How a Network Interface Card Works and Its Key Functions
Updated at Feb 27th 20241 min read
Network interface card is the most necessary hardware component for a network coonnection, install in computers, servers, printers, or any other devices that allow adevice to connect with other devices on a network, used to connect a device to the network.
In this blog, you'll learn more about how NIC cards help enhance networking and processing capabilities to maximize efficiency and ensure optimal performance.

How Does Network Interface Card Work?
A Network Interface Card (NIC) establishes a constant, dedicated connection between a computer and a network. It contains the necessary physical layer components to communicate with data link layer protocols like Ethernet or Wi-Fi. Each NIC acts as a unique device, capable of preparing, transmitting, and managing data flow on the network.
The NIC follows the Open System Interconnection (OSI) model, transmitting signals at the physical layer, sending data packets at the network layer, and functioning as an interface at the TCP/IP layer.
As an intermediary between the computer and the data network, the NIC handles communication requests. For instance, when a user requests a webpage, the computer sends the request to the NIC, which converts it into electrical impulses. These impulses are received by a web server on the internet, which responds by sending the webpage back to the NIC in electrical form. The NIC then decodes these signals into data that the computer can display.
Functions of Network Interface Card
The number of chips on the network interface card is decreasing due to increasing integration. Although there are many types of NICs from different manufacturers, their functions are similar. So what is the function of a network card?
Data Encapsulation
In the encapsulation process, the data can be considered as a packet, and the frame header and frame trailer are the wrappers of the packet. The network interface card encapsulates the computer data as frames by adding a frame header and frame end, and then sends the data to networks through network transmission media. For wired networks, the common transmission media is copper cable or optical fiber, while for wireless WLAN, it is electromagnetic waves.
Data Unpacking
When the NIC receives the data frames transmitted from other network devices, it regroups these data frames into data by removing the frame header and frame terminator, and then transmits the data to the computer.
Link management
If the NIC receives an error data frame, it will automatically discard the error frame and not notify the computer. On the contrary, if it receives a correct frame, it will notify the computer and pass it to the network layer of the protocol stack. When the computer wants to send an IP data packet, the data is delivered to the network interface card through the protocol stack and after being assembled into a frame, it is sent to the LAN.
The other important manifestation of the link management function is to check whether the link status is in an idle state. Since Ethernet is a shared link, if someone else is using the link while you are transmitting data, conflicts will occur.
The link management function is mainly realized by the CSMA/CD (Carrier Sense Multiple Access with Collision Detection) protocol.
Data Encoding and Decoding
Data transmission must be carried on a physical transmission medium. In practice, the transmitted signals are electrical signals or optical signals. The coding and decoding function is mainly reflected in transforming the data into electrical signals or optical signals by using the coding method of Manchester code.
Conclusion
The Network Interface Card (NIC) is a crucial hardware component that serves as the bridge between a computer and a network, responsible for data transmission, reception, and management. Through its functions such as data encapsulation and decapsulation, link management, and data encoding/decoding, the NIC ensures that data can be transmitted reliably and efficiently across the network.
As technology evolves, modern NICs have become increasingly integrated, providing stable and fast network connections for both wired and wireless communications. Understanding how NICs work and their key functionalities is essential for designing and managing networks, ensuring optimal performance, and maintaining secure and efficient data transmission in various network environments.
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