Network Basics: Network Interface Cards

Every computer on a network, both clients and servers, requires a network interface card (or NIC) in order to access the network. A NIC is usually a separate adapter card that slides into one of the server’s motherboard expansion slots. However, most newer computers have the NIC built into the motherboard, so a separate card isn’t needed.

For client computers, you can usually get away with using the inexpensive built-in NIC because client computers are used to connect only one user to the network. However, the NIC in a server computer connects many network users to the server.

It makes sense to spend more money on a higher-quality NIC for a heavily used server. Most network administrators prefer to use name-brand cards from manufacturers such as Intel, SMC, or 3Com.

Most NICs made today support 1 Gbps networking and will also support slower 100 Mbps and even ancient 10 Mbps networks. These cards automatically adjust their speed to match the speed of the network. So you can use a gigabit card on a network that has older 100 Mbps cards without trouble.

You can find inexpensive gigabit cards for as little as $5 each, but a typical name-brand card (such as Linksys or Intel) will cost around $25 or $30.

Here are a few other points to ponder concerning network interface cards:

  • A NIC is a Physical layer and Data Link layer device. Because a NIC establishes a network node, it must have a physical network address, also known as a MAC address. The MAC address is burned into the NIC at the factory, so you can’t change it. Every NIC ever manufactured has a unique MAC address.

  • For server computers, it makes sense to use more than one NIC. That way, the server can handle more network traffic. Some server NICs have two or more network interfaces built into a single card.

  • Fiber-optic networks also require NICs. Fiber-optic NICs are still too expensive for desktop use in most networks. Instead, they’re used for high-speed backbones. If a server connects to a high-speed fiber backbone, it will need a fiber-optic NIC that matches the fiber-optic cable being used.