What is Network Adapter: Function, Construction and Classification of NICs

As trends in artificial intelligence, big data, distributed storage, and cloud services require a lower latency to support real-time applications and services deployed at the edge of the network. Digital transformation across industries and the need to cope with services such as 5G and IoT have led to explosive growth in data centers while putting tremendous pressure on CPUs in computing nodes of server infrastructure. The server network adapter plays an indispensable role in the transition from CPU-centric Onload mode to data-centric Offload mode. In recent years, the industry has been constantly introducing new network cards to meet the latest trends in scenarios of computing such as data centers: high-speed interfaces, parallel capabilities, and resource virtualization. Due to its wide application, there are various types of network adapters in the market, such as gigabit and 10 gigabit NICs, PCI-X, and PCIe NICs. In this article, we give a comprehensive introduction to network cards from their definition, functionality, common components, and types.


What is NIC?
NIC is called Network Interface Card, also known as Network Interface controller. A network card is a network component that works at the second link layer. It is usually a circuit board installed on a computer to connect to the network and provides a private network connection for the computer. Although a network adapter is a small part of the computer network connection, it plays an indispensable role. Network adapters act as a converter, converting data into digital signals that are communicated using cables or wireless routers on the server network. As an interface at the TCP/IP layer, a NIC can transmit signals at the physical layer and packets at the network layer. Regardless of the layer, it acts as an intermediary between the computer/server and the data network. When a user requests a Web page, the LAN gets the data from the user’s device, sends them to the network server, and then receives the required data for presentation to the user.

Components of NIC
Traditionally, a network adapter consists of a controller, a Boot ROM slot, one/more NIC ports, a motherboard port, LED indicators, a bracket, and some other electronic components. Each component has its own unique function:

  • Controller: As the core part of the network card, the controller directly determines the performance of the NIC. The controller acts like a small CPU for processing the incoming data.
  • Boot ROM Slot: This slot allows Boot ROM functionality to be enabled, which allows diskless workstations to connect to the network, thereby increasing security and reducing hardware costs.
  • NIC port: Usually, this port is directly connected to an Ethernet cable or optical module to generate and receive signals from network cables or optical fiber jumpers.
  • Bus interface: This interface is located on the side of the circuit board, the bus interface commonly known as “Golden finger” is inserted in the computer motherboard expansion slot, and used for the connection between the network card and the computer or server.
  • LED indicator: The indicator helps users identify the working status of the network adapter, whether the network is connected, and whether data is being transmitted. For example, Link/Act indicates the active state of the connection, Full indicates whether it is a Full duplex, and Power is the Power indicator.
  • Bracket: There are two kinds of brackets in the PCI network card market, one is the full-height bracket with a height of 120mm, and the other is the half-height bracket with a height of 80mm. The bracket can help the user to fix the network card in the expansion slot of the computer or server.

Types of NIC
Network adapters can be classified into the following types according to the bus interface, transmission speed, and application domain.

Classification by protocol:
According to the transmission protocol, network adapters can be divided into three types: Ethernet card, FC card, and IB card.

  • Ethernet card(Ethernet Adapter): Using IP protocol as the transmission protocol, it is generally connected to the Ethernet switch via fiber optic cable or twisted pair cable. The optical port uses fiber optic cable for data transmission, and the matching module interface is usually SFP, QSFP, etc. The corresponding fiber optic interfaces are LC, SC, MPO, etc. The common interface type of the electrical port is RJ45, which is generally connected with twisted pair cable, and there are also a small number of interfaces connected with coaxial cable.
  • FC card: the scientific name is Fibre Channel. It uses the Fibre Channel transmission protocol and connects to the Fibre Channel switch through optical cables. There are two types of interfaces: optical and electrical. The transmission modes and matching modules of optical ports are similar to those of Ethernet cards, but the corresponding ports are only SC and LC. The electrical interface type is DB9 or HSSDC.
  • IB card: Infiniband is used to connect FC/IP SAN devices, NAS devices, and servers, and is used as the storage protocol of iSCSI RDMA. InfiniBand cards deliver ultra-low latency, ultra-high throughput, and innovative network computing engines that provide the speedup, scalability, and feature-rich technologies required for today’s modern workloads.

Classification by transmission speed:
Depending on the speed, there are 10/100Mbps self-adaptive cards, 1000Mbps gigabit cards, 10G, 25G, 100G, and even higher speed cards.
10Mbps/100Mbps self-adaptive card: It is the popular type of NIC at present. It can automatically adapt to two different bandwidth network requirements. It can be connected to old 10Mbps network devices and can also be applied to the connection of newer 100Mbps network devices, so it has been widely recognized by users.
1000Mbps network adapter: provides higher bandwidth for fast Ethernet. Gigabit Ethernet is a high-speed LAN technology that provides 1Gbps bandwidth over copper wires. The corresponding network card is a gigabit network card, which can also reach 1Gbps bandwidth. There are two kinds of network interfaces for gigabit network adapters, one is the ordinary twisted pair RJ45 interface, and the other is the gigabit SFP/GBIC fiber interface.

  • 10G fiber network card: Its mainstream is 10G Ethernet card. Like Gigabit Ethernet cards, 10G Ethernet cards support single-mode or multi-mode fiber. Using 10G Ethernet cards gives network operators more freedom to locate data centers and support multiple campus networks within 80 kilometers of each other at the same time. In data centers, low-cost multi-mode fiber can be used as the backbone of a 10G network between switches and switches and between switches and servers.
  • 25G fiber network adapter: Compared with 10G fiber network adapter, the larger bandwidth of 25G fiber network adapter meets the network requirements of high performance computing cluster. In the network upgrade of 100G or higher rate, 25G fiber network adapter is one of the indispensable infrastructures. In the process of data center upgrade from 10G/40G to 25G/100G (server interface is 25G, switch interconnection interface is 100G), more and more people support 25GbE, including Google, Microsoft, and other large cloud providers for 25G absolute recognition.
  • 40G optical fiber network card: A 40G QSFP+ port, mainly used for servers and high-end devices. QSFP optical port 40G fiber network adapter provides simple integration into any PCI Express X8 with 40Gigabit network performance optimized so that the system input/output is not a bottleneck in high-performance network applications. It can support 40Gbps transmission bandwidth and PCI-E X8 standard slot, ensuring efficient and stable work of the network card. In addition, the network adapter supports functions such as VLAN, QOS policy, and traffic control, which is suitable for medium-large LAN applications.
  • 100G optical fiber network adapter: With the increasing demand for massive data transmission, servers usually need to install multiple network adapters to meet the high demand for data processing. Because of this feature, the data center network is gradually upgraded from 10G to 100G network adapters or even higher rates. The 100G network adapter has high throughput, low latency network processing, and the ability to assist the CPU to offload network functions, saving CPU computing power and reducing power consumption to the maximum.

Classification by types of bus interface:

  • ISA network card: Industry Standard Architecture was released in 1981, which is a bus structure compatible with IBM standards. Because of the slow I/O speed of the ISA bus interface, it was gradually phased out with the advent of PCI bus technology in the early 1990s and now is rarely seen in the market.
  • PCI network card: It’s called Peripheral Component Interconnect. It is a PC local bus standard introduced in 1993. Because its I/O speed is much faster than that of the ISA bus network card (the highest speed of ISA is only 33MB/s, while the current PCI 64-bit data transfer rate is 266MB/s), it gradually replaced the former ISA standard. This kind of network card is used in the server initially, later also commonly used in the desktop machine, is a mainstream network card interface type. Most computers today do not have expansion cards, but use embedded network cards. Therefore, PCI network cards have been replaced by other bus interfaces such as PCI-X or USB interfaces.
  • PCI-X network card: PCI-X is an enhanced PCI bus technology. Compared with the original PCI, the I/O speed is doubled, and the data transfer speed is also faster than the PCI interface. The PCI-X bus interface card generally has a 32-bit bus width, but also supports 64-bit operation, up to 1064MB/s. In most cases, PCI-X slots are backward compatible with PCI NICs.
  • PCle network card: A PCIe card is a NIC with a PCIe port and is used as an expansion port for motherboard connections. Specifically, PCI-based expansion cards can be inserted into PCIe slots on the mainboard of devices such as hosts, servers, and network switches. Most computer motherboards now have dedicated PCIe slots for PCIe cards. Generally, the width of the slot will be the same as the width of the network card, or even wider.

FiberMall independently develops 1000M, 10G, 25G, 40G, 100G, single-port, dual-port, and 4-port fiber optic NICs based on Intel and NVIDIA controller chips, and provides customized fiber optic NIC solutions.

ClassificationFiberMall PNControllerSpecifications
Gigabit NICFMI210-1G-S1Intel I210PCIe x1 Gigabit SFP 1 Port Fiber Adapter
Gigabit NICFM82576-1G-S2Intel 82576PCIe x4 Gigabit SFP Dual Port Fiber Adapter
Gigabit NICFMI350-1G-S4Intel I350PCIe x4 Gigabit SFP Quad Port Fiber Adapter
10Gb NICFM82599EN-10G-S1Intel 82599ENPCI Express x8 Single Port SFP+ 10 Gigabit Server Adapter
10Gb NICFM82599ES-10G-S2Intel 82599ESPCI Express x8 Dual Port SFP+ 10 Gigabit Server Adapter
10Gb NICFMX710-10G-S2Intel X710-BM2PCI Express v3.0 x8 10Gigabit Dual-port Ethernet Server Adapter
10Gb NICFMXL710-10G-S4Intel XL710-BM1PCI Express v3.0 x8 10Gigabit Quad-port Ethernet Server Adapter
25Gb NICFMXXV710-25G-S2Intel XXV710PCIe v3.0 x8 25 Gigabit Dual-port Ethernet Server Adapter
25Gb NIC4121A-ACAT-25GS2NVIDIA 4121A-ACATConnectX-4 Lx EN Network Adapter, 25GbE Dual-Port SFP28, PCIe3.0 x 8
40Gb NICFMXL710-40G-Q1Intel XL710-BM1PCIe v3.0 x8 40 Gigabit 1 Port Server Ethernet Adapter
40Gb NICFMXL710-40G-Q2Intel XL710PCIe v3.0 x8 40 Gigabit Dual port Server Ethernet Adapter
100Gb NICFME810-100G-Q2Intel E810-CAM2PCIe v4.0 x16 100 Gigabit Dual port Server Ethernet Adapter


Different application scenarios require different types of NICs, and it is difficult for a single NIC to meet complex and diverse acceleration scenarios. With the improvement of market heat and technical capabilities, the future network adapter market will also usher in more possibilities, such as the latest OCP NIC 3.0 network adapter. Therefore, whether you are looking for a home PC network card or a server network card for use in an enterprise or data center, you need to clearly understand the basics of network cards before purchasing.

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