Improved stable switch fault diagnosis technology

Many users respond to slow network connection when using the exchange network. Using the switch fault diagnosis technology, this problem can be well solved. The simplest technical method for vswitch fault diagnosis is to connect a monitoring tool, such as a protocol analyzer, to the idle port of the vswitch. Connect the monitoring tool to an idle port of the vswitch to view the broadcast domain without interrupting the service. This monitoring tool has the same permissions as other sites in the broadcast domain.

Unfortunately, the switch fault diagnosis technology (as a multi-port bridge device) hardly forwards traffic to the monitoring port. Because the bridge device is designed in this way, the traffic is directly forwarded to the destination port, and no other ports are transferred. As a result, the protocol analyzer barely monitors traffic.

A very small amount of traffic is forwarded to other ports. The site and server may forward several thousand frames per second, but the Monitoring port can only see several frames per minute. Almost all the traffic forwarded to the monitoring port is broadcast, including sporadic frames with unknown destination addresses. These sporadic frames are due to the aging of the route forwarding table, and are often frames with unknown destination ports. Some technical staff who are not experienced enough saw such a high broadcast (close to 100%), but did not notice that the port utilization rate was very low, and thus the network encountered a broadcast storm.

In this way, it is almost useless to view the switching network, because the monitoring tool must obtain the traffic. The obtained traffic or query of broadcast domains is helpful for network search and other types of problems, but it does not help solve the problem of slow connection. For most vswitch troubleshooting technologies, there is a better option to back up the port traffic to be monitored to a dedicated idle port. This technology is usually called a port image.

Most switch manufacturers provide backup or image traffic functions. You can connect the monitoring tool to a specially configured port of the switch. The old vswitch fault diagnosis technology must specify a dedicated monitoring port as the mirror port, but now most new vswitches can specify any port as the mirror port.

Although the image implementation methods of switch manufacturers vary, there are some similar monitoring options. It is worth noting that, in almost all cases, the switch fault diagnosis technology filters out errors when forwarding traffic to the mirror port. For vswitch fault diagnosis technology, this means that useful information is filtered out at the same time.

In addition, we need to configure the image through the control port (RS232 port of the switch) or the Telnet process. This means that in addition to monitoring tools, we usually need to bring a computer or terminal to configure the switch. The mirror port is often only a "listener" port, but many switch manufacturers allow this port to be configured in full duplex mode.

With the image port configured, the monitoring tool can view the backup of the actual traffic between the host and the server reporting slow connection. The Image Port can only monitor any port of the vswitch, or even Uplink port, or monitor multiple ports of the vswitch at the same time. However, if a large number of ports are monitored at the same time, excessive traffic may exceed the Image Port's reception capability. Monitoring Port output capability is a very important issue. The image port can be received or sent. During configuration, the Image Port sending function is often disabled. However, whether or not the Image Port sending function is disabled (whether the Image Port is full-duplex or not), the Image Port's reception capability is limited. If the rate of the fully-duplex port to be monitored is the same as that of the mirror port, the switch will easily lose packets when forwarding traffic, but the switch will not notify you.

Assume that you are monitoring a server that connects to the vswitch at a full rate of 100 MB. When the server is working in full duplex, the server's sending and receiving rate is 200 MB, and the total capacity is MB. However, the MB Image Port of the vswitch can only receive MB of traffic at most. Therefore, when the port usage of any vswitch (full-duplex) exceeds 50%, the packets received by the mirror port will be lost.

If you mirror multiple ports to one port, packet loss will become more serious. Because most switches work at low capacity, this issue is not immediately noticed. The average usage of most user connections is low. Only occasional traffic spikes. If you select a High-Speed Image Port, the packet loss problem can be reduced. For example, if the 1000 MB Image Port is changed to MB, the monitoring traffic of MB can be easily received.