Unit -4

NETWORKING

Introduction to Computer Networks

Sharing Resources

The fundamental purpose of computer networks is to provide

access to shared resources, most notably printers and data storage
(both disk drives and tape drives). Local Area Networks (LANs)
involve several primary components:

 Network interconnection (for example, copper wire, fiber

optic cable, infrared, or radio).
 Network Interface Circuitry (NIC) in the individual personal
computers, connected to the network. This circuitry may be
part of the system motherboard or it may be on a separate
plug-in card.
 The shared resources themselves, each with their own NIC
connected to the network.
 Software on the individual personal computers that uses the
NIC to access the shared resources. This software is typically
arranged to present the appearance to the rest of the operating
system that these resources are directly connected. In the
jargon, "emulating local disks and printers."
 Software on the shared resource that coordinates with the
software on the individual machines to provide access to the
shared resources for the users of the multiple individual
personal computers. This software is typically running on a
computer system ("the server") to which the shared resources
are directly attached, and is a multi-user operating system.

The most common case is for the server to be the same sort
of personal computer hardware as the individual personal
 computers on the network (Intel or Macintosh). In this case,
the operating system is called a "network operating system"
to emphasize the difference from the single-user operating
system of the personal computer. Novell is perhaps the most
striking example of this approach.

Alternatives include a laser printer with a microprocessor-

controlled NIC that runs software to manage the printer as a
shared resource (e.g., the JetDirect cards for HP laser
printers), and using a full-blown general-purpose multi-user
server, with an operating system like VMS or unix. Windows
NT Server is perhaps more accurately described as an
example of this latter class.

Network Interconnections

The network interconnection can be described in several ways:

 Speed: how many bits/sec can be transmitted through the

network.
 Topology: bus, ring, or star. Some networks provide a logical
bus or ring topology with a physical star topology (Token
Ring is, as you might suspect, a logical ring, but is a physical
star; twisted-pair ("10baseT") ethernet is logically a bus, but
is usually a physical star, although Farallon "etherwave"
devices permit daisy-chaining).
 Arbitration mechanism: token-passing, collision-detection,
guaranteed data rate, etc.
Network Protocols

The software on the individual personal computers and the

software on the server have to cooperate with each other to provide
access to the shared resources. This is done by designing the
software to use an agreed set of conventions (a "protocol") that is
standardized so that multiple vendors can provide interoperable
systems.

There are several different network protocols in use, and they can
co-exist on the same network interconnection if they are properly
designed. For example, an ethernet network can simultaneously
support general-purpose protocols, such as LAN Manager,
DECnet, TCP/IP, AppleTalk, Novell, and at the same time special-
purpose protocols, such as LAT and XNS.

Protocols specify, for example, that each data packet will have a
header that includes agreed numbers of bits specifying

 the sender's address

 the intended recipient's address
 the type of packet
 the length of the data segment in the packet

and so on. The protocols also specify the circumstances, if any,

under which the recipient is to send an acknowledgment of receipt
of the data packet. Some protocols include a sequence number that
permits the recipient to re-assemble a longer message that has been
split into parts, even if those parts are not delivered in the same
order that they were sent. (This can easily happen in an overloaded
local-area network, or in a complex wide-area network that
includes alternative pathways connecting the two machines.)
Network Infrastructure

In addition to the servers and their clients, a network will usually

include other electronic devices connected to the network signal
cabling.

 Some of this infrastructure is concerned with moving the data

through the network, from the source machine to its
destination.
o Hubs
o Routers
o Gateways
o Bridges
o Switches
o Terminal Servers
 Some of this infrastructure is concerned with maintaining
dedicated databases of network information and providing
that information to the clients and servers so that they can
communicate.
o Domain Name Server
o DHCP Server
o WINS Server to support Microsoft Network Clients
(like DNS)

These electronics may be provided with their own front panel with
control switches or keypad, or they may have dedicated
connections for a dumb terminal to be used as a control console.
More and more, however, they are designed for remote control,
through the network. The standard protocol for accomplishing
remote management of network infrastructure is called SNMP,
"Simple Network Management Protocol."

Types of Networks
There are several different types of computer networks. Computer
networks can be characterized by their size as well as their purpose.
The size of a network can be expressed by the geographic area they
occupy and the number of computers that are part of the network.
Networks can cover anything from a handful of devices within a single
room to millions of devices spread across the entire globe.
Some of the different networks based on size are:

 Personal area network, or PAN

 Local area network, or LAN
 Metropolitan area network, or MAN
 Wide area network, or WAN

In terms of purpose, many networks can be considered general purpose,

which means they are used for everything from sending files to a printer
to accessing the Internet. Some types of networks, however, serve a very
particular purpose. Some of the different networks based on their main
purpose are:

 Storage area network, or SAN

 Enterprise private network, or EPN
 Virtual private network, or VPN

Let's look at each of these in a bit more detail.

Personal Area Network

A personal area network, or PAN, is a computer network organized
around an individual person within a single building. This could be
inside a small office or residence. A typical PAN would include one or
more computers, telephones, peripheral devices, video game consoles
and other personal entertainment devices.
If multiple individuals use the same network within a residence, the
network is sometimes referred to as a home area network, or HAN. In a
very typical setup, a residence will have a single wired Internet
connection connected to a modem. This modem then provides both
wired and wireless connections for multiple devices. The network is
typically managed from a single computer but can be accessed from any
device.
This type of network provides great flexibility. For example, it allows
you to:

 Send a document to the printer in the office upstairs while you are
sitting on the couch with your laptop.
 Upload the photo from your cell phone to your desktop computer.
 Watch movies from an online streaming service to your TV.

If this sounds familiar to you, you likely have a PAN in your house
without having called it by its name.

Local Area Network

A local area network, or LAN, consists of a computer network at a
single site, typically an individual office building. A LAN is very useful
for sharing resources, such as data storage and printers. LANs can be
built with relatively inexpensive hardware, such as hubs, network
adapters and Ethernet cables.
The smallest LAN may only use two computers, while larger LANs can
accommodate thousands of computers. A LAN typically relies mostly on
wired connections for increased speed and security, but wireless
connections can also be part of a LAN. High speed and relatively low
cost are the defining characteristics of LANs.
LANs are typically used for single sites where people need to share
resources among themselves but not with the rest of the outside world.
Think of an office building where everybody should be able to access
files on a central server or be able to print a document to one or more
central printers. Those tasks should be easy for everybody working in
the same office, but you would not want somebody just walking outside
to be able to send a document to the printer from their cell phone! If a
local area network, or LAN, is entirely wireless, it is referred to as a
wireless local area network, or WLAN.
Metropolitan Area Network
A metropolitan area network, or MAN, consists of a computer
network across an entire city, college campus or small region. A MAN is
larger than a LAN, which is typically limited to a single building or site.
Depending on the configuration, this type of network can cover an area
from several miles to tens of miles. A MAN is often used to connect
several LANs together to form a bigger network. When this type of
network is specifically designed for a college campus, it is sometimes
referred to as a campus area network, or CAN.

Wide Area Network

A wide area network, or WAN, occupies a very large area, such as an
entire country or the entire world. A WAN can contain multiple smaller
networks, such as LANs or MANs. The Internet is the best-known
example of a public WAN.

Private Networks
One of the benefits of networks like PAN and LAN is that they can be
kept entirely private by restricting some communications to the
connections within the network. This means that those communications
never go over the Internet.
For example, using a LAN, an employee is able to establish a fast and
secure connection to a company database without encryption since none
of the communications between the employee's computer and the
database on the server leave the LAN. But what happens if the same
employee wants to use the database from a remote location? What you
need is a private network.

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What is Network Topology
The physical topology of a network refers to the configuration of cables,
computers, and other peripherals. Physical topology should not be
confused with logical topology which is the method used to pass
information between workstations. Logical topology was discussed in
the Protocol chapter.
Main Types of Network Topologies In networking, the term
"topology" refers to the layout of connected devices on a network. This
article introduces the standard topologies of computer networking.
One can think of a topology as a network's virtual shape or structure.
This shape does not necessarily correspond to the actual physical layout
of the devices on the network. For example, the computers on a home
 LAN may be arranged in a circle in a family room, but it would be
highly unlikely to find an actual ring topology there.
Network topologies are categorized into the following basic types:
 Star Topology
 Ring Topology
 Bus Topology
 Tree Topology
 Mesh Topology
 Hybrid Topology
More complex networks can be built as hybrids of two or more of the
above basic topologies.
Star Topology Many home networks use the star topology. A star
network features a central connection point called a "hub" that may be a
hub, switch or router. Devices typically connect to the hub with
Unshielded Twisted Pair (UTP) Ethernet.
Compared to the bus topology, a star network generally requires more
cable, but a failure in any star network cable will only take down one
computer's network access and not the entire LAN. (If the hub fails,
however, the entire network also fails.)
See the illustration of Star Network Topology.

Advantages of a Star Topology

 Easy to install and wire.
 No disruptions to the network then connecting or removing devices.
 Easy to detect faults and to remove parts.
Disadvantages of a Star Topology
 Requires more cable length than a linear topology.
 If the hub or concentrator fails, nodes attached are disabled.
 More expensive than linear bus topologies because of the cost of the
concentrators.
The protocols used with star configurations are usually Ethernet or
LocalTalk. Token Ring uses a similar topology, called the star-wired
ring.
Star-Wired Ring
A star-wired ring topology may appear (externally) to be the same as a
star topology. Internally, the MAU of a star-wired ring contains wiring
that allows information to pass from one device to another in a circle or
ring (See fig. 3). The Token Ring protocol uses a star-wired ring
topology.
Ring Topology In a ring network, every device has exactly two
neighbors for communication purposes. All messages travel through a
ring in the same direction (either "clockwise" or "counterclockwise"). A
failure in any cable or device breaks the loop and can take down the
entire network.
To implement a ring network, one typically uses FDDI, SONET, or
Token Ring technology. Ring topologies are found in some office
buildings or school campuses.
See the illustration of Ring Topology.

Bus Topology Bus networks (not to be confused with the system bus of
a computer) use a common backbone to connect all devices. A single
cable, the backbone functions as a shared communication medium that
 devices attach or tap into with an interface connector. A device wanting
to communicate with another device on the network sends a broadcast
message onto the wire that all other devices see, but only the intended
recipient actually accepts and processes the message.
Ethernet bus topologies are relatively easy to install and don't require
much cabling compared to the alternatives. 10Base-2 ("ThinNet") and
10Base-5 ("ThickNet") both were popular Ethernet cabling options
many years ago for bus topologies. However, bus networks work best
with a limited number of devices. If more than a few dozen computers
are added to a network bus, performance problems will likely result. In
addition, if the backbone cable fails, the entire network effectively
becomes unusable.
See the illustration of Bus Network Topology.

Advantages of a Linear Bus Topology

 Easy to connect a computer or peripheral to a linear bus.
 Requires less cable length than a star topology.
Disadvantages of a Linear Bus Topology
 Entire network shuts down if there is a break in the main cable.
 Terminators are required at both ends of the backbone cable.
 Difficult to identify the problem if the entire network shuts down.
 Not meant to be used as a stand-alone solution in a large building.
Tree Topology Tree topologies integrate multiple star topologies
together onto a bus. In its simplest form, only hub devices connect
directly to the tree bus, and each hub functions as the "root" of a tree of
devices. This bus/star hybrid approach supports future expandability of
 the network much better than a bus (limited in the number of devices
due to the broadcast traffic it generates) or a star (limited by the number
of hub connection points) alone.
See the illustration of Tree Network Topology.

Advantages of a Tree Topology

 Point-to-point wiring for individual segments.
 Supported by several hardware and software venders.
Disadvantages of a Tree Topology
 Overall length of each segment is limited by the type of cabling used.
 If the backbone line breaks, the entire segment goes down.
 More difficult to configure and wire than other topologies.
Mesh Topology Mesh topologies involve the concept of routes. Unlike
each of the previous topologies, messages sent on a mesh network can
take any of several possible paths from source to destination. (Recall
that even in a ring, although two cable paths exist, messages can only
travel in one direction.) Some WANs, most notably the Internet, employ
mesh routing.
A mesh network in which every device connects to every other is called
a full mesh. As shown in the illustration below, partial mesh networks
also exist in which some devices connect only indirectly to others.
See the illustration of Mesh Network Topology.
Hybrid Topology
A combination of any two or more network topologies. Note 1:
Instances can occur where two basic network topologies, when
connected together, can still retain the basic network character, and
therefore not be a hybrid network. For example, a tree network
connected to a tree network is still a tree network. Therefore, a hybrid
network accrues only when two basic networks are connected and the
resulting network topology fails to meet one of the basic topology
definitions. For example, two star networks connected together exhibit
hybrid network topologies. Note 2: A hybrid topology always accrues
when two different basic network topologies are connected.
5-4-3 Rule
A consideration in setting up a tree topology using Ethernet protocol is
the 5-4-3 rule. One aspect of the Ethernet protocol requires that a signal
sent out on the network cable reach every part of the network within a
specified length of time. Each concentrator or repeater that a signal goes
through adds a small amount of time. This leads to the rule that between
any two nodes on the network there can only be a maximum of 5
segments, connected through 4 repeaters/concentrators. In addition, only
3 of the segments may be populated (trunk) segments if they are made of
coaxial cable. A populated segment is one which has one or more nodes
attached to it . In Figure 4, the 5-4-3 rule is adhered to. The furthest two
nodes on the network have 4 segments and 3 repeaters/concentrators
between them.
 This rule does not apply to other network protocols or Ethernet networks
where all fiber optic cabling or a combination of a fiber backbone with
UTP cabling is used. If there is a combination of fiber optic backbone
and UTP cabling, the rule is simply translated to 7-6-5 rule.

Considerations When Choosing a Topology

 Money. A linear bus network may be the least expensive way to install a
network; you do not have to purchase concentrators.
 Length of cable needed. The linear bus network uses shorter lengths of
cable.
 Future growth. With a star topology, expanding a network is easily done
by adding another concentrator.
 Cable type. The most common cable in schools is unshielded twisted
pair, which is most often used with star topologies.

Other definition of Network Topology

A network consists of multiple computers connected using some type of

interface, each having one or more interface devices such as a Network
Interface Card (NIC) and/or a serial device for PPP networking. Each
computer is supported by network software that provides the server or
client functionality. The hardware used to transmit data across the
network is called the media. It may include copper cable, fiber optic, or
wireless transmission. The standard cabling used for the purposes of this
document is 10Base-T category 5 Ethernet cable. This is twisted copper
cabling which appears at the surface to look similar to TV coaxial cable.
It is terminated on each end by a connector that looks much like a phone
connector. Its maximum segment length is 100 meters.
In a server based network, there are computers set up to be primary
providers of services such as file service or mail service. The computers
providing the service are called servers and the computers that request
and use the service are called client computers.
In a peer-to-peer network, various computers on the network can act
both as clients and servers. For instance, many Microsoft Windows
based computers will allow file and print sharing. These computers can
act both as a client and a server and are also referred to as peers. Many
networks are combination peer-to-peer and server based networks. The
network operating system uses a network data protocol to communicate
on the network to other computers. The network operating system
supports the applications on that computer. A Network Operating
System (NOS) includes Windows NT, Novell Netware, Linux, Unix and
others

Transmission Modes in Computer Networks

Transmission mode means transferring of data between two devices. It is

also called communication mode. These modes direct the direction of
flow of information. There are three types of transmission mode. They
are :
 Simplex Mode

 Half duplex Mode

 Full duplex Mode

SIMPLEX Mode
In this type of transmission mode data can be sent only through one
direction i.e. communication is unidirectional. We cannot send a
message back to the sender. Unidirectional communication is done in
Simplex Systems.
Examples of simplex Mode is loudspeaker, television broadcasting,
television and remote, keyboard and monitor etc.
HALF DUPLEX Mode
In half duplex system we can send data in both directions but it is done
one at a time that is when the sender is sending the data then at that time
we can’t send the sender our message. The data is sent in one direction.
Example of half duplex is a walkie- talkie in which message is sent one
at a time and messages are sent in both the directions.

FULL DUPLEX Mode

In full duplex system we can send data in both directions as it is
bidirectional. Data can be sent in both directions simultaneously. We can
send as well as we receive the data.
Example of Full Duplex is a Telephone Network in which there is
communication between two persons by a telephone line, through which
both can talk and listen at the same time.
In full duplex system there can be two lines one for sending the data and
the other for receiving data.

FORMS OF DATA TRANSMISSION

1. Parallel transmission

Defination: Within a computing or communication device, the distances

between different subunits are too short. Thus, it is normal practice to
transfer data between subunits using a separate wire to carry each bit of
data. There are multiple wires connecting each sub-unit and data is
exchanged using a parallel transfer mode. This mode of operation
results in minimal delays in transferring each word.

• In parallel transmission, all the bits of data are transmitted

simultaneously on separate communication lines.
• In order to transmit n bits, n wires or lines are used. Thus each bit has
its own line.
• All n bits of one group are transmitted with each clock pulse from one
device to another i.e. multiple bits are sent with each clock pulse.
• Parallel transmission is used for short distance communication.
• As shown in the fig, eight separate wires are used to transmit 8 bit data
from sender to receiver.

Advantage of parallel transmission:

It is speedy way of transmitting data as multiple bits are transmitted

simultaneously with a single clock pulse.

Disadvantage of parallel transmission:

It is costly method of data transmission as it requires n lines to

transmit n bits at the same time.
2. Serial Transmission

Defination: When transferring data between two physically separate

devices, especially if the separation is more than a few kilometers, for
reasons of cost, it is more economical to use a single pair of lines. Data
is transmitted as a single bit at a time using a fixed time interval for each
bit. This mode of transmission is known as bit-serial transmission.

• In serial transmission, the various bits of data are transmitted serially

one after the other.
• It requires only one communication line rather than n lines to transmit
data from sender to receiver.
• Thus all the bits of data are transmitted on single line in serial fashion.
• In serial transmission, only single bit is sent with each clock pulse.
• As shown in fig., suppose an 8-bit data 11001010 is to be sent from
source to destination. Then least significant bit (LSB) i,e. 0 will be
transmitted first followed by other bits. The most significant bit
(MSB) i.e. 1 will be transmitted in the end via single communication
line.
• The internal circuitry of computer transmits data in parallel fashion. So
in order to change this parallel data into serial data, conversion devices
are used.
• These conversion devices convert the parallel data into serial data at
the sender side so that it can be transmitted over single line.
• On receiver side, serial data received is again converted to parallel
form so that the interval circuitry of computer can accept it

• Serial transmission is used for long distance communication.

Advantage of Serial transmission:

Use of single communication line reduces the transmission line cost by

the factor of n as compared to parallel transmission.

Disadvantages of Serial transmission:

1. Use of conversion devices at source and destination end may lead to

increase in overall transmission cost.
2. This method is slower as compared to parallel transmission as bits are
transmitted serially one after the other.

Types of Serial Transmission:

There are two types of serial transmission-synchronous and

asynchronous both these transmissions use 'Bit synchronization'
Bit Synchronization is a function that is required to determine when the
beginning and end of the data transmission occurs.
Bit synchronization helps the receiving computer to know when data
begin and end during a transmission. Therefore bit synchronization
provides timing control.
Asynchronous Transmission:

• Asynchronous transmission sends only one character at a time where a

character is either a letter of the alphabet or number or control
character i.e. it sends one byte of data at a time.
• Bit synchronization between two devices is made possible using start
bit and stop bit.
• Start bit indicates the beginning of data i.e. alerts the receiver to the
arrival of new group of bits. A start bit usually 0 is added to the
beginning of each byte.
• Stop bit indicates the end of data i.e. to let the receiver know that byte
is finished, one or more additional bits are appended to the end of the
byte. These bits, usually 1s are called stop bits.

• Addition of start and stop increase the number of data bits. Hence more
bandwidth is consumed in asynchronous transmission.
• There is idle time between the transmissions of different data bytes.
This idle time is also known as Gap
• The gap or idle time can be of varying intervals. This mechanism is
called Asynchronous, because at byte level sender and receiver need not
to be synchronized. But within each byte, receiver must be synchronized
with the incoming bit stream.

Application of Asynchronous Transmission:

1. Asynchronous transmission is well suited for keyboard type-terminals

and paper tape devices. The advantage of this method is that it does not
require any local storage at the terminal or the computer as transmission
takes place character by character.
2. Asynchronous transmission is best suited to Internet traffic in which
information is transmitted in short bursts. This type of transmission is
used by modems.

Advantages of Asynchronous transmission:

1. This method of data transmission is cheaper in cost as compared to

synchronous e.g. If lines are short, asynchronous transmission is better,
because line cost would be low and idle time will not be expensive.
2. In this approach each individual character is complete in itself,
therefore if character is corrupted during transmission, its successor and
predecessor character will not be affected.
3. It is possible to transmit signals from sources having different bit
rates.
4. The transmission can start as soon as data byte to be transmitted
becomes available.
5. Moreover, this mode of data transmission in easy to implement.

Disadvantages of asynchronous transmission:

1. This method is less efficient and slower than synchronous

transmission due to the overhead of extra bits and insertion of gaps into
bit stream.
2. Successful transmission inevitably depends on the recognition of the
start bits. These bits can be missed or corrupted.

Synchronous Transmission:
• Synchronous transmission does not use start and stop bits.
• In this method bit stream is combined into longer frames that may
contain multiple bytes.
• There is no gap between the various bytes in the data stream.

• In the absence of start & stop bits, bit synchronization is established

between sender & receiver by 'timing' the transmission of each bit.
• Since the various bytes are placed on the link without any gap, it is the
responsibility of receiver to separate the bit stream into bytes so as to
reconstruct the original information.
• In order to receive the data error free, the receiver and sender operates
at the same clock frequency.

Application of Synchronous transmission:

• Synchronous transmission is used for high speed communication

between computers.

Advantage of Synchronous transmission:

1. This method is faster as compared to asynchronous as there are no

extra bits (start bit & stop bit) and also there is no gap between the
individual data bytes.
Disadvantages of Synchronous transmission:

1. It is costly as compared to asynchronous method. It requires local

buffer storage at the two ends of line to assemble blocks and it also
requires accurately synchronized clocks at both ends. This lead to
increase in the cost.

2. The sender and receiver have to operate at the same clock frequency.
This requires proper synchronization which makes the system
complicated.

1-Introduction:

By the turn of the century, information, including access to the Internet,

will be the basis for personal, economic, and political advancement. The
popular name for the Internet is the information superhighway. Whether
you want to find the latest financial news, browse through library
catalogs, exchange information with colleagues, or join in a lively
political debate, the Internet is the tool that will take you beyond
telephones, faxes, and isolated computers to a burgeoning networked
information frontier.
The Internet supplements the traditional tools you use to gather
information, Data Graphics, News and correspond with other people.
Used skillfully, the Internet shrinks the world and brings information,
expertise, and knowledge on nearly every subject imaginable straight to
your computer.

What is the Internet?

The Internet links are computer networks all over the world so that users
can share resources and communicate with each other. Some computers,
have direct access to all the facilities on the Internet such as the
universities. And other computers, eg privately-owned ones, have
indirect links through a commercial service provider, who offers some or
all of the Internet facilities. In order to be connected to Internet, you
must go through service suppliers. Many options are offered with
monthly rates. Depending on the option chosen, access time may vary.
The Internet is what we call a metanetwork, that is, a network of
networks that spans the globe. It's impossible to give an exact count of
the number of networks or users that comprise the Internet, but it is
easily in the thousands and millions respectively. The Internet employs a
set of standardized protocols which allow for the sharing of resources
among different kinds of computers that communicate with each other
on the network. These standards, sometimes referred to as the Internet
Protocol Suite, are the rules that developers adhere to when creating new
functions for the Internet.
The Internet is also what we call a distributed system; there is no central
archives. Technically, no one runs the Internet. Rather, the Internet is
made up of thousands of smaller networks. The Internet thrives and
develops as its many users find new ways to create, display and retrieve
the information that constitutes the Internet.

History & Development of the Internet:

In its infancy, the Internet was originally conceived by the Department

of Defense as a way to protect government communications systems in
the event of a military strike. The original network, dubbed ARPANet
(for the Advanced Research Projects Agency that developed it) evolved
into a communications channel among contractors, military personnel,
and university researchers who were contributing to ARPA projects.
The network employed a set of standard protocols to create an effective
way for these people to communicate and share data with each other.
ARPAnet's popularity continued to spread among researchers, and in the
1980's the National Science Foundation, whose NSFNet, linked several
high speed computers, took charge of the what had come to be known as
the Internet.
By the late 1980's, thousands of cooperating networks were participating
in the Internet.
In 1991, the U.S. High Performance Computing Act established the
NREN (National Research & Education Network). NREN's goal was to
develop and maintain high-speed networks for research and education,
and to investigate commercial uses for the Internet.
The rest, as they say, is history in the making. The Internet has been
improved through the developments of such services as Gopher and the
World Wide Web.
Even though the Internet is predominantly thought of as a research
oriented network, it continues to grow as an informational, creative, and
commercial resource every day and all over the world.

Who Pays for the Internet?

There is no clear answer to this question because the Internet is not one
"thing", it's many things. No one central agency exists that charges
individual Internet users. Rather, individuals and institutions who use the
Internet pay a local or regional Internet service provider for their share
of services. And in turn, those smaller Internet service providers might
purchase services from an even larger network. So basically, everyone
who uses the Internet in some way pays for part of it.

2-what makes the internet work?

The unique thing about the Internet is that it allows many different
computers to connect and talk to each other. This is possible because of
a set of standards, known as protocols, that govern the transmission of
data over the network: TCP/IP (Transmission Control Protocol/Internet
Protocol). Most people who use the Internet aren't so interested in details
related to these protocols. They do, however, want to know what they
can do on the Internet and how to do it effectively.

The Client/Server Model:

The most popular Internet tools operate as client/server systems. You're

running a program called a Web client. This piece of software displays
documents for you and carries out your requests. If it becomes necessary
to connect to another type of service--say, to set up a Telnet session, or
to download a file--your Web client will take care of this, too. Your Web
client connects (or "talks") to a Web server to ask for information on
your behalf.

The Web server is a computer running another type of Web software

which provides data, or "serves up" an information resource to your Web
client.

All of the basic Internet tools--including Telnet, FTP, Gopher, and the
World Wide Web--are based upon the cooperation of a client and one or
more servers. In each case, you interact with the client program and it
manages the details of how data is presented to you or the way in which
you can look for resources. In turn, the client interacts with one or more
servers where the information resides. The server receives a request,
processes it, and sends a result, without having to know the details of
your computer system, because the client software on your computer
system is handling those details.
The advantage of the client/server model lies in distributing the work so
that each tool can focus or specialize on particular tasks: the server
serves information to many users while the client software for each user
handles the individual user's interface and other details of the requests
and results.

The Use of Local Clients:

Every computer should be equipped with basic client software packages
that allow you to perform functions such as electronic mail, Telnet,
Gopher, and FTP.

Electronic mail on the internet:

Electronic mail, or e-mail, is probably the most popular and widely used
Internet function. E-mail, email, or just mail, is a fast and efficient way
to communicate with friends or colleagues. You can communicate with
one person at a time or thousands; you can receive and send files and
other information. You can even subscribe to electronic journals and
newsletters. You can send an e-mail message to a person in the same
building or on the other side of the world.

How does E-mail Work?

E-mail is an asynchronous form of communication, meaning that the

person whom you want to read your message doesn't have to be
available at the precise moment you send your message. This is a great
convenience for both you and the recipient.

On the other hand, the telephone, which is a synchronous

communication medium, requires that both you and your listener be on
the line at the same time in order for you to communicate (unless you
leave a voice message). It will be impossible to discuss all the details of
the many e-mail packages available to Internet users.
Fortunately, however, most of these programs share basic functionality
which allow you to:
*send and receive mail messages
*save your messages in a file
*print mail messages
*reply to mail messages
*attach a file to a mail message
Reading an Internet Address:
To use Internet e-mail successfully, you must understand how the names
and addresses for computers and people on the Internet are formatted.
Mastering this technique is just as important as knowing how to use
telephone numbers or postal addresses correctly.
Fortunately, after you get the hang of them, Internet addresses are
usually no more complex than phone numbers and postal addresses.
And, like those methods of identifying a person, an organization, or a
geographic location--usually by a telephone number or a street address--
Internet addresses have rules and conventions for use.
Sample Internet Address: custcare@aucegypt.edu
The Internet address has three parts:
1.a user name [custcare in the example above]
2.an "at" sign (@)
3.the address of the user's mail server [aucegypt.edu in the example
above] Sometimes it's useful to read an Internet address (like
custcare@aucegypt.edu) or a domain name from right to left because it
helps you determine information about the source of the address.
An address like 201B6DQF@asu.edu doesn't tell me much about the
person who's sending me a message, but I can deduce that the sender is
affiliated with an educational institution because of the suffix edu.
The right-most segment of domain names usually adhere to the naming
conventions listed below:

EDU Educational sites in the United States

COM Commercial sites in the United States
GOV Government sites in the United States
NET Network administrative organizations
MIL Military sites in the United States
ORG Organizations in the U.S. not covered by the categories above
(e.g., non-profit orginaizations).
.xx where xx is the country code (e.g., .eg for Egypt).
Introduction:

Once you've become adept at using e-mail, you may want to

communicate with others on the Internet who share your interests.
Newsgroups are one way to do this; the other is through an electronic
discussion group. An electronic discussion is a group of persons who
have come together to discuss a particular topic via e-mail. There are
several methods that network users can use to participate in electronic
discussions; however, the basic purpose is to bring together persons with
similar interests to share information, ideas, problems, solutions, and
opinions. Since an electronic discussion is conducted by e-mail, it's
commonly called a mailing list.
If you find yourself interested in a topic, you can subscribe to a suitable
mailing list. From then on, any message sent to the mailing list is
automatically distributed as electronic mail to you--as well as to all
previously subscribed members of that particular discussion. The beauty
of a mailing list is that traffic (the mail generated by that list) covers a
specific topic and the
mail it generates comes straight to your electronic mailbox, without any
extra work on your part. There are thousands of mailing lists operating
on the Internet, dedicated to myriad topics. Some are created to serve
local needs only (i.e., a list for the members of a regional computer user
group), while many are open to anyone on the network. There are
discussions on professional topics, vocational subjects, and topics of
personal interest. You can roughly separate the thousands of mailing
lists available on the Internet into the following groups:

Types of discussion lists:

Moderated vs. Unmoderated Lists

Mailing lists can be moderated or unmoderated. The distinction is
whether messages are automatically forwarded to all subscribers
(unmoderated) or whether a moderator (a human being) first screens and
perhaps combines similar messages before sending them to subscribers
(moderated).
Open vs. Closed Lists
Electronic discussions can also be "open" or "closed." Anyone can
subscribe to an open discussion, but a closed discussion is limited to a
particular group of persons, for example, those in a particular
professional field.

Introduction to network news:

Network News (sometimes referred to as Usenet News) is a service

comprised of several thousand electronic discussions providing users an
effective way to share information with others on just about any topic.

If you're unclear about the concept of Network News, it's helpful to

think about a bulletin
board that you might see on campus.
Here, one might find posted messages advertising a futon for sale,
asking for students to join a math study group. In the newsgroup
environment, the same kind of process take place:
User X may access a newsgroup on a particular topic and post a
message, question, or respond to a previously posted message, and
anyone accessing that newsgroup would then be able to see User X's
message.
Network News newsgroups provide this same kind of forum online,
where users have access to the messages posted by all other users of that
newsgroup.
Network News has been described as an "international meeting place"
where you're likely to find a discussion going on just about anything.

How Does Network News work?

Messages posted on Network News newsgroups are sent from host

computer to host computer all over the world, using the network news
transfer protocol.
Because Network News newsgroups are located on one server, Network
News is a very efficient way to share information that might otherwise
be disseminated to several individual users.
This way, several people can read a given newsgroup message, but the
host system stores only one copy of it.

Newsgroups: What's in a Name?

As mentioned before, Network News is essentially made up of

newsgroups, each newsgroup a collection of messages focusing on a
related theme.
You can probably find a newsgroup on any topic, no matter how arcane
or bizarre.
A newsgroup's name gives you a good idea of that group's focus, and
also illustrates the hierarchical naming scheme given to newsgroups.
Newsgroups with the prefix comp, for example, are for computer-related
topics.
After the initial prefix, you'll see an additional series of names assigned
to the newsgroup that tell its specific concern: Note the following
examples:

comp.mac.performa for "computers--macintosh--performas"

rec.auto.antique for "recreation--autos--antiques"
alt.backrubs for "alternative--backrubs"
soc.culture.japan for "social--culture--japan"

Remote Login & File Transfer:

Introduction to telnet:
Telnet is the protocol used to establish a login session on a remote
computer on the network. While many computers on the Internet require
users to have authorization, others are open to the public and can be
logged onto with telnet. Telnet is not a method to transfer files from one
machine to another, but rather is a way to remotely connect to another
system with priveleges to run specific programs on that system. Some
uses of the Telnet protocol include:
connecting to a library catalog to search that library's collection
connecting to a location that allows public priveleges to search its
campus information system connecting to a location that gives you an
up-to-the minute weather report

Basic Telnet Commands

open - establishes a connection to the specified host.close - closes an
open connection and leaves you in the telnet software quit - closes any
open telnet sessions and exits the telnet software. When using a telnet
program like NCSA Telnet, you invoke these commands by way of pull-
down menus or command keys.

Introduction to FTP, File Transfer Protocol:

Basic commands in FTP:
To do FTP, a user invokes one of two commands:
get the command for transferring a file from another server to your own
computer.
put the command for moving a file from your computer to another one.
Who can do FTP? Anonymous vs. authorized priveleges
On many servers, called anonymous FTP servers, anyone can do FTP.
All that is required to login is a username (anonymous) and a password
(your e-mail address). To get an idea of the many resources available via
FTP, you can look at this selected list of FTP servers.
Other servers require you to be a registered "authorized" user before
you're permitted to do FTP. In such a case, you would need to contact
the system operator for the server you wish to access, and request an
authorization and a password. Getting an authorization and password
might mean that you can get and put only to specific subdirectories on
that server.

Resources available to you via FTP

Freeware
When you download freeware, the author continues to carry the
copyright to the software, but permits you to use the program for free.
You can share freeware with others, as long as you don't sell it.
Public Domain
When you download public domain software, you can use it freely. The
creator carries no copyright, and has released it for anyone to use. There
are no limits on distribution or sale--and anyone can modify the
program.

Shareware
When you download shareware, the author continues to carry the
copyright to the software, but you're permitted short-term use of the
program for evaluation purposes.
At the end of evaluation period, you must either pay the copyright
holder for the program or destroy all copies you've made of it.

Introduction to Gopher:

Gopher is a client/server system that allows you to access many Internet

resources simply by making selections from a sequence of menus. Each
time you make a selection, Gopher carries out your request to the
computer that contains the information and "serves" it up. For example,
if you select a menu item that represents a text file, Gopher will get that
file--wherever it happens to be--and display it for you. As you use
Gopher, some menu items lead to other menus. If you choose one of
these, Gopher will retrieve the new menu and display it for you. Thus
you can move from menu to menu, using only a few key strokes or a
mouse to navigate. The power of Gopher is that the resources listed in a
menu may be anywhere on the Internet. As Gopher connects to
computers to comply with your menu selection, you don't need to be
preoccupied with the behind-the-scenes work of connecting to and
disconnecting from these various computers. Gopher does this for you
without your even needing to be aware of it. This automatic connecting
makes Gopher popular and useful.

Where did Gopher come from?

"Born" in April 1991, gopher began as a project at the Microcomputer,

Workstation, and Networks Center at the University of Minnesota to
help people on campus get answers to computer-related questions. At the
time, the computer center staff had accumulated answers to thousands of
questions regarding computers and software.
What was needed was an easy and efficient way to deliver this
information to students, faculty and staff. Thus, the creation of Gopher
reaffirms the adage that necessity is the mother of invention.

Why is it called Gopher?

The name "Gopher" is appropriate for three reasons:

1.Just as a real gopher successfully navigates beneath the prairie, the
Internet Gopher tunnels through the invisible paths of the Internet to
help you find the information you want.
2.The name refers to someone who fetches things or provides service
for other people.
3.The Golden Gopher is the mascot of the University of Minnesota.

Introduction to the World Wide Web

The World Wide Web (also referred to as WWW or W3) is the fastest
growing area of the Internet. While gopher was an important step in
allowing users to "browse" through the Internet's vast resources, the
World Wide Web has raised excitement about the Internet to new
heights.
What makes the World Wide Web appealing and innovative is its use of
hypertext as a way of linking documents to each other. A highlighted
word or phrase in one document acts as a pointer to another document
that amplifies or relates to the first document. When looking at a WWW
document, the reader doesn't have to follow every pointer, or link (also
called a hypertext link), only those that look interesting or useful. In this
way, the user tailors the experience to suit his or her needs or interests.
The other very appealing aspect of the World Wide Web is the use of
graphics and sound capabilities. Documents on the WWW include text,
but they may also include still images, video, and audio for a very
exciting presentation. People who create WWW documents often
include a photograph of themselves along with detailed professional
information and personal interests. (This is often called a person's home
page.)

What makes the WWW work?

WWW is another example of client/server computing. Each time a link

is followed, the client is requesting a document (or graphic or sound file)
from a server (also called a Web server) that's part of the World Wide
Web that "serves" up the document. The server uses a protocol called
HTTP or HyperText Transport Protocol. The standard for creating
hypertext documents for the WWW is HyperText Markup Language or
HTML. HTML essentially codes plain text documents so they can be
viewed on the Web.

Uniform Resource Locators, or URLs:

A Uniform Resource Locator, or URL is the address of a document

you'll find on the WWW. Your WWW browser interprets the
information in the URL in order to connect to the proper Internet server
and to retrieve your desired document. Each time you click on a
hyperlink in a WWW document, you're actually instructing your
browser to find the URL that's embedded within the hyperlink.
The elements in a URL:Protocol://server's address/filename
Hypertext protocol: http://www.aucegypt.edu
Gopher protocol: gopher://gopher.umm.tc.edu
File Transfer Protocol: ftp://ftp.dartmouth.edu
Telnet Protocol: telnet://pac.carl.org
News Protocol: news:alt.rock-n-roll.stones

WWW Clients, or "Broswers":

The program you use to access the WWW is known as a browser

because it "browses" the WWW and requests these hypertext documents.
Browsers can be graphical, like Netscape and Mosaic, allowing you to
see and hear the graphics and audio; text-only browsers (i.e., those with
no sound or graphics capability) are also available. All of these
programs understand
http and other Internet protocols such as FTP, gopher, mail, and news,
making the WWW a kind of "one stop shopping" for Internet users.

Chatting:

Internet Relay Chat (IRC), the other method for Internet conversation, is
less common than talk because someone must set up the Chat before
others can join in. Chat sessions allow many users to join in the same
free-form conversation, usually centered around a discussion topic.
When users see a topic that interests them, they type a command to
join and then type another command to choose a nickname. Nicknames
allow people in the session to find you on IRC Networks or Channels.

A look at search engines:

The World Wide Web is "indexed" through the use of search engines,
which are also referred to as "spiders," "robots," "crawlers," or "worms".
These search engines comb through the Web documents, identifying text
that is the basis for keyword searching. Each search engine works in a
different way. Some engines scan for information in the title or header of
the document; others look at the bold "headings" on the page for their
information. The fact that search engines gather information differently
means that each will probably yield different results. Therefore, it's wise
to try more than one search engine when doing Web searching.

The list below lists several search engines and how each one gathers
information, plus resources that evaluate the search engines.

Selected Search Engines (listed alphabetically)

Alta Vista
Alta Vista, maintained by The Digital Equipment Corp., indexes the full
text of over 16 million pages including newsgroups. Check out the Alta
Vista Tips page.
ExciteNetsearch
Excite includes approximately 1.5 million indexed pages, including
newsgroups. Check out the Excite NetSearch handbook.

InfoSeekNetSearch
Indexes full text of web pages, including selected newsgroups and
electronic journals.
Just under one-half million pages indexed. Check out the InfoSeek
Search Tips.

Inktomi
As of December 1995, the Inktomi search engine offers a database of
approximately 2.8 million indexed Web documents and promises very
fast search retrievals. Results are ranked in order of how many of your
searched terms are used on the retrieved pages.

Lycos
Lycos indexes web pages (1.5 million +), web page titles, headings,
subheadings, URLs, and significant text.
Search results are returned in a ranked order.

Magellan
Magellan indexes over 80,000 web sites. Search results are ranked and
annotated.

OpenTextIndex
Indexes full text of approximately 1.3 million pages. Check out the Open
Text Help pages for tips on using this search engine.

WebCrawler
Maintained by America Online, WebCrawler indexes over 200,000
pages on approximately 75,000 web servers. URLs, titles, and document
content are indexed.
WWW World Wide Web Worm
Approximately 250,000 indexed pages; indexed content includes
hypertext, URLs, and document titles.

Yahoo
A favorite directory and search engine, Yahoo has organized over
80,000 Web sites (including newsgroups) into 14 broad categories.
Yahoo also maintains a comprehensive list of links to Yahoo -
Computers and Internet:Internet:World Wide Web: Searching the Web
other web search engines, indexes, and guides.

Finally the internet is a huge source of information in all fields of

knowledge.
Datum will take your hand through this incredible world of
information to get what you need in a fast, reliable
and professional way.

Hardware and Software Requirements

Hardware Requirements

PC

Any PC (Windows) should work and is what we recommend at this

time, primarily because there are more touch screens whose drivers work
with PCs and more kiosk manufacturers who use them. (Also, there are
some ready-made applications such as Seismic Eruption by Alan Jones
or AmaSeis that run on PCs and can make a nice "second screen" for a
display.)
It could be that for your application a Mac or Linux box will work fine,
but our priority for now is the PC platform.
Select a PC that will fit inside whatever enclosure you may envision
using (also see Kiosk below). We have been using Shuttle PCs, but any
small form factor PC would be a fine choice, and indeed it need not be
small to work. Ideally the PC will have:

 a recent model CPU such as Pentium or Celeron, say 2Ghz or faster

 2GB RAM (1GB is OK but why take a chance)
 Windows XP (Pro or Home) Vista has not yet been tested but should
be fine
 CDROM drive (DVD nice but no real need yet)
 DVI video adapter with at least 32MB RAM and supports 1280x1024
resolution, (VGA OK) - consider ordering a second display adapter if
you may be running two screens off of this PC

Monitor

The monitor must have a native resolution of 1280 x 1024 (SXGA).

AED is designed for this resolution only.
"Native" means that at that resolution images fill the entire screen and
look the sharpest and best that the monitor can display. Alternate, non-
native resolutions either will be stretched slightly resulting in a blurred
look, or have unused black strips on the sides or top of the display.
For touch screen monitors we have had great results with Elo Touch
monitors, in particular the 1928L. They use SAW touch technology
which is the more long-lived (compared to resistive), and also they seem
to keep their calibration quite well, unlike some we tried. The company
is knowledgeable and helpful as well. For embedding in a built-up
display they have various models which have no stands and are ready to
be encased in your own enclosure. We had a bad experience with Planar
quality and calibration characteristics, and did not find 3M touch drivers
to be of sufficient quality.
If you choose a touch screen monitor other than the Elo Touch monitors
recommended above, be sure to read several reviews for your particular
choice of monitor. Accuracy of touch and long term alignment vary
widely among touch screen manufacturers and within price ranges. If
you still need help choosing a monitor you can contact our software
engineer Russ Welti at russ@iris.washington.edu.
For non-touchable installations just about any monitor will do.
Naturally, flat panel LCDs with good contrast ratios and a trusted name
are better choices.
We don't currently support other display resolutions, which includes
most all of the recent crop of inexpensive large screen HDTV-like
monitors on the market. There are a number of reasons but one good one
is that we want to allow for an interactive experience, and the large
screens are generally for multiple people to view from a distance, not for
touching. Also, the aspect ratio of these screens tends to be wide, not
squarish, so our content would not make effective use of the screen's real
estate without redesigning the content (which we are looking into).

Internet connection

Good: T1, T3; wired cable; wired DSL; uncongested, strong wireless
So-So: congested or weak wireless; satellite; ISDN
Not Okay: dial-up connections, non 24-7 connections
Much of the content in the AED can and will be cached by your web
browser, however certain items (mainly the seismicity maps) change
often and therefore cannot be cached. The seismicity maps are currently
about 250-300Kb in size. For this reason, we have had poor results in
our tests using modems or congested wireless networks, such as at
conferences, hotels or exhibition halls.
The AED frameword does support using content local to a given
machine, so in the unusual case where all the content for a display were
on its hard disk, a modem or slow Internet connection could be
acceptable. We are, in fact, exploring a version of AED whose content
would mostly come on a DVD and which would fetch seismicity maps
in the background to the hard disk as a separate task from the display.
Connection types described here.
Test your connection speed here.

Kiosks

There are many companies which

supply ready-made enclosures with
many styles, heights, materials,
custom artwork, dual screens, etc.
Some have wheels on the back bottom
so they can be easily moved. Others
can be disassembled and placed into a
custom travel case for easier shipping.
Some are wall-mounted.
Here is a picture of our prototype
kiosk running an early version of
AED:
Software Requirements

Operating System

Windows XP Pro or Home Edition. (Vista probably works but haven't

tested that yet. Mac or Linux may be OK but we cannot provide much
support.)
Security

This is a very important concern. There will be those who will try to
gain access to the PC, perhaps by finding a way to crash the AED
software and get to the Desktop. (The topic of "PC lockdown" can be
Googled for in-depth information.)
Here are six security measures that can be taken:
1. Minimal, Non-Administrator account
Don't run AED in a public setting from an account which has
Administrator priveleges. Create a separate, "limited" account for
use with AED. On this account, remove all items you can live
without from the Programs menu by either deleting the program's
alias from the menu, or even better by uninstalling it with Add and
Remove Programs. Good things to uninstall include Word, Excel,
Outlook, Messenger and Powerpoint.
Examine the Task Bar closely and consider removing any
extraneous items, many of which are accessible from the Programs
menu anyway.
2. Anti-Virus
We have installed Norton Anti-Virus software and find it to be
OK, though purchasing and keeping it licensed and up-to-date via
their website is difficult and annoying. A free package that seems
to work fine and may be adequate for many users is
called ClamWin Free AntiVirus for Windows. When installing and
configuring, we generally use the defaults, except we try to avoid
settings that will "notify" with popups, as they come up during
AED use. Unfortunately it has been impossible to avoid some level
of messages coming up from the Task Bar such as "Windows
 updates" and so on, but generally these dialogs only have one
button "OK" or "close" so are not a danger.
3. AED loop-forever script
During installation you will install a simple DOS script, which is
simply a forever-looping invocation of the AED software. If AED
crashes (rare but possible) control returns to the script which
simply invokes it again after a user-adjustable delay, during which
you can press control-C to stop the script. With the delay set to
zero, the AED browser comes up again so quickly after a crash that
there is no opportunity to see or access anything else. It's very
simple. (An administrator must use the keyboard and issue the
control-alt-delete to get to the Taskbar and end the looping script
or simply reboot the machine. )
4. PC lockdown software
Microsoft makes a free package that will convert a Windows
acccount to have very few privileges and "locks down" the
machine when that user is logged in. It is called Microsoft Shared
Computer Toolkit. We have not used this because of the time and
energy needed to install and maintain it, and a lack of information
relating to the value and reliability of it. It is for libraries and
Internet cafes. It looks promising but a tad complex.
Another example might be SentryPC, which can do things like
hide the Desktop and Task Bar from a user for about
$50.The installation instructions contain a lot of tips for making
the AED account as little of a security liablilty as possible, and if
the display will be in an area where staff are able to loosely
monitor it then PC lockdown software may be overkill.
If you are in doubt please get additional advice on locking down
your PC and/or installing the Toolkit above. IRIS cannot be
responsible for the lockdown of AED PCs. We welcome advice on
what might be the best solution or product to recommend.
 5. NO LINKS in content (that you create and add to your display)
All content in your display should be devoid of links that go
outside of the content. Scrutinize it carefully for any sort of link. If
you include content with links, even "mailto:" for example,
someone will be able to hijack the browser and from there
anything is possible.
You can still have links in your content, just link to your own
content.
It is best to author content explicitly for use with the display if you
can.
If you link to someone else's content (aside from the content we
provide of course), even if there are no linkss in the content now,
they may insert them at some later time.
6. Hide the keyboard.
The lack of a keyboard or any way to enter text for the AED is a
major limiter to how much damage unauthorized access can cause.
Your keyboard should be kept locked in the display cabinet or
somewhere near, but not with, the display. The AED does not use
the keyboard for normal use.
Browser

At this time we are evaluating whether we want to endorse Internet

Explorer or Firefox as our recommended browser. Most of our
development and testing was done with Internet Explorer, because until
recently, it was the browser with the best full screen support.
These instructions assume you will use IE, but if you have the expertise
and want to use Firefox that's fine.
Benefits of Internet Explorer 7
 Large tooltips
Tooltips presented by such things as seismicity mouseovers can easily
be made nice and large:

(Firefox can do this, too, it turns out. But you have to edit the
userContent.css file and insert a few lines of CSS.)

 Filters and transitions

Some AED content uses filters or transitions which do look nice in
IE. For example the first three pages of content "blend" from one to
the next as you arrow, and the "did you know" lightbulb popups use a
filter to "slide" in and out of view in a nice way. Full screen can be
controlled by a command line parameter "-k" for kiosk. Firefox full
screen mode at startup is a preference that must be turned on and off
manually. ClearType really does make smoother, less pixelated text.
Necessary Plug-ins for Either Browser
 Flash 9
 The "engine" that drives the display and communicates with the IRIS
server uses Flash. For convenience we would like all the displays to
run the same Flash version, the latest version, version 9.
 QuickTime 7
Currently required only for a couple of the pages, the "draggable
globes".
We have converted most movies into Flash-encoded video, but the
draggable globes are QTVR, which is an interactive form of
QuickTime that has no easy conversion, so far. If you don't want
QuickTime then don't install it and just don't use the two draggable
globes pages.
Necessary Add-On for FireFox (2.0+) Users

 If using Firefox (2.0+) we commend the addon called "Full

Fullscreen" 1.5 or higher. During installationyou would also need to
edit the looping script run_aed.bat to invoke FF, and make sure
fullscreen is set to be on "at startup" of browser. You'd want to edit
the userContent.css file. Some minor content appearance differences
may exist.

An intranet often gets confused with the Internet. While there are a lot of
similarities between them, they really are two different things. Simply
put, the Internet is the global World Wide Web, while an intranet is a
private Internet operating within a company. Both the Internet and an
intranet use TCP/IP protocol as well as features like e-mail and typical
World Wide Web standards. One main difference is that users of an
intranet can get on the Internet, but thanks to protection measures like
computer firewalls, global Internet users cannot get onto an intranet
unless they have access to it. In fact, an intranet can be run without an
Internet connection. While Internet technologies like browsers, servers,
and chat scripts are still used, an intranet can be a separate entity as long
as its owners do not require that users have access to information found
on the Internet. When they were first introduced, intranets were
dismissed by critics as the latest in a seemingly endless parade of
technological fads and buzzwords. That soon changed when businesses
started to realize just how important a tool an intranet can be. A
company would want to set up an intranet for many reasons. The broad
bandwidths that are used in intranets allow for speedier communication
and access to information than the Internet. The private internal
networks (such as a LAN) offer security and protection in the form of
the aforementioned firewalls as well as password-protected access and
secure servers. The use of an intranet allows companies to control their
business easier and manage their employees more successfully. Less
paperwork, increased productivity, added flexibility, and versatility are
other factors that intranet users take advantage of. All of this adds up to
a bottom line that is attractive in any business decision: the ability to
save money and increase profits. An extranet is part of a company's
intranet that can be accessed by users outside of the company. Clients,
vendors, suppliers, and business partners are just a few examples of the
types of people who would benefit from this type of private network.
They can exchange large volumes of data using Electronic Data
Interchange (EDI), share exclusive information, collaborate on joint
business ventures, participate in training programs, and share services
between the companies. An extranet is a way to telecommunicate and
share business information securely without having to worry about it
being intercepted over the Internet. This is achieved by taking extra
security and privacy measures with the extranet, including firewalls,
required passwords, and data encryption.
Besides supplying infrastructure for Web applications by providing a
natural developmental and staging area for these applications, intranets
have become so useful that they are now generally recognized as being
necessary even if the organization has no need for Internet applications.

1. Document publication applications

The first application that always comes to mind for intranets in and of
themselves is the publication and distribution of documents. This
application allows for paperless publication of any business information
that is needed for internal employees or external customers or suppliers.
Any type of document may be published on an intranet: policy and
procedure manuals, employee benefits, software user guides, online
help, training manuals, vacancy announcements--the list goes on to
include any company documentation.

2. Electronic resources applications

In the past it has not been easy to share electronic resources across
network nodes. Employees have had problems sharing information for
various reasons including software version inaccuracies and
incompatibilities. Intranets provide the means to catalog resources online
for easy deployment across the network to any authorized user with the
click of a mouse. Software applications, templates, and tools are easily
downloaded to any machine on the network.
3. Interactive communication applications
Two-way communications and collaboration on projects, papers, and
topics of interest become easy across the intranet. Types of
communications that are enhanced and facilitated include e-mail, group
document review, and use of groupware for developing new products.

4. Support for Internet applications

Even though organizational full-service intranets are the next step in
enterprise-wide computing and have enough value to make them
desirable simply for the organizational benefits they bring, they are also
necessary for supporting any Internet applications that are built.

The transactional processes and trading of information that will be done

by all but the most elementary Web applications will require an
infrastructure to store, move, and make use of the information that is
traded. The infrastructure to accomplish those tasks is the organizational
intranet.
The development and maintenance of the Internet application requires
that the organization has a developmental environment and the means to
test the applications prior to placing them on the Internet. This requires
an intranet that mirrors the functionality of the Internet. The
infrastructure also requires that the Internet application be easily updated
and maintained by the staff that has the responsibility for the application.
The infrastructure becomes even more important until the middleware to
easily manage Internet applications becomes available. Because both
intranet and Web application tools are still missing, maintenance on
Internet applications will remain labor intensive for the next 18-24
months.

Others
The most popular intranet application is obviously inter-office e-mail.
This capability allows the employees of a company to communicate with
each other swiftly and easily. If the intranet has access to the Internet, e-
mail can be accessed through the Internet connection. If the intranet is
running without the Internet, special e-mail software packages can be
bought and installed so that employees can take advantage of its many
benefits. An intranet has many other different applications that can be
utilized by a company. These include the Web publishing of corporate
documents, Web forms, and Web-to-database links that allow users to
access information. Newsletters, information on benefits and 401(k)
enrollment, job listings and classifieds, libraries, stock quotes, maps,
historical data, catalogs, price lists, information on competitors'
products, and customer service data are just a few examples of these
types of applications. In addition, there are several other main
applications that are very popular in the intranet format. Every type of
company has to deal with forms of some sort. This is another area where
paperwork can become a problem for a business. Intranet servers can be
equipped with programs that allow for forms to be filled out online.
They could also be downloaded and printed out by the users themselves,
which would cut down on the time it would take to distribute these
forms manually. Organizational policy and procedure manuals are also
handy to have on an intranet. Unlike printed hard copies, online manuals
can be easily accessed by all employees at any time. They are also easier
to organize online, and can be indexed by subject and attached to a
search engine to provide for easier navigation through the manual. In
addition, changes can be made more quickly and easily when they are in
this format. Converting printed materials to Web browser readable
formats is fairly simple and requires either an appropriate html translator
or a way for the original word processor documents to be launched with
a specific application. Phone directories are one of the most useful
intranet applications. Again, this type of application cuts down on
paperwork and the time and money it takes to produce hard copies of
these directories. Instead, employee names, titles, duties, departments,
phone and fax numbers, e-mail addresses, and even photographs can be
stored in an online directory. They then can be easily searched and
updated at any time with minimal effort. It is suggested that a few paper
copies of the employee directory and other important records be kept on
hand in the event that the intranet is experiencing technical difficulties.