This chapter is from the book
This chapter is from the book
This chapter is from the book
Network Interface Cards (NICs)
NICs—sometimes called network cards—are 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. Consider the following when buying a NIC:
Network compatibility—Perhaps 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 a NIC for another networking system.
Bus compatibility—Newly 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, 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. 64-bit slots are referred to as PCI-X and are backward compatible with 32-bit PCI. Figure 3.18 shows 32-bit PCI slots on a system board.
Port compatibility—Generally a 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 compatibility—Before 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.
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Figure 3.18 32-bit PCI slots on a system board. (Photo copyright © Intel Corporation.)
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.
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Figure 3.19 An expansion NIC.
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Figure 3.20 A PCMCIA NIC.
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Figure 3.21 A built-in network interface on a laptop system.
A network interface typically has at least two LEDs that indicate certain conditions:
Link light—This 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 light—This 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 light—This LED indicates that the interface is connected at a certain speed. This feature is normally found on Ethernet NICs that operate at 10Mbps/100Mbps—and 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.
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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 likely that you will have to install a 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 to 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. Always make sure that you have the latest drivers by visiting the website of the NIC manufacturer. The drivers play an important role in the correct functioning of the NIC, so spend a few extra minutes to make sure that the drivers are installed and configured correctly.
NIC configuration utilities—In 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 3.23shows an example of jumpers. Unless you are working with very old equipment, you are unlikely to encounter dip switches.
System resources—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 availability—Most 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 in to 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. Check to make sure that a slot is available before you begin.
Built-in network interfaces—A 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 upgradeable. 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, consult the documentation that came with the system or look for information on the manufacturer’s website.
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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.
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.