Troubleshooting vswitch with hub and shunt

It uses hubs and shunt to solve switch fault diagnosis technology. After broadband is popularized, it is often faced with switch fault diagnosis technology problems. So today, I am going to introduce you to the technology and skills of switch fault diagnosis. I hope this article will teach you more things and bring convenience to your life.

Vswitch fault diagnosis technology: connect to a hub on a link

It is strategic to use a hub. For many networks, most of the sent and received traffic comes from shared devices such as file servers. Access a hub between the switch port and the file server, and then connect the analyzer to the hub. In fact, the analyzer and file server are connected to the same broadcast domain. Using this vswitch fault diagnosis technology, the vswitch Fault Diagnosis technical support staff can see all the incoming and outgoing traffic of the file server and help the vswitch Fault Diagnosis technical support staff solve a series of problems, this includes user login failure, low performance, and connection loss.

Figure 1. Using a hub to monitor vswitch ports

The method for connecting to a hub is often not practical, especially when multiple servers need to be monitored. Where is the access hub suitable? Are all servers connected? If you use a hub to change the connection, you do not want your network to be frequently disturbed. The delay caused by the connection hub often results in connection loss. In addition, many times the monitoring tool does not support the technology or connection rate used by the server.

Using a shared hub to monitor all traffic and errors on a link is still an effective method. This is almost the only way to view and analyze MAC layer errors in an switched network environment. You can also use SNMP to discover these errors. However, for better error analysis, it is most direct to use monitoring tools.

The method for connecting to a hub has two main defects. The server link may not be full-duplex, or it does not match the port duplex status of the hub. This will bring more undesirable error results to the monitoring. In addition, you must have a shared hub.

Nowadays, many new hubs are similar to switches rather than shared forwarding devices. Access to this new hub is equivalent to a new switch fault diagnosis technology, you will not see the traffic you want to view, it does not play a role in monitoring. If anheng is connected to a dual-rate hub, such as a 10 Mbit/s/Mbit/s dual-rate hub, it is possible that each rate provides a broadcast domain and forwarding between two rates.

In this case, you need to confirm that the monitored link and monitoring tool are running at the same rate to use this dual-rate hub. There are also some hubs that provide the forwarding function between all ports. Therefore, it is a misunderstanding to advertise itself as a cheap switch. Neither of them can be used in this monitoring method.

Switch fault diagnosis technology: Use a TAP (Monitoring Interface Box) or shunt

This method is similar to adding a shared hub. The difference is that the TAP link only receives traffic and does not allow monitoring tools to send traffic.

Vswitch fault diagnosis technology: TAP and shunt

Words can be exchanged sometimes, although the shunt is usually used in optical fiber links. On the optical fiber link, the shunt splits the light in the initial path and the monitoring path. Typical split rates include 80: 20, 70: 30, and 50: 50. Taking 80: 20 as an example, 80% of the light is transmitted to the original path through the splitter, and 20% of the light is forwarded to the monitoring path.

If there is a problem with the optical fiber, or the transmission distance is long, the optical shunt will cause 20% light loss, which may easily cause Link problems. The shunt can easily cause 3 dB attenuation on the fiber link. Some shunt is more durable, so even if the shunt is installed at one end of the link, it can be switched to the other end for installation, so that the link can work properly. Optical shunt can work without power supply. Note that the shunt is an Inbound monitoring device, so it is very important that the shunt cable be correctly connected.

The TAP of the electrical port will also cause signal loss, because the TAP needs signals to identify the passing traffic. For cables, this is equivalent to increasing the attenuation. If the link itself has some problems or the link is long, the introduction of TAP may cause connection interruption. The TAP of the electrical port needs a power supply, and the signal is restored and re-transmitted to the monitoring port. If it is well designed, the link should not be interrupted when the TAP power is down.

It is a good way to view the link traffic by monitoring the link using TAP. Once the installation is successful, the TAP is transparent to the monitored device and can be used at any time without any interference. Unfortunately, the link must be temporarily interrupted when accessing the TAP. In addition, the TAP or shunt will provide traffic in two separate directions. In other words, sending and receiving are separated.

To simultaneously monitor requests and responses through the TAP link, a monitoring tool with two input ports is required. The dual-port monitoring tool can monitor each direction separately or combine the two links for analysis. You can also choose to monitor traffic in one direction at a time, but this analysis will be more difficult.

For the TAP, there is no difference in the operation between the monitoring full-duplex link and the half-duplex link. You can select a single-port monitoring tool to monitor a single direction, or select a dual-port monitoring tool to monitor both directions at the same time.