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What Is a PoE Switch and How Does It Work?

Posted on By FS.COM

PoE switch, as a major application of PoE technology, has been the main driving force for the PoE market and network switch market. If you want to figure out the reason behind it, it’s necessary to have an overview of what the PoE switch is and what leads its growth and momentum.

What Is a PoE Switch and How Does It Work?

What is a PoE switch? PoE switch or power over ethernet switch is a network switch that applies Power over Ethernet technology. With a PoE network switch, the network connectivity and the power to run the PD (powered device) can both be efficiently realized over the Ethernet cable. Currently, there are all kinds of PoE network switches filled in the market. Based on the port number, the 8, 12, 24, 48 port PoE switches are commonly seen in the market. When turning to the control level over the network, unmanaged and managed PoE switches are available.

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Why You Need the PoE Switch?

It will be obvious why you need power over Ethernet switch when comparing PoE switch vs non-PoE switch. As the most basic switch, the non-PoE switch refers to the switch that is not PoE enabled to supply power for end-users over Ethernet, which can only send data to network devices. To acquire PoE, users have to deploy a midspan power sourcing equipment (PSE) like the PoE injector between the switch and PDs. This injector or other midspan PSEs can add electrical power while receiving data signals from the cable connected with the non-PoE switch, and then deliver both data and power to PDs (Learn more about PoE injector from What Is a PoE Injector And How to Use It?). In this application, the injector or other midspan PSEs will also need a wire for power. However, comparing with the non-PoE switch, the gigabit PoE switch will make things easier. For a PoE switch, only one power cable for the switch and one network cable to connect PDs are required. Then the PD can be directly plugged into the PoE gigabit switch port for both data transmission and power supply.

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Based on the working mode of PoE vs. non-PoE switch, the PoE switch brings benefits over the following aspects:

Flexibility: Getting rid of the restrictions of non-PoE switches needing additional PSEs and extension cables, the PoE switches gain great flexibility for users’ network cablings. It enables PDs like IP surveillance cameras to be installed based on where it needs to go. Besides, a combination of PoE switch and wireless technology can even make the cable-free environment be possible.

Simplicity: Without the need to consider additional PSEs and installation locations like a non-PoE switch, the PoE switch simplifies the whole network deployment. In addition, good PoE switches also enable simple network management protocol (SNMP), which provides a simpler way to supervise and manage the switch.

Cost-Efficient: With PoE network switch, there is no need for users to purchase and install additional electrical wires and outlets, which creates significant savings on installation and maintenance costs and time.

Frequently Asked Questions About the PoE Switch

1. Do I Need Special Cables for the PoE Switches?

No. Generally, the Ethernet cables that should be used for PoE switches only depend on the data rate of the PoE port, for example, 10/100M can use Cat3 or better cables; 1000M needs Cat5/Cat5e/Cat6 cables. When you're able to deploy 2.5G/5G/10G PoE devices in the future, you may need Cat6a or better cables. But you can never be wrong to buy good quality Ethernet cables made of oxygen-free copper.

2. Can a Computer or Other Non-PoE Devices be Connected to the PoE Switch? And Will a PoE Switch Damage Non-PoE Devices?

The answer depends on your PoE network switch type. Please make sure you use active PoE switch rather than passive Poe switch. That’s because only active PoE switches have auto-sensing PoE ports and they can detect whether the connected device is a PoE device or not. When the PoE ports are connected with non-PoE devices like computers or laptops, the PoE switch will detect it as not having PoE capability and interact with it as if it were a regular switch. Then it will just use the data communications features of the port instead of supplying power. Passive PoE switches, however, always send electric current out over the Ethernet cable at a certain voltage regardless of whether the terminal device support PoE or not. Therefore they may burn out computers and other non-PoE devices. Luckily, PoE switches in the market are basically active types. But passive PoE switches are still supplied by some vendors. Learn more about active and passive PoE switches, you may move on to Active vs. Passive PoE Switch: Which Should We Choose?

3. Can I Connect a PoE Switch to Another PoE Switch?

Yes, you can. Power is supplied by the PSE to PD only when it detects that the device is capable to handle the power. Since the two PoE switches both belong to PSE. They will just do data communications.

4. PoE Switch vs. PoE+ Switch: What’s the Difference?

The main difference between the PoE network switch and PoE+ switch lies in the electrical power that each can carry or supply to the connected PoE PD. The max. PoE power consumption provided over Cat5 cabling is 15.4 watts for PoE PSE and 30 watts for PoE+ PSE. While the max. power received by PD is 12.95 watts for PoE PD and 25.5 watts for PoE+ PD.

5. PoE Managed vs. Unmanaged Switch: What’s the Difference?

The managed PoE switch is a switch that allows access to one or more interfaces for the purpose of configuration or management, such as Spanning Tree Protocol (STP), port speed, VLANs, etc. It can give you more control over your LAN traffic and offer advanced features to control that traffic. On the contrary, the PoE unmanaged switch just simply allows Ethernet devices to communicate with one another, such as a PC or network printer. It is pre-equipped with a fixed configuration and disallows any changes to this configuration.

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