Posted on Leave a comment

How to Choose PoE Powered Switch?

You may even face the problem that the RJ45 network is not enough even you have reserved extra in the beginning. The most simple solution is attaching a new switch to your main router. There are various low cost network switches available in the market. However, as the new switch will stay next to your router and the eventual new devices could be far at the edge. Adding a new switch didn’t solve the problem, and you still need to wire an additional Ethernet cable from the new switch to the edge to provide the network data. Unlike attaching a switch to the router, wiring the additional cable could be a headache, especially when the construction is  completed. PoE powered switch (aka PoE passthrough switch) is a handy tool to increase the network port near the edge without re-wiring the new cables to the router.

Firstly, let’s go through the basic concept of Power over Ethernet (PoE).

What is PoE?

The Power over Ethernet allows the single cat5e/cat6 Ethernet cable to transmit both power and data to the edge device, such as IP camera, access point, VoIP phone. It is a cost-effective solution to handle both power and data in the field. Where the cable reaches, the power and data arrive. Sometimes, we only need the network. So why does the PoE still play such an important role in this case? While we try to increase the network near the edge, we must place the switch at the edge instead of the main router. Like all electronic products, the edge switch requires power, but the power source is not always available at the edge. Thanks to the PoE technology, the PoE powered switch can be powered by a PoE injector at the back end. There is no need for AC power at the edge. We just need to find an existed Ethernet cable close to the new device, and connect it to PoE powered switch. The PoE injector will be needed to send power together with data. The additional RJ45 network ports will come from a new switch instead of the switch next to the main router.

PoE and Non-PoE

How is the existing device which has been pulled off the Ethernet cable? The PoE powered switch can provide one PoE port for existing device. One thing people may get confusion is whether the PoE port can be connected to non-PoE devices or not. The answer is positive. The standard PoE Switch can work with both PoE or non-PoE devices. While the non-POE devices are attached to the PoE port, which will work as a common network port. In a standard PoE system, the PoE Switch will verify the edge equipment before releasing the power. If the edge device doesn’t have a built-in PoE feature, the switch will only provide data.

Power Budget

When we pick PoE powered switch to increase the network port, we will need to know whether the new devices support PoE Power or not. If the PoE ports are not required, you can pick any kind of PoE powered switch. The PoE powered switch consumes very little power. The 15.4W PoE is good enough. However, If your edge devices require PoE power from this new switch e.g. PoE IP cameras, PoE access points, the power budget needs to be considered. You may have heard PoE/PoE+/PoE++ (aka IEEE802.3af/at/bt). One of the key features of this specification is related to the maximum power budget. The PoE supplies 14.4W, the PoE+ supplies 30W, and the PoE++ supplies 60W (class 3) or 90W (class 4). This is the maximum power budget from the PoE injector or POE switch. The actual power budget is about 12W, 25.5W, 71W accordingly at the edge. There is always power loss during the transmission. Let’s take 5543-70 4 ports POE powered switch for example. While the 95W PoE injector is being used, the total power budget is about 65W from 5543-70. There is no problem connecting 4 PoE IP cameras. The average power is about 16W for each port. In PoE powered switch, only one specific port can accept the PoE input, and the rest of the port will output the PoE to new devices.

Indoor or Outdoor

As the PoE powered switch will be deployed at the edge to avoid re-wiring the new cable from the router. The working temperature is critical. Most of the commercial switches are designed for indoor environments with good temperature controls such as A/C. While the switch is being deployed in a harsh environment, the temperature will become challenging. 6100-56 is an outdoor PoE powered switch with IP67 waterproof grade. This switch can even be buried in the ground directly. There are 8 RJ45 ports in toal. Port #8 can receive the PoE from a PoE injector or PoE Switch, so there is no need for an additional AC power source. As we discuss at the beginning, the PoE ports can work with either PoE or non-POE equipment. While the non-PoE equipment was attached to one of the POE ports, the outdoor PoE powered switch will supply the data without the power.

Network Speed

The PoE powered switch re-use the existing Ethernet cable to increase the RJ45 ports. The speed is determined by the PoE powered switch mostly. Most of the cat6 cable can supply 1000Mbps bandwidth. However, if the PoE Switch only supplies 100Mbps, the bandwidth is limited to 100Mbps. Both 5543-70 and 6100-56 are 1000Mbps based network equipment. It can handle data traffic in different applications including IP surveillance, WiFi coverage, VoIP communication.

Network Expanding

One thing people may ignore is the PoE powered solution not only increase the RJ45 ports at the edge but also expand the network to another 100 meters. The TCP/IP network is limited to 100 meters which means the maximum distance is 100 meters from the edge device to your main router unless you have added another POE extender. While the PoE powered switch is being deployed at the edge, the additional 100 meters distance is being added to the network as well. You can wire another 100 meters Ethernet cable from the PoE powered switch to your new edge devices. Both RJ45 ports and the network distance is being expanded. The PoE powered switch makes the network design with great flexibility.

Leave a Reply