What Are Network Cards?

A network card is a piece of computer hardware designed to allow computers to communicate over a computer network. Because it has a MAC address, it belongs to layer 2 of the OSI model. It allows users to connect to each other via cable or wireless. Each network card has a unique 48-bit serial number called the MAC address, which is written in a ROM on the card. Every computer on the network must have a unique MAC address. No two produced network cards have the same address. This is because the Institute of Electrical and Electronics Engineers (IEEE) assigns unique MAC addresses to network interface controller (NIC) vendors.

The network card is equipped with a processor and

1. Encapsulation and decapsulation of data

When transmitting, the data transmitted from the previous layer is added to the header and the tail to become an Ethernet frame. When receiving, the Ethernet frame is stripped of the head and tail, and then sent to the upper layer

Link management

Mainly through

Improve network performance with advanced network card options:

Effective use of CPU: jumbo frames vs. offload

If the server performance is poor, it may be due to heavy network load. The standard Ethernet packet size is 1518 bytes, and most files are split into hundreds or even millions of packets or frames. These small data packets are transmitted through the network and share network bandwidth with many nodes, but sending and receiving data frames will bring CPU overhead.

Most network cards support

Due to the existence of the driver function layer, the protocol driver and the network card driver are independent of each other, which greatly simplifies the complexity of adding network devices and expanding network components. At present, the network protocol stack mainly supports enhanced network device drivers (Enhanced Network Driver, END). ^[1]

According to the different physical layer standards and host interfaces supported by network cards, network cards can be divided into different types, such as Ethernet cards and token ring network cards. The network card is divided into different types according to the connection method of the network card and the bus on the motherboard, the transmission rate of the network card, and the interface connecting the network card to the transmission medium.

According to the types of computers supported by the network card, it is mainly divided into standard Ethernet cards and PCMCIA network cards:

Standard Ethernet cards are used for desktop computer networking, while PCMCIA cards are used for laptop computers.

According to the classification of the transmission rate supported by the network card, it is mainly divided into four categories: 10Mbps network card, 100Mbps network card, 10 / 100Mbps adaptive network card and 1000Mbps network card:

According to the requirements of the transmission rate, 10Mbps and 100Mbps network cards only support 10Mbps and 100Mbps transmission rates. When using unshielded twisted pair UTP as the transmission medium, usually 10Mbps network cards are used in conjunction with category 3 UTP, while 100Mbps network cards are compatible with category 5 UTP. connection. The 10 / 100Mbps adaptive network card is a network card that automatically detects the transmission rate of the network to ensure the compatibility of two different transmission rates in the network. With the continuous improvement of LAN transmission rates, 1000Mbps network cards are mostly used in high-speed servers.

According to the type of bus supported by the network card, it can be divided into ISA, EISA, PCI, etc .:

Due to the rapid development of computer technology, the use of network cards with ISA bus interface is becoming less and less. The EISA bus interface network card can transmit 32-bit data in parallel. The data transmission speed is fast, but the price is more expensive. The PCI bus interface network card has a low CPU usage. The theoretical transfer rate of a commonly used 32-bit PCI network card is 133 Mbps, so the supported data transmission rate can reach 100 Mbps.

In order for two network cards to achieve efficient dual redundant backup, it is necessary to ensure that the two network cards have the same

There are currently two main modes of cooperation between operators and Internet companies. The first is a traffic-free series, which is mainly concentrated in Internet clients, videos, live broadcasts and other products. Users can enjoy low-cost traffic tariffs or targeted traffic-free services; the second is a subsidized traffic card for transaction payment platforms, which is completed. Get traffic after every order. ^[3]

along with

NIC network connection is unstable

When the network card is working normally, the indicator of the network card is always on (while flashing quickly when transmitting data). If it appears dark and bright, and the network connection is always unreachable, the most likely cause is a bad connection between the network card and the PCI slot. As with other PCI devices, this kind of failure can easily be caused when the network card is frequently plugged in or moved out, and it can be solved by replugging the network card or changing to another PCI slot. In addition, dusty, network card "golden fingers" are severely oxidized, network cable connectors (such as damaged water head) will also cause such failures. Just clean up the dust and polish the "golden fingers" with a newspaper. ^[5]

Network card driver failure

Network cards, like other hardware, have imperfect driver programs and are prone to cause malfunctions. Compared with the network cards using Realek RT18469 chips, Net-BIOS TCP / IP errors often occur under Windows. After the cotton driver is updated to the latest version, such problems will be solved. Therefore, when the network card fails for some unknown reason, you can go to the professional website such as "Driver House" to update the driver to solve it. (It is recommended that you first use the driver certified by Microsoft WHQL. The driver that passes this certification is compatible with the Windows system. it's the best). In general, under the premise of eliminating hardware and network faults, upgrading or reinstalling the driver can solve many inexplicable faults. If the network card failure occurred after the driver update, you can use the driver that comes with the network card to recover. ^[5]

Network card magnetic field causes failure

The network card is the same as other electronic products. It is easy to malfunction due to magnetic field interference. Therefore, when the network card and network wiring, it is necessary to use network cables and network card equipment with strong screen performance. At the same time, avoid high-power strong magnetic field equipment such as microwave ovens, refrigerators, and televisions to reduce the probability of network card failure. ^[5]

Network card network card data transmission and reception abnormal

Step 1: Click the Start and Control Panel commands in sequence to bring up the system control panel window, double-click the Network and Sharing Center icon with the mouse, and click the Manage Network Connections button in the interface to enter the network connection In the list window, right-click the "Local Area Connection" icon and execute the "Properties" command in the shortcut menu to open the Local Area Connection Properties dialog box. Select the TCP / IPv4 protocol option and click the "Properties" button to switch to the corresponding protocol properties dialog box. See if the IP address and other parameters are set correctly here. If the user enters the wrong IP address or is not familiar with the network parameter configuration, it will easily cause network failure. After the network parameters are set, the failure phenomenon may disappear automatically.

Step 2: Check whether the working status of the network card device is normal. First, touch the temperature near the network card with your hand to check whether the temperature is too high. In the case of a computer working for a long time, if the computer's thermal performance is not good, it will easily cause the network card to experience performance degradation. When it is confirmed that the network card is not working properly due to the high temperature, as long as the computer is temporarily turned off for a period of time, the problem can be solved. Secondly, check whether some application programs or software systems have restrictions on the operation rights of network card devices. For example, confidential systems or network viruses may affect the working status of network card devices. At this time, as long as you clean and kill the virus, or cancel the program or software Restrictions on network card permissions can restore the operating state of the network card device. Third, determine whether the network card itself has a hardware problem. Open the system device manager window, expand the network adapter node, right-click the target network card device, enter the corresponding device properties dialog box, select the "General" tab, and you can directly see if there is a problem with the network card device in the corresponding tab page . If it is not possible to identify whether the network card is normal, you may wish to add a normal network card to determine whether the old network card has a quality problem. Finally, try to right-click the "Local Area Connection" icon and execute the "Repair" command in the shortcut menu. This may solve some hidden network card errors and restore the working state of the network card.

Step 3: Test the connectivity of the physical line with a professional cable testing instrument to determine whether there are breakpoints in the network cable and whether the crystal head of the network card is in poor contact. If the network cable is found to be broken, you must replace it with a new one. If you see that the crystal head is not in good contact, you may choose a higher quality network module or crystal head to remake the network connector.

Step 4: Check the working status of the switch. After working for a long time, the switch equipment is prone to aging. At this time, all the computers connected to the switch will be abnormally connected to the Internet. Therefore, observe the online status of other computers. There are probably nine or nine switch problems, just replace the switch again. If other computers are connected to the Internet normally, you may wish to try another swap port to see if there is a problem with the port module. Sometimes, a small amount of dust can also cause the performance of the switch or network card device to decline. Therefore, it is necessary to strengthen the maintenance of the device.