What is a POE midspan hub?
POE midspan hubs are simply devices for injecting Power Over Ethernet (POE) power onto a network data cable. Let’s break it down a little:
They’re called midspan devices quite simply because they sit (are installed) at some mid-point along the data network cable lenghth i.e. they do not need to be at the source end (typically the server room, network switch or router position), nor do they need to be at the device location. Typically the midspan will be positioned at some point along the network cable run which is convenient for access/installation; near to a mains socket to supply it with power; and within the normal distance limitation of within 100 metres of the device to be powered by the POE midspan.
Of course, this ‘mid’ point does not have to be in the middle of a network cable length, the midspan could in fact be sited right alongside your central point network switch!
A midspan performs the same function as a single port POE power injector (it injects power onto a data cable), it has simply become convention for multi-port devices to be called midspan hubs rather than multi-port injectors.
The term hub is used to simply reflect the meeting point of cables, potentially lots of cables going in and out of a hub device. Most POE hubs are simply pass-through devices where power is added to the network cable e.g. there will be a ‘Port 1 IN’ and a ‘Port 1 OUT’ – the network cable goes IN with no POE and comes OUT with POE added.
Hubs are available in 4,8,16,24, etc ported versions.
Be careful to ensure that your hub has enough power to supply the number of devices you might want to connect to it; some hubs have a total power budget others promise a certain wattage per port.
POE switches are available, but that’s another topic …
Tags: Power Over Ethernet