Explore the root cause of slow speed

one, the existence of loops in the network causes slow speed

When the number of nodes involved in the network is not many, the structure is not very complex, this phenomenon is generally rare. However, in some more complex networks, there are often redundant spare lines, such as inadvertently connected to form a loop. such as the network cable from the center of the computer to a room, and then from the computer to a room to computer two rooms. At the same time from the network Center and a backup line directly connected to the computer two rooms, if these lines are connected at the same time, the formation of loops, packets will continue to send and verify data, thereby affecting the overall speed.

In order to avoid this situation, we must develop a good habit when laying the network cable: The network cable is marked on the label, there is a spare line of the place to be well documented. When this kind of failure occurs, the method of phasing out partition is generally used.

　Second, network cable problems caused by slow speed

Twisted pairs are tightly twisted together by four pairs of wires in strict terms to reduce crosstalk and background noise effects. At the same time, only 1, 2 and 3, 64 lines of twisted pair are used in the T568A standard and t568b Standard, of which 1, 2 are used for sending, 3, 6 for reception, and 1, 2 must come from a pair, 3, 6 must come from a winding pair. Only in this way can we minimize crosstalk and ensure data transmission. Not according to the correct standard (T586A, t586b) production network cable, there is a great hidden danger.

Performance: One situation is that the Internet speed is very slow at the beginning of the use, the other is the start of the network is normal, but after a period of time, the network speed slowed. The latter situation is very obvious on desktop computers, but the speed of the computer is normal when checked with a laptop. The network cable caused by not according to the correct standard is also related to the quality of the network card.

General desktop computer network card performance is not as good as notebook computer, therefore, in the Exchange method to troubleshoot, using a laptop computer to detect the speed of normal and can not rule out the network cable does not follow the standard of the existence of the problem. We are now required to press T586A, t586b Standard to suppress the network cable, in the detection of failure can not be used in laptops instead of desktop computers.

　Third, a port in the network formed a bottleneck caused by slow speed

Router WAN ports and LAN ports, switch ports, hub ports, and server NICs can all be network bottlenecks.

When the speed is slow, we can use the network management software to view the data traffic of the router, switch, server port during peak time, and also use the netstat command to count the data traffic of each port. This confirms the location of the network data flow bottleneck and tries to increase its bandwidth. Many methods, such as replacing the server network card 100M or 1000M, installing multiple network cards, dividing multiple VLANs, changing the router configuration to increase bandwidth, etc., can effectively alleviate network bottlenecks, can maximize the speed of data transmission.

　　Four, network equipment hardware failure caused by the broadcast storm caused by slow speed

As the main means of discovering unknown equipment, broadcasting plays a very important role in the network. However, as the number of computers in the network increases, the number of broadcast packets will increase sharply. When the number of broadcast packets reaches 30%, the transmission efficiency of the network will be significantly reduced. When the NIC or network device is damaged, the broadcast packet will be sent continuously, causing the broadcast storm and the network communication to be paralyzed.

As a result, network equipment hardware failure can also cause slow speed. When this type of failure is suspected, the first alternative is to replace the hub or switch with a replacement to eliminate the failure of the hub device. If these devices do not fail, turn off the hub or switch power, DOS under the "Ping" command for the computer involved in one test, find the computer with a faulty network card, replace the new network card can restore the speed of normal. Network cards, hubs, and switches are the devices that are most likely to fail and cause slow speeds.

　　V. The impact of worms causes slow speed

The worm virus distributed by e-Mail has more and more serious effects on network speed. The virus causes infected users to send emails as long as they are on the internet, and the virus chooses random documents attached to the user's personal computer to email them at random addresses in the Address book. Hundreds of such spam messages were sent out in line, and some batches were returned to the server. Causes the individual backbone Internet to appear the obvious congestion, the network speed obviously slows, causes the LAN to be nearly paralyzed.

Therefore, we must upgrade the use of anti-virus software in a timely manner, the computer should also upgrade, install the system patches, while uninstalling unnecessary services, shut down unnecessary ports, to improve the security and reliability of the system.

　　Vi. excessive use of firewalls

Excessive use of firewalls can also lead to slow network speed, the processing method Needless to say, uninstall under the unnecessary firewall just keep a powerful enough.

　Vii. Lack of system resources

may be loaded with too many applications in the background to run, reasonable load software or delete useless programs and files, the resources vacated, in order to achieve the purpose of improving speed.