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In many corporate environments the inability to use the company computer system is looked upon as a significant occupational disability. Some of you may know that one of our recent resident graduates was able to locate and rent a home close to her new office by means of the Internet. She accessed the web home page of the local newspaper, and found what she wanted before leaving Galveston.
In 1986, the NSFNET was created by the National Science Foundation. This was a much higher-speed net and it replaced the ARPANET. It operated at 56,000 bits per second, fast enough to send two full typewritten pages every second. Present speeds are faster by orders of magnitude. Gradually, more and more regional networks became connected to the NSFNET, forming a "network of networks", or the Internet. Until very recently, the NSFNET has been the "backbone" of the Internet. As early as 1987 the National Science Foundation awarded a contract to Merit Network Inc., to manage NSFNET. At the present time, the role of the National Science Foundation as NSFNET sponsor is being assumed by commercial organizations, a result of the current federal trend towards privatization of govenmental services.
During the same time as the ARPANET was evolving, Ethernet local area networks (LAN's) were coming into being at universities and research organizations. In 1983, with the advent of the desktop workstation computers, local area networking simply took off. Most of these workstations were Unix machines, enabling their users to communicate directly with the Internet.
As of April, 1994, more than 30,000 individual networks were connected to the Internet, with more appearing almost daily. Responsible observers have predicted that in 1997 the Internet will collapse of it's own complexity, or at least will come to a stumbling halt, as the addressing mechanisms become overloaded.
In 1991 the US Congress Sen. Al Gore sponsored the High-Performance Computing Act of 1991, which autorized construction of a high-speed network connecting all higher-education academic institutions, research centers, and federal organizations in the US. This addition to the Internet is called the National Research and Education Network, (NREN) and is able to transmit data at gigabit speeds (billions of bits per second.)
Digital telephone systems will gradually replace analogue systems in the service of electronic communications, and in many areas, one can replace his residence phone system with ISDN (Integrated Service Digital Network) service, allowing both voice and high-speed data communication, for not much more than one pays currently for analogue voice service. In fact, current telephone services represent one of the significant bottlenecks for expansion of the Internet.
Host: a computer, capable of supporting more than one user at at time, which stores data and programs that can be accessed by remotely sited computers, itself acting as a "terminal emulator", or as a "client."
Server: a computer, usually local to the user, connected as part of a LAN, which acts as a "host" to local "client" machines on that same LAN and provides access to data, programs, and most importantly, to networks beyond the LAN.
Client: a small computer, usually a desktop PC, or a Unix workstation, which accesses a local network "host" or "server" and makes use of the resources provided by the server and by the networks to which that server has access.
Router: a computer system which transfers data between two networks which use the same protocols. It is principally concerned with assuring correct addressing.
Bridge: a form of router which is realized in hardware and is used typically in linking services between nearby buildings having similar LANs.
Gateway: a computer system that transfers data among incompatible networks or applications. Data is reformatted to be acceptable for the new application or network prior to passing it on. Sometimes the term is used (mistakenly) for a "router."
The physical connectivity can be achieved in a number of ways. Much as the connections among members of a LAN can consist of coaxial cable ("Ethernet"), twisted pair ("Cheapernet"), and fiberoptic cable, wide-area networks (WANs) utilize high-speed copper or fiberoptic cable, microwave and satellite transmission. The connection to the user is implemented by the user's LAN, or via local telephone company cable. In the case of amateur radio operators, wireless access to the Internet can be achieved by packet radio repeater stations ("digipeaters") connected to an Internet "wormhole." Commercial wireless service is also available using cellular telephone service and mobile radio communication vendors.
The Internet is not "free," although in the case of academic users, the cost is usually transparent, for the university pays for its connection to a regional network, which in its turn pays a national provider for its access. Residential users, of course, pay providers such as Compuserve, America Online, Prodigy, for access to the Internet. This is in addition to whatever they are billed for telephone services.
To illustrate how information is transferred via the internet, consider the following familiar services: the telephone, the personal radio, and the postal service. The voice telephone provides "full duplex" communication, in that both parties can talk at the same time and still hear each other. The personal radio offers "simplex" communication, or "push-to-talk" interaction. Only one user can talk at one time, hence the convention, "over," common in radio communication. These two methods are examples of "realtime" communication.
The Postal Service provides "packetized" communication, in a "store-and- forward" mode. A small message (a letter) is enclosed in an envelope which bears the address of sender and receiver on the outside, insuring prompt and accurate delivery (in most cases!)
The telephone is a circuit-switched network, in which the user is given complete use of one piece of the network for the duration of the call. The Internet, by contrast, is a packet-switched, store-and-forward system, similar to the Postal Service. Each message or file is broken into small pieces, called "packets" each of which is from one to 1500 characters long. Each packet is stamped with the address of the sender and the intended receiver, and sent on its way. This is accomplished by a collection of software referred to as the Internet Protocol, or IP.
Packets may get lost, or delayed, or arrive out of sequence, resulting in confusion at the receiving end. For this reason, another protocol called Transmission Control Protocol, or TCP is used to supplement the IP. At the receiving end, TCP collects the individual packets, checks for missing or corrupted packets, obtains retransmission when necessary, arranges them in the proper order, and delivers them to the addressee computer system. The protocol is called TCP/IP and is pretty much the standard throughout the Internet.
There are six original high-level domain names:
Additional high-level domain names represent contries, i.e., "ca" indicating Canada. "np" indicating Nepal, etc.
A Compuserve subscriber would have an address like
72355.4455@compuserve.com. An America Online subscriber would have an
address such as "newnose@aol.com" (Jack Kridel's Internet address.) One
can have more than one address, representing either user accounts on
several computers, or aliases for a single account.
E-mail can be encrypted by the user, and decrypted by the receiver, of
course, but a great deal of controversy has arisen over the permissible
degree of encryption, with the federal government making a strong effort
to retain access to encrypted interstate communication (the "Clipper Chip"
issue) ostensibly motivated by its concern over organized crime
activities, the narcotics trade, money laundering, and of course, national
security.
Telnet is a method of accessing a host computer from a remote location.
One is required to have user privileges on the host, and the remote
computer must have a terminal emulation program installed. We used this
function last February in Atlanta, in order to check our e-mail on our
machines here at UTMB.
FTP ("file transfer protocol") is a method of shipping computer files to and
from remote host computers, and may or may not require that the user
have login privileges on the host computer. In some cases, files will
be available via "anonymous ftp" wherein the user logs in as "anonymous"
and enters his e-mail address for the password. In the case of anonymous
ftp access, the user is permitted limited access to the host computer
resources, and is only able to "download" files from the host computer.
The UTMB Otolaryngology Department Grand Rounds files are available on the
Internet via anonymous ftp.
A more versatile access mode is "gopher", named after the Golden Gophers
of the University of Minnesota, where the software was created. A gopher
provides assistance in navigating the connectivity of the Internet and
makes available files on various places around the net, depending on the
number and nature of links to other gophers which the gopher server
maintains. The name, gopher is apt in that the gopher server will "go
for" the information the user is seeking, accessing many widely separated
gopher servers in its search, and retrieving the desired data in a way
that is transparent to the user. Gophers have become so popular that
there are now thousands of them installed at various sites throughout the
world, and it is an exciting experience to find yourself visiting data
collections in Finland, Sweden, Switzerland, Australia, and other distant
sites using only a few keystrokes and in less time than it takes to read
this paragraph.
Enhancements to gopher searching are available (Archie, Veronica.) Archie
("archive") is a service that does keyword searches of all the public
files available on the Internet. Veronica maintains a collection of all
the menu items of most of the Internet gopher servers. The user
institutes a veronica search via a gopher client connected to a veronica
server. Veronica asks for a keyword and answers with a list of menu items
from other gopher servers. The user indicates the item of choice and is
then connected to a computer providing the desired resource. Gopher
server and client software is available free from the University of
Minnesota, and can be downloaded via the Internet. The UTMB
Otolaryngology Grand Rounds are available via a gopher server on one of
our Unix based computer systems.
The latest and most popular access mode is the World Wide Web. This mode
offers the user text, graphics, audio, and images in color. Rather than
presenting information in menu format, WWW offers "hypertext links" to
data, represented either by numbered items or by graphic images on the
screen. Considerable bandwidth is required for transmittal of graphics
and images, and this can be felt by the user as barely acceptable slowness
in navigating and downloading. The newer WWW clients permit telnet, ftp,
and gopher access as well. Some less sophisticated WWW clients are
available without charge via the Internet. The most popular commercial
client software packages are "Mosaic" and "Netscape." An individual or
organization wishing to appear on the WWW will create a "homepage" with
information about the individual or organization, and often a picture of
the person or institution. The "homepage" gives access to hypertext links
to additional information which the person or organization wishes to make
available publicly.
USENET News allows the user to read and post messages sent to public
"newsgroups," which are really bulletin boards or discussion groups.
USENET is the worlds largest bulletin board service, and the categories of
information listed numbers in the hundreds. There is a "sci.med"
newsgroup which boasts several subgroups, among them a pathology
discussion group.
It may not be necessary to invest in this level of connectivity, however.
It is entirely practical to obtain an account on a timesharing computer
system which itself if connected to the Internet. In fact, this is how
most home users access the Internet. In this case, however, one does not
download files directly to the home computer. Rather, files are "ftp'ed"
to the timesharing host computer, then transfered via modem to the
computer in the user's home. Some access vendors use software which makes
this requirement transparent to the user, however. In a nutshell, the
real test of full connectivity is whether or not one can run Mosaic on the
home computer. If so, then your service allows you the full range of
Internet resources.
One need not always spend one's own money to obtain access to the
Internet. Most colleges and universities, as well as many large
corporations, have connections to the Internet which you may be able to
utilize for little or no cost via telephone. Authorized users may find
the services they seek by dialing with their modem. Large organizations
such as universities and major corporations have "dedicated" access,
costing many thousands of dollars anually, but which allows as many
computers as they wish to access the Internet, with each computer a
full fledged member of the Internet.
Less expensive versions of highspeed "dedicated" access are now available
in forms that will operate over dialup telephone lines using a highspeed
modem. These methods are based on SLIP ("Serial Line Internet Protocol")
and more recently, PPP ("Point- to-Point Protocol") and give the user
excellent response characteristics at a much lower cost that true
dedicated access. SLIP and PPP are very useful in connecting a
residential computer to a local network, which itself is connected to the
Internet. This method has considerable appeal to the home user who has
user privileges on a university or large corporate network. It gives the
home user the same environment as she would have if she were actually on
campus or in her corporate office. Again, these protocols require a
highspeed (at least 9600 baud) modem and one must purchase the software
for SLIP or PPP, but a residential dialup telephone is all that is
necessary to accomplish the connection.
One is not, however, limited to a choice between dialup telephone access
and dedicated line. A service, ISDN ("Integrated Services Digital
Network") provides very fast access at low cost, offering, for example,
two 56 or 64 kilobit digital channels for between $20 and $50 per month.
Channels may be multiplexed to implement both voice and data services as
needed. Specially constructed digital telephones are required for voice
use, however, and sometimes it is difficult to find an ISDN service
provider, particularly in rural areas.
Finally, the simplest and cheapest way to connect to the Internet is with
a low- or medium-speed modem, a terminal emulator software package (i.e.,
Kermit,) a residential dialup telephone, and a subscription to a
timesharing computer service, like Compuserve. With this arrangement one
can probably enjoy e-mail, file transfer, and bulletin board access. One
should not expect to run fancy applications such as Mosaic on this kind of
link, but the cost can be less than $100 up front and $30 per month
with perhaps an additional charge for connect time. A local example of
this type of service would be "Phoenix.net" which advertises a $30 onetime
connect charge and a $25 monthly charge.
Morgan, Raches, McGilton, Henry: Introducing Unix System V; McGraw-Hill
1987
Kantor, Andrew: Jack In And Geek Out; Internet World: July 1995 pp 26-28
Internet World: Mecklermedia Corporation
Glowniak, Jerry V. & Bushway, Marilyn K; Computer Networks As A Medical
Resource; JAMA vol. 271, No. 24; Jun 22/29 1994
Mann, Charles: Regulating Cyberspace; Science Vol.268 May 1995; pp 628-9
User access modes: grades of connectivity, vendors, costs
The highest grade of connectivity is TCP/IP. At this level one has access
to the entire list of Internet services: bulletin boards, electronic mail,
file transfer, index programs, remote login, etc. With TCP/IP the user's
computer is part of the Internet and is able to contact every computer
service on the Internet.
The Future:
Security problems are inherent in an "open" network developed in a
Libertarian environment, and migrating to a competitive and commercial
atmosphere. Encryption is the obvious solution but it brings its own set
of problems, such as massivly increased overhead, and the policy of the
federal government of banning encryption schemes which can be exported to
other countries. Court battles over the right to use certain domain names
resembling trademarks are already looming into view. Censorship of
materials deemed obscene is at present being considered in the Congress,
and perhaps worst of all, a patchwork of State regulations may soon
appear, reducing all to confusion. As an example, Tennessee has recently
indicted the operators of a California bulletin board because their files,
presumably images of questionable taste, could be viewed in Tennessee.
The Internet is facing a conflict of cultures, the Libertarian,
jeans-and-teeshirt crowd against the buttoned-down dark gray summer wool
attache case daytimer set. Believe it, things are going to be
different when these two face off. Look what happend to the USSR when it
was hit by Xerox machines and PC's.
BIBLIOGRAPHY
Krol, Ed: The Whole Internet, 2nd ed.; O'Reilley & Assoc. Inc, 1994