Power over Ethernet Switches
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Frequently Asked Questions about PoE Switches
What is the difference between PoE, PoE+, and PoE++?
PoE (power over Ethernet) is a reliable technology that delivers power and data over a single Ethernet cable for LANs. PoE comes in three strengths:
- PoE: This technology was first defined in 2003 by the IEEE 802.3af standard. When functioning as a PSE, a PoE switch can support a maximum power consumption of up to 15.4W per PoE port and has a voltage range between 44V and 57V.
- PoE+: This technology is an upgrade of the IEEE 802.3at standard and was published in 2009. PoE+ supports devices that have higher power consumption. A PoE+ switch delivers up to 25.5W for a PD with a voltage range from 50V to 57V.
- PoE++: To provide even more power, PoE+ was upgraded to PoE++ (IEEE 802.3bt) in 2018. This technology has two classification types: Type 3 and Type 4. Type 3 uses two or all four twisted pairs in a copper cable. Type 4 delivers power over four twisted pairs in an Ethernet cable. A PoE++ switch delivers up to 60W on each port under Type 3 or up to 100W under Type 4.
What is a PoE injector?
A PoE injector (also known as a midspan PoE adapter) is used to make a non-PoE switch work with PoE devices. The use of a PoE injector avoids the need for AC power lines and enables the installation of devices in hard-to-reach areas that have no electrical outlets.
What is a PoE extender?
A PoE extender is used to increase the basic 100m distance limit for twisted-pair Ethernet cables. This technology is used for networks that need to span long distances, such as hotels, sports arenas, school campuses, etc.
What is a PoE splitter?
PoE splitters are used in conjunction with PoE switches and PoE injectors. A splitter separates power from data, feeding it into a separate input. This technology can be used with both legacy and low-power devices. A PoE splitter enables a non-PoE device to be upgraded to PoE.
What is the difference between a PoE switch and a regular switch?
The primary difference between a PoE switch and a regular switch is access to Power over Ethernet, as a regular switch is not PoE-enabled. However, a regular switch can be made PoE compliant by connecting it to a PoE injector or PoE splitter.
Can a PoE switch be used as a regular switch?
Yes, it happens all the time. PoE will only send power if a device requests it. If PoE is not asked for, the PoE switch will function just like a regular switch.
As most businesses these days have some form of structured cabling solution, the demand for connectivity grows daily. Power over Ethernet (PoE) technology offers both data connection and electrical power to powered devices (PDs) through just one cable. The network switch is a crucial component of any smoothly running network. The goal of this article is to provide a comprehensive guide to PoE switches.
What is PoE?
Power over Ethernet technology is a networking protocol defined by the Institute of Electrical and Electronics Engineers (IEEE) 802.3af PoE), 802.3at (Poe+), and 802.3bt (PoE++) standards. This technology sends 10/100/1000 megabits per second (Mbps) of data and 15/30/60 watts (W) of power budget over Cat5e and Cat6 Ethernet cables for a maximum distance of 100 meters (m).
What is a PoE switch?
PoE-capable devices come in different categories: power sourcing equipment (PSE), powered devices (PDs), or in some cases, both. The device that supplies the power is the PSE, while the device that receives the power is the PD. In most cases, PSEs are either network switches or PoE injectors that are used with non-PoE switches. It is the switch that enables PDs on a network to communicate. There are regular switches and PoE switches on the market. A PoE switch has the PoE function built into it.
What devices can use POE?
Here are some noteworthy statistics:
- There will be 41 billion Internet of Things (IoT) devices by the year 2027.
- Every second, another 127 devices are connected to the internet.
- Companies will invest up to $1.1 trillion in IoT by 2023
That is a lot of devices—many of which are powered by PoE. Here is a list of the primary devices that currently use power from the Ethernet:
Low Watt PoE Devices
- VoIP phones: These devices utilize the internet to provide telephone service instead of the standard pair of direct copper wires.
- Internet Protocol (IP) cameras: These digital video cameras are similar to a webcam; they transmit and receive data over a network or the internet.
- Wireless access point (WAP): This networking device creates a wireless local area network (WLAN) that allows Wi-Fi devices to connect to a wired network, enabling remote positioning.
- Thin Clients: These devices are computers that have no localized hard drive. Instead, they work by being remotely connected to a centralized server.
- Audio devices: Many amplifiers can use a PoE/PoE+ switch to generate the power needed to drive a speaker. A PoE-enabled speaker can cover greater areas and overcome higher ambient noise levels than standard speakers.
- Remote computer terminals: PoE-enabled computers significantly reduce the need for electrical outlets because power is delivered over a single Ethernet cable.
High Watt PoE Devices
- TVs: The latest PoE standard (IEEE 802.3bt-Type 4) can power some energy-efficient SMART TVs.
- Computer monitors: An example of these devices is the panel PC, which is now becoming standard for checking-in to medical facilities, leisure facilities, activity centers, and AirBnB properties.
A sector to look at for the future is the recent PoE applications developing for SMART home automation. This cutting edge PoE technology includes LED lighting, heating and air conditioning, appliances, voice assistants, and even electric car charging stations.
PoE Switches vs. Regular Switches
The most significant difference between a PoE switch and a regular (non-PoE) switch is Power over Ethernet access. With a PoE switch, PoE and non-PoE devices can be mixed. However, with a regular switch, mixing PoE and non-PoE devices is not possible. A regular switch can be made “PoE ready” by installing a PoE injector.
What are the benefits of PoE switches?
While regular switches can be made PoE ready, as noted above, there are some distinct advantages to using a PoE switch. Here are a few:
- Flexible: PDs that PoE powers can be located almost anywhere—even in hard-to-reach areas that are not close to an electrical outlet.
- Sound Performance: PoE switches have state-of-the-art features such as high-performance hardware and software, auto-sensing to determine if a PD is PoE-enable or not, and network security.
- Cost-Effective: With a PoE switch, there is no need to purchase extra electrical wiring or install additional outlets. Ethernet cables cost less and can be installed without the need for an expensive electrician.
- Power Conservation: A PoE switch can determine the power supply needs of a PD and delivers only the amount required, eliminating power waste and saving money.
- Future Proof: New PoE devices flood the market daily. The integration of PoE switches into your network infrastructure enables cutting-edge devices and will ultimately enhance your business posture.
What are the limitations of PoE switches?
- Power Limitation: For some applications, a PoE switch may not provide sufficient power (for instance, a network PTZ camera).
- Centralized Risk: A single PoE switch is usually connected to several PDs. If one of these network devices fails, all of the devices will stop working.
- Distance Limitation: The maximum distance a PoE switch can transmit power is 100 m. With the support of a PoE extender, the transmission can be increased to 4000 m. However, this may still be inadequate for large networks in corporations, campuses, hotels, hospitals, etc.
What type of PoE switch should I buy?
There are three basic types of PoE switches: the unmanaged PoE switch, the smart (or hybrid) PoE switch, and the managed PoE switch. Deciding which of these is best suited for your specific needs and budget can feel overwhelming. Our goal is to simplify this process as much as possible by cutting through some of the complexity. Let’s begin.
The Unmanaged PoE Switch
Unmanaged PoE switches are basic, plug-and-play devices with no remote configuration, management, or monitoring options. These switches are recommended for home or small networks or can add temporary groups of systems to an extensive network. These switches have a built-in Quality of Service (QoS) service to ensure they work well. Unmanaged switches have basic security measures, such as a lockable port cover to ensure the device is not tampered with. However, an unmanaged PoE switch is never recommended for networks that handle sensitive information. As this is a basic, no-frills device, it is also the least expensive.
The Smart (Hybrid) PoE Switch
Smart PoE switches offer a “lite” version of network management, QoS, and security functions. Security levels include 502.1x endpoint authentication and, in some cases, a limited number of access control lists (ACLs). However, these switches cannot monitor or troubleshoot and cannot be accessed remotely. Smart switches are best suited for simple networks or at the edge of a large network where managed switches are the core infrastructure.
The Managed PoE Switch
A managed PoE switch provides the most comprehensive levels of management, configuration, and security available. These devices have features such as user traffic prioritization, network partitioning, the ability to connect to different types of networks, and traffic monitoring. Managed PoE switches provide QoS that is far beyond any offered by an unmanaged or smart PoE switch.
Security measures include:
- Private virtual local area networks (VLANS)
- Secure management (through SCP, Web-based Authentication, Radius/TACAS AAA, etc.)
- Control Plane Policing (CoPP)
- Rich support for 802.1x
The managed PoE switch is best used for business networks and data centers. We strongly recommend the purchase of a managed PoE switch whenever your budget allows.
Active vs. Passive PoE Switch
When we talk about active PoE (also known as standard PoE), we refer to the negotiation of the proper voltage between a PSE and a PD. An active PoE switch is rated as compliant with the IEEE 802.3af, IEEE 802.3at, or IEEE802.3bt standard. An active switch can also be classified as PoE, PoE+, or PoE++. When an active PoE switch first powers up, it tests and checks to ensure that the switch and the PD’s electrical power are compatible. If the electrical power is not compatible, the active switch will not deliver power, ensuring no PD damage.
Passive PoE (also known as non-standard) also delivers power but without the negotiation process. A passive PoE switch does not adhere to any IEEE standards. When using a passive switch model, the power is always “on” and sends a prescribed voltage whether the PD supports it or not. This can result in damage to the PD.
Because active PoE switches have a built-in power controller and passive PoE switches do not, it is evident that an active switch is safer and more desirable.
Layer 2 vs. Layer 3 PoE Switch
The Open Systems Interconnection (OSI) model is used to describe a network system’s functions. There are seven layers that help us visualize how networks operate. This article will concentrate on the Data Link Layer (Layer 2) and the Network Layer (Layer 3). When choosing a PoE switch, you will need to select a Layer 2 model or a Layer 3 model.
The difference between these two layers has to do with their routing functions.
Layer 2 PoE switches use a device’s Media Access Control (MAC) address to decide where to forward frames. This is known as static routing.
Layer 3 switches can do static and dynamic routing, as they have both MAC address and Internal Protocol (IP) routing tables. In addition, this switch operates intra-VLAN communication and packets routing between different VLANS.
When deciding which Layer type to choose, it is important to consider these key factors:
- Forwarding (throughput) rate
- Backbone bandwidth
- Number of VLANs
- MAC memory
Additional Factors to Consider When Choosing a PoE Switch
How many ports do I need?
The number of ports on a switch can vary from 4-port models to 54-port models. When purchasing a PoE switch, it is wise not only to consider your present needs but also to anticipate your future needs. You will need a switch with enough wired RJ45 connections for each internet connection, with a few more available for the future. In general, 4-port and 8-port models will work for a home network, while the 24-port and 45-port models are sufficient for a business or data center.
How much speed will my PoE switch provide?
PoE switches come in four speed categories:
- Fast Ethernet: 10/100 Mbps
- Gigabit Ethernet: 10/100/1000 Mbps
- Ten Gigabit: 10/100/1000/10000 Mbps
- 40/100 Gbps
Speed is everything. For most businesses and other enterprises, the use of Gigabit Ethernet or higher is the way to go.
What about power consumption?
It is vital to estimate the amount of power it will take to operate all your PDs before searching for a PoE switch, as their total power consumption must not exceed the maximum power supply of the PoE switch.
For example: If you purchase a 4-port PoE switch that complies with IEEE 802.3at/af standard, the switch will have a power budget of 60W. Therefore this switch can simultaneously connect four 15W devices (4x 15W=60W)—OR—two 30W devices (2x30W=60W).
Do I have to worry about PoE compatibility?
All PoE switches do not work with all PDs. You must ensure that you purchase a switch that will work with your devices. Here’s what to look for:
- Be sure the PoE switch supports the same PoE standard required by your PDs. For example, if your PDs use the PoE+ standard, then your PoE switch must be PoE+, too.
- Confirm that the power supply modes of the switch and the PD are the same. If a PD is designed for PoE mode A, but the PoE switch you are looking at is designed for mode B, they will not work together.
- Make sure your PDs are not locked into working only with PSEs produced by a specific manufacturer.
What type of redundancy will I need for my network?
Here’s the question: Should I buy one 16-port PoE switch or go with two 8-port models?
To make this decision, you need to evaluate things like the urgency of uptime, network management, space availability, and, of course, your budget. If these variables are not prohibitive, then the best choice will usually be to purchase the two 8-port models.
Generally speaking, redundancy improves reliability. It’s simple: If you have a single switch and it experiences a failure, your whole network goes down. If you have two switches and one experiences problems, only half of your network goes down.
Redundancy is always an important consideration, especially if you manage sensitive personal or financial data.
What level of technical support will I need?
Determining the amount of technical support you will need after your purchase is vital. With some purchases, there will be a limited window of time allotted for configuring or troubleshooting. And in some cases, no technical support will be offered at all.
You may even need to be prepared for the fact that it will be necessary to contract with an outside support team to get the help you require. Settling this aspect of your purchase will save time, money, and frustration in the long run.
A Short Word About Cables
We recommend using Ethernet cables that use oxygen-free wire as they offer less power and signal loss. The maximum transmission length between a PoE switch and a PD is 100 m. The further the distance between the devices, the weaker the signal gets. Should you need a longer transmission distance, a PoE extender will help.
Why We Recommend That Your Network Needs a Managed PoE Switch
As previously stated, we strongly recommend the use of a managed PoE switch over an unmanaged or smart switch. Simply put: A managed switch is always the best solution. Here’s why:
- Managed switches have port security that can disable ports and prevent unauthorized access. This greatly minimizes the threat of a virus and prevents unauthorized users from wreaking havoc on your network.
- Managed switches have redundancy which protects a network should a connection or cable fail by providing an alternative traffic path for data. The feature helps prevent costly downtime.
- Another feature of a managed PoE switch is QoS. This function enables the prioritization of local area network (LAN) traffic, ensuring that the most important data gets through. This allows for consistent network performance by preventing other network traffic from causing a malfunction.
- Managed switches can create private VLANs that allow the segmentation and isolation of network traffic. This feature dramatically improves network performance and is an additional security measure as well.
- Managed switches use Simple Network Management Protocol (SNMP) to monitor network services’ traffic and performance—even remotely if desired. This allows for quick problem detection and repair.