What are the common problems when using POE switches?

No matter how good a PoE switch claims to be and how powerful its performance is, some problems cannot be avoided, after all, it is also a machine. Many customers have complained about some minor problems, but they are actually caused by incomplete understanding. Here are some common sense points related to PoE switches. Let's learn together!

Network cable requirements

A PoE switch can only be implemented through a network cable. A network cable is both a medium and a carrier. The network cable is not good. To achieve a good power supply effect, you must use standard network cables, that is, Category 5 network cables, super Category 5 network cables, Category 6 network cables, and so on.

PoE standard

PoE switches need to comply with power supply standards. There are two, IEEE802.3af and IEEE802.3at. The power supply powers of 15.4W and 30W are defined respectively, but due to the loss in the transmission process, the actual power supply power is 12.95W and 25W.

When using a PoE switch supporting the IEEE802.3af standard, the power of the powered device cannot exceed 12.95W; Similarly, when using a PoE switch of the IEEE802.3at standard, the power of the powered device cannot exceed 25W.

Non-standard PoE

There are also some non-standard PoE switches in the market. This type of PoE switch does not have an automatic detection function. It does not detect whether the powered device supports PoE power supply before power is supplied. It may burn out the powered device during power supply, so there is a certain level of security. Risk, when you have to use it, you must match the voltage.

It is generally recommended to use as few non-standard PoE switches as possible, so as not to outweigh the costs.

True and false PoE

The fake PoE switch is different from the non-standard PoE switch mentioned above. The fake PoE device only combines DC power into the network cable through a PoE combiner. It cannot be powered by a standard PoE switch, otherwise the device will burn out.

Switch cascading

The number of switch cascades involves the calculation of bandwidth. A 100 mega switch cascade has an effective bandwidth of about 60 Mbps. If each switch is connected to a monitoring device with a total bit rate of 15Mbps, that is, the bandwidth of a single switch is 15M, then 45 / 15≈3, and three switches can be cascaded.

Access and uplink ports

Ports of PoE switches are divided into access and uplink. The purpose is to define different port roles to better distinguish services and simplify maintenance.

Access port: As the name implies, it is the interface (IPC, wireless AP, PC, etc.) that directly connects to the terminal.

Uplink port: The port connected to the aggregation or core network. Generally, the interface rate is higher and the PoE function is not supported.