802.3at

  Power over Ethernet (PoE) and Power over Ethernet Plus (PoE+) are both standards for delivering power and data over Ethernet cables, but they differ in terms of power output and application capabilities. Here’s a detailed comparison:   1. Power Delivery PoE (IEEE 802.3af): --- Maximum Power Output (at PSE - Power Sourcing Equipment): 15.4W per port --- Power Available for Devices (at PD - Powered Device): 12.95W (after accounting for power loss over the cable) --- Typical Applications: Basic IP cameras, VoIP phones, and low-power wireless access points. PoE+ (IEEE 802.3at): --- Maximum Power Output (at PSE): 30W per port --- Power Available for Devices (at PD): 25.5W --- Typical Applications: Higher-power devices such as PTZ (Pan-Tilt-Zoom) cameras, advanced wireless access points, and video phones.     2. Voltage Range PoE: --- Voltage Range: 44-57V DC PoE+: --- Voltage Range: 50-57V DC     3. Power Allocation and Usage PoE: --- Power Allocation: Provides enough power for devices with lower power requirements. PoE+: --- Power Allocation: Provides extra power for devices with higher power needs, allowing for the use of more advanced or power-hungry equipment.     4. Compatibility PoE: --- Backward Compatibility: PoE+ (802.3at) and PoE++ (802.3bt) can power devices compliant with the PoE standard (802.3af). PoE+: --- Backward Compatibility: PoE+ can power devices that comply with the PoE standard (802.3af).     5. Cable and Infrastructure PoE: --- Cable Requirements: Typically uses Cat5e or higher cables. PoE+: --- Cable Requirements: Also uses Cat5e or higher cables, but with the increased power, higher quality cables (Cat6 or Cat6a) are recommended for maintaining performance and reducing power loss.     6. Application Scenarios PoE: --- Use Cases: Ideal for basic network devices that do not require significant power, such as entry-level IP cameras, basic VoIP phones, and simple wireless access points. PoE+: --- Use Cases: Suitable for devices with higher power demands, such as advanced PTZ cameras, high-performance wireless access points, and devices with built-in heaters or lights.     Summary Table Feature PoE (IEEE 802.3af) PoE+ (IEEE 802.3at) Maximum Power Output 15.4W per port 30W per port Power Available for Devices 12.95W 25.5W Voltage Range 44-57V DC 50-57V DC Typical Devices Basic IP cameras, VoIP phones PTZ cameras, advanced WAPs, video phones Compatibility Compatible with PoE+ Backward compatible with PoE Cable Type Cat5e or higher Cat5e or higher (Cat6 recommended)     Choosing Between PoE and PoE+ PoE is suitable for most standard network devices with lower power needs. It is cost-effective and meets the requirements of basic IP devices. PoE+ should be used when devices require more power, such as high-performance cameras and advanced network equipment. It ensures that devices receive sufficient power for full functionality and additional features.     In summary, PoE+ offers more power and flexibility compared to PoE, supporting a wider range of higher-power devices and applications.    

  PoE+ (802.3at) is an enhanced version of Power over Ethernet (PoE), standardized under the IEEE 802.3at specification. It builds upon the original PoE standard (802.3af) by providing more power to connected devices, making it suitable for powering more demanding network equipment. Here’s a detailed breakdown of PoE+:   Key Features of PoE+ (802.3at): 1.Increased Power Output: --- PoE (802.3af) delivers a maximum of 15.4 watts of power per port to connected devices. --- PoE+ (802.3at) significantly increases the available power to 30 watts per port. After accounting for power losses in the cable, the actual available power at the device (powered device or PD) is about 25.5 watts. --- This higher power output enables PoE+ to support devices with greater power requirements. 2.Device Support: PoE+ (802.3at) is designed to power more demanding network devices that cannot be powered efficiently by standard PoE. Some examples include: --- PTZ (Pan-Tilt-Zoom) cameras with advanced features like motorized controls and heaters. --- Wireless access points (APs) with multiple radios, MIMO technology, or higher data transmission requirements. --- VoIP phones with video screens or additional features. --- Video conferencing equipment. --- Some network switches or IP cameras with added features like night vision or additional sensors. 3.Backward Compatibility: --- PoE+ (802.3at) is fully backward compatible with PoE (802.3af) devices, meaning that a PoE+ switch can power both PoE and PoE+ devices. --- However, PoE devices that comply only with the 802.3af standard will still receive a maximum of 15.4 watts, even when connected to a PoE+ switch. 4.Cable Requirements: --- PoE+ (802.3at) works over standard Cat5e or higher Ethernet cables, just like regular PoE. However, to achieve optimal performance and minimize power losses, it is recommended to use Cat5e, Cat6, or better cabling, especially for longer cable runs. --- PoE+ uses two pairs of wires (just like PoE) to deliver both power and data. Power Negotiation (LLDP): --- PoE+ uses a more advanced power negotiation system known as Link Layer Discovery Protocol (LLDP) to negotiate the exact amount of power a device needs. This makes PoE+ more energy-efficient as it can supply just the right amount of power rather than delivering a fixed wattage.     Differences Between PoE (802.3af) and PoE+ (802.3at): Feature PoE (802.3af) PoE+ (802.3at) Power Output Up to 15.4 watts per port Up to 30 watts per port Available Power at Device Up to 12.95 watts (after losses) Up to 25.5 watts (after losses) Device Types VoIP phones, basic IP cameras, small APs High-end cameras, multi-radio APs, PTZ cameras Backward Compatibility Compatible with PoE devices (802.3af) Backward compatible with PoE (802.3af) Cable Type Cat5 or higher Cat5e or higher recommended     Applications of PoE+ (802.3at): PoE+ is ideal for devices that require more power than what standard PoE can provide, such as: --- Surveillance systems: Advanced IP cameras, especially those with features like motorized zoom or heating elements. --- Wireless networks: High-performance wireless access points (APs) in businesses or public spaces. --- VoIP phones: Phones with large color screens or video conferencing capabilities. --- Digital signage: Larger or more complex displays that need higher power.     Summary: PoE+ (802.3at) offers a higher power output than the original PoE standard, making it suitable for more power-hungry devices while maintaining backward compatibility with older PoE standards. This makes it a flexible and scalable solution for modern network infrastructure, especially in settings like security, Wi-Fi networks, and smart buildings.