What PoE Switch Should We Use: Active or Passive?


We can now see that there are active and passive PoE switches on the market. What exactly are they? Should we use active PoE or passive PoE switches in our network?

PoE Switch

A PoE switch provides network connectivity as well as the power to one PoE-powered device through a single Ethernet cable (PD). As the demand for deploying PD devices such as IP phones, IP cameras, and access points increases, PoE switches are becoming more common in today’s world of cloud computing, enterprise, and campus networks. They assist in reducing implementation complexity and cost. We can now see that there are active and passive PoE switches on the market. What exactly are they? Should we use active PoE or passive PoE switches in our network?

What is the Difference Between Active PoE and Active PoE Switch?

Standard PoE refers to any form of PoE that negotiates the correct voltage between the power supply equipment (PSE) and the PD system. Active PoE is short for active Power over Ethernet. Since an active PoE switch complies with standard PoE, it is also known as a standard PoE switch. This switch is compatible with IEEE 802.3af, IEEE 802.3at, or IEEE 802.3bt standards. Until turning on, the active PoE switch will test and verify that the electrical power between the switch and the remote system is compatible. If it isn’t, the active PoE switch won’t deliver electricity, preventing harm to non-PoE devices.

What is the Difference between Passive PoE and Passive PoE Switch?

The passive Power over Ethernet, also known as passive PoE, is a non-standard PoE. It can also deliver power over Ethernet lines without needing any kind of negotiation or communication. There is no IEEE standard for a passive PoE switch. When using a passive PoE switch in a network, the power is “always on,” which means it sends an electric current out through the Ethernet cable at a specific voltage regardless of whether the terminal system supports PoE or not. As a result, if the terminal devices aren’t prepared for electrified Ethernet cables, using a passive PoE switch can cause them to burn out.

In PoE Mode B, power is injected onto pins 4, 5, 7, and 8. Also, 4-pair PoE simultaneously supplies power to all 8 pins. Active PoE switches support PoE Mode A, PoE Mode B, and 4-pair PoE, while passive PoE switches only support PoE Mode B.

Explained: Power over Ethernet (PoE) Switches

Let’s use the PoE network switch as an example to see how it works, the PoE supply mode, and the PoE distance for powering to better understand the working principles of the PoE power supply.

PoE Switch Detection of PDs: This is the first step in the PoE switch’s process to determine if the system is a true PD or not. The PoE-powered switch tests the current and sends a detection voltage pulse to the PD. The system connected to the PoE switch is verified as a true PD if it detects a valid resistance with a specified value.

Active vs. Passive PoE Switch Ethernet Support

Active PoE switches can accommodate 10/100/1000Mbps Ethernet up to 100m over Cat5/5e/6 cable. In contrast, passive PoE switches normally support 10/100 Mbps Ethernet over a distance of 100 metres. Active PoE switches can also be used in both 10/100BASE-T and 1000BASE-T PoE networks. Passive PoE switches were once widely used in 10BASE-T and 100BASE-T PoE networks.

Cost of Active vs. Passive PoE Switches

The built-in PoE power controller in all active PoE switches performs the purpose of PD system detection and classification. The passive PoE switch, on the other hand, lacks such a component and functions. As a result, it’s understandable that the active PoE switch costs more than the passive PoE switch.

Which PoE Switch to Use: Active or Passive?

Based on the information provided above, we can infer that active PoE switches should always be our first option for powering remote IP phones, IP cameras, wireless access points, and other PD devices due to safety concerns. If you’re on a tight budget, you may want to suggest passive PoE switches.

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