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diff --git a/doc/rfc/rfc1935.txt b/doc/rfc/rfc1935.txt new file mode 100644 index 0000000..1927572 --- /dev/null +++ b/doc/rfc/rfc1935.txt @@ -0,0 +1,619 @@ + + + + + + +Network Working Group J. Quarterman +Request For Comments: 1935 S. Carl-Mitchell +Category: Informational TIC + April 1996 + + + What is the Internet, Anyway? + +Status of This Memo + + This memo provides information for the Internet community. This memo + does not specify an Internet standard of any kind. Distribution of + this memo is unlimited. + +Copyright (c) 1994 TIC + + From Matrix News, 4(8), August 1994 + Permission is hereby granted for redistribution of this article + provided that it is redistributed in its entirety, including + the copyright notice and this notice. + Contact: mids@tic.com, +1-512-451-7602, fax: +1-512-452-0127. + http://www.tic.com/mids, gopher://gopher.tic.com/11/matrix/news + A shorter version of this article appeared in MicroTimes. + +Introduction + + 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 + + + +Quarterman & Carl-Mitchell Informational [Page 1] + +RFC 1935 What is the Internet, Anyway? April 1996 + + + 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, + + + +Quarterman & Carl-Mitchell Informational [Page 2] + +RFC 1935 What is the Internet, Anyway? April 1996 + + + 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 + + + +Quarterman & Carl-Mitchell Informational [Page 3] + +RFC 1935 What is the Internet, Anyway? April 1996 + + + 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 + + + +Quarterman & Carl-Mitchell Informational [Page 4] + +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 + + + +Quarterman & Carl-Mitchell Informational [Page 5] + +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. + + + +Quarterman & Carl-Mitchell Informational [Page 6] + +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. + + + +Quarterman & Carl-Mitchell Informational [Page 7] + +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. + 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. + + + +Quarterman & Carl-Mitchell Informational [Page 8] + +RFC 1935 What is the Internet, Anyway? April 1996 + + + 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 + + + +Quarterman & Carl-Mitchell Informational [Page 9] + +RFC 1935 What is the Internet, Anyway? April 1996 + + + 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 tic@tic.com 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 + + + +Quarterman & Carl-Mitchell Informational [Page 10] + +RFC 1935 What is the Internet, Anyway? April 1996 + + + 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. + +Security Considerations + + Security issues are not discussed in this memo. + +Authors' Addresses + + John S. Quarterman + Smoot Carl-Mitchell + + EMail: tic@tic.com + + + + + + + + + + + + + + + +Quarterman & Carl-Mitchell Informational [Page 11] + |