▾PoE – the possibility of power over a network cable
Network ethernet cables are typically used for data transmission. However, the IEEE 802.3af and 802.3at standards also define the function of power over a network cable. This way, you can power small network devices without the need for an additional power cable. Let's focus on the advantages and disadvantages of PoE (Power over Ethernet) and its specifics.
The motivation for the creation of PoE was the boom of internet telephony
At the turn of the millennium, internet telephony technology, known as VoIP, became widely popular. One of the disadvantages of IP phones was the need for a separate power cable connected to a power source. The elimination of an additional power source was the main motivation for the creation of PoE. This function enabled IP phones to be powered and data to be transmitted through a single cable, which made device connections easier and saved on cables.
Two types of power sources for PoE
For power to be transmitted through a data cable, power must be injected into them. This is done in two ways, either using a PoE-supporting switch (usually active) or using special PoE injectors (passive).
Network switches with PoE capability
Some data switches directly support the function of active or passive PoE. All ports may have support for power over data cables. In such cases, it is important to note that the switch's power source is not designed for simultaneous powering on all ports. To avoid overloading, do not connect more than half the devices over PoE compared to the total number of ports. For example, a switch with 10 ports is unlikely to power more than 5 devices simultaneously, often fewer. There are also network switches that have clearly marked PoE-supported ports. With these, full power output is guaranteed, but you always need to verify which ports are data-only and which are powered.
PoE injectors
PoE injectors operate on the principle of passive PoE, where the required voltage is simply brought to the unused wires in the network cable. These are added to individual ethernet cables and serve to power a single device. The use of injectors is a simple and cheap solution but brings several disadvantages and risks. Using PoE injectors can result in significant voltage drops on long cables. Incorrect use of cabling or incompatible devices may even risk equipment damage. If a cable with passive Power over Ethernet power is connected to a standard interface that uses all wire pairs in the cable for bidirectional data transmission, a short circuit and burnout can occur.
For what devices is PoE power used
Besides the mentioned IP phones, PoE power is mainly used for web cameras. This eliminates the concern of drawing long power cables for individual IP cameras, with data transmission and power solved by a single ethernet cable. PoE power is also supported by some types of access points (Wi-Fi Access Points) to extend the range of the wireless signal.
If you decide to power some of your devices through an ethernet cable, choose the most suitable voltage injection method. While using PoE injectors is easy and cheap, it brings several risks that need to be considered.
Are you chatting with a human or a bot? How to identify AI in chat
Online chats are often handled by artificial intelligence today, and at first glance, the responses appear to be from a real person. This is especially true for customer support, where speed and fluency are key. We'll look at how to identify AI in chat, what signs you can use to distinguish it from a human, and where the line of recognition becomes very thin.
What is ransomware and why does it no longer threaten only large companies?
Ransomware attacks are among the most common cyber threats today and are no longer just a concern for large companies. Just one careless click can cost you access to your data. We'll explain what ransomware is, how it works, and why attackers are increasingly targeting average users and smaller businesses.
How zero trust works: why mere connectivity no longer means safety
Connecting to the internet today is not just a matter of speed but also of trust. Networks handle more and more devices, sensitive data, and services that communicate almost constantly. This is why an approach called zero trust has emerged, where nothing is automatically considered safe. The article explains why this model was created and how it subtly influences everyday internet functioning.
10 reasons why your phone is drained sooner than expected
It happens that the battery life decreases faster than one would expect, even when the device is not particularly stressed during the day. Often, it's not a single specific error but a sum of small influences that gradually accumulate. This article explains what has the greatest impact on battery life, when idle draining occurs, and why this can turn into an issue causing the phone not to last even one day.
Wi-Fi on a plane? Yes, but it works differently than at home
Connecting to the internet during a flight is no longer an exception, but it still doesn't work as you're used to at home. In-flight Wi-Fi depends on the technology used, the type of aircraft, and network congestion, and paying for access doesn't always mean fast connection. In this article, we'll explain how in-flight internet works, why it can be slow, and when you can rely on it.
RCS messages: what they are, how they work, and when it's better to turn them off
RCS chat is appearing more frequently in mobile devices, especially with the arrival of iOS 18 and the gradual phasing out of older networks. It is a method of communication that uses the internet, offering higher quality sharing of photos and videos than traditional SMS. We'll explain what RCS means and when it makes sense to keep it enabled.