Tag Archive | PoE switch

Power over Ethernet Switch: Passive PoE Vs Active PoE

Power over Ethernet (PoE) is a technology for wired LANs. This allows a single cable usually Ethernet cable to provide both data connection and electric power to devices such as IP cameras, NVR recorders, wireless access points, etc. A PoE switch, compared with other Gigabit network switches, has power over Ethernet injection built in. This feature allows end-user to power PoE capable devices without the need for a separate power supply or the need for an electrical outlet near the powered device. If you have read about the how-to-understand-poe-and-poe-switches, you must know clearer about the difference between PoE and PoE+ switches. However, today’s article will help you understand active PoE and passive PoE.

What is PoE Switch?

As mentioned before, a PoE switch not only supply power to devices but also carries network connection. In general, a PoE switch usually contains multiple Ethernet ports, e.g. a PoE switch with 8 ports, PoE switch with 16 ports, 24 ports PoE switch, or PoE switch with 48 ports. If you are looking for PoE switch to cover all your devices, it’s important to check the port number first.

8-port PoE managed siwtch

The following image shows the 8-port PoE managed switch.

 

Passive Power over Ethernet vs. Active PoE

To safeguard a voltage range, the Power over Ethernet devices must communicate according to established procedures. In simple terms, active PoE refers to any type of PoE that negotiates the correct voltage between the switch and PoE-powered device. Passive PoE does no such negotiation, and as such is always sending electric current out over the Ethernet cable at a certain voltage regardless of the device it’s going to.

Active PoE

If your PoE switch uses 48V 802.3af or 802.3at standard, it is considered to be active PoE. The power supply unit inside the active PoE switch usually tests the connection before providing the supplying voltage, meaning that PoE switch will check the power coming in, and if it doesn’t meet the device requirement, it won’t power up.

Passive PoE

Passive PoE refers to any devices using PoE that is not 802.3af or 802.3at. Unlike active PoE switch, In passive PoE, no negotiation takes place between the two devices, but instead the known cable layout is used from Standard 802.3af, mode B. Therefore, it is extremely important to know what PoE voltage your devices requires before plugging in the Ethernet cable and powering it up. If you connect the wrong voltage, you may cause permanent electrical damage. Passive PoE is like plugging a 120V appliance into a 240V outlet, but with devices than cost much more than a simple toaster.

Conclusion

The big advantage of Power over Ethernet switch is that it allows greater flexibility in locating devices, as you don’t have to be situated near a power source—power is carried to them right in the Ethernet cable. That also frequently results in significantly lower installation costs, especially where many Access Points must be setup. The difference between Passive PoE and active PoE switch is quite obvious. For more, you can go through previous articles.

 

How to Understand PoE and PoE+ Switches

Power-over-Ethernet (PoE) is the technology that allows network switches to transmit power and data through an Ethernet cable at the same time. PoE switch streamlines both of the processes of powering and providing data to the device, which makes it a straightforward and reliable device for home network and small enterprise application. This article describes two types of PoE (PoE and PoE+) that are commonly used and provides information on what types of PoE can be used according to different applications.

PoE Versus non-PoE Technology

Power over Ethernet technology facilitates powering a device (such as an IP phone, IP Surveillance Camera, or NVR recorder) over the same Ethernet cable as the data traffic. Figure 1 shows an Ethernet Network with IP camera, PoE Switch, NVR recorder and Wireless router. Compared to non-PoE devices, PoE devices feature with flexibility that allow you to easily place endpoints anywhere in the business, even places where it might be difficult to run a power outlet.

Wireless Home Network with POE switch

PoE Versus PoE+ Technology

PoE was first defined in the IEEE 802.3af standard. PoE devices utilize PoE standard, which can provide up to 15.4W of DC power to each port. A later standard, IEEE 802.3at, known as PoE+, increases the amount of power to 30 W. The major difference between 802.3af (PoE) and 802.3at (PoE+) is that PoE+ PSEs can provide almost twice as much power over a single Ethernet cable.

PoE and PoE+

Can PoE+ devices work over PoE Ports, Or vice versa? The PoE+ standard provides support for legacy PoE devices, meaning that an IEEE 802.3af powered device (PD) can operate normally when connected to IEEE 802.3at (PoE+) power sourcing equipment (PSE). PoE+ PSEs can supply power to both PoE and PoE+ PDs. However, as PoE+ PDs require more power than PoE PSEs can provide, PoE PSEs can only supply power to PoE PDs.

PoE Switch Or PoE+ Switch

Whether to use PoE or PoE+ switch for your network, you need to calculate your required power budget carefully for all of the PDs you plan to connect. PoE+ IEEE 802.3at devices can supply a maximum of 30 watts per port, while PoE IEEE 802.3af devices can supply a maximum of 15.4 watts per port. However, some power is always lost over the length of the cable, and more power is lost over longer cable runs. The minimum guaranteed power available at the PD is 12.95 watts per port for PoE and 25.5 watts per port for PoE+.

For most endpoints, 802.3af is sufficient but there are devices, such as Video phones or Access Points with multiple radios, which have higher power needs. It’s important to point out that there are other PoE standards currently being developed that will deliver even high levels of power for future applications. Optical switches have a power budget set aside for running the switch itself, and also an amount of power dedicated for PoE endpoints.

POE switch

FS PoE Switches

FS POE switches can supply power to network equipment such as weather-proof IP cameras, AP and IP telephones. They are featured with high flexibility, high stability and high resistance to electromagnetic interference. All FS PoE switches come with a one-year limited warranty, including any quality problems during the free maintenance. The following above shows 1G PoE Switch with 24 1000BASE-T and 4 SFP ports.

Original Source: How to Understand PoE and PoE+ Switches