College】 【weak network switch buffer overflow caused by viruses.

<br> <BR> LAN switch is a very important data exchange, processing equipment, which directly affects the performance of local area network data transmission capacity and network transmission speed. .Normally, the switch device performance is relatively stable, especially for general two-story switches rarely a problem, but recently a unit of a local area network using ordinary floor switch there is not normal. .Taking into account this phenomenon rarely occurs, resolve the anomalies in the process is different, and now this unusual phenomenon to the process of resolving the detailed contributions out for my friends refer to the exchange! .<BR> <BR> Playback <BR> <BR> failure of a unit is not large-scale local area network, 10 offices in about 40 workstations, two models were connected to the same common 24 TP-Link brand switch .This two-story two switches as LAN switches, routers directly to the unit cascaded device, the router device and then through the broadband fiber optic lines connected to the network and the Internet, usually all workstations in the LAN can share access to each other, each .a workstation through the LAN routers have direct access to Internet network, the content of the target site. .<BR> <BR> Recently, some workstations in the LAN to access either does not work the other workstations within the network system to share content, can not access the Internet network, the content of the target site, but was able to access other workstations within the network, .also can access the Internet. .Taking into account a number of workstations in the LAN can access the Internet network, which means that the working status of local area network router device is normal, those who can not access the workstation is likely to be their own reasons or by the ordinary two-story with a problem caused by the switch. .<BR> <BR> Trace the cause of <BR> <BR> order to understand the specific cause of the malfunction, the author free from the LAN can not access the Internet to find a common network workstation, the workstation system, open the Run dialog box, in which the use of .ping command, followed by testing the local LAN device IP address, switch IP address, the router's IP address and found the IP address of the local LAN device can be through the normal ping, the IP address of the other two devices can not ping through the normal, which .that the work of the local workstation NIC device status is normal, the local LAN switching equipment and router equipment to the physical lines between devices may be a problem, in order to determine whether this problem caused by the cable network connection, I immediately hired the professional .cable test equipment to the cable connection on the target network connectivity test, the test found that the physical connection cable is normal. .Since the physical connection <BR> <BR> line is smooth, then why fault the workstation NIC device to switch between devices and network router equipment does not work ping line through it? .Confirm the work status of the LAN equipment is normal, will not fault the workstation is connected to the switch port status is not working properly, or to switch the entire second floor of what had happened there it? .Thought of it, I immediately connected along the cable network connection failure workstation to find the connection that failed workstation switch ports, I immediately try to switch to other switch ports to test and found that the tests are not normal. .I once again failed workstation connected switching equipment was carefully checked and found that the device control panel all the lights are not flashing at full brightness, it is clear this state is not normal, because normally when a switch port forwarding .to deal with online data, the corresponding port should be in the light flashing lights, and now the lights are not flashing all ports that connect to this story that the switch does not exist in the data forwarding all workstations act, then the two .layer switch all of the following does not work naturally workstations online. .Troubleshooting <BR> <BR> <BR> switch working conditions encountered in the second floor is not normal, we tend to look at the device as long as the restart will solve the problem, after all, the hardware layer switch quality rare; according to this .analysis, I immediately switch off the power switch failure, over a period of time to re-power, sure enough, to be stable after the failure to restart the switch, the LAN can not access the previous failure of the workstation immediately resume the normal network connection status. .<BR> <BR> Thought here, and LAN workstations can not access the fault even if some solution is successful, but who would have thought, but also every one hour, those who can not access the workstation again the same symptoms, this time .observed that Taiwan failed again when the switch device, I see the device control panel and all the lights are not flashing at full brightness, and this shows that the story took place in the same switch fault; after repeated testing and practice, the author found .Even if Taiwan is not connected to any workstation layer switch will occur at the same time period the same symptoms, this is why? .Why LAN switches work the other one two-story state is always normal? .<BR> <BR> The unit even though I know there are a lot of LAN workstations present in the system with different kinds of network viruses, but considering that the same two brands of ordinary two-story switches, connections are the same, or even their configuration is .exactly the same, and now only one switch device there is a problem, so I estimated that the switch must be the fault occurred in Taiwan, hardware damage, in order to thoroughly solve the problem, the only way is to replace the floor switch. .<BR> <BR> As the author has no ready-made switches on hand equipment can be replaced, do I intend to in the first local area network to conduct a thorough inventory of the virus, you must ensure that the new equipment in place before the switch, the entire local area network is very "clean .", and there is no network of virus or Trojan. .In the LAN cleaned all the virus program, after all, the author has conveniently failed to restart a bit switching equipment, switching equipment, after I saw the work of state failure and normal, because I was something in the body to first leave the fault .the scene the next morning at work, I saw that the way the working status of Taiwan, the switch failure, so I pleasantly surprised that even the working status of the switch has been normal; When I find a free workstation can not access the previous test system .found that the network connection status now they have returned to normal. .Continue to observe a period of time, they still have the normal state of the Internet, thus it can not access the workstation is part of the final settlement for the failure phenomenon, the phenomenon caused by this failure the ultimate "culprit" is obviously the LAN network virus. .Deep Analysis <BR> <BR> <BR> <BR> the failure phenomenon from the surface, is due to the second floor of the LAN switch caused by abnormal working conditions, in fact, the working status of the switch failure has been the impact of network viruses .; the existence of the LAN network virus, network virus had caused a local area network broadcast storm phenomenon, which led to failure switch buffer overflow error occurred, and ultimately making the switch occurred in paralysis, which is the failure of the lights switch on all ports .state are in full light is not flashing reasons. .When all of the LAN network virus cleaned after all the fault after restarting the switch after it disappeared buffer overflow errors, then it's working state can be back to normal, and after the virus does not continue to affect the network .switch, so the working status of the fault also be able to switch remain normal. .<BR> <BR> In addition, the LAN switch another reason why a network virus attacks have not been, is likely to be relatively stable performance of the switch, in other words, there may be components switchboard equipment failure phenomenon of aging, which .kinds of phenomena cause a failure the ability to switch network virus resistance relatively low, so that the same type of two layer switches, the natural state of their work is not necessarily identical to the. .<BR> <BR> By the network in order to avoid any symptoms of this virus, we set up local area network, you should try to use more stable performance, large-capacity switching equipment cache; while the use of legitimate anti-virus software regularly .to remove the LAN network viruses, prevent the broadcast storm phenomenon. .<BR>.