THE LAN TUTORIAL SERIES


PART 1: Buying a LAN


This short article kicks off LAN Magazine's new series of
"clip-and-save" tutorials about LANs. Each month we will print an
easy-to-read tutorial -- aimed at users new to networking --
covering one aspect of LAN purchase, installation and management.
This first tutorial is a very basic introduction to the issues
involved in buying a LAN. Along the way is an overview of the
components of a LAN and a list of the next 12 topics to be
covered.

A year from now, if you clip carefully, you should have a short,
easy-to- understand introductory pamphlet about the principles of
local area networking.

A Definition
A LAN is a data communications network spanning a limited
geographical area, a few miles at most. It allows users to share
information and computer resources, including mass data storage,
backup facilities, software, printers, plotters and processors.

Typically, a LAN is made up of network interface cards (circuit
boards) that fit inside the connected computers, cable to connect
these computers, protocol software to move data from computer to
computer, user interface software to connect user and network,
and operating system software to actually service users' needs
for things like files and printers.

Why Buy a LAN?
LANs require a certain mind set, something different from
traditional MIS (Management of Information Services) thinking.
Once a LAN is installed, things like initiative, democracy,
participation, communication and independence take over.
Hierarchy, dependence, regulation and isolation are thrown out
the window.

If you have the right mind set, the four best reasons to buy a
LAN are:

@Communication. A LAN connects the people in your company. Once
connected, every possible form of discourse is possible, from
electronic "yellow sticky things" to formal legal briefs. People
like to communicate.

@Democracy. A LAN distributes your company's computer resources
to everyone connected. Once the LAN is installed, everyone from
mail clerk to CEO will want, and should have, access.

@Productivity. A LAN's ability to share computer resources and
information easily helps people do their jobs quickly,
efficiently and with less hassle. The LAN will quickly become the
heart of your business. It's the heart of ours.

@Savings. A LAN saves money by allowing users to share expensive
computer resources -- printers, plotters, hard disks, WORM
drives, CPUs, software, etc.

If you don't have the right mind set, the four best reasons not
to buy a LAN are:

@Communication. Connecting all the people in your company might
let them talk to each other. Who knows, they might plot your
overthrow.

@Democracy. Distributing resources will give everyone in the
company a measure of power. Who knows, they might not do what you
tell them.

@Productivity. Doing the job in new and better ways might lead to
the elimination of dull, tedious work. Who knows, it might mean
the elimination of your job.

@Savings. Sharing expensive computer resources saves money. Who
knows, you might have to save money all the time.

LAN Components
Buying and installing a LAN is not simple. There are many things
to think about. Here are 12 that cover the basics of LAN purchase
and installation.

1. The OSI Model , which stands for the Open Systems
Interconnection model of the International Standards
Organization, is a useful categorization of the different parts
of a LAN. It is an overview of how a network works.

2. The Access Method is the way the network arbitrates which
device may use the cable and for how long. It is necessary since
two devices can't talk at the same time. Different access methods
provide different network performance and reliability.

3. The Interface Card is the device that connects the computer to
the cable. These vary by type, size, speed and much more.
Performance is a key issue.

4. The Cabling is the physical connection between networked
devices. Fiber optic, coaxial and twisted-pair are the main
choices. Each has advantages and drawbacks.

5. LAN Protocols are software that run in the computer and on the
network interface card. They provide the means for shipping data
between devices. Certain sets of protocols are good for certain
applications. Which you choose depends upon what you use your
network for.

6. The LAN Operating System is the software that resides in the
computer. It provides the interface between the user or
application and the network. The key issues here are performance,
compatibility and ease of use.

7. The File Server stores and distributes program and data files
to be shared by users on the network. It is a hardware/software
combination heavily dependent on the LAN operating system and the
type of work you are doing.

8. Network Printing allows many users to share one or more
printing devices. Some LAN operating systems do it better than
others. Sometimes you'll need special network print utilities.

9. Tape backup, done regularly, maintains data integrity on a LAN
by recording data on tape instead of disk. Key issues include
capacity, speed, compatibility and ease of use.

10. LAN Security covers the methods used to protect data from
corruption by unknowing users, accidents and intruders. These
include physical security, encryption and passwords. But the type
of security you use depends mostly on the type of work you are
doing on your network.

11. Bridges and gateways connect networks. Each uses different
methods with different results. Bridges connect networks at a
lower level than gateways, making them more versatile. On the
other hand, gateways connect networks that bridges can't.
Performance and compatiblity are the key issues.

12. LAN Management is the name given to the best job in the
world: taking care of the network. Different LANs provide
different levels of management to make the job easier. Your level
of skill and confidence will be crucial here.

Application Specific
The type of LAN you buy depends primarily on the work it will do.
Before evaluating different vendor options, assess your company's
computer needs and resources, present and future. As much as
possible, conserve your present computing power, even if you plan
to upgrade.

Will the network be used mostly to share peripherals like
printers and hard disks? If so, access methods and performance
are less important than reliability and ease of use. Will the
network be used mostly for large database access? If so,
performance is paramount. Will the network be used mostly for
communications and electronic mail? If so, wide-range standards
compatibility may be the most important issue in your decision.

Usually, you want the network to do everything: start out
peripheral sharing, add databases then connect to mainframes.
Thus, growth potential and standards are very important to your
decision, since you're laying a foundation upon which you will
build.

Other overall considerations include: the education of users
(beginners and experts); the types of computers you are
connecting (PCs, minicomputers and/or mainframes); and the amount
of money you have (lots or a little.)

Unfortunately, no LAN does everything. Vendors make compromises,
sacrificing ease of use for performance, performance for
compatibility or vice versa. Since this is the case, get to know
exactly what you want before you buy. 

-- Aaron Brenner