With the deepening of office automation, more and more units are engaged in microcomputer interconnection, and how to form an economical and practical LAN has become a hot topic. Naturally, network maintenance has become a hot topic. During the use of a small LAN in the unit, if the network is managed or set up improperly, the network transmission speed will be very slow and the network cannot play its due role. In order to help everyone use the network efficiently and reasonably, the author will compile his experience in maintaining and managing the network into a document, hoping that these contents will be helpful to everyone.
1. Troubleshooting
1. First check the network card when there is a fault
In LANs, network blockage often occurs. Once we encounter problems like this, we should first carefully check whether the network card settings are normal in each machine connected to the network. When checking, we can open the "Control Panel/System/Device Management/Network Adapter" setting window with the mouse, and check whether there are interrupt numbers and I/O address conflicts in this window (it is best to set the interrupts of each machine to the same for comparison) until the "This device is running normally" appears in the properties of the network adapter, and at least you can find yourself in "Online Neighbor", which means there is no problem with the configuration of the network card.
2. Confirm that the network cable and network equipment are working properly
When we check that there is no problem with the network card, we can use the online neighbors to look at other computers in the network. If we cannot see other machines in the network, this situation may be due to the problem of network connection interruption. Network connection failures usually include internal fractures of the network cable, twisted pair cables, poor contact with the RJ-45 crystal head, or the quality of the network connection equipment itself, or the connection problem. At this time, we can use a line measuring instrument to detect whether the line is broken, and then use an alternative method to test whether there is any problem with the quality of the network equipment. When there is no problem with the network cable and the network card themselves, let’s take a look at whether it is the software setting. For example, if the interrupt number is incorrect, it may also cause a failure.
3. Check whether the driver is complete
After checking and confirming the hardware, check whether the driver itself is damaged. If it is not damaged, check whether the installation is correct. If these can be judged to be normal and the device does not conflict, it means that it cannot be connected to the network. At this time, the network adapter can be deleted in the system configuration, and then restart the computer. The system will detect the existence of new hardware, and then automatically find the driver and then install it. The author has used this method many times to solve the problem of "not being able to access the network".
4. Correctly set up the network card
If you make sure that there is no problem with the network media but it still cannot be connected, then return to the network card settings. Check whether there are device resource conflicts. In many cases, conflicts do not have prompts. Possible device resource conflicts include: NE2000 compatible network cards and COM2 conflicts, both use IRQ3, (Realtek RT8029) PCI Ethernet network cards and graphics cards "like" IRQ10. In order to resolve the conflicts of this kind of device, we can set it according to the following steps: first block COM2 in the settings window and forcefully set the network card interrupt to 3; if there is a conflict between the network card and the graphics card of the PCI interface, we can use the method of not allocating IRQ to the graphics card to solve it, that is, set the Assign IRQ for VGA in CMOS to "Disable".
5. Disable the PnP function of the network card
Although some network cards support PnP function, they find that they cannot work well after installation, or even cannot work. To this end, we can use the method of blocking the PnP function of the network card to solve this problem. To disable the PnP function of the network card, you must run the network card setup program (usually in the driver package). After starting the setup program, enter the settings menu. Disable the PnP function of the network card and modify the IRQ item that can be set to a fixed value. Save the settings and exit the settings program, so that if no other devices occupy the IRQ, you can ensure that there will be no IRQ conflicts. In addition, if you want to install the Windows 95/98 operating system, it must be ensured that the operating system will not process the corresponding interrupt type as an IRQ with PnP function, so the type of interrupt must be changed from "PCI/ISA PnP" to "Legacy ISA" in "CMOS". This method can resolve device conflicts in most PnP network cards, but it may not be effective for all PCI network cards, because some network cards' setup programs do not provide the option to disable PnP function at all.
2. Performance optimization
1. Reasonably set up the server's hard disk
Users who work on LAN often use the network to print materials and access files. For some reason, the speed of network access may be abnormal. At this time, we often mistakenly believe that the reason for the reduction in network speed may be that some devices in the network have bottlenecks, such as network cards, switches, hubs, etc. In fact, the most impact on network speed is the speed of the server hard disk. Therefore, correctly configuring and configuring the hard disk of the server in the LAN will greatly improve the network performance in the entire LAN. Usually, we need to consider the following factors when setting up a hard drive:
A. The hard disk in the server should try to choose the one with a fast speed and large capacity, because the hard disk speed is fast, the faster it can access data on the server through the network;
B. The hard disk interface in the server is preferably of the SCSI model, because the interface is faster than the IDE or EIDE interface when transmitting data. It uses the parallel transmission mode to send and receive data;
C. If conditions permit, we can install a hard disk array card for the network server, because the hard disk array card can greatly improve the read and write performance and security of the hard disk;
D. Of course, everyone should also note here that in the same SCSI channel, do not share low-speed SCSI devices (such as CDs) with the hard disk, otherwise the performance of high-speed data transmission of the hard disk's SCSI interface will not be achieved.
2. Correct use of "bridge" equipment
"Bridge" devices are usually network devices for the same network segment, while routers are network devices for different segments. The author's unit once installed a set of microwave networking equipment. After the physical equipment is connected, it will be debugged online. The server always prompts the current network segment number to be the other party's network segment number. After changing the server's network segment number to the same as the other party, the server's alarm disappears. ah! It turns out that this is a set of equipment with bridge properties. Later, we installed microwave networking equipment with another location and replaced the products of another manufacturer. Before connecting, we changed the network segment numbers on both sides to the same. However, after installing the equipment, an alarm appeared on the server: the current routing error. After modifying the network segment on one side, the alarm disappeared. It can be seen from this that correctly distinguishing between "routing" devices and "bridge" devices is very important in setting network parameters.
3. Connect according to the rules
As we all know, connecting to each computer in a LAN is done by twisted pair cable, but it is not possible to simply connect the two computers to each other by simply connecting them to each other. We must connect according to certain wiring rules. The author once tried to connect two computers 100 meters apart with twisted pair wires to achieve communication, but no matter how hard I tried, I couldn't connect them successfully. Later, with experts' guidance, the connection distance of twisted pair wires could not exceed 100 meters. In addition, if we need to connect two computers more than 100 meters, we must use the conversion device. When connecting the conversion device and the switch, we must also perform jumpers. This is because in Ethernet, two pairs of twisted pair wires are generally used, arranged at positions 1, 2, 3, and 6. If you are not using two pairs of wires, but using the original paired wires separately, a series of windings will be formed, resulting in greater crosstalk (NEXT). It has a great impact on network performance. This situation is not obvious in a 10M network environment. If the traffic volume or distance is long in a 100M network environment, the network will not be able to connect.
4. Strictly implement grounding requirements
Since in the local area network, all the weak signals are transmitted, if the operation is improper or the specific operation requirements of the network equipment are not carried out, interference information may occur during the network connection, which may cause the entire network to be blocked. In particular, some network transfer devices, because they involve remote lines, have very strict requirements on grounding, otherwise the network equipment will not reach the specified connection rate, resulting in various inexplicable failures during the network connection process. The author once accidentally plugged the power plug of the router into the mains socket, but the 128K DDN dedicated line just couldn't connect with the Internet. It was normal for people from the telecommunications bureau to check the circuit. Finally, they checked the zero-ground voltage of the router power supply. They found that something was wrong, so they switched back to the UPS socket and everything returned to normal. Another time, the grounding end of the router's power plug was broken, resulting in frequent data packets being lost. When doing PING connection, it is sometimes good and sometimes bad, and everything is normal after replacing the power cord. It can be seen that when we use network equipment, we must do it under the conditions specified by the equipment, otherwise it will cause great trouble to our work.
5. Use new network cards with good quality and fast speed
In a local area network, it is normal for computers to not communicate with each other, and there may be many causes of failures. The author once counted that most of the faults in the LAN are related to the network card, or the network card is not installed correctly, or the network line is poor, or the network line contact may be due to the old network card and cannot be correctly identified by the computer. In addition, some network cards are installed in the server and cannot withstand the impact of large-capacity data and eventually scrapped. Therefore, in order to avoid the above phenomenon, we must be willing to invest. If the network card is installed in the server, we must use a high-quality network card, because the server generally runs continuously, and only a good-quality network card can "work" for a long time. In addition, because the server transmits data large capacity, the capacity of the network card we purchased must match it, so that we can achieve "a good horse and a good saddle".
6. Set up the switch reasonably
Switches are an important data switching device in the LAN. Correct and reasonable use of switches can also improve the data transmission performance in the network. The author once configured the switch port as 100M full duplex, and a network card with the model Intel100M EISA was installed on the server. Everything was normal after installation, but when data transmission is high-traffic load, the speed became extremely slow. Finally, I found that this network card does not support full duplex. After changing the switch port to half duplex, the fault disappears. This means that the switch ports must be consistent with the network card's speed and duplex method. Currently, there are many adaptive network cards and switches. According to the principle, they should be able to correctly adapt to the speed and duplex mode, but in fact, due to inconsistent brands, the full duplex mode is often not correctly implemented. The server network card is clearly set to full duplex, but the switch's duplex light is not on, and it can only be solved by manual forced settings. Therefore, when setting network device parameters, we must refer to the network device parameters on the server or other workstations to try to make each device match and work as much as possible.