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An Introduction to Intranet Setup.
The Intranet is a new word for an old concept. Like generally happens, when "new" people get old concepts they suppose are new things, but are wrong. The concept of Network, LAN (Local Area Network) or WAN (Wide Area Network) ... are very old concepts.
However, when the Internet become real popular starting from the US, and "cover" the world covering and expanding the concept of network. With the introduction of Linux, a free Operating system, free in every sense and without limitation advantages and disvantages apperas in any sense.
The advantages are basically that "people" without any previous or professional experience start to install networks. Also, founding companies for these purpose. Again, because they really have no experience this is a problem.
Please consider the following figure:
Therefore Intranet is a new word to describe a non-Internet network. So, while the Internet is the Worldwide network composed by thousand of computer, the Intranet is the local network, valid for big companies, from 500 PC, or small from two PC, up to 499, and same is valid for Local Area Network (small distances) or WAN (Wide Area Network), high distances.
Network needs minimal two PC. A single PC is not a network, neither when connected to the Internet.
The Network Transmission types.
In the next two sections we will introduce the some "internal" and "hardware" explanations about networks. We will cover the transmission network types, or how we will connect PC each others. The transmission types or how the bytes are sent using the cable from one computer to other. The Transmission types are also called the "protocol" types.
The point-to-Point network (PPP) may be visualized as in the figure:
In this mode, there are one-system ... connected to each PC.
On Linux the PPP or Point to Point Protocol is used generally to connect the PC to the ISP (Internet Service Provider).
[root@ftosx1 orlando]# rpm -qi ppp
Name : ppp
Relocations: (not relocateable)
Version : 2.4.1
Vendor: Red Hat, Inc.
Release : 2
Build Date: Fri 10 Aug 2001 05:54:58 PM CEST
Install date: Wed 09 Jan 2002 02:16:53 PM CET
Build Host: stripples.devel.redhat.com
Group : System Environment/Daemons
Source RPM: ppp-2.4.1-2.src.rpm
Size : 340483
License: distributable
Packager : Red Hat, Inc. <http://bugzilla.redhat.com/bugzilla>
Summary : The PPP (Point-to-Point Protocol)
daemon.
Description :
The ppp package contains the PPP (Point-to-Point Protocol) daemon
and
documentation for PPP support. The PPP protocol provides a method
for
transmitting datagrams over serial point-to-point links. PPP
is
usually used to dial in to an ISP (Internet Service Provider)
or other
organization over a modem and phone line.
[root@ftosx1 orlando]#
However, PPP may be also used with the Serial line (SLIP). You can also check the Linux Kernel Documentation to understand it.
The MultiPoint-to-Point is one system connected to a net of PC. This
is the traditional Server-Client mode.
Using Sharing facility is possible to transform the previous Client-Server network in a Distributed network.
In the previous example, each user have its hard-disk and its data. Only Transfers are possible from one-to-other PC. Not sharing is active in the previous example.
Basically is the same, with the different that hardware resources like Hard-Disk and Printers are shared. For example, suppose suppose that images are located on a Mac system. The images directory is shared using netatalk with the a specific machine.
And again suppose that these directory is exported via NFS to the entire local network.
Under Linux the concept of shared printer is wrong. Shared is basically a word used by hard-disk. Of course, a network printer will be a printer "shared" with the PCs capable to use it.
Actual networks uses a mix between point-to-point and multipoint. The Network Hub play the role of MultiPoint-to-Point. Computers between them haves a point-to-Hub connection, that is a point-to-multiple.
Transmission Protocols: Synchronous, Asynchronous and Isosynchronous
In the previous section we introduce Point-to-Point and Multi-Point networks. Here we will cover the transmission types, or how the bytes are send thought the line.
Suppose you get the following exercise from your teacher:
A building is wired with 10MHz Ethernet cable. Assuming a velocity of propagation 20 cm per nanosecond, calculate the number of wavelengths of the 10MHz signal along a 30 metre length of cable.
Answer ........ One cycle at 10MHz is 100
nsecs occupying a distance of 2000 cm or 20 metres, so there are 1.5 whole
cycles or wavelengths along the cable. One could not run arbitrarily spaced
synchronous computers on a
cable like this at a clock speed of 10
MHz, without including some synchronising apparatus in hardware or software
that would impose a speed penalty on the system. The preferred technology
for modern high speed
communications at a distance between digital
machines is called Asynchronous Transfer Mode (ATM is the acronym). This
technology is designed to circumvent the delay and synchronisation problems.
From a common dictionary we will get that the Asynchronous transmission is the following:
A communications system in which data
transmission may start at any time and is indicated by a
start bit, e.g. EIA-232. A data byte (or other element
defined by the protocol) ends with a stop bit. A
continuous marking condition (identical to stop bits but not
quantized in time), is then maintained until data resumes.
Without to enter in details, a short definition is the following:
Because the Asynchronous mode is the most used in High Speed connections
like: ISDN (Integrated Services Digital Network) and ADSL (Asymmetric Digital
Subscriber Line), we includes here a diagram.
A protocol is the mode the bytes are send between system in the network: TCP/IP (Transmission Control Protocol/Internet Protocol) is a protocol, ICMP (Internet Control Message Protocol) is a protocol, FTP (File Transfer Protocol) is used for a stable download, IPX (Internetwork Packet eXchange) is the Novell protocol, HTTP (is the Hypertext Transfer Protocol), The AppleTalk, is the normal protocol used by Apple to connect its Macs, the NetBUI (NetBios ). Samba uses NetBIOS over TCP/IP (NetBIOS stand for NetBios Extended User Interface) protocols, etc.
The concept of LAN (Local Area Network) and WAN (Wide Area Network) are equivalent to the concept of Local and Wide distance, from the network perspective. LAN is used where the distance between the nodes are (In SI: meters), in English System are foots or inches. Not kilometers or milles.
For example, while the Network inside a company generally is a Local Area Network; the system used by the phone company is a WAN. Not only for the distance but also for the speed of connection involved between the nodes.
We present here a WAN,
Therefore the difference between LAN and WAN are characteritized by the following points:
Depending of its geometry a LAN/WAN may have the following forms:
In the network with the a form of Star, all the PC are connected to the Server. We visualize it here:
This is the form used in the "Siracuse-Rome-Itaca" network in the presentation figure above.
The network with the form of chain only one computer is computer to
the Server. All the other nodes are connected each others. Therefore there
are a first node and a last node that includes a terminator. This network
type was used in the 90, and is now 'obsolete'.
The Network with a Bus-Form is the following:
This form is used basically (but not necessarily) on schools, colleges and training facilities.
Different Intranet Configurations
In this latest section we cover the possibilities to use an MS Window or Mac Operating System on the the clients and Linux in the Server, evaluating vantages and disvantages.
Note. In some sub-sections here the Author (Dr. Giovanni A. Orlando) may advice the use of Linux as a Desktop. These comments are based on the more than twelve years of daily use of UNIX (Sun, HP, Interactive) and now Linux (basically FTOSX) as a Desktop. The author apologize if these advices, or the evaluation of this possibility may be offensive for non-Linux-desktop users.
Linux server with MS-Windows clients
The mode UNIX and then Linux was introduced in companies was as a Server machine. In the 90, UNIX was used as a terminal-based Operating System, then with the inclusion of Apache in Linux distro, Linux become popular as a WebServer.
Of course, also NT as Server and MS Windows as client were (and are) full accepted around the world.
The adoption of this solution is based on the logic that MS Windows includes all the necessary software like: MS Office, MS SQL Server, and only MS Windows have.
This conclusion is not logical but wrong. StarOffice developed by StarDivision GmbH and actually free under the OpenOffice is completely equivalent to MS Office.
This is a simple example, there are other thousands.
Of course, MS Windows continue to be the most used Operating System.
I suppose that Linux may be used very well as a commercial arena for companies like Adobe, Macromedia and also Microsoft ... with its Office suite, explorer and other product; like actually these companies does on Apple Mac OS X, a UNIX based OS.
These companies does not move to Linux in a clear and definitive mode, because 'there are no a commander' in the Linux arena. While Apple is a company that adopt UNIX, neither Caldera, RedHat, SuSE and other minor does not represent a valid reason to invite these companies to move.
There are, however a special space reserved for a good business in this arena.
Linux server and Linux client.
This is probably the most futuristic approach. While MS Window continues to release its software, Similar or better software is available on Linux, in native mode offering the similar or better results.
Personally, I think are different times and seasons for everything. Basically the PC born in Apple and they actually continues to support only a specific type of hardware. IBM, re-invent the Personal Computer using Intel processors, and installing D.O.S. Then was the time for Microsoft, starting for its D.O.S., and then its Microsft Windows Serie, actually still in charge.
I think that this is Linux time. Of course because Linux start to be used as a WebServer, like UNIX was a Server, some persons may suppose that Linux may don't work as a client. These persons make these statements simply because they don't know Linux and X Window.
Hundred of companies offers a mode to run MS Windows binaries on Linux. Of course this is usefull, but use a native product is better than an emulator.
OpenOffice is better than MS Office using VMWARE ... and less expensive!
The use of Linux in any sense is possible.
Heterogeneous networks: UNIX, Linux, Macintosh and others.
Depending of the software you need to run inside your company you may install a MS Window, a Mac or other. Generally, companies uses MS Windows for everything. Other uses a mix between Mac and UNIX, other simply Linux.
The results you need to get make the difference. If you need Adobe Illustrator, would be better to use it on the Mac, actually. If you need to use Office, the better solution is to use OpenOffice, the native flavor made available by OpenOffice.org.
Of course, may be necessary to adopt a specific Operating System, depending of your business.
We present here the most heterogenous possible network including also
X-Terminals, Novell Servers as well a Mini and a MainFrame. Normally, the
most popular network are in the bottom-right side, without to includes
the X-Terminal.
Read the answers
to the exercises.
Check the Interactive Exam Cram WebMaster: 
Internet Resources for this Chapter.