rfc1935.txt

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   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



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RFC 1935             What is the Internet, Anyway?            April 1996


   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



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RFC 1935             What is the Internet, Anyway?            April 1996


   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.



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RFC 1935             What is the Internet, Anyway?            April 1996


   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.



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RFC 1935             What is the Internet, Anyway?            April 1996


   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.