Page 34 - DCAP311_DCAP607_WIRELESS_NETWORKS

Wireless Networks

Notes 2.1.4 Network Interface Cards (NICs)

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. As a result, 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:

z z 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.
z z 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.
z z 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.
The network interface card (NIC) is installed in an expansion slot of the computer. This card
(Figure 1.2) connects the computer to a network, and contains information on the computer’s
location and also instructions for sending and receiving data over the network.
It adds a serial port to the computer and the port connects directly to a network. NIC converts the
computers’ low power signals to high power signals that can be transmitted over the network.
NIC’s speed is measured in megabits per second (Mbps).
Figure 2.5: Network Interface Card (NIC)

Source: www.netguidea.com/2012/09/introduction-2-network-interface-cards.html

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