802.3af

  Active PoE and Passive PoE are two methods of delivering power over Ethernet cables, but they differ significantly in terms of functionality, safety, and compatibility.   1. Active PoE Active PoE adheres to official standards, such as IEEE 802.3af, 802.3at (PoE+), and 802.3bt (PoE++). It involves intelligent communication between the power source (PoE switch or injector) and the powered device (e.g., IP camera or access point) to determine if the device is PoE-compatible and how much power is needed. Key Characteristics of Active PoE: --- Standards-Based: Follows IEEE standards (802.3af/at/bt). --- Power Negotiation: The PoE switch or injector communicates with the device to deliver the correct amount of power, preventing damage to non-PoE devices. --- Voltage: Commonly 44-57V for IEEE 802.3af/at and up to 57V for IEEE 802.3bt. --- Compatibility: Ensures safe operation with any IEEE-compliant PoE device, including backward compatibility with previous PoE versions. --- Safety: Built-in detection mechanisms to avoid delivering power to non-PoE devices, reducing the risk of over-voltage damage. Applications: --- Commonly used in enterprise-grade networks where safety, reliability, and standard compliance are critical. --- Powers devices like VoIP phones, IP cameras, wireless access points, and other networked devices.     2. Passive PoE Passive PoE does not follow any specific standard and does not include any form of power negotiation. It sends a fixed voltage over the Ethernet cable, regardless of whether the connected device is PoE-capable or not. Key Characteristics of Passive PoE: --- No Power Negotiation: Delivers power without checking whether the device is PoE-compatible. --- Fixed Voltage: Typically operates at a fixed voltage, usually 24V or 48V, depending on the system. --- Compatibility Issues: Requires devices to be specifically designed to work with the fixed voltage. Connecting a non-PoE device or a device with incompatible power requirements may result in damage. --- Less Safe: Since there is no detection mechanism, it is easier to damage non-PoE devices by accidentally supplying power to them. Applications: --- Often used in small or specialized networks, such as wireless ISP equipment or specific home networking setups, where cost is a factor, and power negotiation isn't needed. --- Powers devices like some proprietary wireless access points, cameras, and outdoor networking gear that is designed for Passive PoE.     Key Differences: Feature Active PoE Passive PoE Standards Follows IEEE standards (802.3af/at/bt) Non-standard (no IEEE compliance) Power Negotiation Yes, detects device compatibility No, fixed voltage sent directly Safety High, avoids powering non-PoE devices Lower, risk of damaging non-PoE devices Voltage 44-57V (standardized) Typically 24V or 48V (fixed) Applications Enterprise networks, VoIP, IP cameras Wireless ISP setups, specific devices Compatibility Compatible with any IEEE-compliant device Requires devices designed for fixed voltage     Which One to Choose? Active PoE is the better option for most scenarios, especially in enterprise networks, as it ensures compatibility, safety, and scalability. Passive PoE is more cost-effective but should only be used with devices specifically designed for it. It’s more common in niche applications or smaller network setups where cost is a priority, and users are aware of the risks.   If you are unsure about the device’s compatibility, Active PoE is the safer choice.    

  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.