What's wrong with LAN getting slower

Fault analysis of local area network speed slow de

In many network failures, the most vexing is that the network is pass, but the speed is slow. The first face of this kind of "soft" failure, often some people will be helpless, this article for you to cause such "soft" fault common causes and elimination methods, improve the ability to deal with practical problems.

1, network cable problem

We know that twisted pair is made by 4 pairs of lines strictly and reasonably tightly twisted together to reduce crosstalk and background noise effects. At the same time, only 1, 2 and 3 and 64 lines of twisted pair are used in the T568A standard and the T568B standard. where 1, 2 is used for sending, 3, 6 is used for reception, and 1, 2 must come from a pair of windings, 3, 6 must come from a pair of windings. Only in this way can the maximum avoid crosstalk and ensure data transmission. In practice, I found that not according to the correct standard (T586A, t586b) The production of network cable, there are a lot of hidden dangers. Some begin to use normal for a period of time, but after a period of time, performance drops, network speed slows down. Therefore, we now require all press T586A, T586B Standard to suppress network cable.

2, Circuit problems

Generally, this phenomenon rarely occurs when the number of nodes involved in the network is not many and the structure is not very complex. But in some more complex networks, because some reasons often have redundant lines, it will constitute a circuit, the packet will continue to send and verify data, thus affecting the overall speed, and find more difficult. In order to avoid this situation, we must be in the laying of the network of good habits, network cable marked on the label, there is a standby line of the place to do a good record.

3. Broadcast Storm

As the main means of discovering unknown devices, broadcasting plays a very important role in the network. However, as the number of network computers increases, the number of broadcast packets will increase dramatically. When the number of broadcast packets reaches 30%, the efficiency of network transmission will decrease obviously. When the NIC or network device is damaged, the broadcast packet will be sent continuously, causing the broadcast storm and paralyzing the network communication. Therefore, when the network equipment hardware failure will also cause slow speed. When you suspect such a failure, you can first replace a hub or switch with a replacement to troubleshoot a hub device failure. Then turn off the power of the hub and use ping to test each of the involved computers, find a computer with a faulty network card, and replace the new network card to restore normal speed.

4. Port bottleneck

In fact, the router's WAN port and LAN port, switch port, hub port, and server network card are all likely to become network bottlenecks. We can use Network management software to view routers, switches, server port data traffic (using the netstat command can also count the data flow of each port), confirm the location of network data circulation bottleneck, try to increase its bandwidth. such as replacing the server network card for 100M or 1000M, installing multiple network cards, by changing the configuration on the router to increase bandwidth and other methods can effectively alleviate network bottlenecks, to maximize the speed of data transmission.

5. Worm virus

The worm affects the speed of the network more and more seriously. The virus causes infected users to keep sending emails as long as they surf the internet, and the virus chooses a random document in the user's personal computer to attach a random address to the phone book on the user's machine to send mail. Hundreds of such spam messages are queued to be sent out, and some are returned to heap on the server in batches. Cause individual backbone Internet appears obvious congestion, individual LAN near paralysis. Therefore, we should always pay attention to a variety of new virus notification, to understand the characteristics of various viruses, timely upgrade the use of anti-virus software. Computers also need to upgrade and install system patches in a timely manner, while uninstalling unnecessary services and shutting down unnecessary ports to improve system security and reliability.

In short, the application of computer network is more and more extensive, how to improve the management level of computer network, continuous learning, pay attention to theoretical knowledge and practical experience accumulation is very important.