Illustration of functions and materials of the Ethernet Card Used for beginners of cainiao (1)

What are the most basic components in the network? Not a vswitch or a vro, but a small but ubiquitous Nic. If the network adapter has nothing to do with you five years ago, but in today's Internet era, no matter whether surfing the internet or playing games online, you cannot do without the network adapter. What's more, even if you don't have to worry about it, most boards also integrate an onboard Nic for you. Therefore, for readers who want to enter the network door, first understanding the network card will make you more comfortable in various network applications.

I. MAIN FEATURES OF NICs

Network Interface Card (NIC), also known as Network adapter, is a device connecting a computer and a LAN. A network card is required to connect to a LAN, whether it is a common computer or a high-end server. If necessary, two or more NICs can be installed on one computer.

10/100 Mbps PCI Nic

When computers communicate with each other, data is transmitted in frames instead of streams. We can regard frame as a data packet, which not only contains data information, but also contains the data sending location, receiving location information and data validation information. An ENI consists of two layers of the OSI model: the physical layer and the data link layer. The physical layer defines the electrical and optical signals, line statuses, clock baselines, data encoding, and circuits required for data transmission and receiving, and provides standard interfaces to data link layer devices. The data link layer provides addressing mechanisms, data frame construction, data error check, transfer control, and standard data interfaces to the network layer.

Two main functions of the network adapter are as follows: first, the computer data is encapsulated into frames and data is sent to the network through the network cable (electromagnetic waves for wireless networks; the second is to receive frames transmitted by other devices on the network, recombine the frames into data, and send them to the computer. The network adapter can receive all signals transmitted over the network, but normally only accept frames and broadcast frames sent to the computer, and discard the remaining frames. Then, it is sent to the system CPU for further processing. When the computer sends data, the network adapter waits for the appropriate time to insert the group into the data stream. Whether the received system notifies the computer of the complete arrival of the message. If there is a problem, the recipient will be asked to resend the message.

2. Graphic Nic

Graphical PCI Nic

Taking the most common PCI interface Nic as an example, a card consists of a PCB circuit board, a main chip, data mercury, and a golden finger (bus slot interface), BOOTROM, EEPROM, crystal oscillator, RJ45 interface, indicator light, fixed chip, and some diodes, resistance and capacitance. Next, let's take a look at the main components.

● Main chip

The most common 8139D Chip

The main control chip of the network card is the core component of the network card. The performance of a network card is good or bad, and the strength of the function is many, mainly depends on the quality of this chip. Take the RTL8139C and RTL8139D launched by Realtek as an example. The two are slightly different in encapsulation. The former is 128pin QFP/LQFP, and the latter is 100pin. The second is the combined EEPROM, 8139C has more support for 93c56 than the latter, while 8139D is 93C46. However, 8139D is more powerful in terms of functions. It provides support for PCI Multi-function and PCI-bridge I/F, PCI Multi-function allows the RTL8139D chip and other functional chips (such as hardware modulation and demodulation chips) to work collaboratively on the same PCB to form different types of Multi-function cards, among them, the role of 8139 is to identify the LAN signal or PCI bus signal; 8139D also enhances the power management function.