Solve the problem of switch network loop by reasonable configuration

Reasonable configuration solves the problem of Switch network loop, in the way of judging switch network loop, this paper makes a preliminary analysis of switch network loop problem from log information and enabled state, then rationally configures the switch and finally solves the switch network loop problem.

In large-scale LAN network, often encountered network channel is seriously blocked phenomenon, resulting in a lot of reasons for this failure, such as network encounter virus attacks, network equipment hardware damage, network port transmission bottlenecks.

However, from the statistical probability that the network jam phenomenon occurs, changes in the network or changes in the location of the most prone to failure phenomenon, because the frequent changes in the network is very easy to trigger the switch network loop, and the network loop caused by the switch network congestion often has a strong concealment, not conducive to the efficient exclusion of fault phenomenon.

So can we find a suitable way to efficiently solve the network channel blockage caused by the switch network loop? In fact, the smart configuration of the switch loopback monitoring function, we can quickly determine whether there is a network of switches in the LAN circuit, so that the switch network loop caused by the fault phenomenon can be quickly resolved!

Thinking of judging switch network loop

Since the newly bought switch almost all support the port loopback monitoring function, we can enable the switch to automatically determine if the switch network loop is occurring in the specified communication port by using this feature skillfully. Once we enable loopback monitoring on a specified Ethernet communication port, the switch device can automatically scan all communication ports at timed intervals to determine if there is a switch network loop phenomenon in the communication port.

If a switched port is detected to be loopback by the network, the switching port is automatically loopback monitored, and the switch automatically shuts down the specified switch port or automatically reports log information for the corresponding port, depending on the switch port parameter setting and the port type.

In the future, as long as we look at the log information or according to the port's enabled state, we can quickly determine whether there is a switch network loop phenomenon in the LAN. Now, this article takes the H3C S3050 model switch as the Operation Blueprint, introduces to you in detail the use loopback monitoring function to judge the Switch network loop phenomenon the concrete configuration step.

Enable port loopback Monitoring

In order for the switch to automatically determine whether there is a switch network loop in the local area network, we need to enable the switch's port loopback monitoring function, but also enable the port loopback monitoring of the controlled function, but in the default state, these features are turned off, we need to manually configure the switch, To enable the switch to specify the port loopback monitoring function and the port loopback monitoring controlled function.

When the switch port loopback monitoring function is enabled, we can login to the switch background management interface remotely with system administrator privileges, enter the string command "SYS" at the command prompt of the interface, and click the ENTER key to switch the switch to System view state;

Then, in the System view state, execute the string command "loopback-detection enable" so that the switch's global port loopback monitoring function is successfully enabled.

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Below, we also need to enable the switch to specify the Ethernet switching Port loopback monitoring feature enabled; For example, if we want to enable the loopback monitoring feature of Ethernet 16 ports, you can enter the string command "interface Gigabitethernet" in the system view state of the switch. 1/0/16 ", when you click Enter, the interaction configuration state will enter the view state of Ethernet 16 port.

The switch's command line prompt also automatically becomes "H3C-GIGABITETHERNET1/0/16", and the string command "loopback-detection enable" is executed again at the command line prompt. As a result, the switch's Ethernet 16-port loopback monitoring function was successfully enabled;

Next, we need to enable the network loopback monitoring of the hybrid port and trunk port in the Ethernet 16 Port view state, when enabled, we only need to execute the string command at the "h3c-gigabitethernet1/0/16" command Prompt " Loopback-detection control to enable "on it.

Monitoring of different VLAN loops

With the above configuration, the switching system performs network loopback monitoring only in the default VLAN of the hybrid port and trunk port under the specified Ethernet port, and cannot perform automatic monitoring operations on other VLANs. In this way, if there is a switch network loop phenomenon in other virtual working subnets in the LAN, the switch still cannot be judged automatically.

For this reason, we need to use the appropriate settings to enable the switching system to automatically perform network loopback monitoring operations on other VLANs, for example, to enable the switch to perform a network loopback monitoring operation on the hybrid port under Ethernet 16 and all VLANs that the trunk port belongs to. The following configuration actions are required:

Switch to the System view mode first, then enter the Ethernet 16 Port view, and at the "h3c-gigabitethernet1/0/16" command prompt, enter the string command "Loopback-detection Per-vlan enable" , the switch system will be able to perform network loopback monitoring operations on all VLANs to which the hybrid port and the trunk port belong after clicking the Enter key.

Of course, after all the string commands above have been successfully executed, we also need to exit the system view state of the switch through the "quit" command, and then execute the "save" command to save the port configuration parameters of the switch, otherwise the switch will be restarted at a later time. The various configuration operations that were previously performed will be automatically lost.