Switch troubleshooting: Use a layer of equipment to help the Detector

Switch troubleshooting: a layer of equipment is used to help the detector. You are very interested in troubleshooting the switch. Before giving you a detailed description of how to troubleshoot a vswitch, let's first take a look at a layer of equipment, such as a hub, to help the monitor collect the required information.

Since the vswitch is a layer-2 device, it cannot forward all information traffic. So let's think, can we use a device, such as a hub, to help the monitor collect the required information? In fact, the network of many enterprises is a large broadcast domain.

For example, we add a hub to a key link in the middle. Connect the network monitor to the idle port of the hub. In this case, the network monitor can collect the required network traffic without configuring the Image Port.

The difficulty of troubleshooting A vswitch is that the network administrator must select a proper location to place the hub. If you choose improperly, the network monitor still cannot collect the required content. Currently, most enterprises adopt network applications based on the server/client or server/browser mode.

This is different from the previous network deployment mode. In the past, when an enterprise deployed a network, each host may have a shared folder for access by other employees. But now it is different. To improve the security and sharing of enterprise files, network administrators usually deploy a dedicated File Server to manage these shared files. Improve file security through a unified backup and File Access Authorization solution.

At this time, the traffic between the enterprise server and the customer segment is usually the most concentrated. If the network administrator deploys the hub on one end of the server and places the network monitor on the idle port of the hub, most of the network traffic can be monitored. So that the network monitor can produce a relatively reasonable diagnosis result.

Deploying a hub and other network devices at one end of the server helps the network administrator collect data traffic from user logon failures, access conflicts, packet loss, and authentication failures, this provides data support for solving the problem. In particular, the vswitch troubleshooting method is adopted.

We can determine whether there is a fault on the switch side or a problem on other layers. As the saying goes, I don't know the true colors of the mountains, but I am born here. Sometimes, removing a vswitch from the vswitch can help our network administrator quickly locate the vswitch fault.

In addition, so far, this is also the only method I know that can be used to view and analyze physical address layer errors in a switched network environment. This method can be used to identify whether IP Address Resolution errors exist in network devices such as switches. Especially for discovering ARP attacks. However, using hubs to identify faults of Cisco switches still has some defects.

First, frequent plugging and removal of hubs may cause daily network access problems. Because it is impossible for the network administrator to place an inefficient hub device between the server and the customer segment. This greatly reduces the server performance. The network administrator can temporarily deploy a hub between the server and the customer segment only when the network is faulty and requires maintenance. In this case, you need to temporarily interrupt network access and establish a connection.

Second, if the working status of the hub port is different from that of other adjacent devices, for example, if the server link is not full-duplex or does not match the duplex status of the hub port, instead, it will bring many additional error results. These error results will confuse the network administrator's ideas for solving the problem.

Therefore, the author suggests that if you want to use a hub to identify the switch failure, it is best to confirm that the working status of the hub port matches the existing network before this. Avoid unnecessary troubles due to non-matching.

Third, the network administrator can only passively use this method. It is silly to place a hub near the server. Therefore, network administrators usually deploy a hub only when a problem occurs for network troubleshooting. Therefore, this network monitoring cannot be a daily behavior. Therefore, this method is relatively passive for network administrators.

The preceding two troubleshooting methods are often used in the enterprise network composed of vswitches. These two methods can help the network administrator solve most of the network problems caused by switch troubleshooting. However, in practice, some switch faults cannot be solved in this way. However, the network administrator's experience is required to discover the problem. After all, relying on existing technologies and tools, it is almost impossible to look at the entire enterprise exchange network in some simple ways.