A Brief Discussion on Local Area Network Maintenance

As office automation deepens, more and more organizations are connecting their microcomputers, leading to the growing popularity of building an economical and practical local area network (LAN). Naturally, LAN management has also become a hot topic. During the use of small LANs within an organization, there are often occurrences of "disconnection," where perhaps only a few machines cannot communicate or sometimes the entire network fails to work. Of course, this depends on the type of network topology you have. Based on my experience in maintaining LANs, I will discuss my views using a star network topology as an example:

1. When a network disconnection occurs, during LAN maintenance, first check if the network card settings on each machine connected to the network are normal. This can be done by checking the "Control Panel," "System," "Device Manager," and "Network Adapter" for any interrupt conflicts or I/O address issues (it's best to set all machines to have the same interrupt for easier comparison) until the property of the network adapter shows "This device is working properly." Additionally, ensure that "Network Neighborhood" can at least find itself, indicating that the network card configuration is correct. Of course, using and setting up network cards requires skill, especially PCI network cards.

2. When a particular machine cannot access the network, the first step is to confirm that the network cable is not the issue. This can be resolved through substitution methods. Then use the same method to determine if the network card itself is faulty. If both the network cable and the network card are fine, then check if the problem lies in software settings.

3. Additionally, check if the driver itself is corrupted, and if not, ensure it is installed correctly. If everything checks out normally with no device conflicts but still cannot connect to the network, delete the network adapter from system settings and restart the computer. The system will detect new hardware and automatically search for and install the appropriate driver. I have used this method multiple times while installing Windows 98 peer-to-peer networks to solve "unable to access the network" issues.

4. If each machine can find itself in "Network Neighborhood," this indicates that the network adapter installation is correct. However, if it cannot see other machines on the network, this is likely due to network media problems such as faulty twisted-pair cables or RJ-45 connectors. Since it's a star connection, you can replace the connections of a faulty workstation with those of a functioning one to pinpoint the exact fault.

5. After confirming that the network media has no issues but still cannot connect, return to the network card settings. Check for any device resource conflicts, which may not always prompt warnings. Possible conflicts include: NE2000 compatible network cards conflicting with COM2 both using IRQ3 (Realtek RT8029), PCI Ethernet cards and graphics cards both "liking" IRQ10, resulting in neither being able to function properly. Solutions include disabling COM2 and forcibly setting the network card interrupt to 3; for PCI interface network card conflicts with the graphics card, you can resolve this by not assigning an IRQ to the graphics card, i.e., setting the "Assign IRQ for VGA" option in CMOS to "Disable." Additionally, to make network card installation simpler, disabling the PnP (Plug and Play) function of the network card is a good solution. To disable the PnP function, you must run the network card setup program. After launching the setup program, enter the setup menu, disable the PnP function, and modify the IRQ setting to a fixed value. Save these settings and exit the setup program. If no other devices occupy this IRQ, you can ensure no IRQ conflict arises. Moreover, if installing Windows 95/98 operating systems, ensure the operating system does not handle the corresponding interrupt as a PnP-enabled IRQ, so change the interrupt type in "CMOS" from "PCI/ISA PNP" to "Legacy ISA." Using this method can resolve most PnP network card device conflicts, though it may not be effective for all PCI network cards since some do not provide an option to disable PnP functionality. In such cases, you may need to seek other solutions, or perhaps it's time to replace your "pitiful" network card.