Network card must have two technologies: network card driver and I/O technology. The driver makes the network card compatible with the network operating system and realizes the communication between PC and network. I/O technology can realize the communication between PC and network card through data bus. Network card is the most basic element in computer network. In the computer local area network, if a computer does not have a network card, then this computer will not be able to communicate with other computers, that is, this computer will be isolated from the network.
Network card classification is different: according to different network technologies, the classification of network cards is also different, such as well-known ATM network cards, token ring network cards, Ethernet network cards and so on. According to statistics, at present, about 80% of local area networks adopt Ethernet technology. It is specially designed according to the working characteristics of different servers, which is expensive but has good performance. As far as compatible network cards are concerned, the current network cards are generally divided into ordinary workstation network cards and server-specific network cards. Server-specific network cards are classified according to the following standards: 10M network card, 100M network card, 10/ 100M adapter network card and 1000M network card according to the bandwidth supported by network cards; According to the different bus types of network cards, they are mainly divided into three categories: ISA network cards, EISA network cards and PCI network cards, among which ISA network cards and PCI network cards are commonly used. The bandwidth of ISA bus network card is generally 10M, and that of PCI bus network card ranges from 10M to 1000M. The same is the 10M network card. Because the ISA bus is 16 bits and the PCI bus is 32 bits, the PCI network card is faster than the ISA network card.
Interface types of network cards: According to different transmission media, there are three interface types of network cards: AUI interface (thick cable interface), BNC interface (thin cable interface) and RJ-45 interface (twisted pair interface). Therefore, when choosing a network card, you should pay attention to the interface type supported by the network card, otherwise it may not be suitable for your network. The common 10M network cards in the market mainly include single-port network cards (RJ-45 interface or BNC interface) and dual-port network cards (RJ-45 and BNC interface), and there are few network cards with AUI thick cable interface. 100M and 1000M network cards are generally single-port cards (RJ-45 interface). In addition to the interface of the network card, we often pay attention to whether the network card supports diskless startup when choosing the network card. If necessary, consider whether the network card supports optical fiber connection.
Selection and purchase of network cards: According to statistics, most local area networks adopt Ethernet technology at present, so take Ethernet network cards as an example to discuss some problems that should be paid attention to when selecting network cards. Pay attention to the following points when buying:
Network card applications-At present, there are 10M, 100M, 10M/ 100M Ethernet cards and Gigabit network cards. For large-scale data networks, servers should use Gigabit Ethernet cards, which are mostly used for the connection between servers and switches to improve the response speed of the whole system. 10M, 100M and 10M/ 100M network cards are commonly used network devices, and the prices of these three products are not much different. The so-called 10M/ 100M adaptation means that the network card can automatically negotiate with the remote network equipment (hub or switch) to determine whether the current available rate is 10M or 100M. For common applications such as file sharing, 10M network card is enough, but for voice, video and other applications that may appear in the future, 100M network card will be more conducive to the transmission of real-time applications. For the existing foundation of 10M technology (such as hubs and switches, etc.). ), the usual workaround is to buy 10M/ 100M network card, which is beneficial to protect the existing investment and further expand the network. In terms of overall price and technical development, it will take some time for Gigabit Ethernet to reach the desktop, but the era of 10M has gradually gone. Therefore, for small and medium-sized enterprises, 10M/ 100M network card should be the first choice when purchasing.
Pay attention to the bus interface mode-the common bus interface mode in desktop and notebook computers can be found from mainstream network card manufacturers. However, it is worth noting that it is difficult to find a 100M network card with ISA interface in the market. Since 1994, PCI bus architecture has increasingly become the preferred bus for network cards, and has now firmly established its position in servers and high-end desktop computers. The coming change is that this network card will be extended to all desktop computers. The high performance, ease of use and enhanced reliability of PCI Ethernet card make it widely adopted by standard Ethernet and supported by PC industry.
Network card compatibility and application technology-Fast Ethernet generally adopts 100BaseTX technology at the desktop level, and the transmission medium is UTP. Therefore, the fast Ethernet network card has RJ45 interface. Because twisted pair is widely used as transmission medium and structured wiring in small office networks, it is enough to select a single RJ45 interface network card. A network card with good applicability must pass the authentication of major operating systems, and at least be driven by the following operating systems: Windows, Netware, Unix, OS/2. The intelligent network card has its own processor or specially designed AISC chip, which can undertake some tasks that are undertaken by the computer processor when using non-intelligent network cards, so it rarely takes up the computer's memory and CPU time even in the case of large network information traffic. Intelligent network card has good performance and high price, and is mainly used for servers. In addition, some network cards make a fuss about BootROM to increase anti-virus function; Some network cards cooperate with the motherboard and wake up with some software. Open? LAN (Remote Wake-up) function, which can remotely start the computer through the network; Other computers just integrate the network card into the motherboard.
Network card manufacturers-Due to the maturity of network card technology, at present, in addition to foreign companies such as 3Com, Intel and IBM, manufacturers in Taiwan Province Province also have the advantages of strong production capacity and many factories in mainland China, and their prices are relatively cheap.
Although there are many kinds of network cards, one thing is consistent, that is, each network card has a unique ID number in the world, also called MAC (Media Access Control) address. The MAC address is burned in the ROM of the network card, just like the genetic code DNA of each of us, which will never be repeated even in the world. MAC address is used to identify the identity of computers in the network and realize communication and information exchange between different computers in the network.
[3] Basic functions
Parallel to serial data conversion, package assembly and disassembly, network access control, data caching and network signals. Currently, there are mainly 8-bit and 16-bit network cards.
[1][2] Several factors that should be considered when purchasing a network card:
Network type: Ethernet, token ring network, FDDI network, etc. Now they are all popular, so you should choose the corresponding network card according to the network type.
Transmission rate: the transmission rate of the network card should be selected according to the bandwidth requirements of the server or workstation and the maximum transmission rate that can be provided by the physical transmission medium. Take Ethernet as an example, there are 10Mbps,1100 Mbps, 1000Mbps or even 10Gbps, but the higher the rate, the better.
Bus type: The common bus slot types in computers are ISA, ISA, VESA, PCI and PCMCIA. Intelligent network cards with PCI or EISA bus are usually used in servers, ordinary network cards with PCI or ISA bus are used in workstations, network cards with PCMCIA bus or portable network cards with parallel interfaces are used in notebook computers.
Cable interface supported by network card: the network card is ultimately connected to the network, so there must be an interface through which the network cable is connected with other computer network devices. Different network interfaces are suitable for different network types. At present, the common interfaces mainly include RJ-45 interface of Ethernet, BNC interface of thin coaxial cable, AUI interface of thick coaxial cable, FDDI interface and ATM interface.
(1)RJ-45 interface: This is the most common network card and the most widely used interface type network card, mainly due to the popularity of twisted-pair Ethernet applications.
(2)AUI interface: This interface type of network card is used in Ethernet or Token Network with thick coaxial cable as transmission medium. At present, this interface type of network card is rare.
(3)FDDI interface: The network card of this interface is suitable for FDDI (Optical Fiber Distributed Data Interface) network, and its bandwidth is 100Mbps, but its transmission medium is optical fiber.
(4)BNC interface: This interface card is used for Ethernet or token network with thin coaxial cable as transmission medium. At present, this kind of interface network card is relatively rare, mainly because there are few networks with thin coaxial cable as transmission medium.
(5)ATM interface: This type of interface network card is used in ATM (Asynchronous Transfer Mode) optical fiber (or twisted pair) networks. It can provide physical transmission speed as high as 155Mbps.
Price and brand: the price of network cards with different speeds and brands varies greatly.
[3] Interface type of network card
Interface types of network cards: According to different transmission media, there are three interface types of network cards: AUI interface (thick cable interface), BNC interface (thin cable interface) and RJ-45 interface (twisted pair interface). Therefore, when choosing a network card, you should pay attention to the interface type supported by the network card, otherwise it may not be suitable for your network. The common 10M network cards in the market mainly include single-port network cards (RJ-45 interface or BNC interface) and dual-port network cards (RJ-45 and BNC interface), and there are few network cards with AUI thick cable interface. 100M and 1000M network cards are generally single-port cards (RJ-45 interface). In addition to the interface of the network card, we often pay attention to whether the network card supports diskless startup when choosing the network card. If necessary, consider whether the network card supports optical fiber connection.