What is a network adapter - definition, functions and types

by sogrow team

What is a network adapter? 

Before introducing the definition of NIC, you should know that there are quite a few names for the network interface based on customs in different regions, such as card, network card, ethernet adapter after the technology name, an additional device that allows the computer to interact with other network devices. In today's personal and notebook computers, the controller and components that perform the functions of a network card are often incorporated into motherboards for convenience, including unifying the controller and reducing the cost of the entire computer.


Network adapter role 

The definition of a network adapter is very simple, but what does a network card do, and what is its role? In the OSI system model, the network adapter is responsible for operating the second link layer. Along with the controller, it also powers the physical hardware. Each manufacturer solves for itself the division of tasks between them. Also, the OS (operating system) module is responsible for the data link layer. Together they perform two main operations: send and receive data from the network to a PC and vice versa, and they also participate in the following tasks: 

  • Monitoring incoming/outgoing traffic; 
  • Remote configuration change; 
  • Improved performance and prioritization of the network; 
  • Remote activation from a central workstation; 
  • Encoding / decoding of sent / received data; 
  • Package formation (send / receive mode).


Network adapter components 

Traditionally, a network adapter consists primarily of a controller, a boot ROM socket, one or more NIC ports, a motherboard interconnect interface, LEDs, a profile bracket, and some other electronic components. Each component of the network card has its unique function: 

Controller: The controller is like a mini processor; it processes the received data. As the main part of the network adapter, the driver directly determines the performance of the network adapter. 

Boot ROM Slot - This connector on the circuit board provides the option to boot ROM. Boot ROM allows hard disk workstations to connect to the network, improving security and reducing hardware costs. 

Cable / Module NIC Port - Typically, this port connects directly to an Ethernet cable or module that can generate and receive electronic signals that are overlaid on a fibre optic cable or network. 

Bus interface: This interface is located on the side of the circuit board, which serves as a connection between the network card and a computer or server through a connection to its expansion slot. 

LED Indicators - Indicators help users determine the operational status of the network adapter, whether the network is connected, and whether data is being transmitted. 

Profile Brackets: There are two types of Profile Brackets on the market. One is called a 12cm long full height stand, and the other is called an 8cm long low profile stand. This bracket can help users to connect the network adapter to the expansion slot of a computer or server.


Types of network adapters

Network adapters can be classified into different types based on different functions such as host interface, baud rate, and application. The next part gives details.


Classification based on network connections

Depending on how the network adapter accesses the network, there is a wired network adapter and a wireless network adapter. As the name suggests, a wired network adapter usually needs to connect a host to the network using a cable such as an Ethernet cable and fibre optic cable. A wireless network adapter often comes with a small antenna that uses radio waves to communicate with an access point to connect to a wireless network.


Classification based on bus interfaces

ISA (Industry Standard Architecture: ISA network adapter was developed in 1981 and was the standard bus architecture for IBM-compatible devices. Due to the low card transfer rate (9 Mbps), the ISA bus interface is no longer a generally accepted type, and it is difficult to find it in modern stores.

Peripheral Component Interconnect (PCI) network adapter was developed in 1990 to replace the previous ISA standard. It has a fixed width of 32 bits (133 MB / s data transfer) and 64 bits (266 MB / s data transfer). This type The network adapter was first used on servers and then gradually applied to PCs.Today, most PCs do not have expansion cards but rather devices integrated into the motherboard. As a result, the PCI network adapter has been replaced by other bus interfaces such as PCI-X or USB.

PCI-X (Peripheral Component Interconnect eXtended) Network Adapter: PCI-X is an advanced PCI bus technology. It runs at 64-bit speed and is capable of speeds up to 1064MB / s. In many cases, PCI-X is backwards compatible with PCI NIC cards.

PCIe (Peripheral Component Interconnect Express) network adapter: This is the latest standard and is now popular on computer and server motherboards. The PCIe NIC adapter is available in five versions, and each version supports five-line types at different speeds.

USB Network Adapter (Universal Serial Bus): USB is an external bus standard. It has three versions with different baud rates and can work together with different devices. In addition, a wireless network adapter is also a type of network adapter NIC that is designed for Wi-Fi connectivity.


Classification based on the port type

According to the different cables connected, there are four types of NIC ports that can be found on the market. RJ-45 port is used for twisted pair cable (such as Cat5 and Cat6), AUI port is used for thick coaxial cable (such as AUI cable for modules), BNC port for thin coaxial cable (such as BNC cable) and optical port for the module (for example, 10G / 25G module).


Classification based on bit rate

Based on different speeds, there are adaptive cards on the market of 10 Mbps, 100 Mbps, 10/100 Mbps, 1000 Mbps, 10 Gbps, 25 Gbps, or even higher speed. 10 Mbps, 100 Mbps and 10/100 Mbps adaptive NICs are suitable for small LANs, home use, or day-to-day offices. 1000Mbps NIC provides higher bandwidth on a gigabit network. As for 10Gbps NICs and 25Gbps NICs or even higher speed ones, they are welcomed by large enterprises or data centres.


Application classifications

Computer NIC: Most new computers nowadays have a built-in network card, so a separate network adapter is not required. It usually comes at 10/100 Mbps and 1 Gbps and allows one computer to communicate with other computers or networks.

Server NIC: The main function of a server NIC is to manage and process network traffic. Compared to the regular PC network adapters, server adapters usually require higher data transfer rates, such as 10G, 25G, 40G and even 100G. In addition, server adapters have low CPU utilization because they have a dedicated network controller that can perform many tasks from the CPU. To meet the different user requirements for the speed of using server adapters, FS has released 10G PCIe adapters and 25G / 40G NICs. Based on the Intel controller, these PCIe adapters support multi-core processors and optimize server and network virtualization.



The performance of the NIC directly affects the data transfer rate of the entire network. Whether you're looking for network adapters for home use or a server network adapter for SMB or datacenters, you need to understand what a network adapter is, the component and functions of a network adapter, and the types of network adapters before purchasing a network adapter.