Imagine you have a network where you need to connect desk phones, access points, and security cameras. These devices require power, but having a separate power socket for each one can be impractical and messy. Enter Power over Ethernet (PoE), a convenient alternative that allows you to supply power over a regular network cable.
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What is Power over Ethernet (PoE)?
PoE is a technology that enables the transmission of power over a network cable along with data. With PoE, any device that connects to your network can be powered without the need for a separate power socket. These devices, known as powered devices or PDs, are generally smaller devices like phones and access points that only require a few watts of power to function.
To power a PD using PoE, you simply connect the network cable to the device’s designated port. The device will automatically start booting up without the need for any additional power source. This not only simplifies the setup process but also eliminates the need for bulky power adapters and messy cables.
PoE Standards: From Cisco Inline Power to IEEE Standards
Cisco originally introduced powered interfaces over 20 years ago with “Cisco inline power.” This technology could deliver up to 7 watts of power per port at a maximum speed of 100 Megabits. However, it was limited to Cisco switches.
To address the need for a standardized PoE solution, the Institute of Electrical and Electronics Engineers (IEEE) released several PoE standards that can be used by any vendor. The original PoE standard, now known as type 1 PoE or 802.3 AF, provides 15.4 watts of power per port using two powered wires. It is commonly used to power small appliances like desk phones and wireless access points.
PoE+: Increased Power for Demanding Devices
While type 1 PoE is suitable for low-power devices, there are devices that require more power to run efficiently. This includes security cameras with multiple functions, tablets, LCD screens, and other power-hungry devices. To cater to these demands, PoE+ was developed.
PoE+ (802.3at) offers 30 watts of power per port, doubling the power capacity compared to type 1 PoE. This higher power capability allows for better performance and functionality for devices that require more power.
PoE++: Unleashing Even More Power
But why stop at PoE+? The IEEE has introduced two additional standards: PoE++ type 3 (802.3bt type 3) and PoE++ type 4 (802.3bt type 4), which can deliver 60 and 100 watts per port, respectively. Cisco also has its own versions called uPoE and uPoE+.
These higher-powered standards, capable of powering devices that demand more energy, are ideal for applications such as teleconferencing solutions, kiosk terminals, small switches, laptops, and small TV screens. They can also power devices that switch power classes over time, adapting to changing power requirements.
Considerations for Power Over Ethernet
When implementing PoE, there are a few important considerations:
- Cabling: PoE requires copper cabling, as power cannot be transmitted over fiber. The cable length should not exceed 100 meters and should ideally be Cat5e or better.
- Safety: While PoE is relatively safe as it uses DC power and provides a smaller amount of power compared to a traditional wall socket, it’s still important to exercise caution. The IEEE standard ensures that power is only supplied to devices that request it, preventing damage to devices without PoE compatibility.
- Compatibility: Ensure that your devices support the specific PoE standard you intend to use. Different devices may require different power classes, and not all devices will be compatible with all PoE standards.
FAQs
Q: Is PoE safe?
A: Yes, PoE is considered safe. It provides a smaller amount of power than a typical wall socket and uses DC power, which is safer at lower power levels. Additionally, the IEEE standard ensures that power is only supplied to devices that request it, preventing damage to incompatible devices.
Q: Can PoE be used over any type of cabling?
A: PoE requires copper cabling; fiber cables cannot transmit power. It is recommended to use Cat5e or better cabling for optimal performance.
Conclusion
Power over Ethernet (PoE) is a versatile technology that simplifies power distribution in networked environments. It eliminates the need for separate power sockets for each device, resulting in a cleaner and more efficient setup. With various PoE standards available, you can power a wide range of devices, from simple desk phones to power-hungry security cameras and teleconferencing solutions.
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