Network Working Group E. Krol
Request for Comments: 1462 University of Illinois
FYI: 20 E. Hoffman
Merit Network, Inc.
May 1993
FYI on "What is the Internet?"
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard. Distribution of this memo is
unlimited.
Abstract
This FYI RFC answers the question, "What is the Internet?" and is
produced by the User Services Working Group of the Internet
Engineering Task Force (IETF). Containing a modified chapter from Ed
Krol's 1992 book, "The Whole Internet User's Guide and Catalog," the
paper covers the Internet's definition, history, administration,
protocols, financing, and current issues such as growth,
commercialization, and privatization.
Introduction
A commonly asked question is "What is the Internet?" The reason such
a question gets asked so often is because there's no agreed upon
answer that neatly sums up the Internet. The Internet can be thought
about in relation to its common protocols, as a physical collection
of routers and circuits, as a set of shared resources, or even as an
attitude about interconnecting and intercommunication. Some common
definitions given in the past include:
* a network of networks based on the TCP/IP protocols,
* a community of people who use and develop those networks,
* a collection of resources that can be reached from those
networks.
Today's Internet is a global resource connecting millions of users
that began as an experiment over 20 years ago by the U.S. Department
of Defense. While the networks that make up the Internet are based on
a standard set of protocols (a mutually agreed upon method of
communication between parties), the Internet also has gateways to
networks and services that are based on other protocols.
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To help answer the question more completely, the rest of this paper
contains an updated second chapter from "The Whole Internet User's
Guide and Catalog" by Ed Krol (1992) that gives a more thorough
explanation. (The excerpt is published through the gracious
permission of the publisher, O'Reilly & Associates, Inc.)
The Internet (excerpt from "The Whole Internet User's Guide and
Catalog")
The Internet was born about 20 years ago, trying to connect together
a U.S. Defense Department network called the ARPAnet and various
other radio and satellite networks. The ARPAnet was an experimental
network designed to support military research--in particular,
research about how to build networks that could withstand partial
outages (like bomb attacks) and still function. (Think about this
when I describe how the network works; it may give you some insight
into the design of the Internet.) In the ARPAnet model, communication
always occurs between a source and a destination computer. The
network itself is assumed to be unreliable; any portion of the
network could disappear at any moment (pick your favorite
catastrophe--these days backhoes cutting cables are more of a threat
than bombs). It was designed to require the minimum of information
from the computer clients. To send a message on the network, a
computer only had to put its data in an envelope, called an Internet
Protocol (IP) packet, and "address" the packets correctly. The
communicating computers--not the network itself--were also given the
responsibility to ensure that the communication was accomplished. The
philosophy was that every computer on the network could talk, as a
peer, with any other computer.
These decisions may sound odd, like the assumption of an "unreliable"
network, but history has proven that most of them were reasonably
correct. Although the Organization for International Standardization
(ISO) was spending years designing the ultimate standard for computer
networking, people could not wait. Internet developers in the US, UK
and Scandinavia, responding to market pressures, began to put their
IP software on every conceivable type of computer. It became the only
practical method for computers from different manufacturers to
communicate. This was attractive to the government and universities,
which didn't have policies saying that all computers must be bought
from the same vendor. Everyone bought whichever computer they liked,
and expected the computers to work together over the network.
At about the same time as the Internet was coming into being,
Ethernet local area networks ("LANs") were developed. This technology
matured quietly, until desktop workstations became available around
1983. Most of these workstations came with Berkeley UNIX, which
included IP networking software. This created a new demand: rather
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than connecting to a single large timesharing computer per site,
organizations wanted to connect the ARPAnet to their entire local
network. This would allow all the computers on that LAN to access
ARPAnet facilities. About the same time, other organizations started
building their own networks using the same communications protocols
as the ARPAnet: namely, IP and its relatives. It became obvious that
if these networks could talk together, users on one network could
communicate with those on another; everyone would benefit.
One of the most important of these newer networks was the NSFNET,
commissioned by the National Science Foundation (NSF), an agency of
the U.S. government. In the late 80's the NSF created five
supercomputer centers. Up to this point, the world's fastest
computers had only been available to weapons developers and a few
researchers from very large corporations. By creating supercomputer
centers, the NSF was making these resources available for any
scholarly research. Only five centers were created because they were
so expensive--so they had to be shared. This created a communications
problem: they needed a way to connect their centers together and to
allow the clients of these centers to access them. At first, the NSF
tried to use the ARPAnet for communications, but this strategy failed
because of bureaucracy and staffing problems.
In response, NSF decided to build its own network, based on the
ARPAnet's IP technology. It connected the centers with 56,000 bit per
second (56k bps) telephone lines. (This is roughly the ability to
transfer two full typewritten pages per second. That's slow by
modern standards, but was reasonably fast in the mid 80's.) It was
obvious, however, that if they tried to connect every university
directly to a supercomputing center, they would go broke. You pay for
these telephone lines by the mile. One line per campus with a
supercomputing center at the hub, like spokes on a bike wheel, adds
up to lots of miles of phone lines. Therefore, they decided to create
regional networks. In each area of the country, schools would be
connected to their nearest neighbor. Each chain was connected to a
supercomputer center at one point and the centers were connected
together. With this configuration, any computer could eventually
communicate with any other by forwarding the conversation through its
neighbors.
This solution was successful--and, like any successful solution, a
time came when it no longer worked. Sharing supercomputers also
allowed the connected sites to share a lot of other things not
related to the centers. Suddenly these schools had a world of data
and collaborators at their fingertips. The network's traffic
increased until, eventually, the computers controlling the network
and the telephone lines connecting them were overloaded. In 1987, a
contract to manage and upgrade the network was awarded to Merit
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Network Inc., which ran Michigan's educational network, in
partnership with IBM and MCI. The old network was replaced with
faster telephone lines (by a factor of 20), with faster computers to
control it.
The process of running out of horsepower and getting bigger engines
and better roads continues to this day. Unlike changes to the highway
system, however, most of these changes aren't noticed by the people
trying to use the Internet to do real work. You won't go to your
office, log in to your computer, and find a message saying that the
Internet will be inaccessible for the next six months because of
improvements. Perhaps even more important: the process of running out
of capacity and improving the network has created a technology that's
extremely mature and practical. The ideas have been tested; problems
have appeared, and problems have been solved.
For our purposes, the most important aspect of the NSF's networking
effort is that it allowed everyone to access the network. Up to that
point, Internet access had been available only to researchers in
computer science, government employees, and government contractors.
The NSF promoted universal educational access by funding campus
connections only if the campus had a plan to spread the access
around. So everyone attending a four year college could become an
Internet user.
The demand keeps growing. Now that most four-year colleges are
connected, people are trying to get secondary and primary schools
connected. People who have graduated from college know what the
Internet is good for, and talk their employers into connecting
corporations. All this activity points to continued growth,
networking problems to solve, evolving technologies, and job security
for networkers.
What Makes Up the Internet?
What comprises the Internet is a difficult question; the answer
changes over time. Five years ago the answer would have been easy:
"All the networks, using the IP protocol, which cooperate to form a
seamless network for their collective users." This would include
various federal networks, a set of regional networks, campus
networks, and some foreign networks.
More recently, some non-IP-based networks saw that the Internet was
good. They wanted to provide its services to their clientele. So they
developed methods of connecting these "strange" networks (e.g.,
Bitnet, DECnets, etc.) to the Internet. At first these connections,
called "gateways", merely served to transfer electronic mail between
the two networks. Some, however, have grown to translate other
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services between the networks as well. Are they part of the Internet?
Maybe yes and maybe no. It depends on whether, in their hearts, they
want to be. If this sounds strange, read on--it gets stranger.
Who Governs the Internet?
In many ways the Internet is like a church: it has its council of
elders, every member has an opinion about how things should work, and
you can either take part or not. It's your choice. The Internet has
no president, chief operating officer, or Pope. The constituent
networks may have presidents and CEO's, but that's a different issue;
there's no single authority figure for the Internet as a whole.
The ultimate authority for where the Internet is going rests with the
Internet Society, or ISOC. ISOC is a voluntary membership
organization whose purpose is to promote global information exchange
through Internet technology. (If you'd like more information, or if
you would like to join, contact information is provided in the "For
More Information" section, near the end of this document.) It
appoints a council of elders, which has responsibility for the
technical management and direction of the Internet.
The council of elders is a group of invited volunteers called the
Internet Architecture Board, or the IAB. The IAB meets regularly to
"bless" standards and allocate resources, like addresses. The
Internet works because there are standard ways for computers and
software applications to talk to each other. This allows computers
from different vendors to communicate without problems. It's not an
IBM-only or Sun-only or Macintosh-only network. The IAB is
responsible for these standards; it decides when a standard is
necessary, and what the standard should be. When a standard is
required, it considers the problem, adopts a standard, and announces
it via the network. (You were expecting stone tablets?) The IAB also
keeps track of various numbers (and other things) that must remain
unique. For example, each computer on the Internet has a unique 32-
bit address; no other computer has the same address. How does this
address get assigned? The IAB worries about these kinds of problems.
It doesn't actually assign the addresses, but it makes the rules
about how to assign addresses.
As in a church, everyone has opinions about how things ought to run.
Internet users express their opinions through meetings of the
Internet Engineering Task Force (IETF). The IETF is another volunteer
organization; it meets regularly to discuss operational and near-term
technical problems of the Internet. When it considers a problem
important enough to merit concern, the IETF sets up a "working group"
for further investigation. (In practice, "important enough" usually
means that there are enough people to volunteer for the working
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group.) Anyone can attend IETF meetings and be on working groups; the
important thing is that they work. Working groups have many different
functions, ranging from producing documentation, to deciding how
networks should cooperate when problems occur, to changing the
meaning of the bits in some kind of packet. A working group usually
produces a report. Depending on the kind of recommendation, it could
just be documentation and made available to anyone wanting it, it
could be accepted voluntarily as a good idea which people follow, or
it could be sent to the IAB to be declared a standard.
If you go to a church and accept its teachings and philosophy, you
are accepted by it, and receive the benefits. If you don't like it,
you can leave. The church is still there, and you get none of the
benefits. Such is the Internet. If a network accepts the teachings of
the Internet, is connected to it, and considers itself part of it,
then it is part of the Internet. It will find things it doesn't like
and can address those concerns through the IETF. Some concerns may be
considered valid and the Internet may change accordingly. Some of
the changes may run counter to the religion, and be rejected. If the
network does something that causes damage to the Internet, it could
be excommunicated until it mends its evil ways.
Who Pays for It?
The old rule for when things are confusing is "follow the money."
Well, this won't help you to understand the Internet. No one pays for
"it"; there is no Internet, Inc. that collects fees from all Internet
networks or users. Instead, everyone pays for their part. The NSF
pays for NSFNET. NASA pays for the NASA Science Internet. Networks
get together and decide how to connect themselves together and fund
these interconnections. A college or corporation pays for their
connection to some regional network, which in turn pays a national
provider for its access.
What Does This Mean for Me?
The concept that the Internet is not a network, but a collection of
networks, means little to the end user. You want to do something
useful: run a program, or access some unique data. You shouldn't have
to worry about how it's all stuck together. Consider the telephone
system--it's an internet, too. Pacific Bell, AT&T, MCI, British
Telephony, Telefonos de Mexico, and so on, are all separate
corporations that run pieces of the telephone system. They worry
about how to make it all work together; all you have to do is dial.
If you ignore cost and commercials, you shouldn't care if you are
dealing with MCI, AT&T, or Sprint. Dial the number and it works.
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You only care who carries your calls when a problem occurs. If
something goes out of service, only one of those companies can fix
it. They talk to each other about problems, but each phone carrier is
responsible for fixing problems on its own part of the system. The
same is true on the Internet. Each network has its own network
operations center (NOC). The operation centers talk to each other and
know how to resolve problems. Your site has a contract with one of
the Internet's constituent networks, and its job is to keep your site
happy. So if something goes wrong, they are the ones to gripe at. If
it's not their problem, they'll pass it along.
What Does the Future Hold?
Finally, a question I can answer. It's not that I have a crystal ball
(if I did I'd spend my time on Wall Street instead of writing a
book). Rather, these are the things that the IAB and the IETF discuss
at their meetings. Most people don't care about the long discussions;
they only want to know how they'll be affected. So, here are
highlights of the networking future.
New Standard Protocols
When I was talking about how the Internet started, I mentioned the
International Standards Organization (ISO) and their set of protocol
standards. Well, they finally finished designing it. Now it is an
international standard, typically referred to as the ISO/OSI (Open
Systems Interconnect) protocol suite. Many of the Internet's
component networks allow use of OSI today. There isn't much demand,
yet. The U.S. government has taken a position that government
computers should be able to speak these protocols. Many have the
software, but few are using it now.
It's really unclear how much demand there will be for OSI,
notwithstanding the government backing. Many people feel that the
current approach isn't broke, so why fix it? They are just becoming
comfortable with what they have, why should they have to learn a new
set of commands and terminology just because it is the standard?
Currently there are no real advantages to moving to OSI. It is more
complex and less mature than IP, and hence doesn't work as
efficiently. OSI does offer hope of some additional features, but it
also suffers from some of the same problems which will plague IP as
the network gets much bigger and faster. It's clear that some sites
will convert to the OSI protocols over the next few years. The
question is: how many?
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International Connections
The Internet has been an international network for a long time, but
it only extended to the United States' allies and overseas military
bases. Now, with the less paranoid world environment, the Internet is
spreading everywhere. It's currently in over 50 countries, and the
number is rapidly increasing. Eastern European countries longing for
western scientific ties have wanted to participate for a long time,
but were excluded by government regulation. This ban has been
relaxed. Third world countries that formerly didn't have the means to
participate now view the Internet as a way to raise their education
and technology levels.
In Europe, the development of the Internet used to be hampered by
national policies mandating OSI protocols, regarding IP as a cultural
threat akin to EuroDisney. These policies prevented development of
large scale Internet infrastructures except for the Scandinavian
countries which embraced the Internet protocols long ago and are
already well-connected. In 1989, RIPE (Reseaux IP Europeens) began
coordinating the operation of the Internet in Europe and presently
about 25% of all hosts connected to the Internet are located in
Europe.
At present, the Internet's international expansion is hampered by the
lack of a good supporting infrastructure, namely a decent telephone
system. In both Eastern Europe and the third world, a state-of-the-
art phone system is nonexistent. Even in major cities, connections
are limited to the speeds available to the average home anywhere in
the U.S., 9600 bits/second. Typically, even if one of these countries
is "on the Internet," only a few sites are accessible. Usually, this
is the major technical university for that country. However, as phone
systems improve, you can expect this to change too; more and more,
you'll see smaller sites (even individual home systems) connecting to
the Internet.
Commercialization
Many big corporations have been on the Internet for years. For the
most part, their participation has been limited to their research and
engineering departments. The same corporations used some other
network (usually a private network) for their business
communications. After all, this IP stuff was only an academic toy.
The IBM mainframes that handled their commercial data processing did
the "real" networking using a protocol suite called System Network
Architecture (SNA).
Businesses are now discovering that running multiple networks is
expensive. Some are beginning to look to the Internet for "one-stop"
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network shopping. They were scared away in the past by policies which
excluded or restricted commercial use. Many of these policies are
under review and will change. As these restrictions drop, commercial
use of the Internet will become progressively more common.
This should be especially good for small businesses. Motorola or
Standard Oil can afford to run nationwide networks connecting their
sites, but Ace Custom Software couldn't. If Ace has a San Jose office
and a Washington office, all it needs is an Internet connection on
each end. For all practical purposes, they have a nationwide
corporate network, just like the big boys.
Privatization
Right behind commercialization comes privatization. For years, the
networking community has wanted the telephone companies and other
for-profit ventures to provide "off the shelf" IP connections. That
is, just like you can place an order for a telephone jack in your
house for your telephone, you could do this for an Internet
connection. You order, the telephone installer leaves, and you plug
your computer into the Internet. Except for Bolt, Beranek and Newman,
the company that ran the ARPAnet, there weren't any takers. The
telephone companies have historically said, "We'll sell you phone
lines, and you can do whatever you like with them." By default, the
Federal government stayed in the networking business.
Now that large corporations have become interested in the Internet,
the phone companies have started to change their attitude. Now they
and other profit-oriented network purveyors complain that the
government ought to get out of the network business. After all, who
best can provide network services but the "phone companies"? They've
got the ear of a lot of political people, to whom it appears to be a
reasonable thing. If you talk to phone company personnel, many of
them still don't really understand what the Internet is about. They
ain't got religion, but they are studying the Bible furiously.
(Apologies to those telephone company employees who saw the light
years ago and have been trying to drag their employers into church.)
Although most people in the networking community think that
privatization is a good idea, there are some obstacles in the way.
Most revolve around the funding for the connections that are already
in place. Many schools are connected because the government pays part
of the bill. If they had to pay their own way, some schools would
probably decide to spend their money elsewhere. Major research
institutions would certainly stay on the net; but some smaller
colleges might not, and the costs would probably be prohibitive for
most secondary schools (let alone grade schools). What if the school
could afford either an Internet connection or a science lab? It's
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unclear which one would get funded. The Internet has not yet become a
"necessity" in many people's minds. When it does, expect
privatization to come quickly.
Well, enough questions about the history of the information highway
system. It's time to walk to the edge of the road, try and hitch a
ride, and be on your way.
Acknowledgments
We would like to thank O'Reilly & Associates for permission to
reprint the chapter from their book by Ed Krol (1992), "The Whole
Internet User's Guide and Catalog."
For More Information
Hoffman, E. and L. Jackson. (1993) "FYI on Introducing the Internet
--A Short Bibliography of Introductory Internetworking Readings for
the Network Novice," 4 p. (FYI 19, RFC 1463).
To find out how to obtain this document and other on-line
introductory readings, send an e-mail message to:
[email protected], with the following text:
send access.guide.
Krol, Ed. (1992) The Whole Internet User's Guide and Catalog,
O'Reilly & Associates, Sebastopol, CA. ISBN 1-56592-025-2.
Quarterman, J. (1993) "Recent Internet Books," 15 p. (RFC 1432).
The Internet Society
Phone: (703) 620-8990
Fax: (703) 620-0913
E-mail:
[email protected]
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Security Considerations
Security issues are not discussed in this memo.
Authors' Addresses
Ed Krol
Computing and Communications Service Office
Univ. of Illinois Urbana Champaign (UIUC)
1304 W Springfield
Urbana, IL 61801
Phone: (217)333-7886
EMail:
[email protected]
Ellen Hoffman
Merit Network, Inc.
2901 Hubbard, Pod-G
Ann Arbor, MI 48105
Phone: (313) 936-3000
EMail:
[email protected]
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