1 The working of wireless network card :
1 The working of wireless network card When the wireless network card sends data, the card checks whether there is media carrier (the carrier by the voltage of instructions). If so, it is that other sites is to disseminate information, to continue listening medium. Once the communication media in a certain period of time (known as the interframe gap IFG = 9.6 microseconds) There is no data, that is, other sites were not occupied, then begin sending frame data, while continuing to listen for communication media, to detect the conflict.
If the conflict is detected, then the immediate cessation of the meeting sent to the media to send a "block" signal to inform other sites of conflict has occurred, thus discarding those who may have been damaged in the reception frame data, and wait for some random period of time (CSMA / CD set waiting time algorithm is binary exponential backoff algorithm). If the repeated retransmission later (more than 16 times) is still in conflict, they give up sending.
Slide 3:
Received, the mini pci-e card visit the media transmission of each frame, if its length is less than 64 bytes, then that is a conflict of debris. If the received frame is not a conflict of debris, and the destination address is a local address, then check the integrity of the frame, if the frame length is greater than 1518 bytes (known as the long frames, may be caused by the wrong LAN driver or due to interference) or failed CRC check is considered to have taken place in the frame distortion. Through the validation of the frame is considered to be effective, it receives to carry out a card will be processed locally.
2 The factors that affect the network cards work :
2 The factors that affect the network cards work Ability to work depends on the NIC card connected to switching equipment and its setting as well as the card work environment arising from interference. Such as signal interference, ground interference, power supply interference, radiated interference, etc. can have a significant impact on the performance of the card, some interference may also be a direct result of network card is damaged.
PC, often leading to power failure on the mini pci-e Bluetooth wifi card is not working properly. Generated when the power failure signals may interfere with the discharge he went to NIC output port, on entering the network will take up a lot of network bandwidth, undermining the normal data packets to other stations, forming a large number of FCS Frame Check erroneous data packets, resulting in a large number of re - hair frames and invalid frames, its proportion with the actual flow of the various workstations increases, seriously interfere with the operation of the entire network system.
Slide 5:
Ground interference effects card often work in bad ground and a hdd docking station is a must, static electricity due to the release of nowhere continue to accumulate in the chassis, so that the grounding terminal adapter (through the NIC upper iron plates connected directly with the chassis) voltage is not normal, eventually led to NIC is not working properly, this situation will be serious or even breakdown card controller chip on the card caused the damage.
Is very susceptible to interference, and sometimes because of network card and graphics card will be inserted too close to interfere. Interference is not serious, the card can be forced to work when the user data traffic is not always feel, but with large amounts of data traffic, in the Windows98 will appear under the "network insufficient resources" prompt, resulting in the phenomenon of the machine crashes.
Slide 6:
NIC settings will also directly affect the speed of the workstation. NIC works for full 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, they will generate a large number of collisions the frame and a number of FCS checksum error frame, access speed will become very slow, from the server, copy a 20MB file may also need 5 to 10 minutes.
Slide 7:
This kind of mistake is often due to network maintenance personnel's negligence, most of the time they use the default settings, but does not verify the actual state.
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