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Failure does not only affect the workstation card itself, but also often affects the normal operation of the entire network must be caused by network administrators attention. In Ethernet, the network card for connection and control of media access media access, Ethernet uses Carrier Sense Multiple Access / Collision Detection (CSMA / CD) is to be achieved in the card.

Meanwhile, the NIC is also responsible for the formation of the upper layer protocol data unit protocol (PDU) composed of Ethernet data frames sent to the network,price of ACER Aspire 3680 battery and is responsible for receiving and processing network, the Ethernet frames coming.

First, the card works

Send data, listen for the media card if the first carrier (the carrier by the voltage directive), if so, then that information is being transmitted to other sites, continue to listen media. Once the communication medium in a certain period of time (called the frame gap IFG = 9.6 microseconds) is quiet, that is not occupied by other sites, then send the data to begin the frame, while continuing to listen for communication media, to detect the conflict. During the transmission of data.

If a conflict is detected, immediately stop the meeting to send to the media to send a “block” signal to the other site has a conflict, thus discarding those who may have been damaged in the received frame data, and wait a random time (CSMA / CD algorithm to determine wait time is the binary exponential backoff algorithm). Waiting for a random time,Sony PCGA-BP2V battery then a new transmission. If, after re-transmission times (greater than 16) are still in conflict to give up the transmission.

Received, the NIC visit each frame transmitted on the media, if its length is less than 64 bytes, is considered to be fragments of the conflict. If the received frame is not a conflict of debris and the destination address is local address, then check the integrity of the frame, if the frame length is greater than 1518 bytes (known as jumbo frames, may be caused by the wrong LAN driver or due to interference) or failed CRC check, the distortion that occurred in the frame. By checking the frame is considered to be effective, it receives to carry out a card will be processed locally. Computer Basics

Second, the factors that affect the network card work

LAN card depends on its ability to work connected to the switching equipment and network card set produced by the interference of the working environment. Such as signal interference, ground interference,Dell LATITUDE D500 Battery power supply interference, radiated interference can have a significant impact on the performance of the card, some interference may also be a direct result of card damage. Computer

PC-card power failure led to often not working properly. Power failure may have fled to the discharge card jamming signal output port, before entering the network will take up a lot of network bandwidth, undermining the normal data packets of other stations to form a frame check a large number of FCS error packets, cause a lot of weight made frames and invalid frames, each workstation with its proportion of the increase of the actual flow, seriously interfere with the operation of the whole network system.

Impact of card grounding interference often work in bad ground, no place to release static electricity due to the accumulation in the chassis, so that the card ground (the top iron through the network card is connected directly with the chassis) voltage is not normal, eventually leading to the work card is not normal, even when serious this breakdown control chip on the NIC card causing damage.

Is very vulnerable to interference,APPLE A1181 laptop battery and sometimes the network card and graphics card will be inserted too close to interfere. Interference is not serious, the card can barely work when the user data traffic is not often feel, but a large amount of data during the communication, under Windows98 will appear in the “network of insufficient resources” message, causing the machine crash phenomenon.

NIC settings will also directly affect the speed of the workstation. PC card work for full-duplex and half duplex, when the servers, switches, workstations, working conditions do not match, such as servers, workstations, network card is set to full duplex state, switches, hubs, and so work in half-duplex state, will have a large impact frame and frame number of FCS error checking, access speed will become very slow, from the server, copy a 20MB file may also need 5 to 10 minutes.

This mistake is often due to the negligence of the network maintenance personnel, most of the time they use the default settings, but does not verify the actual state.