A network interface card connects your computer to the world.
The network interface card is one of the most important computer components in the modern inter-connected world. The NIC is typically integrated onto the computer's motherboard, but may also be installed as a separate card in a computer's expansion slot. Regardless of the implementation, the card is there to convert computer data to digital signals and manage the network link over which to transmit them.
Networking Models
The Internet networking model developed by the Department of Defense has four layers that map to the seven layers of the OSI networking model. Each of these layers provides different functionality, including physical and data connectivity, network routing, host connectivity and application support.
NIC Layers
A network interface card works at the bottom two layers of the OSI model, which are the Physical Layer and the Data Link Layer. These two layers are combined into the Network Access Layer in the Internet model. In both cases, these layers are responsible for establishing and managing the physical network connection and converting computer data into digital signals for transmission on the network.
Physical Connectivity
Physical connectivity depends on the network topology involved. For wired networks the connection involves connecting the computer to the network with an actual wire and an RJ-45 jack. For wireless networks the "physical" access is the connection to the radio signal in the air. In both situations, the NIC is responsible for establishing and managing the physical connection.
Data Transmission
To transmit data across a network connection the data must be converted to digital signals. In addition, the NIC must accept the data from the computer via a parallel connection, which means that bits flow into the NIC from the computer across multiple paths simultaneously. Since a network connection is a serial connection, the NIC must translate the parallel bit arrangement to serial format before transmission. Conversely, the NIC must accept serial data from the network and convert it to parallel form before passing it along to the computer.
Tags: digital signals, interface card, network connection, network interface, network interface card