Active vs. Passive PoE Switch: Which Should You Choose?
This blog outlines the fundamentals of passive PoE and active PoE switches, delves into their key differences, and guides you on selecting the most suitable option for your requirements.
A Power over Ethernet (PoE) switch sends both power and data through Ethernet cables to devices on the network, such as Wi-Fi access points, security cameras, phones, or other switches.
There are different types of PoE switches, but we'll focus on two main kinds in this blog.
Active PoE
Active PoE, or active Power over Ethernet, negotiates the proper voltage between the power supply equipment (PSE) and the PD device.
Active PoE Switch
The active PoE switch is a device that tests and ensures the electrical power compatibility between itself and the remote device before powering up. If it isn't compatible, the active PoE switch will not deliver power, preventing any potential damage to the non-PoE device.
It is rated to be compliant with PoE standards: IEEE 802.3af, IEEE 802.3at, or IEEE 802.3bt.
Common Use Cases for Active PoE Switch
Active PoE Switch can be used for,
- Camera systems
- Remote monitoring
- PoE wireless access points
In addition, any system utilizing hybrid equipment (meaning some devices draw power over Ethernet while others don’t) should exclusively utilize an active PoE switch. The active design is crucial in these cases because non-PoE devices can be damaged by power delivery through Ethernet cables.
Passive PoE
Passive PoE, short for passive Power over Ethernet, delivers power over Ethernet lines, but without the negotiation or communication process.
Passive PoE Switch
A Passive PoE switch is a device that continuously sends electric current over the Ethernet cable at a certain voltage, regardless of whether the terminal device supports PoE or not. Thus, using a passive PoE switch may damage the terminal devices if they are not prepared for electrified Ethernet cables.
It does not adhere to any IEEE standard.
Common Use Cases for Passive PoE Switch
The primary use case for passive PoE lies in legacy systems that necessitate it. Certain endpoint devices are designed for specific passive PoE setups, often utilizing proprietary or specialized injectors and/or adapters for Ethernet and power.
If you are using such devices, then sourcing appropriate passive PoE switches for them is likely more cost-effective than converting all your equipment to standard PoE injectors and functions.
Active vs. Passive PoE Switch: What Are Their Differences?
| Features | Active PoE Switch | Passive PoE Switch |
|---|---|---|
| Standard | IEEE 802.3af/at/bt | N/A |
| Power Injection | After Negotiation | Immediately |
| Power Supply Mode | PoE Mode A/PoE Mode B/4-Pair PoE | PoE Mode B |
| Ethernet Support | 10/100/1000BASE-T | 10/100BASE-T |
| Max. Distance | 100m | 100m |
| Safety | High | Low |
| Cost | Medium | Low |
Active vs. Passive PoE Switch: Which to Choose?
In conclusion, it's advisable to prioritize active PoE switches for safety reasons when powering up remote IP phones, IP cameras, wireless access points, and other PD devices. However, passive PoE switches may be considered if budget constraints are a concern.
It's crucial to note that passive PoE switches lack power detection functionality. Therefore, it's essential to ensure that the passive PoE switch you purchase precisely matches the power specifications of the PD device you intend to power. Otherwise, there's a risk of damaging your PD device. Furthermore, it's important to never connect computers and other non-PoE devices to passive PoE switches.
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