Installation option - POE (24V) Switch with fibre

I am currently testing a Mikrotik RB260GSP (CSS106-1G-4P-1S) a managed switch with five Ethernet and one fibre (adapter) ports.

I've used the non POE version for a while mainly as a fibre convertor but never though of this use, or the benefit of non-standard POE.
What I'm trying currently is the small DC-DC adapters on each of the powered ports, feeding a couple of Raspberry Pi's and a single Kiwi, the advantage being I gain remote power control capability.
The switch will run from 12-30V and comes with a 24V 2.5A switcher.
The web interface is clean and each of the four POE out ports can be controlled and individually pass up to 1A (Total all ports 2A).

I did think it would be a sure way to fill the HF spectrum with noise but so far my few minutes testing it seems OK (normal for here).

My reason for posting is for those considering remote operation as there is a complete router version with the same type outputs (wider voltage range).
It should be possible to set up the router version on 24V (solar?) and use the built in VPN and POE capabilities to make a nice remote secure station that allows the Kiwi's to be completely powered off individually.
The only extra bits required are some way to get the POE out before the Kiwi (I use readily available adapters) then wire the DC-DC with a barrel plug for the Kiwi/ other item as appropriate.
There is of course nothing to stop you using a spare output to switch a relay, or if you want to power the Kiwi from some other voltage source, control that via the POE supply voltage.

One small thing I just discovered, don't leave the power on "Auto" as when the Kiwi is "cleanly shut down" the switch spots that it is taking "too little power" and power cycles it, causing it to start up again.
Clever but not in this use...


  • Interesting. Can you measure the power consumption of the switch alone. Their web site says 5W but I'm wondering if that is typical. For a remote (solar) site power can sometimes be a secondary issue.
  • edited January 2020
    I'll have a go later, I have found Mikrotik equipment generally very efficient so would guess at more like 3W max in this switch setup.
    it obviously will depend on throughput/ enabled ports / type of Fibre module fitted so let me know what level of use to try at (I'm not going to do a spreadsheet ;-))


    Haven't got a calibrated meter or PSU so any meaningful tests will have to wait.
    I did do a little more browsing.
    If someone doesn't need the Gig ports or fibre how about an RB750P-PBr2, external router with POE? -2W

  • 2W sounds like a good estimate.
    I think that this might be workable, especially on a 28V system.
    One 28V panel, two 12V deep cycle/marine batteries, a linear battery charge controller (may have to build it and add an Arduino/PIC to get good performance with lead-acid cells) and run the kiwi(s) and active antennas from the individual ~1 MHz buck converters which have proven to be OK for the purpose.

    What does the other end of a compatible fiber link need to look like? I've never used fiber for LAN so wondering if it is one way to reduce/avoid LAN noise currents. WiFi still possible but wondering if there is a solution with fewer components.
  • I'll get some kit together and do some real world tests, what I think the running power would be, depends on too many variables including the type / make of fibre module.
    The fibre convertors do get warm so must add some to the power budget, if the link is long fibre would be better than wireless but if the distance is short, low power wifi probably has the edge on consumption.

    The "other end" can be a simple fibre to ethernet converter or another switch\router with a fibre port (SFP port with a module). Looking at the options I might buy a hEx lite router with POE to try (6-30V 100mb ports), only a little more than the (gig) POE switch.
    I don't need the faster networking for this and the full hEx router has a voltage range of 12-57V.

    I have fibre from my modem to the router, then to three switches, another pair front-to-back of house for CCTV and separate virtual machine LAN, would not live without it now, that amount of copper would be hard to keep quiet (even in this small house).
    The next Carrington event will be a great salesman for optical networking.
  • Just to put some power consumption detail on this.

    I purchased a RB750UPr2 hEX Lite router (no fibre) to compare to the switch above.

    The router on its own seems to take in the region of 1.6W (at 23V)
    With one normal Kiwi powered through a POE port and DC-DC ~ 6.1W

    The Gig switch with no fibre adapter is in the region of 0.8W and with Fibre 1.5W (Ubiquiti 1G Multimode duplex).
    The Gig POE Switch with Fibre module enabled (one Ethernet port running) Kiwi powered through a POE port and DC-DC ~5W

    Other rant
    The small hEX router needed to be updated from new and the small size of memory they put on it means it needs to be done from a separate (normally windows) netboot server.
    I've done this before but it took me a few goes due to firewalls, having to disable other interfaces, set fixed IP addresses in the range, long story short right pain.
    The switch needed to be updated and it took a few seconds and a couple of clicks on the web browser interface.

    Take away for me.
    Use the POE switch, fibre back to the net connection then do any/all the routing switching there.

    The power measurements were done through the Mikrotik devices so I don't know how accurate they are, but I'm happy the switch is pretty efficient.
    The last measurement I took was Switch, One BBG Kiwi, two Raspberry PI's (with RTL dongle and RSP1A respectively) around 11W, that seems too low, I might do more tests if I can find the time and motivation, split out the POE feeds.
  • as nice as Mikrotik are once working, configuration can become an adventure
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