Lesson 4: Ensuring Hardware Compatibility
Networking is hardware-dependent, and not all hardware products are compatible.
In Chapter 6, "Defining Network Protocols,"
we learned that in order for two computers to communicate, they must use
the same protocol. Computer hardware raises similar issues. In some instances,
two pieces of hardware simply can't communicate with each other. For example,
consider an analogy to automobile parts: two parts might look alike and
be able to perform the same function, but each is designed to work in a
different car. This lesson examines the issue of ensuring hardware compatibility
and what you can do to resolve incompatibilities.
When Hardware Is a Problem
Hardware incompatibilities are a fact of life. In today's computer industry,
hundreds of manufacturers develop hardware and software. Each developer
has a unique perspective on the best way to accomplish the same task, and
each will provide a unique solution. Copyright and patent issues further
complicate the matter.
Evaluating and selecting hardware is a major part of planning for network
implementation. If you have the luxury of designing a network from the
ground up, you can choose vendors and place the burden of compatibility
on them. Before you make a purchase, give them a list of the hardware you
plan to use and ask them to certify that those items are compatible with
the vendor's products. Also, don't be too quick to accept one vendor's
opinion. For example, if you are considering the purchase of two devices—X
and Y—ask the vendors of X if their product is compatible with Y, and ask
the vendors of Y if their product is compatible with X. Then compare the
responses you get; they may help you to find an incompatibility you would
otherwise fail to detect.
It is likely that you will have to create a network out of an existing
collection of hardware. In such cases, the likelihood that problems stemming
from incompatible hardware will arise is very high. It is sometimes more
cost-effective to discard the old hardware and start over.
The most common incompatibilities occur between hardware and software.
Changing or upgrading a computer or network operating system can lead to
major problems. As discussed in the previous lesson, you might need to
update hardware drivers at the same time you upgrade the software. Be sure
to address this issue before you start.
Reading the Documentation
Read all the documentation about the products involved. Your hardware or
software might have a recurring problem or might conflict with another
product. Frequently, the manufacturer will document these conflicts and
provide a fix. If you do not find the solution in the supplied documentation,
you might contact the manufacturer of the product and ask for undocumented
conflicts. Search the manufacturer's Web site for additional information.
Detection During Installation
When you install a new computer or network operating system, your computer
will usually attempt to detect the hardware in the system during the installation
process and load the appropriate drivers for it. Check the list of detected
hardware and ensure that it matches what is already in the machine. If
you are installing Novell's IntranetWare, for example, the install utility
will automatically scan your computer for hardware such as hard disks,
CD-ROM drives, and NICs. If the devices are recognized, the appropriate
drivers will then be loaded for the recognized devices.
Checking Minimum Requirements
As a first step before you install, make sure that you exceed the minimum
requirements for the resources in the computer. These resources include
processor speed, memory, and disk space. Table 8.2 lists some minimum hardware
requirements for common network software.
Table 8.2 Minimum Hardware Requirements for Network Software
||Windows NT Server 4.0
||486 33 MHz or higher
||486 66 MHz or higher
||3.5 high density
Remember that these are published minimum requirements. Treat these
minimum requirements as you would, for example, treat a statement that
a bicycle is the minimum requirement for riding up Pikes Peak. It can be
done, but it would be much easier and a lot more fun in a powerful car.
Windows NT Server with 16 MB of RAM will run and function in a 33MHz processor,
but not quickly.
Network hardware is not as susceptible as software to conflicts and compatibility
problems. Chapter 7, Lesson 1: Connectivity Devices,
covers the basics of how these devices (repeaters, bridges, routers, brouters,
and gateways) work. These devices operate at the two lower layers of the
OSI reference model (the physical and data-link layers). Since these devices
are common to many different types of networks and work mainly with data
packets, they are less likely to present conflicts. The manufacturers of
these products maintain strict adherence to the IEEE 802.x standards. Therefore,
any device that meets an IEEE standard can communicate with another device
that meets the same standard. The only situation in which you can expect
incompatibility issues to arise is when two devices meet different standards.
For example, Ethernet and Token Ring networks use different methods of
accessing the network. Therefore, a device designed to meet the 802.3 Ethernet
standard will not communicate with a device designed to operate with the
802.5 Token Ring standard.
Exercise 8.4: Upgrading a Network
Knowing what we now know about network and computer compatibility issues,
let's take a look at our bicycle company and see what, if any, problems
we might encounter.
Assume that you and the Managing Director have decided that the best
long-term solution is to install a server-based network. The director has
also decided that she wants to base the network on Windows NT. Provide
the answers to the following questions:
Which resources do you anticipate are likely to present problems in the
future and, therefore, should be upgraded or replaced?
What do you suggest as the minimum operational requirements for equipment
to be acquired in the future?
The following points summarize the main elements of this lesson:
Many manufacturers produce computer networking hardware, each with unique
designs and specifications. Not all hardware products are compatible.
To minimize hardware conflicts, read the documentation that comes with
the hardware product.
Minimum hardware requirements represent values that are sufficient only
to allow the system to start.
Decisions made before installation will either limit or open up future
expansion and performance of a network.