Network Cards (NICs)
NICssometimes called network cardsare the mechanisms by which computers connect to a network. NICs come in all shapes and sizes, and they come in prices to suit all budgets. You need to consider the following when buying an NIC:
Network compatibilityPerhaps this is a little obvious, but sometimes people order the wrong type of NIC for the network. Given the prevalence of Ethernet networks, you are likely to have to specify network compatibility only when buying an NIC for another networking system.
Bus compatibilityNewly purchased NICs will almost certainly use the Peripheral Component Interconnect (PCI) bus, although if you are replacing a card in an older system, you might have to specify an Industry Standard Architecture (ISA) bus card instead. If the card you are buying is PCI, you should check to see what kind of PCI interface is being used. Many high-end server systems now come with 64-bit PCI slots; if you have them, it is definitely worth taking advantage of the extra performance they offer. Such 64-bit PCI slots can be easily identified because they are the same color and width as 32-bit PCI slots, but are longer. Figure 3.18 shows 32-bit PCI slots on a system board.
Port compatibilityGenerally an NIC has only one port, for twisted-pair cabling. If you want some other connectivity, you need to be sure to specify your card accordingly; for example, you might need a fiber-optic or coaxial cable port.
Hardware compatibilityBefore installing a network card into a system, you must verify compatibility between the network card and the operating system on the PC in which you are installing the NIC. If you are using good-quality network cards from a recognized manufacturer, such verification should be little more than a formality.
Many different terms are used to refer to NICs, such as network card, network adapter, and LAN adapter. All refer to the same thing.
Figure 3.18 32-bit PCI slots on a system board. (Photo copyright © 2001, Intel Corporation.)
Sometimes an NIC has a twisted-pair socket, a coaxial connector, and an attachment unit interface (AUI) port. These cards are referred to as combo cards. Today, the dominance of twisted-pair cabling means that most NICs have only a twisted-pair connection.
Types of Network Interfaces
Network interfaces come as add-in expansion cards or as PCMCIA cards used in laptop systems. In some cases, rather than have an add-in NIC, the network interface is embedded into the motherboard. Figure 3.19 shows an example of an add-in NIC, Figure 3.20 shows a PCMCIA network card, and Figure 3.21 shows a built-in network interface in a laptop system.
Figure 3.19 An expansion NIC. (Photo courtesy TRENDware International, http://www.trendware.com.)
Figure 3.20 A PCMCIA NIC.
Figure 3.21 A built-in network interface on a laptop system.
The False Economy of NICs
The difference between an inexpensive network card and an expensive one is less than you might think; but even so, people are tempted to go for the low-cost option. In many cases, this turns out to be a false economy. Not only do higher-end cards tend to be easier to install, they are generally easier to troubleshoot as well. An hour trying to troubleshoot a misbehaving inexpensive network card can negate any cost savings from the purchase. This is particularly relevant on server systems, where a problem network card will not only cause you frustration, but will most likely cause the users of the server problems. In fact, if you are working on server systems, it's worth investigating fault-tolerant network card configurations, such as adapter teaming.
You might notice that the modem in Figure 3.20 is the same card used in Figure 3.17. No, it's not a mistake: This PCMCIA card is a network card and a modem. Clever, eh?
A network interface typically has at least two LEDs that indicate certain conditions:
Link lightThis LED indicates whether a network connection exists between the card and the network. An unlit link light is an indicator that something is awry with the network cable or connection.
Activity lightThis LED indicates network activity. Under normal conditions, the light should flicker sporadically and often. Constant flickering may indicate a very busy network or a problem somewhere on the network that is worth investigating.
Speed lightThis LED indicates that the interface is connected at a certain speed. This feature is normally found on Ethernet NICs that operate at 10Mbps/100Mbpsand then only on certain cards.
Some network cards combine the functions of certain lights by using dual-color LEDs. PCMCIA cards sometimes have no lights, or the lights are incorporated into the media adapter that comes with the card. You can see an example in Figure 3.22.
Figure 3.22 Indicator lights on a media adapter for a PCMCIA NIC.
Installing Network Cards
At some point in your networking career, it is very likely that you will have to install an NIC into a system. For that reason, an understanding of the procedures and considerations related to NIC installations is useful. Here are some of the main things you should consider:
Drivers Almost every NIC is supplied with a driver disk, but the likelihood of the drivers on the disk being the latest drivers is slim. You should always ensure that you have the latest drivers by visiting the Web site of the NIC manufacturer. The drivers play a very important role in the correct functioning of the NIC, so spend a few extra minutes to make sure the drivers are installed and configured correctly.
NIC configuration utilitiesIn days gone by, NICs were configured with small groups of pins known as jumpers, or with small plastic blocks of switches known as dip switches. Figure 3.23 shows an example of jumpers. Unless you are working with very old equipment, you are unlikely to encounter dip switches.
System resourcesIn order to function correctly, NICs must have certain system resources allocated to them: the interrupt request (IRQ) and memory addresses. In some cases, you might need to assign the values for these manually. In most cases, you can rely on plug-and-play, which assigns resources for devices automatically.
Physical slot availabilityMost modern PCs have at least three or four usable expansion slots. Not only that, but the increasing trend toward component integration on the motherboard means that devices such as serial and parallel ports and sound cards are now built into the system board and therefore don't use up valuable slots. If you're working on older systems or systems that have a lot of add-in hardware, you might be short of slots. You should check to ensure that a slot is available before you begin.
Built-in network interfacesA built-in network interface is a double-edged sword. The upsides are that it doesn't occupy an expansion slot and hardware compatibility with the rest of the system is almost guaranteed. The downside is that a built-in component is not upgradable. For this reason, you might find yourself installing an add-in NIC and at the same time disabling the on-board network interface. Disabling the on-board interface is normally a straightforward process, achieved by going into the BIOS setup screen or, on some systems, a system configuration utility. In either case, you should consult the documentation that came with the system or look for information on the manufacturer's Web site.
When installing any component in a system, you need to observe proper and correct procedures to guard against electrostatic discharge (ESD). ESD into a computer component can cause it to fail immediately or degrade so that it fails at some point in the future. Proper ESD precautions include wearing an antistatic wrist strap and properly grounding yourself.
Figure 3.23 A block of jumpers.
Although these methods were efficient and easy to use, they have now largely been abandoned in favor of software configuration utilities, which allow you to configure the settings for the card (if any) and to test whether the card is working properly. Other utilities can be used through the operating system to obtain statistical information, help, and a range of other features. Figure 3.24 shows an example of one such utility, called PROSet, for the Intel 8255x series of NICs.
Figure 3.24 The Intel PROSet utility.
As time goes on, NIC and operating system manufacturers are making it increasingly easy to install NICs in systems of all sorts and sizes. By understanding the requirements of the card and the correct installation procedure, you should be able to install cards simply and efficiently.