Common troubleshooting methods for local Area network substitution

Network failures are unavoidable, and it is important to isolate and troubleshoot them quickly. The maintenance personnel of Internet cafes should have basic network knowledge, and can solve some common network problems. This article enumerates several common network fault analysis, hope to be able to improve everyone's analytical ability and the ability to solve the problem.

Fault one, 100Mb LAN speed without 10Mb LAN speed is fast

Specific performance: Because all workstations are 10-100MB Adaptive network card, and the original all used is 10Mb switch, now the network upgrade, all replaced by 100Mb switch, found that after the switch, the speed is not the original fast. Some machines can't even surf the internet.

Failure Analysis: We ping the local area network Gateway Ping, found that the switch phenomenon is serious, with a wire detector check twisted pair of wires, found that everything is normal. Check the network cable, found that the cable is the original use of the three types of lines, does not support 100Mb network. Since we upgraded the network, only the network switching device was upgraded, ignoring the upgrade transmission media-the network cable.

WORKAROUND: Replace the network cable

Description: When you upgrade the network, we must check their own equipment such as network card, network cable whether support 100MB work environment, do not blindly upgrade one of them, resulting in a small horse-drawn cart not supporting the phenomenon. According to their own resources, reasonable use. For the current network, everyone in the wiring, not as one-step, buy amp (AMP) Super Five types of network cable, one is to facilitate future upgrades, both can make their own network speed stability.

Fault two, new internet cafes, often drop the line or unable to log on to the network

Specific performance: A newly opened internet café, an area of 300 square, 50 machines, equipped with a dedicated room, place switches and servers. The results show that when the machine is debugged, it often drops or fails to log on to the network.

Failure Analysis: ping command to check, found that serious packet loss and timeout, the network all with the test line tester, all normal. Inadvertently found the distance from the switch to work is too long, carefully measured the distance, 100 meters. The transmission distance of twisted pair is generally not more than 100 meters, the actual transmission distance is about 95 meters. Internet café owners only in order to pursue high-end, equipped with a dedicated room, but ignored the network cable transmission distance limit.

WORKAROUND: Relocate the switch location.

Note: In the integrated wiring, it is necessary to choose the location of the switch, the center switch is best placed in the central location of the Internet bar. The following switches should also be placed at the center of the connected computer. This kind of placement method, one is to save the network cable, the second is can make the net reach the best transmission state.

Fault three, IP address and address string conflict

Specific performance: All machines, IP address in the network settings are unique, there are always two machines, at the time of startup, an address and IP address conflict with a series of address conflicts. Change the IP address still. And in times of conflict, only one machine can surf the Internet.

Fault analysis: A careful look at the conflict of the hint, is a series of addresses, will not be a physical address conflict, that is, MAC address conflict caused it? But you can't always find each one. Use Ipbook Super Network Neighborhood, friends hint to. Using Ipbook's Super Network Neighborhood, scanning the entire segment, it turns out that the MAC address of the two machines ' Nic is exactly the same.

WORKAROUND: Replace the NIC. The problem is resolved after the NIC is replaced.

Description: All network devices working in the network, including NIC, switch, router have a physical address, called MAC address. The MAC address contains the manufacturer of the network device and the unique serial number on the global network device. All network data exchange is based on the MAC address Exchange, not on the IP address Exchange. Therefore, if the MAC address conflicts, the IP address does not conflict, will also cause network disruption, because the data can not find the end point. Therefore, when you buy a network card, you must buy authentic, not to covet cheap, bought defective. If it is a network card MAC address conflict, change a piece, or small. If a MAC address conflict occurs on a switch, you're in a lot of trouble.

Fault four, 100MB network network speed is not stable

Specific performance: The NIC adopts 10-100MB Adaptive network card, the switch is full duplex 10-100MB switch. When surfing the internet, the network speed is fast and slow

Failure Analysis: ping command to check the time, there is no swap phenomenon, all normal, but the speed is not normal. Checked the network settings, also normal. After looking closely at the LEDs of a switch, it was found that the switch was always converted in 10Mb and 100Mb two working states. The problem is fixed.

Solution: Find the problem, how not to let him automatically switch working state AH. Carefully looked at the machine network card properties, the value specified in the speed is auto, I changed him to 100Mb full. Tested it, everything was fine.

Note: Some network problems occur, to first check all the network equipment, and then analyze the reasons, believe that the speed of solving problems will soon.

Failure five, all machines in the network all IP address conflict

Specific performance: After the machine started, all the machines appear IP address conflict. Check the IP address settings, no duplicates. Work with the WinXP operating system.

Failure Analysis: All workstations after the boot, into the desktop, automatically pop-up IP address conflict prompts, and each client uses a fixed IP address, no address conflict. So I decided to look at the network configuration under XP DOS. Ran a ipconfig/all, found that there is a DHCP server in the network running, the dynamic assigned to this machine IP address and other machine IP address conflict. Explain, the DHCP server is network management in the cloning, in order to facilitate the establishment. Results after network cloning ended, forgot to stop the service.

Workaround: 1, turn the DHCP server off 2, change the IP address pool of the DHCP service, and exclude all the fixed IP addresses that are being used.