is called a "Local Area Network" (or LAN). Your Local Area Network
is connected to a whole bunch of other Local Area Networks, creating
a big network. This network is then connected to other big networks,
creating the Internet ("a network of networks").

Remember earlier when we said that the military wanted a system that
could ensure safe transport of the data shipped between the mainframes,
and that had unlimited alternate routes? How can you make sure that the
route that something is going to follow over the Internet is safe?
If the "enemy" knows the route that something is going to follow,
doesn't it make sense for the enemy to destroy that route?

The Internet solves this problem by letting letters and other
"packets" sent over the Internet follow a completely random route.
In real life (sometimes abbreviated "IRL"), the shortest distance
between two neighboring cities is a straight line. In virtual life
("IVL"), the shortest distance between two neighboring cites is
irrelevant. An e-mail letter sent from Dallas to Fort Worth could
quite possibly be routed through Tibet!

This brings up two final questions (and knowing the answers to
these two questions will mean that you know more about the Internet
than over 90% of the people on the planet). First, considering that
traffic on the Internet follows a completely random route, is
communication over the Internet instantaneous? The answer is no. It
is quite possible for e-mail (and other things) sent over the Internet
to take hours, and sometimes even DAYS, to reach its final destination).

Second, is the Internet now -- or has is ever been -- "free?"
The answer to that question is also no. Remember how much money
it cost to build the ARPANet? That money came from the taxpayers of
the United States of America.

But what if you have an Internet account, and it doesn't cost
you anything? Isn't that account "free?" No, it isn't. If you
have a "free" account on the Internet, it is because someone --
usually your college or employer -- has paid a heck of a lot of
money to connect to the Internet, and is kind enough not to
pass the costs on to you (at least not directly).

So, that's the Internet. Its set up like the U.S. Interstate highway
system, with a whole bunch of LANs connected into networks and
those networks connected to other networks. Communication on the
Internet is not instantaneous, and the Internet has NEVER been "free."


SOURCES:

(1) from Rich Zellich, founder of the Lists-of Lists, and self-proclaimed
    ARPANet denizen from 15+ years ago; in a letter to Patrick Crispen
    dated 8 Oct 94


   PATRICK DOUGLAS CRISPEN    THE VIEWS EXPRESSED IN THIS LETTER DO NOT
    PCRISPE1@UA1VM.UA.EDU      NECESSARILY REPRESENT THE VIEWS OF THE
  THE UNIVERSITY OF ALABAMA      UNIVERSITY OF ALABAMA - TUSCALOOSA

      ROADMAP: COPYRIGHT PATRICK CRISPEN 1994. ALL RIGHTS RESERVED.