The network speed suddenly slows down caused by the blockage of the faulty Switch

Slow network speed is a common type of switch failure. We need to carefully analyze the error records of the faulty switch so that we can fundamentally solve the problem and avoid repeated errors later. When the network scale is relatively large, the "load" of switches that shoulder network data forwarding, content filtering, and management control tasks will be very heavy. In addition, like a person's health, after a switch is overloaded for a long time, its health is also prone to problems, and the switch is slow to respond, serious hardware damage can occur directly, which may affect the running status of the entire network.

This is not the case. I have an ordinary switch on the network of my building, which has been quietly working for the building users for many years. It has always been "Serving" us around the clock ". However, many computers cannot access the Internet at the same time in the building network recently. After careful inspection by the network administrator, it was found that this common switch had encountered an accident, all of its signal lights are flashing constantly. Considering the universality of such a fault, I will restore the troubleshooting process of the faulty switch's error records in detail, this helps you to improve fault resolution efficiency!

Network Worm Rate

A friend of the author rented a training data center in a certain unit building to provide Internet training for nearby college students. About 80 computers are in the training data center, all these computers are connected to two general switches through a common m twisted pair cable. To facilitate the control of the computer's Internet access status on each training terminal, all computers are connected through a proxy server, the Network egress line is a dedicated 2 m broadband line of a local telecommunications company. at ordinary times, the Internet access speed of each computer is relatively fast, and each computer shares access to each other, the speed is also very fast.

Recently, in order to meet the intermediate computer examination, a friend is going to debug the connection between each computer in the training room to ensure that they can be accessed normally with the proxy server. However, when a friend opens a terminal computer and tries to access the data in the proxy server over the Internet, he finds that the computer browses the content of the proxy server site very slowly, crawling like a snail bait. At the beginning, my friends thought that this terminal computer was running a lot of applications at the same time, resulting in excessive consumption of local computer system resources, resulting in slow response to the Internet, so I immediately restarted the computer system. After the computer was restarted successfully, I went online again for a test and found that the access speed was the same as that of a snail bait.

Find the main causes of faulty switches one by one

1. Eliminate terminal computer Factors

At first, my friends suspected that this was only a problem with the terminal computer itself, resulting in a very slow access speed to the proxy server. Then, he opened the system running dialog box of the faulty computer and used the ping command to test the IP address of the proxy server. The test was unsuccessful. After a new IP address was changed, the network access test continued, but the results were still the same. Is there a fault in the network connection line between the computer and the proxy server? A friend was a little worried. He immediately tried to pull out the crystal head of the network cable connecting to the faulty switch, and re-inserted it according to the normal method; will the network cable itself be short-circuited or broken? Find a professional network testing instrument to test the connectivity of the network cable and find that the connectivity between the computer and the switch is normal, it seems that the problem has nothing to do with the network cable connecting to the faulty computer.

After finding the terminal computer's own problems, a friend suspected that the computer system was faulty and planned to re-install the system. However, considering that the system had been re-installed for a long time, in addition, as long as the operating system can be started normally, its status will rarely affect the network connection status. Check the network connection status of other computers and decide to reinstall the system! With this in mind, my friend opened another computer in the training room and tried to access the proxy server in the computer system. What never imagined was that he started from this computer, the access speed to the proxy server was not normal. Later, my friend tried to test the network access status of several computers and found that they were all as fast as snails. Obviously, this abnormal fault has nothing to do with the factors of the terminal computer itself, so the task of re-installing the operating system can be avoided.

2. Remove Proxy Server Factors

Since network access Tests on several end computers are the same as failures, will the proxy server be slow to respond, why does it fail to respond to the Internet requests of various end users? Considering that the agent server runs for a long time, its system resources are easily consumed. In this case, the agent server is slow to respond. Therefore, A friend decided to restart the proxy server system to release its valuable system resources. After thinking of doing so, a friend immediately rushed to the proxy server and started the system again. After the system was started successfully, the friend first conducted an Internet access test on the proxy server, the test found that this operation was normal, and then tried to access the data in the proxy server from the terminal computer. Who thought this method could solve the problem, this kind of effort has not achieved any effect.

Is it possible that the firewall in the proxy server is secretly working? In order to eliminate various possible factors, a friend decided to temporarily close the firewall program installed on the proxy server system to ensure that it will not affect the access of each terminal computer to the proxy server; however, when a friend temporarily closes the firewall program, he finds that the network access test of the terminal computer is still as slow as before, this shows that the failure of the network speed is not directly related to the firewall program installed in the agent server system.

After I disabled the network firewall, my friend found that it did not play any role and began to doubt whether there was a network virus in the proxy server system, in many cases, network viruses can create a variety of strange faults. Will this time the network virus block the network transmission channel to the proxy server? To verify your conjecture, A friend found the latest version of anti-virus software and thoroughly inspected all corners of the proxy server system, during the scanning and removal process, my friend found some network viruses. After seeing these viruses cleared, my friend simply thought that the failure of normal access to the proxy server should automatically disappear, however, when we test the network access status again, we find that all faults are the same. This shows that the agent server is running normally.

3. Eliminate network connection Factors

Through the above check, my friend found that after the proxy server system was restarted, the operation was smooth and there was no system crash. Moreover, starting from the proxy server, my friend could access the Internet normally, this indicates that the Internet channel is smooth. Now the firewall program in the proxy server has been disabled, and the network virus has been cleared, the only thing that is not checked is that the network connection between the proxy server and the switch is not checked. Is the network connection channel between the proxy server and the switch blocked, so that other computers in the LAN cannot quickly access the data in the proxy server?

So my friend decided to check the network connection status between the proxy server and the switch. He first opened the system running dialog box of the proxy server, and executed the ping command to test the IP address of the switch. He found that the IP address can be pinged and sometimes cannot be pinged, if the IP address of the vswitch fails to be pinged when a slightly larger data test package is sent to the vswitch, the network connection channel between the proxy server and the vswitch does not exist. Will the proxy server's intranet connection interface become loose? My friend planned to pull the network cable connecting to the Intranet from the Intranet Nic of the proxy server and plug it again to see if the intranet connection is loose? To do this, my friend immediately unplugged the network cable connecting to the Intranet, but I was surprised that when I re-inserted the network cable again, my friend noticed that the network card signal immediately went into a flash and seemed to be constantly processing data information. When I first accessed the network, how could the proxy server suddenly receive such large data volumes? Is the Intranet Nic abnormal? A friend was a bit skeptical, but opened the Device Manager window for the corresponding system, found the Intranet Nic device option, and right-click the device option, run the "properties" command from the shortcut menu to open the attribute setting interface of the Intranet Nic, and click the "General" tab, on the corresponding tab page, a friend found that the Intranet Nic is working normally. Since the NIC device is normal, why is the signal of the NIC device still flashing, is the switch constantly sending data packets to it? A friend immediately arrived at the scene of the target switch and found the connection interface of the internal network card of the proxy server according to the label description pasted on each switch port. The result showed that the signal lights of the corresponding switch port were also in a non-stop flash state, what's more strange is that some switch ports clearly do not have network cables connected, but the signal lights on these ports are still blinking. Is the switch blocked by large data volumes?

Remedies for faults

The switch ports that do not have access to the Internet can also flash constantly, which indicates that the LAN switch is working properly. In this way, when any computer attempts to access the proxy server through the switch, naturally, it is not normal. As the fault location is located, it is easy to solve the fault. A friend estimated that all the signal lights of the faulty switch were flashing constantly, possibly due to the blockage of large-volume data. This blocking can easily make the switch "too busy, he tried to shut down the power of the faulty switch for a while, then re-connected it, and started the agent server system to prevent memory effect. After doing this, my friend once again observed the proxy server's internal network card signal, and found that this time it was working normally. Then he rushed to the faulty Switch site, he found that all the signal lights of the switch have returned to normal. It seems that the switch has been blocked.

After "Dredging" the network channel between the proxy server and the switch, a friend selects a terminal computer and tries to access the data content of the proxy server system in the system, after finding that the Internet access speed has indeed recovered to normal, I randomly selected other computers in the LAN for Internet access tests. My friend found that all computers can access the Internet normally, the network's crazy slow fault has been successfully solved, and the "sin" of this fault is naturally the switch that is blocked by large data volumes.