According to WiKi, “switch is a network device used for electrical (or optical) signal forwarding. It provides an exclusive electrical signal path for any two network nodes that access the switch.” Generally speaking, the network switch connects multiple ip devices together and provides the platform for these devices to data exchanging.
PoE (Power over Ethernet) switch is a special switch that can transport not only data but also power at the same time through single cat5e or cat6. For example, some of IP devices need to be connected to network in home or small office. Like all other electronic equipments, these devices require power and network communicating. With convenient switch, you have to wire 2 separated cables in order to send both power and data. PoE switch has integrated power source into network switch which can supply both within one cable. The extra power cord can be removed eventually. The PoE switch reduces the number of cables being used and simplifies system installation.
How to pick the suitable PoE switch? Consider the following points.
- Managed vs Unmanaged
Managed PoE switch provides the most comprehensive functions to manage your network including VLAN, CLI, IP routing, etc. User can access the switch by using web browser and set the limitations to each port. Those operations will be able to deliver more security for private and business network. Usually users require comprehensive knowledge to configure the managed PoE switch. The cost is always higher.
- Umanaged switch is designed for users who don’t want to tweak the network setting. There is no web browser built-in to configure the parameters. It is simply plug and play. The features such as CIL, may not be available with unmanaged PoE switch.
There is new form of PoE switch appears now – visual PoE switch. The visual PoE switch had LCD screen Display built-in with some press keys on the front panel. User can access the switch by using the LCD screen and those press key. Visual PoE switch doesn’t own all the features of managed switch. Only the critical functions such as VLAN, PoE power assignment, network monitoring are available. The visual PoE switch is the form between managed and unmanaged. Providing necessary controls of PoE network while still maintains the easy of operating. It is fit for small and medium-sized company who needs easily use and higher security.333
The visual LCD screen brings extra benefit, it displays the critical information of the switch in real time including power budget taking by each ip device, data rate, and any errors messages from the switch. You don’t have to make a fuss when you meet exceptions because you know exactly which parts had gone wrong.
- Power budget
PoE switch provides the data exchange as well as output DC power to the remote device. Check the specific before you choose the PoE switch, make sure you will have enough power budget for remote devices. The IEEE 802.3af PoE can deliver at most 15.4 watts while IEEE802.3at PoE+ can deliver at most 30 watts. Latest IEEE 802.3bt which has been named as next generation PoE is capable of output 95w high power. There is trap with these specifications. Those power budget is not the actual power the remote devices are receiving. For example, the IEEE 802.3at (PoE+) identify the maximum power injecting to the Ethernet cable is 30W, but maximum remain power has been set to 25.5w according to PoE+ standard. The power loss on the cable has to be considered when IEEE802.3 standard was developed. The remaining power for IEEE802.3af is 12W while IEEE802.3bt standard has 72W remain power.
Not only the power budget in single PoE port, but also the total budgets need to be considered as well. The PoE switch usually uses a sharing power source. A 24-port PoE+ switch with 380W total budget is capable of supplying 380W in the system, but it doesn’t mean you can connect 24 PoE+ (30W) network devices to this witch. Otherwise it will require 720W totally power budget, not 380W. It is necessarily to calculate the totally budget the system require, not only the maximum output in single ports. The PoE+ specific each ports is capable of output 30W, it doesn’t guarantee full 30W output on all the ports. It depends on the remaining power budget after taking by existed devices.
- PoE ports – 4/8/16/24/48
There are different types of PoE switch with different PoE ports available. Usually the PoE switch has one or two extra uplink ports without power which can be connected to the main network. It is always better to preserve some ports for future usage. You never know when you will need to add the new device to the network. The second uplink port is developed these years which can be used for video recorder while setup the ip cameras surveillance system.
- Cooling system.
The PoE switch has integrated the power sources which generate much more heat than convenient network switch. For most of electronic products, good heat dissipation and stability lead to better performance. Heat dissipation would straightly affect use life. Bad heat dissipation causes high temperature, which easily lead to short circuit and error. Especially when the PoE switch is deployed outdoors. The PoE switch need to have well cooling designed.
- Network Self Recovering
Some of the network may hangs and freeze after long time running. Usually unplugged the network cable from PoE port can force remote device to reboot and bring back the connection. Some of PoE switch has ability to self recovering, It will detect communication link between remote IP devices, such as VoIP camera, access point. Once remote devices are hangs or freezes, the PoE switch can reboot devices automatically by switch off the power and switch on after.
So let’s sum up all the picking points:
1. Managed or unmanaged and visual PoE switch
2. Power budget (IEEE 802.3 af/at/bt standard)
3. Enough PoE ports.
4.Product performance（heat dissipation/cooling system）
5.network Self recovering（camera/access point）
Consider PoE products when you upgrade the existed system.
It saves cost and installing time. Where the network goes, the power source followed.