A Beginner's Guide to the Internet/INTERNET.ISO/text/guides/info/whats_in.pap

Text File | 1996-05-06 | 26.7 KB | 489 lines

What is the Internet, Anyway?

John S. Quarterman
Smoot Carl-Mitchell
[e-mail]
Copyright (c) 1994  TIC

        From Matrix News, 4(8), August 1994
        Premission is hereby granted for redistribution of this article
        provided that it is redistributed in its entirety, including
        the copyright notice and this notice.
        Contact: [e-mail], [phone], fax: [phone].
        http://www.tic.com/mids, gopher://gopher.tic.com/11/matrix/news
        A shorter version of this article appeared in MicroTimes.

We often mention the Internet, and in the press you read about the
Internet as the prototype of the Information Highway; as a research
tool; as open for business; as not ready for prime time; as a place
your children might communicate with (pick one) a. strangers, b.
teachers, c. pornographers, d. other children, e. their parents; as
bigger than Poland; as smaller than Chicago; as a place to surf; as the
biggest hype since Woodstock; as a competitive business tool; as the
newest thing since sliced bread.

A recent New York Times article quoting one of us as to the current
size of the Internet has particularly stirred up quite a ruckus.  The
exact figures attributed to John in the article are not the ones we
recommended for such use, but the main point of contention is whether
the Internet is, as the gist of the article said, smaller than many
other estimates have said.  Clearly lots of people really want to
believe that the Internet is very large.  Succeeding discussion has
shown that some want to believe that so much that they want to count
computers and people that are probably *going to be* connected some
time in the future, even if they are not actually connected now.  We
prefer to talk about who is actually on the Internet and on other
networks now.  We'll get back to the sizes of the various networks
later, but for now let's discuss a more basic issue that is at the
heart of much confusion and contention about sizes: what is the
Internet, anyway?

Starting at the Center

For real confusion, start trying to get agreement on what is part of
the Internet:  NSFNET?  CIX?  Your company's internal network?
Prodigy?  FidoNet?  The mainframe in accounting?  Some people would
include all of the above, and perhaps even consider excluding anything
politically incorrect.  Others have cast doubts on each of the above.

Let's start some place almost everyone would agree is on the Internet.
Take RIPE, for example.  The acronym stands for European IP Networks.
RIPE is a coordinating group for IP networking in Europe.
(IP is the Internet protocol, which is the basis of the Internet.
IP has a suite of associated protocols, including the Transmission
Control Protocol, or TCP, and the name IP, or sometimes TCP/IP,
is often used to refer to the whole protocol suite.)
RIPE's computers are physically located in Amsterdam.
The important feature of RIPE for our purposes is that you can
reach RIPE (usually by using its domain, ripe.net)
from just about anywhere anyone would agree is on the Internet.

Reach it with what?  Well, just about any service anyone would agree is
related to the Internet.  RIPE has a WWW (World Wide Web) server, a
Gopher server, and an anonymous FTP server.  So they provide documents
and other resources by hypertext, menu browsing, and file retrieval.
Their personnel use client programs such as Mosaic and Lynx to access
other people's servers, too, so RIPE is a both distributor and a
consumer of resources via WWW, Gopher, and FTP.  They support TELNET
interfaces to some of their services, and of course they can TELNET out
and log in remotely anywhere they have personal login accounts or
someone else has an anonymous TELNET service such a library catalog
available.  They also have electronic mail, they run some mailing
lists, and some of their people read and post news articles to USENET
newsgroups.

WWW, Gopher, FTP, TELNET, mail, lists, and news:  that's a pretty
characteristic set of major Internet services.  There are many more
obscure Internet services, but it's pretty safe to say that an
organization like RIPE that is reachable with all these services is on
the Internet.

Reachable from where?  Russia first connected to the Internet in 1992.
For a while it was reachable from networks in the Commercial Internet
Exchange (CIX) and from various other networks, but not from NSFNET,
the U.S. National Science Foundation network.  At the time, some people
considered NSFNET so important that they didn't count Russia as
reachable because it wasn't accessible through NSFNET.  Since there are
now several other backbone networks in the U.S. as fast (T3 or 45Mbps)
as NSFNET, and routing through NSFNET isn't very restricted anymore,
few people would make that distinction anymore.  So for the moment
let's just say reachable through NSFNET or CIX networks, and get back
to services.

Looking at Firewalls

Many companies and other organizations run networks that are
deliberately firewalled so that their users can get to servers like
those at ripe.net, but nobody outside the company network can get to
company hosts.  A user of such a network can thus use WWW, Gopher, FTP,
and TELNET, but cannot supply resources through these protocols to
people outside the company.  Since a network that is owned and operated
by a company in support of its own operations is called an enterprise
network, let's call these networks enterprise IP networks, since they
typically use the Internet Protocol (IP) to support these services.
Some companies integrate their enterprise IP networks into the Internet
without firewalls, but most do use firewalls, and those are the ones
that are of interest here, since they're the ones with one-way access
to these Internet services.  Another name for an enterprise IP network,
with or without firewall, is an enterprise Internet.

For purposes of this distinction between suppliers and consumers, it
doesn't matter whether the hosts behind the firewall access servers
beyond the firewall by direct IP and TCP connections from their own IP
addresses, or whether they use proxy application gateways (such as
SOCKS) at the firewall.  In either case, they can use outside services,
but cannot supply them.

So for services such as WWW, Gopher, FTP, and TELNET, we can draw a
useful distinction between supplier or distributor computers such as
those at ripe.net and consumer computers such as those inside
firewalled enterprise IP networks.  It might seem more obvious to say
producer computers and consumer computers, since those would be more
clearly paired terms.  However, the information distributed by a
supplier computer isn't necessarily produced on that computer or within
its parent organization.  In fact, most of the information on the
bigger FTP archive servers is produced elsewhere.  So we choose to say
distributors and consumers.  Stores and shoppers would work about as
well, if you prefer.

Even more useful than discussing computers that actually are suppliers
or consumers right now may be a distinction between supplier-capable
computers (not firewalled) and consumer-capable computers
(firewalled).  This is because a computer that is not supplying
information right now may be capable of doing so as soon as someone
puts information on it and tells it to supply it.  That is, setting up
a WWW, Gopher, or FTP server isn't very difficult; much less difficult
than getting corporate permission to breach a firewall.  Similarly, a
computer may not be able to retrieve resources by WWW, Gopher, at the
moment, since client programs for those services usually don't come
with the computer or its basic software, but almost any computer can be
made capable of doing so by adding some software.  In both cases, once
you've got the basic IP network connection, adding capabilities for
specific services is relatively easy.

Let's call the non-firewalled computers the core Internet, and the core
plus the consumer-capable computers the consumer Internet.  Some people
have referred to these two categories as the Backbone Internet and the
Internet Web.  We find the already existing connotations of "Backbone"
and "Web" confusing, so we prefer core Internet and consumer Internet.

It's true that many companies with firewalls have one or two computers
carefully placed at the firewall so that they can serve resources.
Company employees may be able to place resources on these servers, but
they can't serve resources directly from their own computers.  It's
rather like having to reserve space on a single company delivery truck,
instead of owning one yourself.  If you're talking about companies,
yes, the company is thus fully on the core Internet, yet its users
aren't as fully on the Internet as users not behind a firewall.

If you're just interested in computers that can distribute information
(maybe you're selling server software), that's a much smaller Internet
than if you're interested in all the computers that can retrieve such
information for their users (maybe you have information you want to
distribute).  A few years ago it probably wouldn't have been hard to
get agreement that firewalled company networks were a different kind of
thing than the Internet itself.  Nowadays, firewalls have become so
popular that it's hard to find an enterprise IP network that is not
firewalled, and the total number of hosts on such consumer-capable
networks is probably almost as large as the number on the
supplier-capable core of the Internet.  So many people now like to
include these consumer-capable networks along with the supplier-capable
core when discussing the Internet.

Some people claim that you can't measure the number of consumer-capable
computers or users through measurements taken on the Internet itself.
Perhaps not, but you can get an idea of how many actual consumers there
are by simply counting accesses to selected servers and comparing the
results to other known facts about the accessing organizations.  And
there are other ways to get useful information about consumers on the
Internet, including asking them.

Mail, Lists, and News

But what about mail, lists, and news?  We carefully left those out of
the discussion of firewalls, because almost all the firewalled networks
do let these communications services in and out, so there's little
useful distinction between firewalled and non-firewalled networks on
the basis of these services.  That's because there's a big difference
between these communications services and the resource sharing (TELNET,
FTP) and resource discovery (Gopher, WWW) services that firewalls
usually filter.  The communications services are normally batch,
asynchronous, or store-and-forward.  These characterizations mean more
or less the same thing, so pick the one you like best.  The point is
that when you send mail, you compose a message and queue it for
delivery.  The actual delivery is a separate process; it may take
seconds or hours, but it is done after you finish composing the
message, and you normally do not have to wait for the message to be
delivered before doing something else.  It is not uncommon for a mail
system to batch up several messages to go through a single network link
or to the same destination and then deliver them all at once.  And mail
doesn't even necessarily go to its final destination in one hop;
repeated storing at an intermediate destination followed by forwarding
to another computer is common; thus the term store-and-forward.
Mailing lists are built on top of the same delivery mechanisms as
regular electronic mail.  USENET news uses somewhat different delivery
mechanisms, but ones that are also typically batch, asynchronous, and
store-and-forward.  Because it is delivered in this manner, a mail
message or a news article is much less likely to be a security problem
than a TELNET, FTP, Gopher, or WWW connection.  This is why firewalls
usually pass mail, lists, and news in both directions, but usually stop
incoming connections of those interactive protocols.

Because WWW, Gopher, TELNET, and FTP are basically interactive, you
need IP or something like it to support them.  Because mail, lists, and
news are asynchronous, you can support them with protocols that are not
interactive, such as UUCP and FidoNet.  In fact, there are whole
networks that do just that, called UUCP and FidoNet, among others.
These networks carry mail and news, but are not capable of supporting
TELNET, FTP, Gopher, or WWW.  We don't consider them part of the
Internet, since they lack the most distinctive and characteristic
services of the Internet.

Some people argue that networks such as FidoNet and UUCP should also be
counted as being part of the Internet, since electronic mail is the
most-used service even on the core, supplier-capable Internet.  They
further argue that the biggest benefit of the Internet is the community
of discussion it supports, and mail is enough to join that.  Well, if
mail is enough to be on the Internet, why is the Internet drawing such
attention from press and new users alike?  Mail has been around for
quite a while (1972 or 1973), but that's not what has made such an
impression on the public.  What has is the interactive services, and
interfaces to them such as Mosaic.  Asynchronous networks such as
FidoNet and UUCP don't support those interactive services, and are thus
not part of the Internet.  Besides, if being part of a community of
discussion was enough, we would have to also include anyone with a fax
machine or a telephone.  Recent events have demonstrated that all
readers of the New York Times would also have to be included.  With
edges so vague, what would be the point in calling anything the
Internet?  We choose to stick with a definition of the Internet as
requiring the interactive services.

Some people argue that anything that uses RFC-822 mail is therefore
using Internet mail and must be part of the Internet.  We find this
about as plausible as arguing that anybody who flies in a Boeing 737 is
using American equipment and is thus within the United States.
Besides, there are plenty of systems out there that use mail but not
RFC-822.

So what to call systems that can exchange mail, but aren't on the
Internet?  We say they are part of the Matrix, which is all computer
systems worldwide that can exchange electronic mail.  This term is
borrowed (with permission) from Bill Gibson, the science fiction
writer.

Other people refer to the Matrix as global E-mail.  That's accurate,
but is a description, rather than a name.  Some even call it the e-mail
Internet.  We find that term misleading, since if a system can only
exchange mail, we don't consider it part of the Internet.  Not to
mention not everything in the world defines itself in terms of the
Internet, or communicates through the Internet.  FidoNet and WWIVnet,
for example, have gateways between themselves that have nothing to do
with the Internet.  Referring to the Matrix as the Internet is rather
like referring to the United Kingdom as England.  You may call it
convenient shorthand; the Scots may disagree.

What about news?  Well, the set of all systems that exchange news
already has a name: USENET.  USENET is presumably a subset of the
Matrix, since it's hard to imagine a USENET node without mail, even
though USENET itself is news, not mail.  USENET is clearly not the same
thing as the Internet, since many (almost certainly most) Internet
nodes do not carry USENET news, and many USENET nodes are on other
networks, especially UUCP, FidoNet, and BITNET.

A few years ago it was popular in some corners of the press to attempt
to equate USENET and the Internet.  They're clearly not the same.
News, like mail, is an asynchronous, batch, store-and-forward service.
The distinguishing services of the Internet are interactive, not news.

Asynchronous Compared to Dialup

Please note that interactive vs. asynchronous isn't the same thing as
direct vs. dialup connections.  Dialup IP is still IP and can support
all the usual IP services.  It's true that for the more
bandwidth-intensive services such as WWW, you'll be a lot happier with
a *fast* dialup IP connection, but any dialup IP connection can support
WWW.  Some people call these on-demand IP connections, or part-time IP
access.  They're typically supported over SLIP, PPP, ISDN, or perhaps
even X.25.

It's also true that it's a lot easier to run a useful interactive
Internet supplier node if you're at least dialed up most of the time so
that consumers can reach your node, but you can run servers that are
accessible over any dialup IP connection whenever it's dialed up.  It's
true that some access providers handle low-end dialup IP connections
through a rotary of IP addresses, and that's not conducive to running
servers, since it's difficult for users to know how to reach them.  But
given a dedicated IP address, how long you stay dialed up is a matter
of degree more than of quality.  A IP connection that's up the great
majority of the time is often called a dedicated connection regardless
of whether it's established by dialing a modem or starting software
over a hardwired link.

It's possible to run UUCP over a dedicated IP connection, but it's
still UUCP, and still does not support interactive services.

Some people object to excluding the asynchronous networks from a
definition of the Internet just because they don't support the
interactive services.  The argument they make is that FTP, Gopher, and
WWW can be accessed through mail.  This is true, but it's hardly the
same, and hardly interactive in the same sense as using FTP, Gopher, or
WWW over an IP connection.  It's rather like saying a mail-order
catalog is the same as going to the store and buying an item on the
spot.  Besides, we've yet to see anyone log in remotely by mail.

Is IP Characteristic?

We further choose to define the Internet as being those networks that
use IP to permit users to use both the communication services and at
least TELNET and FTP among the interactive services we have listed.
This requirement for IP has been questioned by some on the basis that
there are now application gateways for other protocol suites such as
Novell Netware that permit use of such services.  This kind of
application gateway is actually nothing new, and is not yet
widespread.  We choose to think of such networks, at least for the
moment, as yet another layer of the onion, outside the core and
consumer layers of the Internet.

Others have objected to the use of IP as a defining characteristic of
the Internet because they think it's too technical.  Actually, we find
far fewer people confused about whether a software package or network
supports IP than about whether it's part of the Internet or not.

Some people point out that services like WWW, Gopher, FTP, TELNET,
etc.  could easily be implemented on top of other protocol suites.
This is true, and has been done.  However, people seem to forget to ask
why these services developed on top of IP in the first place.  There
seems to be something about IP and the Internet that is especially
conducive to the development of new protocols.  We make no apologies
about naming IP, because we think it is important.

There is also the question of IP to where?  If you have a UNIX shell
login account on a computer run by an Internet access provider, and
that system has IP access to the rest of the Internet, then you are an
Internet user.  However, you will not be able to use the full graphical
capabilities of protocols such as WWW, because the provider's system
cannot display on a bitmapped screen for you.  For that, you need IP to
your own computer with a bitmapped screen.  These are two different
degrees of Internet connectivity that are important to both end users
and marketers.  Some people refer to them as text-only interactive
access and graphical interactive access.  Some people have gone so far
as to say you have to have graphical capabilities to have a full
service Internet connection.  That may or may not be so, but in the
interests of keeping the major categories to a minimum, we are simply
going to note these degrees and say no more about them in this
article.  However, we agree that the distinction of graphical access is
becoming more important with the spread of WWW and Mosaic.

Conferencing Systems and Commercial Mail Systems

Conferencing systems such as Prodigy and CompuServe that support mail
and often something like news, plus database and services.  But most of
them do not support the characteristic interactive services that we
have listed.  The few that do (Delphi and AOL), we simply count as part
of the Internet.  The others, we count as part of the Matrix, since
they all exchange mail.

We find that users of conferencing systems have no particular
difficulty in distinguishing between the conferencing system they use
and the Internet.  CompuServe users, for example, refer to "Internet
mail", which is correct, since the only off-system mail CompuServe
supports is to the Internet, but they do not in general refer to
CompuServe as part of the Internet.

Similarly, users of the various commercial electronic mail networks,
such as MCI Mail and Sprint-Mail, seem to have no difficulty in
distinguishing between the mail network they use and the Internet.
Since they all seem to have their own addressing syntax, this is hardly
surprising.  We count these commercial mail networks as part of the
Matrix, but not part of the Internet.  Many of them have IP links to
the Internet, but they don't let their users use them, instead limiting
the services they carry to just mail.

Russian Dolls

So let's think of a series of nested Chinese boxes or Russian dolls;
the kind where inside Boris Yeltsin is Mikhail Gorbachov, inside
Gorbachov is Brezhnev, then Kruschev, Stalin, Lenin, and maybe even
Tsar Nicholas II.  Let's not talk about that many concentric layers,
though, rather just three: the Matrix on the outside, the consumer
Internet inside, and the core Internet inside that.

                 the core        the consumer    the Matrix
                 Internet        Internet

 interactive     supplier-       consumer-       by mail
 services        capable         capable

                 stores and      shoppers        mail
                 shoppers                        order

 asynchronous    yes             yes             yes services

Some people have argued that these categories are bad because they are
not mutually exclusive.  Well, we observe that in real life networks
have differing degrees of services, and the ones of most interest share
the least common denominator of electronic mail.  Thus concentric
categories are needed to describe the real world.  You can, however,
extract three mutually-exclusive categories by referring to the core
Internet, the interactive consumer-only part of the Internet, and to
asynchronous systems.

Other people have argued that these categories are not sequential.
They look sequential to us, since if you start with the core Internet
and move out, you subtract services, and if you start at the outside of
the Matrix and move in, you add services.

Outside the Matrix

In addition to computers and networks that fit these classifications,
there are also LANs, mainframes, and BBSes that don't exchange any
services with other networks or computers; not even mail.  These
systems are outside the Matrix.  For example, many companies have an
AppleTalk LAN in marketing, a Novell NetWare LAN in management, and a
mainframe in accounting that aren't connected to talk to anything
else.  In addition, there are a few large networks such as France's
Teletel (commonly known as Minitel) that support very large user
populations but don't communicate with anything else.  These are all
currently outside all our Chinese boxes of the core Internet, the
consumer Internet, and the Matrix.

DNS and Mail Addresses

There are other interesting network services that make a difference to
end users.  For example, DNS (Domain Name System) domain names such as
tic.com and domain addresses such [e-mail] can be set up for systems
outside the Internet.  We used tic.com when we only had a UUCP
connection, and few of our correspondents noticed any difference when
we added an IP connection (except our mail was faster).  This would be
more or less a box enclosing the consumer Internet and within the
Matrix.  But the other three boxes are arguably the most important.

Some people have claimed that anything that uses DNS addresses is part
of the Internet.  We note that DNS addresses can be used with the UUCP
network, which supports no interactive services, and we reject such an
equation.

It is interesting to note that over the years various attempts have
been made to equate the Internet with something else.  Until the
mid-1980s lots of people tried to say the Internet was the ARPANET.  In
the late 1980s many tried to say the Internet was NSFNET.  In the early
1990s many tried to say the Internet was USENET.  Now many are trying
to say the Internet is anything that can exchange mail.  We say the
Internet is the Internet, not the same as anything else.

Summary

So, here we have a simple set of categories for several of the
categories of network access people talk about most these days.  Any
such categories are at least somewhat a matter of opinion, and other
people will propose other categories and other names.  We like these
categories, because they fit our experience of what real users actually
perceive.

You'll notice we've avoided use of the words "connected" and
"reachable" because they mean different things to different people at
different times.  For either of them to be meaningful, you have to say
which services you are talking about.  To us, reachable usually means
pingable with ICMP ECHO, which is another way to define the core
Internet.  To others, reachable might mean you can send mail there,
which is another way to define the Matrix.

Once we have terms for networks of interest, we can talk about how big
those networks are.  We think the terms we have defined here refer to
groups of computers that people want to use, and that some people want
to measure.  Many marketers want to know about users.  Well, users of
mail are in the Matrix, and users of interactive services such as WWW
and FTP are in the Internet.  Other people are more interested in
suppliers or distributors of information.  Suppliers of information by
mail can be anywhere in the Matrix, but suppliers of information by WWW
or FTP are in the core Internet.  It is easy to define more and finer
degrees of distinctions of capabilities and connectivity, but these
three major categories handle the most important cases.

We invite our readers to tell us what distinctions they find important
about the various networks and their services.
..

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