Network management experience: two common vswitch connection faults (1)

In network management, network optimization and network obstacle elimination are the two most challenging tasks. I have been engaged in network management for nearly ten years and have accumulated many typical cases of network faults. I share this platform for your reference. Today, let's talk about common faults in the vswitch connection process.

Fault 1: Switch cascade fault

Fault situation: a customer adds available Ethernet interfaces by connecting the vswitch to the cascade mode. After a new switch is added at one time, it is found that the newly added switch port cannot be connected to the enterprise network. They use Uplink ports of vswitches for connection. That is to say, the two switches are directly connected through Uplink ports using a direct connection line, resulting in a connection failure. The current network cable is normal, and the port of the switch is normal. However, the host connected to these ports cannot connect to the enterprise's network.

Cause Analysis: Generally, a port on a vswitch consists of an Uplink port and other common ports. Generally, the connections between vswitches can be established through Uplink ports, or through common ports. Uplink is used for connection in two cases. One case is that the Uplink port is connected to the Uplink port of another vswitch, and the other case is that the Uplink port is connected to the normal port of another vswitch. However, different connection methods have different network cable requirements. Generally, it is recommended that the Uplink port be used between the vswitch and the vswitch (one end uses the Uplink interface and the other end uses the normal port ). In this case, you can use a direct connection. If both vswitches use Uplink ports, they must be connected through a crossover line. The current connection method adopted by this customer is to directly connect the Uplink interfaces of the two switches, and the use is indeed a direct connection. As a result, the two vswitches cannot communicate with each other.

Fault relief: The cause is found, which makes it easier to solve the problem. Change the network cable to a crossover line. If you do not want to change the network cable, you can change the connection port of the switch. Set the Uplink port of a vswitch to a normal port.

Fault Summary: In the vswitch Interconnection Environment, it is generally recommended that one end use the Uplink port while the other side use the common port. In this case, you can use a direct connection. Generally, the same port is not recommended on both sides. This is because the connection can be completed only through a crossover line. In vswitch cascade, this is a basic rule. Cascade refers to connecting two or more devices with network cables by using common or special ports of the vswitch. Generally, a vswitch can be cascaded with a vro or other devices, but the cascade method varies depending on the port used. Some vendors also provide Uplink and other similar row connection ports on their own devices to meet cascade needs. In practice, when a vswitch or other devices have a dedicated Uplink port for Uplink connection, you can use a pass-through jumper to connect this port to a common port of another device (that is, any port other than the Uplink port ).

When talking about vswitch cascade, I should emphasize a little bit at last. That is to say, although vswitch cascade is feasible, it is generally recommended that there be not too many cascade layers. For example, we recommend that you do not have more than five layers. Otherwise, the performance of the enterprise network will be reduced due to the limitations of vswitches (such as the inability to isolate broadcast domains.