one thing ive never been clear on, and have always wondered (and had issues with)- on the routerboard hexPOE (ie RB960PGS), in terms of what it can put out on ports 2-5:
The mikrotik docs say: 1A max per eth out port (2A max total). (https://i.mt.lv/cdn/rb_files/hEX_poe-161215110435.pdf)
But is that based on 12v or poe ~48v ? or whatever volts the RB is being powered with (ie if powering the hexPOE with normal POE AF / AT, ~48v , 1amp now = ~48w ! 2amp = ~ 96w ! ).
in general ive seen hexPOE’s reboot themselves when pulling more than 15-20w from a single eth out port (other ports out, un used) when powered with 48v poe AT).
can anyone (or mikrotik support) clear this up please.
tks
So based on that we should expect max ~ 24w max per port with AT/AF. (assuming just powering one of the 4x hex’s ports, ie: im sure we should not expect to be able to hook up 4x devices to the hex, each pulling ~24w of AT for a total of ~96w)
Maybe that could be done (4x24W) but in that case it would need a powersupply that is able to provide that, i.e. 100W at 48V.
Note that it is quite common for PoE equipment to be “overcommitted” in that it can supply some max power per port but it cannot supply that power on all ports simultaneously.
In somewhat more established equipment (manufacturers that are in the 802.11af/at business a bit longer), there is usually configuration to handle conflicts.
You can setup a priority for PoE output, i.e. when the total draw of power exceeds the limitations you can define which ports will be dropped first.
And also there is the capability for devices to request how much power the desire to have, and how much they absolutely need to operate. E.g. for extra TX chains, extra TX output power etc.
The leaflet already indicates that hex POE does not support al this. It is likely a very simple design. But then it is quite cheap as well.
It remains my opinion that for full-featured switches you better look at other manufacturers than MikroTik. They are much further ahead in things like this.
However, hex POE is not a switch, it is a router. In that case the decision becomes a little more difficult.
BELOW Is the excellent reply i got from MT support (email) , provides great info / detail:
As stated here: https://mikrotik.com/product/RB960PGS
Max out per port output (input > 30 V) 450 mA
Max out per port output (input < 30 V) 1A
2A is total output current for both 12V and 48V, which means that you can reach the maximum of 2A in multiple scenarios:
When hEX PoE is powered with voltage higher than 30V, you can power 4 devices with consumption of 450mA each, so you will reach approximately 1.8A total;
When hEX PoE is powered with voltage lower than 30V, you can either power a device with consumption of 500mA on all four PoE-out capable interfaces (4x500mA = 2A), or you can, for example, power two devices consuming 1000mA each on ether2 and ether3, but you will not be able to add any PoE device on interfaces ether4 and ether5, as the total consumption of 2A is already reached by the devices on ether2 and ether3.
The scenarios above are possible if you power the hEX either via DC jack or via PoE-in by using passive PoE injector. When speaking of powering from a 802.3af/at device, you should not only take in account the numbers mentioned in data sheet (maximum output per interface, maximum output in total), but you also should understand that the 802.3af/at device also impacts the PoE-out capability of the hEX PoE. As you see here https://en.wikipedia.org/wiki/Power_over_Ethernet#Standard_implementation, 802.3af/at devices are capable to output ~30W of power. So, if you power hEX PoE from 802.3af/at device, which outputs 48V, the maximum current your af/at device will provide would be around 30/48=625mA. hEX itself without any devices attached to PoE out would consume about 5W, so 105mA, which only leaves 625-105=520mA for PoE-out, so 130mA for each interface.
To sum up, it is better to power hEX PoE via DC or passive PoE injector, if you want to achieve its full PoE-out potential. As the device comes with 24V 2.5A power adapter, it is actually the preferred power source.