10.4 Power over Ethernet (PoE) Explained
Key Concepts of Power over Ethernet (PoE)
Power over Ethernet (PoE) is a technology that allows the transmission of electrical power along with data on Ethernet cabling. Key concepts include:
- PoE Standards: Different standards that define the power levels and capabilities of PoE.
- PoE Components: The devices involved in delivering and receiving PoE, such as PoE switches, injectors, and PDs (Powered Devices).
- PoE Detection and Classification: The process by which a PoE switch identifies and classifies devices to determine the appropriate power level.
- PoE Management: Techniques to monitor and control PoE delivery, including power budgeting and prioritization.
PoE Standards
PoE standards define the power levels and capabilities of PoE. The most common standards include:
- PoE (IEEE 802.3af): Delivers up to 15.4 watts of power.
- PoE+ (IEEE 802.3at): Delivers up to 30 watts of power.
- PoE++ (IEEE 802.3bt): Delivers up to 100 watts of power, divided into Type 3 (60 watts) and Type 4 (100 watts).
Example: A MikroTik switch with PoE+ capabilities can power devices like IP cameras and VoIP phones that require up to 30 watts of power, ensuring they operate efficiently without the need for additional power supplies.
PoE Components
PoE involves several components that work together to deliver power over Ethernet cabling:
- PoE Switch: A network switch that provides power to connected devices.
- PoE Injector: A device that adds power to the Ethernet cable, typically used when the switch does not support PoE.
- Powered Device (PD): A device that receives power over the Ethernet cable, such as IP phones, cameras, and wireless access points.
Example: In a small office, a MikroTik PoE switch can power multiple IP phones and wireless access points directly through the Ethernet cables, simplifying the installation and reducing the need for additional power outlets.
PoE Detection and Classification
PoE detection and classification is the process by which a PoE switch identifies and classifies devices to determine the appropriate power level. This ensures that the correct amount of power is delivered to each device.
Example: When a VoIP phone is connected to a MikroTik PoE switch, the switch detects the device and classifies it as a Class 2 device, which requires up to 7 watts of power. The switch then delivers the appropriate amount of power to the phone, ensuring it operates correctly.
PoE Management
PoE management involves techniques to monitor and control PoE delivery, including power budgeting and prioritization. This ensures that power is distributed efficiently and that critical devices receive the necessary power.
Example: In a large enterprise network, a MikroTik PoE switch can be configured to prioritize power delivery to critical devices like IP cameras and VoIP phones. If the total power demand exceeds the available budget, the switch can automatically reduce power to non-critical devices to ensure that critical devices continue to operate.