Explanation of switch port status

The following describes how to solve problems such as switch port faults and related switch ports. When the NIC device is abnormal in the future, the first thing to consider is whether the switch port is faulty.

During normal work, the failure of workstations to access the Internet is generally caused by the switch port. Currently, many technical forums have provided some solutions to switch ports, these methods provide us with ideas and methods for efficient network management.

However, when solving Nic faults, we often need to go to the fault site to understand the working status of NIC equipment and determine the fault of NIC equipment. In fact, in many cases, we do not need to go to the fault site, you only need to observe the status of the switch port that is directly connected to the NIC device, and then the status information of the target Nic device can be transparent.

I have encountered a fault. The red "X" icon appears on the network connection icon in the system tray area of the workstation, at the beginning, I thought it was caused by unexpected disconnection of the NIC device, long network connection cable, wrong line sequence of the network cable, or poor jumper contact, so I tried to modify the online settings of the workstation system, change the network connection cable, and restart the workstation system. However, these operations did not solve the network failure.

Later, I remotely log on to the floor switch system connected to the target Nic device from my workstation system and switch the system to the superuser management status, execute the string command "displayintere0/2" at the command line prompt in this status (intere0/2 is the switch port connected to the target Nic device ).

The result page shows that the working status of the corresponding switch port is "err-disabled", and the result page shows that the corresponding port has a large value of Collisions, the value obviously exceeds the specified range. In the end, the switch system mistakenly considers that there is a network loop on the corresponding switching port, and forcibly sets the port's working status to "err-disabled ".

If a port of the vswitch is in the active state of "err-disabled", it is likely that the NIC device of the workstation is not properly installed, the working mode of the NIC device does not match the working mode of the corresponding port of the switch, or the usage of the network cable is not standard. For example, the transmission distance of the network cable exceeds the maximum communication distance, or an inappropriate cable type is selected.

According to this analysis, the author first completely uninstalls the NIC Driver of the common workstation from the system, and re-installs the NIC driver according to the correct method, then, a compliant network cable was created to connect the NIC device and the switch.

However, this effort still cannot solve the problem. Is it because the NIC device does not match the switch port working mode, resulting in the switch port connected to the NIC working status changing to "err-disabled "? In order to verify my guess, I immediately click the "Start"/"set"/"network connection" command in the normal workstation system.

In the displayed system network connection List window, right-click the target local connection icon and run the "properties" command from the shortcut menu, open the attribute settings window for the local connection. Click the "General" tab in the settings window and select the target Nic device on the corresponding tab settings page.

At the same time, click the "Configure" button to open the Property setting interface of the target Nic device, and then click the "advanced" tab, on the label settings page that appears later, I can see that the target Nic device is in the M half duplex status, but checks the switch port status that is connected to the target Nic device.

I can see that the working status of the corresponding switch port is m full duplex. This shows that the reason for the increasing number of Collisions conflicts is that the duplex mode of the NIC device and the Switch Connection port is not consistent, in this way, the workstation cannot access the Internet.

After finding the cause of the fault, I immediately changed the working mode of the NIC device to m in the normal workstation system, and then restarted the workstation system, at this time, I found that the normal workstation can access the Internet immediately.

From the troubleshooting process above, we cannot rashly use the method of replacing the NIC device to solve the fault if the NIC device is abnormal in the future, this can improve the efficiency of solving network faults, but it cannot take full advantage of the residual heat of the NIC equipment.

Let alone solve the fault caused by mismatch of the duplex mode of the NIC. Instead, we should be good at starting from the connection port of the switch, and carefully check the status of the NIC device and the switch port status it is connected, from these status information, we are able to find effective solutions to network faults.

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