Network Interface Cards

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A NIC is a circuit board that is inserted into an available bus expansion slot on a computer system’s motherboard. It allows a computer to connect to and communicate with other computers on a network or LAN.

A NIC operates at the MAC sublayer of the OSI reference model’s data link layer and has a 10-digit unique MAC address stored on its ROM chip. As mentioned earlier, a device such as a bridge can identify a computer on the network by its MAC address.

ROM chips, such as EEPROM on an NIC, store vital information, such as the NIC’s I/O address, IRQ, and MAC address.

On a 10BaseT Ethernet network, a twisted-pair wire with an RJ-45 connector is plugged into the back of a typical 10/100Mbps PCI-bus NIC. If the NIC has been properly attached to the network, the green and amber LEDs on the back of the NIC will flicker on and off.

NIC cards are typically available at network access speeds of 10Mbps, or both 10Mbps and 100Mbps. If your network can support transmission speeds of higher than 10Mbps, and you are only using a 10Mbps NIC, you will not be able to take full advantage of your network’s bandwidth. Your NIC will cause what is known as a bottleneck.

NICs are fairly easy to install if you have purchased a popular brand name and are utilizing a plug-and-play operating system. Most newer operating systems have fully compliant software drivers built in that support newer NICs. However, if you are using an ancient, legacy NIC, or your operating system does not support plug-and-play, it will be necessary to use the software driver that came with the NIC. If you do not have the installation software or drivers for the NIC, you should consult the NIC manufacturer’s Web site for a possible free driver download.

There are several ways that settings on NICs can be configured. Older, legacy NICs were configured with the use of jumpers or DIP switches on the card itself. Today, most NIC settings are configured with the use of software provided by the manufacturer, or simply by letting plug-and-play make the necessary setting automatically if your NIC card is plug-and-play.

NICs and their connections are notorious for causing network-related trouble if they are malfunctioning or improperly connected. If you or a customer cannot connect to your network, first verify that the NIC and the patch cable connected to it are in working order. If all the hardware is intact and you see flashing lights on the back of the NIC, you may want to try typing in the correct password to access your network resources.

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